From 1ea2a07a532b0e22aabe7e8483f935c672b9e7ed Mon Sep 17 00:00:00 2001 From: Lu Baolu Date: Mon, 18 Apr 2022 08:49:50 +0800 Subject: [PATCH 01/12] iommu: Add DMA ownership management interfaces Multiple devices may be placed in the same IOMMU group because they cannot be isolated from each other. These devices must either be entirely under kernel control or userspace control, never a mixture. This adds dma ownership management in iommu core and exposes several interfaces for the device drivers and the device userspace assignment framework (i.e. VFIO), so that any conflict between user and kernel controlled dma could be detected at the beginning. The device driver oriented interfaces are, int iommu_device_use_default_domain(struct device *dev); void iommu_device_unuse_default_domain(struct device *dev); By calling iommu_device_use_default_domain(), the device driver tells the iommu layer that the device dma is handled through the kernel DMA APIs. The iommu layer will manage the IOVA and use the default domain for DMA address translation. The device user-space assignment framework oriented interfaces are, int iommu_group_claim_dma_owner(struct iommu_group *group, void *owner); void iommu_group_release_dma_owner(struct iommu_group *group); bool iommu_group_dma_owner_claimed(struct iommu_group *group); The device userspace assignment must be disallowed if the DMA owner claiming interface returns failure. Signed-off-by: Jason Gunthorpe Signed-off-by: Kevin Tian Signed-off-by: Lu Baolu Reviewed-by: Robin Murphy Link: https://lore.kernel.org/r/20220418005000.897664-2-baolu.lu@linux.intel.com Signed-off-by: Joerg Roedel --- drivers/iommu/iommu.c | 153 +++++++++++++++++++++++++++++++++++++++++- include/linux/iommu.h | 31 +++++++++ 2 files changed, 181 insertions(+), 3 deletions(-) diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index f2c45b85b9fc2..eba8e8ccf19d8 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -48,6 +48,8 @@ struct iommu_group { struct iommu_domain *default_domain; struct iommu_domain *domain; struct list_head entry; + unsigned int owner_cnt; + void *owner; }; struct group_device { @@ -294,7 +296,11 @@ int iommu_probe_device(struct device *dev) mutex_lock(&group->mutex); iommu_alloc_default_domain(group, dev); - if (group->default_domain) { + /* + * If device joined an existing group which has been claimed, don't + * attach the default domain. + */ + if (group->default_domain && !group->owner) { ret = __iommu_attach_device(group->default_domain, dev); if (ret) { mutex_unlock(&group->mutex); @@ -2109,7 +2115,7 @@ static int __iommu_attach_group(struct iommu_domain *domain, { int ret; - if (group->default_domain && group->domain != group->default_domain) + if (group->domain && group->domain != group->default_domain) return -EBUSY; ret = __iommu_group_for_each_dev(group, domain, @@ -2146,7 +2152,11 @@ static void __iommu_detach_group(struct iommu_domain *domain, { int ret; - if (!group->default_domain) { + /* + * If the group has been claimed already, do not re-attach the default + * domain. + */ + if (!group->default_domain || group->owner) { __iommu_group_for_each_dev(group, domain, iommu_group_do_detach_device); group->domain = NULL; @@ -3095,3 +3105,140 @@ static ssize_t iommu_group_store_type(struct iommu_group *group, return ret; } + +/** + * iommu_device_use_default_domain() - Device driver wants to handle device + * DMA through the kernel DMA API. + * @dev: The device. + * + * The device driver about to bind @dev wants to do DMA through the kernel + * DMA API. Return 0 if it is allowed, otherwise an error. + */ +int iommu_device_use_default_domain(struct device *dev) +{ + struct iommu_group *group = iommu_group_get(dev); + int ret = 0; + + if (!group) + return 0; + + mutex_lock(&group->mutex); + if (group->owner_cnt) { + if (group->domain != group->default_domain || + group->owner) { + ret = -EBUSY; + goto unlock_out; + } + } + + group->owner_cnt++; + +unlock_out: + mutex_unlock(&group->mutex); + iommu_group_put(group); + + return ret; +} + +/** + * iommu_device_unuse_default_domain() - Device driver stops handling device + * DMA through the kernel DMA API. + * @dev: The device. + * + * The device driver doesn't want to do DMA through kernel DMA API anymore. + * It must be called after iommu_device_use_default_domain(). + */ +void iommu_device_unuse_default_domain(struct device *dev) +{ + struct iommu_group *group = iommu_group_get(dev); + + if (!group) + return; + + mutex_lock(&group->mutex); + if (!WARN_ON(!group->owner_cnt)) + group->owner_cnt--; + + mutex_unlock(&group->mutex); + iommu_group_put(group); +} + +/** + * iommu_group_claim_dma_owner() - Set DMA ownership of a group + * @group: The group. + * @owner: Caller specified pointer. Used for exclusive ownership. + * + * This is to support backward compatibility for vfio which manages + * the dma ownership in iommu_group level. New invocations on this + * interface should be prohibited. + */ +int iommu_group_claim_dma_owner(struct iommu_group *group, void *owner) +{ + int ret = 0; + + mutex_lock(&group->mutex); + if (group->owner_cnt) { + ret = -EPERM; + goto unlock_out; + } else { + if (group->domain && group->domain != group->default_domain) { + ret = -EBUSY; + goto unlock_out; + } + + group->owner = owner; + if (group->domain) + __iommu_detach_group(group->domain, group); + } + + group->owner_cnt++; +unlock_out: + mutex_unlock(&group->mutex); + + return ret; +} +EXPORT_SYMBOL_GPL(iommu_group_claim_dma_owner); + +/** + * iommu_group_release_dma_owner() - Release DMA ownership of a group + * @group: The group. + * + * Release the DMA ownership claimed by iommu_group_claim_dma_owner(). + */ +void iommu_group_release_dma_owner(struct iommu_group *group) +{ + mutex_lock(&group->mutex); + if (WARN_ON(!group->owner_cnt || !group->owner)) + goto unlock_out; + + group->owner_cnt = 0; + /* + * The UNMANAGED domain should be detached before all USER + * owners have been released. + */ + if (!WARN_ON(group->domain) && group->default_domain) + __iommu_attach_group(group->default_domain, group); + group->owner = NULL; +unlock_out: + mutex_unlock(&group->mutex); +} +EXPORT_SYMBOL_GPL(iommu_group_release_dma_owner); + +/** + * iommu_group_dma_owner_claimed() - Query group dma ownership status + * @group: The group. + * + * This provides status query on a given group. It is racy and only for + * non-binding status reporting. + */ +bool iommu_group_dma_owner_claimed(struct iommu_group *group) +{ + unsigned int user; + + mutex_lock(&group->mutex); + user = group->owner_cnt; + mutex_unlock(&group->mutex); + + return user; +} +EXPORT_SYMBOL_GPL(iommu_group_dma_owner_claimed); diff --git a/include/linux/iommu.h b/include/linux/iommu.h index 9208eca4b0d1a..77972ef978b59 100644 --- a/include/linux/iommu.h +++ b/include/linux/iommu.h @@ -675,6 +675,13 @@ struct iommu_sva *iommu_sva_bind_device(struct device *dev, void iommu_sva_unbind_device(struct iommu_sva *handle); u32 iommu_sva_get_pasid(struct iommu_sva *handle); +int iommu_device_use_default_domain(struct device *dev); +void iommu_device_unuse_default_domain(struct device *dev); + +int iommu_group_claim_dma_owner(struct iommu_group *group, void *owner); +void iommu_group_release_dma_owner(struct iommu_group *group); +bool iommu_group_dma_owner_claimed(struct iommu_group *group); + #else /* CONFIG_IOMMU_API */ struct iommu_ops {}; @@ -1031,6 +1038,30 @@ static inline struct iommu_fwspec *dev_iommu_fwspec_get(struct device *dev) { return NULL; } + +static inline int iommu_device_use_default_domain(struct device *dev) +{ + return 0; +} + +static inline void iommu_device_unuse_default_domain(struct device *dev) +{ +} + +static inline int +iommu_group_claim_dma_owner(struct iommu_group *group, void *owner) +{ + return -ENODEV; +} + +static inline void iommu_group_release_dma_owner(struct iommu_group *group) +{ +} + +static inline bool iommu_group_dma_owner_claimed(struct iommu_group *group) +{ + return false; +} #endif /* CONFIG_IOMMU_API */ /** From 25f3bcfc54bcf7b0e45d140ec8bfbbf10ba11869 Mon Sep 17 00:00:00 2001 From: