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intel-iommu: Unify hardware and software passthrough support
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This makes the hardware passthrough mode work a lot more like the
software version, so that the behaviour of a kernel with 'iommu=pt'
is the same whether the hardware supports passthrough or not.

In particular:
 - We use a single si_domain for the pass-through devices.
 - 32-bit devices can be taken out of the pass-through domain so that
   they don't have to use swiotlb.
 - Devices will work again after being removed from a KVM guest.
 - A potential oops on OOM (in init_context_pass_through()) is fixed.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
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David Woodhouse authored and David Woodhouse committed Aug 4, 2009
1 parent 0815565 commit 19943b0
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Showing 2 changed files with 76 additions and 103 deletions.
5 changes: 2 additions & 3 deletions arch/x86/kernel/pci-swiotlb.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -71,9 +71,8 @@ void __init pci_swiotlb_init(void)
{
/* don't initialize swiotlb if iommu=off (no_iommu=1) */
#ifdef CONFIG_X86_64
if ((!iommu_detected && !no_iommu && max_pfn > MAX_DMA32_PFN) ||