Lu Baolu Date: Mon, 18 Apr 2022 08:49:51 +0800 Subject: [PATCH 02/12] driver core: Add dma_cleanup callback in bus_type The bus_type structure defines dma_configure() callback for bus drivers to configure DMA on the devices. This adds the paired dma_cleanup() callback and calls it during driver unbinding so that bus drivers can do some cleanup work. One use case for this paired DMA callbacks is for the bus driver to check for DMA ownership conflicts during driver binding, where multiple devices belonging to a same IOMMU group (the minimum granularity of isolation and protection) may be assigned to kernel drivers or user space respectively. Without this change, for example, the vfio driver has to listen to a bus BOUND_DRIVER event and then BUG_ON() in case of dma ownership conflict. This leads to bad user experience since careless driver binding operation may crash the system if the admin overlooks the group restriction. Aside from bad design, this leads to a security problem as a root user, even with lockdown=integrity, can force the kernel to BUG. With this change, the bus driver could check and set the DMA ownership in driver binding process and fail on ownership conflicts. The DMA ownership should be released during driver unbinding. Signed-off-by: Lu Baolu Reviewed-by: Greg Kroah-Hartman Reviewed-by: Jason Gunthorpe Link: https://lore.kernel.org/r/20220418005000.897664-3-baolu.lu@linux.intel.com Signed-off-by: Joerg Roedel --- drivers/base/dd.c | 5 +++++ include/linux/device/bus.h | 3 +++ 2 files changed, 8 insertions(+) diff --git a/drivers/base/dd.c b/drivers/base/dd.c index 3fc3b5940bb31..94b7ac9bf4596 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -671,6 +671,8 @@ static int really_probe(struct device *dev, struct device_driver *drv) if (dev->bus) blocking_notifier_call_chain(&dev->bus->p->bus_notifier, BUS_NOTIFY_DRIVER_NOT_BOUND, dev); + if (dev->bus && dev->bus->dma_cleanup) + dev->bus->dma_cleanup(dev); pinctrl_bind_failed: device_links_no_driver(dev); device_unbind_cleanup(dev); @@ -1199,6 +1201,9 @@ static void __device_release_driver(struct device *dev, struct device *parent) device_remove(dev); + if (dev->bus && dev->bus->dma_cleanup) + dev->bus->dma_cleanup(dev); + device_links_driver_cleanup(dev); device_unbind_cleanup(dev); diff --git a/include/linux/device/bus.h b/include/linux/device/bus.h index a039ab809753f..d8b29ccd07e56 100644 --- a/include/linux/device/bus.h +++ b/include/linux/device/bus.h @@ -59,6 +59,8 @@ struct fwnode_handle; * bus supports. * @dma_configure: Called to setup DMA configuration on a device on * this bus. + * @dma_cleanup: Called to cleanup DMA configuration on a device on + * this bus. * @pm: Power management operations of this bus, callback the specific * device driver's pm-ops. * @iommu_ops: IOMMU specific operations for this bus, used to attach IOMMU @@ -103,6 +105,7 @@ struct bus_type { int (*num_vf)(struct device *dev); int (*dma_configure)(struct device *dev); + void (*dma_cleanup)(struct device *dev); const struct dev_pm_ops *pm; From 4a6d9dd564d0e7339fc15ecc5ce66db4ad842be2 Mon Sep 17 00:00:00 2001 From: Lu Baolu Date: Mon, 18 Apr 2022 08:49:52 +0800 Subject: [PATCH 03/12] amba: Stop sharing platform_dma_configure() Stop sharing platform_dma_configure() helper as they are about to have their own bus dma_configure callbacks. Signed-off-by: Lu Baolu Reviewed-by: Jason Gunthorpe Link: https://lore.kernel.org/r/20220418005000.897664-4-baolu.lu@linux.intel.com Signed-off-by: Joerg Roedel --- drivers/amba/bus.c | 19 ++++++++++++++++++- drivers/base/platform.c | 3 +-- include/linux/platform_device.h | 2 -- 3 files changed, 19 insertions(+), 5 deletions(-) diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c index d3bd14aaabf6e..76b52bd2c2a44 100644 --- a/drivers/amba/bus.c +++ b/drivers/amba/bus.c @@ -20,6 +20,8 @@ #include #include #include +#include +#include #define to_amba_driver(d) container_of(d, struct amba_driver, drv) @@ -273,6 +275,21 @@ static void amba_shutdown(struct device *dev) drv->shutdown(to_amba_device(dev)); } +static int amba_dma_configure(struct device *dev) +{ + enum dev_dma_attr attr; + int ret = 0; + + if (dev->of_node) { + ret = of_dma_configure(dev, dev->of_node, true); + } else if (has_acpi_companion(dev)) { + attr = acpi_get_dma_attr(to_acpi_device_node(dev->fwnode)); + ret = acpi_dma_configure(dev, attr); + } + + return ret; +} + #ifdef CONFIG_PM /* * Hooks to provide runtime PM of the pclk (bus clock). It is safe to @@ -341,7 +358,7 @@ struct bus_type amba_bustype = { .probe = amba_probe, .remove = amba_remove, .shutdown = amba_shutdown, - .dma_configure = platform_dma_configure, + .dma_configure = amba_dma_configure, .pm = &amba_pm, }; EXPORT_SYMBOL_GPL(amba_bustype); diff --git a/drivers/base/platform.c b/drivers/base/platform.c index 8cc272fd5c99a..d7915734d931d 100644 --- a/drivers/base/platform.c +++ b/drivers/base/platform.c @@ -1454,8 +1454,7 @@ static void platform_shutdown(struct device *_dev) drv->shutdown(dev); } - -int platform_dma_configure(struct device *dev) +static int platform_dma_configure(struct device *dev) { enum dev_dma_attr attr; int ret = 0; diff --git a/include/linux/platform_device.h b/include/linux/platform_device.h index 7c96f169d2740..17fde717df68c 100644 --- a/include/linux/platform_device.h +++ b/include/linux/platform_device.h @@ -328,8 +328,6 @@ extern int platform_pm_restore(struct device *dev); #define platform_pm_restore NULL #endif -extern int platform_dma_configure(struct device *dev); - #ifdef CONFIG_PM_SLEEP #define USE_PLATFORM_PM_SLEEP_OPS \ .suspend = platform_pm_suspend, \ From 512881eacfa72c2136b27b9934b7b27504a9efc2 Mon Sep 17 00:00:00 2001 From: Lu Baolu Date: Mon, 18 Apr 2022 08:49:53 +0800 Subject: [PATCH 04/12] bus: platform,amba,fsl-mc,PCI: Add device DMA ownership management The devices on platform/amba/fsl-mc/PCI buses could be bound to drivers with the device DMA managed by kernel drivers or user-space applications. Unfortunately, multiple devices may be placed in the same IOMMU group because they cannot be isolated from each other. The DMA on these devices must either be entirely under kernel control or userspace control, never a mixture. Otherwise the driver integrity is not guaranteed because they could access each other through the peer-to-peer accesses which by-pass the IOMMU protection. This checks and sets the default DMA mode during driver binding, and cleanups during driver unbinding. In the default mode, the device DMA is managed by the device driver which handles DMA operations through the kernel DMA APIs (see Documentation/core-api/dma-api.rst). For cases where the devices are assigned for userspace control through the userspace driver framework(i.e. VFIO), the drivers(for example, vfio_pci/ vfio_platfrom etc.) may set a new flag (driver_managed_dma) to skip this default setting in the assumption that the drivers know what they are doing with the device DMA. Calling iommu_device_use_default_domain() before {of,acpi}_dma_configure is currently a problem. As things stand, the IOMMU driver ignored the initial iommu_probe_device() call when the device was added, since at that point it had no fwspec yet. In this situation, {of,acpi}_iommu_configure() are retriggering iommu_probe_device() after the IOMMU driver has seen the firmware data via .of_xlate to learn that it actually responsible for the given device. As the result, before that gets fixed, iommu_use_default_domain() goes at the end, and calls arch_teardown_dma_ops() if it fails. Cc: Greg Kroah-Hartman Cc: Bjorn Helgaas Cc: Stuart Yoder Cc: Laurentiu Tudor Signed-off-by: Lu Baolu Reviewed-by: Greg Kroah-Hartman Reviewed-by: Jason Gunthorpe Reviewed-by: Robin Murphy Tested-by: Eric Auger Link: https://lore.kernel.org/r/20220418005000.897664-5-baolu.lu@linux.intel.com Signed-off-by: Joerg Roedel --- drivers/amba/bus.c | 18 ++++++++++++++++++ drivers/base/platform.c | 18 ++++++++++++++++++ drivers/bus/fsl-mc/fsl-mc-bus.c | 24 ++++++++++++++++++++++-- drivers/pci/pci-driver.c | 18 ++++++++++++++++++ include/linux/amba/bus.h | 8 ++++++++ include/linux/fsl/mc.h | 8 ++++++++ include/linux/pci.h | 8 ++++++++ include/linux/platform_device.h | 8 ++++++++ 8 files changed, 108 insertions(+), 2 deletions(-) diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c index 76b52bd2c2a44..a0ec61232b6c4 100644 --- a/drivers/amba/bus.c +++ b/drivers/amba/bus.c @@ -22,6 +22,8 @@ #include #include #include +#include +#include #define to_amba_driver(d) container_of(d, struct amba_driver, drv) @@ -277,6 +279,7 @@ static void amba_shutdown(struct device *dev) static int amba_dma_configure(struct device *dev) { + struct amba_driver *drv = to_amba_driver(dev->driver); enum dev_dma_attr attr; int ret = 0; @@ -287,9 +290,23 @@ static int amba_dma_configure(struct device *dev) ret = acpi_dma_configure(dev, attr); } + if (!ret && !drv->driver_managed_dma) { + ret = iommu_device_use_default_domain(dev); + if (ret) + arch_teardown_dma_ops(dev); + } + return ret; } +static void amba_dma_cleanup(struct device *dev) +{ + struct amba_driver *drv = to_amba_driver(dev->driver); + + if (!drv->driver_managed_dma) + iommu_device_unuse_default_domain(dev); +} + #ifdef CONFIG_PM /* * Hooks to provide runtime PM of the pclk (bus clock). It is safe to @@ -359,6 +376,7 @@ struct bus_type amba_bustype = { .remove = amba_remove, .shutdown = amba_shutdown, .dma_configure = amba_dma_configure, + .dma_cleanup = amba_dma_cleanup, .pm = &amba_pm, }; EXPORT_SYMBOL_GPL(amba_bustype); diff --git a/drivers/base/platform.c b/drivers/base/platform.c index d7915734d931d..70bc30cf575c5 100644 --- a/drivers/base/platform.c +++ b/drivers/base/platform.c @@ -30,6 +30,8 @@ #include #include #include +#include +#include #include "base.h" #include "power/power.h" @@ -1456,6 +1458,7 @@ static void platform_shutdown(struct device *_dev) static int platform_dma_configure(struct device *dev) { + struct platform_driver *drv = to_platform_driver(dev->driver); enum dev_dma_attr attr; int ret = 0; @@ -1466,9 +1469,23 @@ static int platform_dma_configure(struct device *dev) ret = acpi_dma_configure(dev, attr); } + if (!ret && !drv->driver_managed_dma) { + ret = iommu_device_use_default_domain(dev); + if (ret) + arch_teardown_dma_ops(dev); + } + return ret; } +static void platform_dma_cleanup(struct device *dev) +{ + struct platform_driver *drv = to_platform_driver(dev->driver); + + if (!drv->driver_managed_dma) + iommu_device_unuse_default_domain(dev); +} + static const struct dev_pm_ops platform_dev_pm_ops = { SET_RUNTIME_PM_OPS(pm_generic_runtime_suspend, pm_generic_runtime_resume, NULL) USE_PLATFORM_PM_SLEEP_OPS @@ -1483,6 +1500,7 @@ struct bus_type platform_bus_type = { .remove = platform_remove, .shutdown = platform_shutdown, .dma_configure = platform_dma_configure, + .dma_cleanup = platform_dma_cleanup, .pm = &platform_dev_pm_ops, }; EXPORT_SYMBOL_GPL(platform_bus_type); diff --git a/drivers/bus/fsl-mc/fsl-mc-bus.c b/drivers/bus/fsl-mc/fsl-mc-bus.c index 8fd4a356a86ec..76648c4fdaf4b 100644 --- a/drivers/bus/fsl-mc/fsl-mc-bus.c +++ b/drivers/bus/fsl-mc/fsl-mc-bus.c @@ -21,6 +21,7 @@ #include #include #include +#include #include "fsl-mc-private.h" @@ -140,15 +141,33 @@ static int fsl_mc_dma_configure(struct device *dev) { struct device *dma_dev = dev; struct fsl_mc_device *mc_dev = to_fsl_mc_device(dev); + struct fsl_mc_driver *mc_drv = to_fsl_mc_driver(dev->driver); u32 input_id = mc_dev->icid; + int ret; while (dev_is_fsl_mc(dma_dev)) dma_dev = dma_dev->parent; if (dev_of_node(dma_dev)) - return of_dma_configure_id(dev, dma_dev->of_node, 0, &input_id); + ret = of_dma_configure_id(dev, dma_dev->of_node, 0, &input_id); + else + ret = acpi_dma_configure_id(dev, DEV_DMA_COHERENT, &input_id); + + if (!ret && !mc_drv->driver_managed_dma) { + ret = iommu_device_use_default_domain(dev); + if (ret) + arch_teardown_dma_ops(dev); + } + + return ret; +} + +static void fsl_mc_dma_cleanup(struct device *dev) +{ + struct fsl_mc_driver *mc_drv = to_fsl_mc_driver(dev->driver); - return acpi_dma_configure_id(dev, DEV_DMA_COHERENT, &input_id); + if (!mc_drv->driver_managed_dma) + iommu_device_unuse_default_domain(dev); } static ssize_t modalias_show(struct device *dev, struct device_attribute *attr, @@ -312,6 +331,7 @@ struct bus_type fsl_mc_bus_type = { .match = fsl_mc_bus_match, .uevent = fsl_mc_bus_uevent, .dma_configure = fsl_mc_dma_configure, + .dma_cleanup = fsl_mc_dma_cleanup, .dev_groups = fsl_mc_dev_groups, .bus_groups = fsl_mc_bus_groups, }; diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c index 4ceeb75fc8996..f83f7fbac68f8 100644 --- a/drivers/pci/pci-driver.c +++ b/drivers/pci/pci-driver.c @@ -20,6 +20,7 @@ #include #include #include +#include #include "pci.h" #include "pcie/portdrv.h" @@ -1601,6 +1602,7 @@ static int pci_bus_num_vf(struct device *dev) */ static int pci_dma_configure(struct device *dev) { + struct pci_driver *driver = to_pci_driver(dev->driver); struct device *bridge; int ret = 0; @@ -1616,9 +1618,24 @@ static int pci_dma_configure(struct device *dev) } pci_put_host_bridge_device(bridge); + + if (!ret && !driver->driver_managed_dma) { + ret = iommu_device_use_default_domain(dev); + if (ret) + arch_teardown_dma_ops(dev); + } + return ret; } +static void pci_dma_cleanup(struct device *dev) +{ + struct pci_driver *driver = to_pci_driver(dev->driver); + + if (!driver->driver_managed_dma) + iommu_device_unuse_default_domain(dev); +} + struct bus_type pci_bus_type = { .name = "pci", .match = pci_bus_match, @@ -1632,6 +1649,7 @@ struct bus_type pci_bus_type = { .pm = PCI_PM_OPS_PTR, .num_vf = pci_bus_num_vf, .dma_configure = pci_dma_configure, + .dma_cleanup = pci_dma_cleanup, }; EXPORT_SYMBOL(pci_bus_type); diff --git a/include/linux/amba/bus.h b/include/linux/amba/bus.h index 6562f543c3e04..2ddce9bcd00ed 100644 --- a/include/linux/amba/bus.h +++ b/include/linux/amba/bus.h @@ -79,6 +79,14 @@ struct amba_driver { void (*remove)(struct amba_device *); void (*shutdown)(struct amba_device *); const struct amba_id *id_table; + /* + * For most device drivers, no need to care about this flag as long as + * all DMAs are handled through the kernel DMA API. For some special + * ones, for example VFIO drivers, they know how to manage the DMA + * themselves and set this flag so that the IOMMU layer will allow them + * to setup and manage their own I/O address space. + */ + bool driver_managed_dma; }; /* diff --git a/include/linux/fsl/mc.h b/include/linux/fsl/mc.h index 7b6c42bfb660f..27efef8affb1a 100644 --- a/include/linux/fsl/mc.h +++ b/include/linux/fsl/mc.h @@ -32,6 +32,13 @@ struct fsl_mc_io; * @shutdown: Function called at shutdown time to quiesce the device * @suspend: Function called when a device is stopped * @resume: Function called when a device is resumed + * @driver_managed_dma: Device driver doesn't use kernel DMA API for DMA. + * For most device drivers, no need to care about this flag + * as long as all DMAs are handled through the kernel DMA API. + * For some special ones, for example VFIO drivers, they know + * how to manage the DMA themselves and set this flag so that + * the IOMMU layer will allow them to setup and manage their + * own I/O address space. * * Generic DPAA device driver object for device drivers that are registered * with a DPRC bus. This structure is to be embedded in each device-specific @@ -45,6 +52,7 @@ struct fsl_mc_driver { void (*shutdown)(struct fsl_mc_device *dev); int (*suspend)(struct fsl_mc_device *dev, pm_message_t state); int (*resume)(struct fsl_mc_device *dev); + bool driver_managed_dma; }; #define to_fsl_mc_driver(_drv) \ diff --git a/include/linux/pci.h b/include/linux/pci.h index 60adf42460abb..b933d2b08d4dd 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -895,6 +895,13 @@ struct module; * created once it is bound to the driver. * @driver: Driver model structure. * @dynids: List of dynamically added device IDs. + * @driver_managed_dma: Device driver doesn't use kernel DMA API for DMA. + * For most device drivers, no need to care about this flag + * as long as all DMAs are handled through the kernel DMA API. + * For some special ones, for example VFIO drivers, they know + * how to manage the DMA themselves and set this flag so that + * the IOMMU layer will allow them to setup and manage their + * own I/O address space. */ struct pci_driver { struct list_head node; @@ -913,6 +920,7 @@ struct pci_driver { const struct attribute_group **dev_groups; struct device_driver driver; struct pci_dynids dynids; + bool driver_managed_dma; }; static inline struct pci_driver *to_pci_driver(struct device_driver *drv) diff --git a/include/linux/platform_device.h b/include/linux/platform_device.h index 17fde717df68c..b3d9c744f1e59 100644 --- a/include/linux/platform_device.h +++ b/include/linux/platform_device.h @@ -210,6 +210,14 @@ struct platform_driver { struct device_driver driver; const struct platform_device_id *id_table; bool prevent_deferred_probe; + /* + * For most device drivers, no need to care about this flag as long as + * all DMAs are handled through the kernel DMA API. For some special + * ones, for example VFIO drivers, they know how to manage the DMA + * themselves and set this flag so that the IOMMU layer will allow them + * to setup and manage their own I/O address space. + */ + bool driver_managed_dma; }; #define to_platform_driver(drv) (container_of((drv), struct platform_driver, \ From 18c7a349d072a222ff80598373035820c194747b Mon Sep 17 00:00:00 2001 From: Lu Baolu Date: Mon, 18 Apr 2022 08:49:54 +0800 Subject: [PATCH 05/12] PCI: pci_stub: Set driver_managed_dma The current VFIO implementation allows pci-stub driver to be bound to a PCI device with other devices in the same IOMMU group being assigned to userspace. The pci-stub driver has no dependencies on DMA or the IOVA mapping of the device, but it does prevent the user from having direct access to the device, which is useful in some circumstances. The pci_dma_configure() marks the iommu_group as containing only devices with kernel drivers that manage DMA. For compatibility with the VFIO usage, avoid this default behavior for the pci_stub. This allows the pci_stub still able to be used by the admin to block driver binding after applying the DMA ownership to VFIO. Signed-off-by: Lu Baolu Reviewed-by: Jason Gunthorpe Acked-by: Bjorn Helgaas Link: https://lore.kernel.org/r/20220418005000.897664-6-baolu.lu@linux.intel.com Signed-off-by: Joerg Roedel --- drivers/pci/pci-stub.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/pci/pci-stub.c b/drivers/pci/pci-stub.c index e408099fea525..d1f4c1ce7bd1b 100644 --- a/drivers/pci/pci-stub.c +++ b/drivers/pci/pci-stub.c @@ -36,6 +36,7 @@ static struct pci_driver stub_driver = { .name = "pci-stub", .id_table = NULL, /* only dynamic id's */ .probe = pci_stub_probe, + .driver_managed_dma = true, }; static int __init pci_stub_init(void) From c7d469849747ce380785536173d08b30a820a83c Mon Sep 17 00:00:00 2001 From: Lu Baolu Date: Mon, 18 Apr 2022 08:49:55 +0800 Subject: [PATCH 06/12] PCI: portdrv: Set driver_managed_dma If a switch lacks ACS P2P Request Redirect, a device below the switch can bypass the IOMMU and DMA directly to other devices below the switch, so all the downstream devices must be in the same IOMMU group as the switch itself. The existing VFIO framework allows the portdrv driver to be bound to the bridge while its downstream devices are assigned to user space. The pci_dma_configure() marks the IOMMU group as containing only devices with kernel drivers that manage DMA. Avoid this default behavior for the portdrv driver in order for compatibility with the current VFIO usage. We achieve this by setting ".driver_managed_dma = true" in pci_driver structure. It is safe because the portdrv driver meets below criteria: - This driver doesn't use DMA, as you can't find any related calls like pci_set_master() or any kernel DMA API (dma_map_*() and etc.). - It doesn't use MMIO as you can't find ioremap() or similar calls. It's tolerant to userspace possibly also touching the same MMIO registers via P2P DMA access. Suggested-by: Jason Gunthorpe Suggested-by: Kevin Tian Signed-off-by: Lu Baolu Reviewed-by: Jason Gunthorpe Acked-by: Bjorn Helgaas Link: https://lore.kernel.org/r/20220418005000.897664-7-baolu.lu@linux.intel.com Signed-off-by: Joerg Roedel --- drivers/pci/pcie/portdrv_pci.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/pci/pcie/portdrv_pci.c b/drivers/pci/pcie/portdrv_pci.c index 4b8801656ffbb..7f8788a970ae1 100644 --- a/drivers/pci/pcie/portdrv_pci.c +++ b/drivers/pci/pcie/portdrv_pci.c @@ -202,6 +202,8 @@ static struct pci_driver pcie_portdriver = { .err_handler = &pcie_portdrv_err_handler, + .driver_managed_dma = true, + .driver.pm = PCIE_PORTDRV_PM_OPS, }; From 70693f470848f05fae04144675e6e41b105d45fe Mon Sep 17 00:00:00 2001 From: Lu Baolu Date: Mon, 18 Apr 2022 08:49:56 +0800 Subject: [PATCH 07/12] vfio: Set DMA ownership for VFIO devices Claim group dma ownership when an IOMMU group is set to a container, and release the dma ownership once the iommu group is unset from the container. This change disallows some unsafe bridge drivers to bind to non-ACS bridges while devices under them are assigned to user space. This is an intentional enhancement and possibly breaks some existing configurations. The recommendation to such an affected user would be that the previously allowed host bridge driver was unsafe for this use case and to continue to enable assignment of devices within that group, the driver should be unbound from the bridge device or replaced with the pci-stub driver. For any bridge driver, we consider it unsafe if it satisfies any of the following conditions: 1) The bridge driver uses DMA. Calling pci_set_master() or calling any kernel DMA API (dma_map_*() and etc.) is an indicate that the driver is doing DMA. 2) If the bridge driver uses MMIO, it should be tolerant to hostile userspace also touching the same MMIO registers via P2P DMA attacks. If the bridge driver turns out to be a safe one, it could be used as before by setting the driver's .driver_managed_dma field, just like what we have done in the pcieport driver. Signed-off-by: Lu Baolu Reviewed-by: Jason Gunthorpe Acked-by: Alex Williamson Link: https://lore.kernel.org/r/20220418005000.897664-8-baolu.lu@linux.intel.com Signed-off-by: Joerg Roedel --- drivers/vfio/fsl-mc/vfio_fsl_mc.c | 1 + drivers/vfio/pci/vfio_pci.c | 1 + drivers/vfio/platform/vfio_amba.c | 1 + drivers/vfio/platform/vfio_platform.c | 1 + drivers/vfio/vfio.c | 10 +++++++++- 5 files changed, 13 insertions(+), 1 deletion(-) diff --git a/drivers/vfio/fsl-mc/vfio_fsl_mc.c b/drivers/vfio/fsl-mc/vfio_fsl_mc.c index 6e2e62c6f47ae..3feff729f3ce8 100644 --- a/drivers/vfio/fsl-mc/vfio_fsl_mc.c +++ b/drivers/vfio/fsl-mc/vfio_fsl_mc.c @@ -588,6 +588,7 @@ static struct fsl_mc_driver vfio_fsl_mc_driver = { .name = "vfio-fsl-mc", .owner = THIS_MODULE, }, + .driver_managed_dma = true, }; static int __init vfio_fsl_mc_driver_init(void) diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c index 2b047469e02fe..58839206d1ca7 100644 --- a/drivers/vfio/pci/vfio_pci.c +++ b/drivers/vfio/pci/vfio_pci.c @@ -194,6 +194,7 @@ static struct pci_driver vfio_pci_driver = { .remove = vfio_pci_remove, .sriov_configure = vfio_pci_sriov_configure, .err_handler = &vfio_pci_core_err_handlers, + .driver_managed_dma = true, }; static void __init vfio_pci_fill_ids(void) diff --git a/drivers/vfio/platform/vfio_amba.c b/drivers/vfio/platform/vfio_amba.c index badfffea14fbd..1aaa4f721bd2c 100644 --- a/drivers/vfio/platform/vfio_amba.c +++ b/drivers/vfio/platform/vfio_amba.c @@ -95,6 +95,7 @@ static struct amba_driver vfio_amba_driver = { .name = "vfio-amba", .owner = THIS_MODULE, }, + .driver_managed_dma = true, }; module_amba_driver(vfio_amba_driver); diff --git a/drivers/vfio/platform/vfio_platform.c b/drivers/vfio/platform/vfio_platform.c index 68a1c87066d76..04f40c5acfd67 100644 --- a/drivers/vfio/platform/vfio_platform.c +++ b/drivers/vfio/platform/vfio_platform.c @@ -76,6 +76,7 @@ static struct platform_driver vfio_platform_driver = { .driver = { .name = "vfio-platform", }, + .driver_managed_dma = true, }; module_platform_driver(vfio_platform_driver); diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c index a4555014bd1e7..56e741cbccce1 100644 --- a/drivers/vfio/vfio.c +++ b/drivers/vfio/vfio.c @@ -1198,6 +1198,8 @@ static void __vfio_group_unset_container(struct vfio_group *group) driver->ops->detach_group(container->iommu_data, group->iommu_group); + iommu_group_release_dma_owner(group->iommu_group); + group->container = NULL; wake_up(&group->container_q); list_del(&group->container_next); @@ -1282,13 +1284,19 @@ static int vfio_group_set_container(struct vfio_group *group, int container_fd) goto unlock_out; } + ret = iommu_group_claim_dma_owner(group->iommu_group, f.file); + if (ret) + goto unlock_out; + driver = container->iommu_driver; if (driver) { ret = driver->ops->attach_group(container->iommu_data, group->iommu_group, group->type); - if (ret) + if (ret) { + iommu_group_release_dma_owner(group->iommu_group); goto unlock_out; + } } group->container = container; From 31076af0cb001f698138c8158c798ec9f4a8bbae Mon Sep 17 00:00:00 2001 From: Lu Baolu Date: Mon, 18 Apr 2022 08:49:57 +0800 Subject: [PATCH 08/12] vfio: Remove use of vfio_group_viable() As DMA ownership is claimed for the iommu group when a VFIO group is added to a VFIO container, the VFIO group viability is guaranteed as long as group->container_users > 0. Remove those unnecessary group viability checks which are only hit when group->container_users is not zero. The only remaining reference is in GROUP_GET_STATUS, which could be called at any time when group fd is valid. Here we just replace the vfio_group_viable() by directly calling IOMMU core to get viability status. Signed-off-by: Lu Baolu Reviewed-by: Jason Gunthorpe Acked-by: Alex Williamson Link: https://lore.kernel.org/r/20220418005000.897664-9-baolu.lu@linux.intel.com Signed-off-by: Joerg Roedel --- drivers/vfio/vfio.c | 18 ++++++------------ 1 file changed, 6 insertions(+), 12 deletions(-) diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c index 56e741cbccce1..8a9347f732a5a 100644 --- a/drivers/vfio/vfio.c +++ b/drivers/vfio/vfio.c @@ -1313,12 +1313,6 @@ static int vfio_group_set_container(struct vfio_group *group, int container_fd) return ret; } -static bool vfio_group_viable(struct vfio_group *group) -{ - return (iommu_group_for_each_dev(group->iommu_group, - group, vfio_dev_viable) == 0); -} - static int vfio_group_add_container_user(struct vfio_group *group) { if (!atomic_inc_not_zero(&group->container_users)) @@ -1328,7 +1322,7 @@ static int vfio_group_add_container_user(struct vfio_group *group) atomic_dec(&group->container_users); return -EPERM; } - if (!group->container->iommu_driver || !vfio_group_viable(group)) { + if (!group->container->iommu_driver) { atomic_dec(&group->container_users); return -EINVAL; } @@ -1346,7 +1340,7 @@ static int vfio_group_get_device_fd(struct vfio_group *group, char *buf) int ret = 0; if (0 == atomic_read(&group->container_users) || - !group->container->iommu_driver || !vfio_group_viable(group)) + !group->container->iommu_driver) return -EINVAL; if (group->type == VFIO_NO_IOMMU && !capable(CAP_SYS_RAWIO)) @@ -1438,11 +1432,11 @@ static long vfio_group_fops_unl_ioctl(struct file *filep, status.flags = 0; - if (vfio_group_viable(group)) - status.flags |= VFIO_GROUP_FLAGS_VIABLE; - if (group->container) - status.flags |= VFIO_GROUP_FLAGS_CONTAINER_SET; + status.flags |= VFIO_GROUP_FLAGS_CONTAINER_SET | + VFIO_GROUP_FLAGS_VIABLE; + else if (!iommu_group_dma_owner_claimed(group->iommu_group)) + status.flags |= VFIO_GROUP_FLAGS_VIABLE; if (copy_to_user((void __user *)arg, &status, minsz)) return -EFAULT; From 93219ea94388b5195d1eeadb0bda6ed1471fba56 Mon Sep 17 00:00:00 2001 From: Jason Gunthorpe Date: Mon, 18 Apr 2022 08:49:58 +0800 Subject: [PATCH 09/12] vfio: Delete the unbound_list commit 60720a0fc646 ("vfio: Add device tracking during unbind") added the unbound list to plug a problem with KVM where KVM_DEV_VFIO_GROUP_DEL relied on vfio_group_get_external_user() succeeding to return the vfio_group from a group file descriptor. The unbound list allowed vfio_group_get_external_user() to continue to succeed in edge cases. However commit 5d6dee80a1e9 ("vfio: New external user group/file match") deleted the call to vfio_group_get_external_user() during KVM_DEV_VFIO_GROUP_DEL. Instead vfio_external_group_match_file() is used to directly match the file descriptor to the group pointer. This in turn avoids the call down to vfio_dev_viable() during KVM_DEV_VFIO_GROUP_DEL and also avoids the trouble the first commit was trying to fix. There are no other users of vfio_dev_viable() that care about the time after vfio_unregister_group_dev() returns, so simply delete the unbound_list entirely. Reviewed-by: Chaitanya Kulkarni Signed-off-by: Jason Gunthorpe Signed-off-by: Lu Baolu Acked-by: Alex Williamson Link: https://lore.kernel.org/r/20220418005000.897664-10-baolu.lu@linux.intel.com Signed-off-by: Joerg Roedel --- drivers/vfio/vfio.c | 74 ++------------------------------------------- 1 file changed, 2 insertions(+), 72 deletions(-) diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c index 8a9347f732a5a..b2f19d17d0c3f 100644 --- a/drivers/vfio/vfio.c +++ b/drivers/vfio/vfio.c @@ -62,11 +62,6 @@ struct vfio_container { bool noiommu; }; -struct vfio_unbound_dev { - struct device *dev; - struct list_head unbound_next; -}; - struct vfio_group { struct device dev; struct cdev cdev; @@ -79,8 +74,6 @@ struct vfio_group { struct notifier_block nb; struct list_head vfio_next; struct list_head container_next; - struct list_head unbound_list; - struct mutex unbound_lock; atomic_t opened; wait_queue_head_t container_q; enum vfio_group_type type; @@ -340,16 +333,8 @@ vfio_group_get_from_iommu(struct iommu_group *iommu_group) static void vfio_group_release(struct device *dev) { struct vfio_group *group = container_of(dev, struct vfio_group, dev); - struct vfio_unbound_dev *unbound, *tmp; - - list_for_each_entry_safe(unbound, tmp, - &group->unbound_list, unbound_next) { - list_del(&unbound->unbound_next); - kfree(unbound); - } mutex_destroy(&group->device_lock); - mutex_destroy(&group->unbound_lock); iommu_group_put(group->iommu_group); ida_free(&vfio.group_ida, MINOR(group->dev.devt)); kfree(group); @@ -381,8 +366,6 @@ static struct vfio_group *vfio_group_alloc(struct iommu_group *iommu_group, refcount_set(&group->users, 1); INIT_LIST_HEAD(&group->device_list); mutex_init(&group->device_lock); - INIT_LIST_HEAD(&group->unbound_list); - mutex_init(&group->unbound_lock); init_waitqueue_head(&group->container_q); group->iommu_group = iommu_group; /* put in vfio_group_release() */ @@ -571,19 +554,8 @@ static int vfio_dev_viable(struct device *dev, void *data) struct vfio_group *group = data; struct vfio_device *device; struct device_driver *drv = READ_ONCE(dev->driver); - struct vfio_unbound_dev *unbound; - int ret = -EINVAL; - mutex_lock(&group->unbound_lock); - list_for_each_entry(unbound, &group->unbound_list, unbound_next) { - if (dev == unbound->dev) { - ret = 0; - break; - } - } - mutex_unlock(&group->unbound_lock); - - if (!ret || !drv || vfio_dev_driver_allowed(dev, drv)) + if (!drv || vfio_dev_driver_allowed(dev, drv)) return 0; device = vfio_group_get_device(group, dev); @@ -592,7 +564,7 @@ static int vfio_dev_viable(struct device *dev, void *data) return 0; } - return ret; + return -EINVAL; } /* @@ -634,7 +606,6 @@ static int vfio_iommu_group_notifier(struct notifier_block *nb, { struct vfio_group *group = container_of(nb, struct vfio_group, nb); struct device *dev = data; - struct vfio_unbound_dev *unbound; switch (action) { case IOMMU_GROUP_NOTIFY_ADD_DEVICE: @@ -663,28 +634,6 @@ static int vfio_iommu_group_notifier(struct notifier_block *nb, __func__, iommu_group_id(group->iommu_group), dev->driver->name); break; - case IOMMU_GROUP_NOTIFY_UNBOUND_DRIVER: - dev_dbg(dev, "%s: group %d unbound from driver\n", __func__, - iommu_group_id(group->iommu_group)); - /* - * XXX An unbound device in a live group is ok, but we'd - * really like to avoid the above BUG_ON by preventing other - * drivers from binding to it. Once that occurs, we have to - * stop the system to maintain isolation. At a minimum, we'd - * want a toggle to disable driver auto probe for this device. - */ - - mutex_lock(&group->unbound_lock); - list_for_each_entry(unbound, - &group->unbound_list, unbound_next) { - if (dev == unbound->dev) { - list_del(&unbound->unbound_next); - kfree(unbound); - break; - } - } - mutex_unlock(&group->unbound_lock); - break; } return NOTIFY_OK; } @@ -889,29 +838,10 @@ static struct vfio_device *vfio_device_get_from_name(struct vfio_group *group, void vfio_unregister_group_dev(struct vfio_device *device) { struct vfio_group *group = device->group; - struct vfio_unbound_dev *unbound; unsigned int i = 0; bool interrupted = false; long rc; - /* - * When the device is removed from the group, the group suddenly - * becomes non-viable; the device has a driver (until the unbind - * completes), but it's not present in the group. This is bad news - * for any external users that need to re-acquire a group reference - * in order to match and release their existing reference. To - * solve this, we track such devices on the unbound_list to bridge - * the gap until they're fully unbound. - */ - unbound = kzalloc(sizeof(*unbound), GFP_KERNEL); - if (unbound) { - unbound->dev = device->dev; - mutex_lock(&group->unbound_lock); - list_add(&unbound->unbound_next, &group->unbound_list); - mutex_unlock(&group->unbound_lock); - } - WARN_ON(!unbound); - vfio_device_put(device); rc = try_wait_for_completion(&device->comp); while (rc <= 0) { From 3b86f317c9c71c9fe17409db5743b6a27114f248 Mon Sep 17 00:00:00 2001 From: Lu Baolu Date: Mon, 18 Apr 2022 08:49:59 +0800 Subject: [PATCH 10/12] vfio: Remove iommu group notifier The iommu core and driver core have been enhanced to avoid unsafe driver binding to a live group after iommu_group_set_dma_owner(PRIVATE_USER) has been called. There's no need to register iommu group notifier. This removes the iommu group notifer which contains BUG_ON() and WARN(). Signed-off-by: Lu Baolu Reviewed-by: Jason Gunthorpe Acked-by: Alex Williamson Link: https://lore.kernel.org/r/20220418005000.897664-11-baolu.lu@linux.intel.com Signed-off-by: Joerg Roedel --- drivers/vfio/vfio.c | 147 -------------------------------------------- 1 file changed, 147 deletions(-) diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c index b2f19d17d0c3f..0c766384cee0f 100644 --- a/drivers/vfio/vfio.c +++ b/drivers/vfio/vfio.c @@ -71,7 +71,6 @@ struct vfio_group { struct vfio_container *container; struct list_head device_list; struct mutex device_lock; - struct notifier_block nb; struct list_head vfio_next; struct list_head container_next; atomic_t opened; @@ -274,8 +273,6 @@ void vfio_unregister_iommu_driver(const struct vfio_iommu_driver_ops *ops) } EXPORT_SYMBOL_GPL(vfio_unregister_iommu_driver); -static int vfio_iommu_group_notifier(struct notifier_block *nb, - unsigned long action, void *data); static void vfio_group_get(struct vfio_group *group); /* @@ -395,13 +392,6 @@ static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group, goto err_put; } - group->nb.notifier_call = vfio_iommu_group_notifier; - err = iommu_group_register_notifier(iommu_group, &group->nb); - if (err) { - ret = ERR_PTR(err); - goto err_put; - } - mutex_lock(&vfio.group_lock); /* Did we race creating this group? */ @@ -422,7 +412,6 @@ static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group, err_unlock: mutex_unlock(&vfio.group_lock); - iommu_group_unregister_notifier(group->iommu_group, &group->nb); err_put: put_device(&group->dev); return ret; @@ -447,7 +436,6 @@ static void vfio_group_put(struct vfio_group *group) cdev_device_del(&group->cdev, &group->dev); mutex_unlock(&vfio.group_lock); - iommu_group_unregister_notifier(group->iommu_group, &group->nb); put_device(&group->dev); } @@ -503,141 +491,6 @@ static struct vfio_device *vfio_group_get_device(struct vfio_group *group, return NULL; } -/* - * Some drivers, like pci-stub, are only used to prevent other drivers from - * claiming a device and are therefore perfectly legitimate for a user owned - * group. The pci-stub driver has no dependencies on DMA or the IOVA mapping - * of the device, but it does prevent the user from having direct access to - * the device, which is useful in some circumstances. - * - * We also assume that we can include PCI interconnect devices, ie. bridges. - * IOMMU grouping on PCI necessitates that if we lack isolation on a bridge - * then all of the downstream devices will be part of the same IOMMU group as - * the bridge. Thus, if placing the bridge into the user owned IOVA space - * breaks anything, it only does so for user owned devices downstream. Note - * that error notification via MSI can be affected for platforms that handle - * MSI within the same IOVA space as DMA. - */ -static const char * const vfio_driver_allowed[] = { "pci-stub" }; - -static bool vfio_dev_driver_allowed(struct device *dev, - struct device_driver *drv) -{ - if (dev_is_pci(dev)) { - struct pci_dev *pdev = to_pci_dev(dev); - - if (pdev->hdr_type != PCI_HEADER_TYPE_NORMAL) - return true; - } - - return match_string(vfio_driver_allowed, - ARRAY_SIZE(vfio_driver_allowed), - drv->name) >= 0; -} - -/* - * A vfio group is viable for use by userspace if all devices are in - * one of the following states: - * - driver-less - * - bound to a vfio driver - * - bound to an otherwise allowed driver - * - a PCI interconnect device - * - * We use two methods to determine whether a device is bound to a vfio - * driver. The first is to test whether the device exists in the vfio - * group. The second is to test if the device exists on the group - * unbound_list, indicating it's in the middle of transitioning from - * a vfio driver to driver-less. - */ -static int vfio_dev_viable(struct device *dev, void *data) -{ - struct vfio_group *group = data; - struct vfio_device *device; - struct device_driver *drv = READ_ONCE(dev->driver); - - if (!drv || vfio_dev_driver_allowed(dev, drv)) - return 0; - - device = vfio_group_get_device(group, dev); - if (device) { - vfio_device_put(device); - return 0; - } - - return -EINVAL; -} - -/* - * Async device support - */ -static int vfio_group_nb_add_dev(struct vfio_group *group, struct device *dev) -{ - struct vfio_device *device; - - /* Do we already know about it? We shouldn't */ - device = vfio_group_get_device(group, dev); - if (WARN_ON_ONCE(device)) { - vfio_device_put(device); - return 0; - } - - /* Nothing to do for idle groups */ - if (!atomic_read(&group->container_users)) - return 0; - - /* TODO Prevent device auto probing */ - dev_WARN(dev, "Device added to live group %d!\n", - iommu_group_id(group->iommu_group)); - - return 0; -} - -static int vfio_group_nb_verify(struct vfio_group *group, struct device *dev) -{ - /* We don't care what happens when the group isn't in use */ - if (!atomic_read(&group->container_users)) - return 0; - - return vfio_dev_viable(dev, group); -} - -static int vfio_iommu_group_notifier(struct notifier_block *nb, - unsigned long action, void *data) -{ - struct vfio_group *group = container_of(nb, struct vfio_group, nb); - struct device *dev = data; - - switch (action) { - case IOMMU_GROUP_NOTIFY_ADD_DEVICE: - vfio_group_nb_add_dev(group, dev); - break; - case IOMMU_GROUP_NOTIFY_DEL_DEVICE: - /* - * Nothing to do here. If the device is in use, then the - * vfio sub-driver should block the remove callback until - * it is unused. If the device is unused or attached to a - * stub driver, then it should be released and we don't - * care that it will be going away. - */ - break; - case IOMMU_GROUP_NOTIFY_BIND_DRIVER: - dev_dbg(dev, "%s: group %d binding to driver\n", __func__, - iommu_group_id(group->iommu_group)); - break; - case IOMMU_GROUP_NOTIFY_BOUND_DRIVER: - dev_dbg(dev, "%s: group %d bound to driver %s\n", __func__, - iommu_group_id(group->iommu_group), dev->driver->name); - BUG_ON(vfio_group_nb_verify(group, dev)); - break; - case IOMMU_GROUP_NOTIFY_UNBIND_DRIVER: - dev_dbg(dev, "%s: group %d unbinding from driver %s\n", - __func__, iommu_group_id(group->iommu_group), - dev->driver->name); - break; - } - return NOTIFY_OK; -} - /* * VFIO driver API */ From a5f1bd1afacd7b1e088f93f66af5453df0d8be9a Mon Sep 17 00:00:00 2001 From: Lu Baolu Date: Mon, 18 Apr 2022 08:50:00 +0800 Subject: [PATCH 11/12] iommu: Remove iommu group changes notifier The iommu group changes notifer is not referenced in the tree. Remove it to avoid dead code. Suggested-by: Christoph Hellwig Signed-off-by: Lu Baolu Reviewed-by: Jason Gunthorpe Link: https://lore.kernel.org/r/20220418005000.897664-12-baolu.lu@linux.intel.com Signed-off-by: Joerg Roedel --- drivers/iommu/iommu.c | 75 ------------------------------------------- include/linux/iommu.h | 23 ------------- 2 files changed, 98 deletions(-) diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index eba8e8ccf19d8..0c42ece258540 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -18,7 +18,6 @@ #include #include #include -#include #include #include #include @@ -40,7 +39,6 @@ struct iommu_group { struct kobject *devices_kobj; struct list_head devices; struct mutex mutex; - struct blocking_notifier_head notifier; void *iommu_data; void (*iommu_data_release)(void *iommu_data); char *name; @@ -632,7 +630,6 @@ struct iommu_group *iommu_group_alloc(void) mutex_init(&group->mutex); INIT_LIST_HEAD(&group->devices); INIT_LIST_HEAD(&group->entry); - BLOCKING_INIT_NOTIFIER_HEAD(&group->notifier); ret = ida_simple_get(&iommu_group_ida, 0, 0, GFP_KERNEL); if (ret < 0) { @@ -905,10 +902,6 @@ int iommu_group_add_device(struct iommu_group *group, struct device *dev) if (ret) goto err_put_group; - /* Notify any listeners about change to group. */ - blocking_notifier_call_chain(&group->notifier, - IOMMU_GROUP_NOTIFY_ADD_DEVICE, dev); - trace_add_device_to_group(group->id, dev); dev_info(dev, "Adding to iommu group %d\n", group->id); @@ -950,10 +943,6 @@ void iommu_group_remove_device(struct device *dev) dev_info(dev, "Removing from iommu group %d\n", group->id); - /* Pre-notify listeners that a device is being removed. */ - blocking_notifier_call_chain(&group->notifier, - IOMMU_GROUP_NOTIFY_DEL_DEVICE, dev); - mutex_lock(&group->mutex); list_for_each_entry(tmp_device, &group->devices, list) { if (tmp_device->dev == dev) { @@ -1075,36 +1064,6 @@ void iommu_group_put(struct iommu_group *group) } EXPORT_SYMBOL_GPL(iommu_group_put); -/** - * iommu_group_register_notifier - Register a notifier for group changes - * @group: the group to watch - * @nb: notifier block to signal - * - * This function allows iommu group users to track changes in a group. - * See include/linux/iommu.h for actions sent via this notifier. Caller - * should hold a reference to the group throughout notifier registration. - */ -int iommu_group_register_notifier(struct iommu_group *group, - struct notifier_block *nb) -{ - return blocking_notifier_chain_register(&group->notifier, nb); -} -EXPORT_SYMBOL_GPL(iommu_group_register_notifier); - -/** - * iommu_group_unregister_notifier - Unregister a notifier - * @group: the group to watch - * @nb: notifier block to signal - * - * Unregister a previously registered group notifier block. - */ -int iommu_group_unregister_notifier(struct iommu_group *group, - struct notifier_block *nb) -{ - return blocking_notifier_chain_unregister(&group->notifier, nb); -} -EXPORT_SYMBOL_GPL(iommu_group_unregister_notifier); - /** * iommu_register_device_fault_handler() - Register a device fault handler * @dev: the device @@ -1650,14 +1609,8 @@ static int remove_iommu_group(struct device *dev, void *data) static int iommu_bus_notifier(struct notifier_block *nb, unsigned long action, void *data) { - unsigned long group_action = 0; struct device *dev = data; - struct iommu_group *group; - /* - * ADD/DEL call into iommu driver ops if provided, which may - * result in ADD/DEL notifiers to group->notifier - */ if (action == BUS_NOTIFY_ADD_DEVICE) { int ret; @@ -1668,34 +1621,6 @@ static int iommu_bus_notifier(struct notifier_block *nb, return NOTIFY_OK; } - /* - * Remaining BUS_NOTIFYs get filtered and republished to the - * group, if anyone is listening - */ - group = iommu_group_get(dev); - if (!group) - return 0; - - switch (action) { - case BUS_NOTIFY_BIND_DRIVER: - group_action = IOMMU_GROUP_NOTIFY_BIND_DRIVER; - break; - case BUS_NOTIFY_BOUND_DRIVER: - group_action = IOMMU_GROUP_NOTIFY_BOUND_DRIVER; - break; - case BUS_NOTIFY_UNBIND_DRIVER: - group_action = IOMMU_GROUP_NOTIFY_UNBIND_DRIVER; - break; - case BUS_NOTIFY_UNBOUND_DRIVER: - group_action = IOMMU_GROUP_NOTIFY_UNBOUND_DRIVER; - break; - } - - if (group_action) - blocking_notifier_call_chain(&group->notifier, - group_action, dev); - - iommu_group_put(group); return 0; } diff --git a/include/linux/iommu.h b/include/linux/iommu.h index 77972ef978b59..6ef2df258673b 100644 --- a/include/linux/iommu.h +++ b/include/linux/iommu.h @@ -407,13 +407,6 @@ static inline const struct iommu_ops *dev_iommu_ops(struct device *dev) return dev->iommu->iommu_dev->ops; } -#define IOMMU_GROUP_NOTIFY_ADD_DEVICE 1 /* Device added */ -#define IOMMU_GROUP_NOTIFY_DEL_DEVICE 2 /* Pre Device removed */ -#define IOMMU_GROUP_NOTIFY_BIND_DRIVER 3 /* Pre Driver bind */ -#define IOMMU_GROUP_NOTIFY_BOUND_DRIVER 4 /* Post Driver bind */ -#define IOMMU_GROUP_NOTIFY_UNBIND_DRIVER 5 /* Pre Driver unbind */ -#define IOMMU_GROUP_NOTIFY_UNBOUND_DRIVER 6 /* Post Driver unbind */ - extern int bus_set_iommu(struct bus_type *bus, const struct iommu_ops *ops); extern int bus_iommu_probe(struct bus_type *bus); extern bool iommu_present(struct bus_type *bus); @@ -478,10 +471,6 @@ extern int iommu_group_for_each_dev(struct iommu_group *group, void *data, extern struct iommu_group *iommu_group_get(struct device *dev); extern struct iommu_group *iommu_group_ref_get(struct iommu_group *group); extern void iommu_group_put(struct iommu_group *group); -extern int iommu_group_register_notifier(struct iommu_group *group, - struct notifier_block *nb); -extern int iommu_group_unregister_notifier(struct iommu_group *group, - struct notifier_block *nb); extern int iommu_register_device_fault_handler(struct device *dev, iommu_dev_fault_handler_t handler, void *data); @@ -878,18 +867,6 @@ static inline void iommu_group_put(struct iommu_group *group) { } -static inline int iommu_group_register_notifier(struct iommu_group *group, - struct notifier_block *nb) -{ - return -ENODEV; -} - -static inline int iommu_group_unregister_notifier(struct iommu_group *group, - struct notifier_block *nb) -{ - return 0; -} - static inline int iommu_register_device_fault_handler(struct device *dev, iommu_dev_fault_handler_t handler, From 0286300e60455534b23f4b86ce79247829ceddb8 Mon Sep 17 00:00:00 2001 From: Jason Gunthorpe via iommu Date: Mon, 9 May 2022 13:19:19 -0300 Subject: [PATCH 12/12] iommu: iommu_group_claim_dma_owner() must always assign a domain Once the group enters 'owned' mode it can never be assigned back to the default_domain or to a NULL domain. It must always be actively assigned to a current domain. If the caller hasn't provided a domain then the core must provide an explicit DMA blocking domain that has no DMA map. Lazily create a group-global blocking DMA domain when iommu_group_claim_dma_owner is first called and immediately assign the group to it. This ensures that DMA is immediately fully isolated on all IOMMU drivers. If the user attaches/detaches while owned then detach will set the group back to the blocking domain. Slightly reorganize the call chains so that __iommu_group_set_core_domain() is the function that removes any caller configured domain and sets the domains back a core owned domain with an appropriate lifetime. __iommu_group_set_domain() is the worker function that can change the domain assigned to a group to any target domain, including NULL. Add comments clarifying how the NULL vs detach_dev vs default_domain works based on Robin's remarks. This fixes an oops with VFIO and SMMUv3 because VFIO will call iommu_detach_group() and then immediately iommu_domain_free(), but SMMUv3 has no way to know that the domain it is holding a pointer to has been freed. Now the iommu_detach_group() will assign the blocking domain and SMMUv3 will no longer hold a stale domain reference. Fixes: 1ea2a07a532b ("iommu: Add DMA ownership management interfaces") Reported-by: Qian Cai Tested-by: Baolu Lu Tested-by: Nicolin Chen Co-developed-by: Robin Murphy Signed-off-by: Robin Murphy Signed-off-by: Jason Gunthorpe -- Just minor polishing as discussed v3: - Change names to __iommu_group_set_domain() / __iommu_group_set_core_domain() - Clarify comments - Call __iommu_group_set_domain() directly in iommu_group_release_dma_owner() since we know it is always selecting the default_domain - Remove redundant detach_dev ops check in __iommu_detach_device and make the added WARN_ON fail instead - Check for blocking_domain in __iommu_attach_group() so VFIO can actually attach a new group - Update comments and spelling - Fix missed change to new_domain in iommu_group_do_detach_device() v2: https://lore.kernel.org/r/0-v2-f62259511ac0+6-iommu_dma_block_jgg@nvidia.com v1: https://lore.kernel.org/r/0-v1-6e9d2d0a759d+11b-iommu_dma_block_jgg@nvidia.com Reviewed-by: Kevin Tian Link: https://lore.kernel.org/r/0-v3-db7f0785022b+149-iommu_dma_block_jgg@nvidia.com Signed-off-by: Joerg Roedel --- drivers/iommu/iommu.c | 127 ++++++++++++++++++++++++++++++------------ 1 file changed, 91 insertions(+), 36 deletions(-) diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index 0c42ece258540..0b22e51e90f41 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -44,6 +44,7 @@ struct iommu_group { char *name; int id; struct iommu_domain *default_domain; + struct iommu_domain *blocking_domain; struct iommu_domain *domain; struct list_head entry; unsigned int owner_cnt; @@ -82,8 +83,8 @@ static int __iommu_attach_device(struct iommu_domain *domain, struct device *dev); static int __iommu_attach_group(struct iommu_domain *domain, struct iommu_group *group); -static void __iommu_detach_group(struct iommu_domain *domain, - struct iommu_group *group); +static int __iommu_group_set_domain(struct iommu_group *group, + struct iommu_domain *new_domain); static int iommu_create_device_direct_mappings(struct iommu_group *group, struct device *dev); static struct iommu_group *iommu_group_get_for_dev(struct device *dev); @@ -596,6 +597,8 @@ static void iommu_group_release(struct kobject *kobj) if (group->default_domain) iommu_domain_free(group->default_domain); + if (group->blocking_domain) + iommu_domain_free(group->blocking_domain); kfree(group->name); kfree(group); @@ -1907,6 +1910,24 @@ void iommu_domain_free(struct iommu_domain *domain) } EXPORT_SYMBOL_GPL(iommu_domain_free); +/* + * Put the group's domain back to the appropriate core-owned domain - either the + * standard kernel-mode DMA configuration or an all-DMA-blocked domain. + */ +static void __iommu_group_set_core_domain(struct iommu_group *group) +{ + struct iommu_domain *new_domain; + int ret; + + if (group->owner) + new_domain = group->blocking_domain; + else + new_domain = group->default_domain; + + ret = __iommu_group_set_domain(group, new_domain); + WARN(ret, "iommu driver failed to attach the default/blocking domain"); +} + static int __iommu_attach_device(struct iommu_domain *domain, struct device *dev) { @@ -1963,9 +1984,6 @@ static void __iommu_detach_device(struct iommu_domain *domain, if (iommu_is_attach_deferred(dev)) return; - if (unlikely(domain->ops->detach_dev == NULL)) - return; - domain->ops->detach_dev(domain, dev); trace_detach_device_from_domain(dev); } @@ -1979,12 +1997,10 @@ void iommu_detach_device(struct iommu_domain *domain, struct device *dev) return; mutex_lock(&group->mutex); - if (iommu_group_device_count(group) != 1) { - WARN_ON(1); + if (WARN_ON(domain != group->domain) || + WARN_ON(iommu_group_device_count(group) != 1)) goto out_unlock; - } - - __iommu_detach_group(domain, group); + __iommu_group_set_core_domain(group); out_unlock: mutex_unlock(&group->mutex); @@ -2040,7 +2056,8 @@ static int __iommu_attach_group(struct iommu_domain *domain, { int ret; - if (group->domain && group->domain != group->default_domain) + if (group->domain && group->domain != group->default_domain && + group->domain != group->blocking_domain) return -EBUSY; ret = __iommu_group_for_each_dev(group, domain, @@ -2072,38 +2089,49 @@ static int iommu_group_do_detach_device(struct device *dev, void *data) return 0; } -static void __iommu_detach_group(struct iommu_domain *domain, - struct iommu_group *group) +static int __iommu_group_set_domain(struct iommu_group *group, + struct iommu_domain *new_domain) { int ret; + if (group->domain == new_domain) + return 0; + /* - * If the group has been claimed already, do not re-attach the default - * domain. + * New drivers should support default domains and so the detach_dev() op + * will never be called. Otherwise the NULL domain represents some + * platform specific behavior. */ - if (!group->default_domain || group->owner) { - __iommu_group_for_each_dev(group, domain, + if (!new_domain) { + if (WARN_ON(!group->domain->ops->detach_dev)) + return -EINVAL; + __iommu_group_for_each_dev(group, group->domain, iommu_group_do_detach_device); group->domain = NULL; - return; + return 0; } - if (group->domain == group->default_domain) - return; - - /* Detach by re-attaching to the default domain */ - ret = __iommu_group_for_each_dev(group, group->default_domain, + /* + * Changing the domain is done by calling attach_dev() on the new + * domain. This switch does not have to be atomic and DMA can be + * discarded during the transition. DMA must only be able to access + * either new_domain or group->domain, never something else. + * + * Note that this is called in error unwind paths, attaching to a + * domain that has already been attached cannot fail. + */ + ret = __iommu_group_for_each_dev(group, new_domain, iommu_group_do_attach_device); - if (ret != 0) - WARN_ON(1); - else - group->domain = group->default_domain; + if (ret) + return ret; + group->domain = new_domain; + return 0; } void iommu_detach_group(struct iommu_domain *domain, struct iommu_group *group) { mutex_lock(&group->mutex); - __iommu_detach_group(domain, group); + __iommu_group_set_core_domain(group); mutex_unlock(&group->mutex); } EXPORT_SYMBOL_GPL(iommu_detach_group); @@ -3088,6 +3116,29 @@ void iommu_device_unuse_default_domain(struct device *dev) iommu_group_put(group); } +static int __iommu_group_alloc_blocking_domain(struct iommu_group *group) +{ + struct group_device *dev = + list_first_entry(&group->devices, struct group_device, list); + + if (group->blocking_domain) + return 0; + + group->blocking_domain = + __iommu_domain_alloc(dev->dev->bus, IOMMU_DOMAIN_BLOCKED); + if (!group->blocking_domain) { + /* + * For drivers that do not yet understand IOMMU_DOMAIN_BLOCKED + * create an empty domain instead. + */ + group->blocking_domain = __iommu_domain_alloc( + dev->dev->bus, IOMMU_DOMAIN_UNMANAGED); + if (!group->blocking_domain) + return -EINVAL; + } + return 0; +} + /** * iommu_group_claim_dma_owner() - Set DMA ownership of a group * @group: The group. @@ -3111,9 +3162,14 @@ int iommu_group_claim_dma_owner(struct iommu_group *group, void *owner) goto unlock_out; } + ret = __iommu_group_alloc_blocking_domain(group); + if (ret) + goto unlock_out; + + ret = __iommu_group_set_domain(group, group->blocking_domain); + if (ret) + goto unlock_out; group->owner = owner; - if (group->domain) - __iommu_detach_group(group->domain, group); } group->owner_cnt++; @@ -3132,18 +3188,17 @@ EXPORT_SYMBOL_GPL(iommu_group_claim_dma_owner); */ void iommu_group_release_dma_owner(struct iommu_group *group) { + int ret; + mutex_lock(&group->mutex); if (WARN_ON(!group->owner_cnt || !group->owner)) goto unlock_out; group->owner_cnt = 0; - /* - * The UNMANAGED domain should be detached before all USER - * owners have been released. - */ - if (!WARN_ON(group->domain) && group->default_domain) - __iommu_attach_group(group->default_domain, group); group->owner = NULL; + ret = __iommu_group_set_domain(group, group->default_domain); + WARN(ret, "iommu driver failed to attach the default domain"); + unlock_out: mutex_unlock(&group->mutex); }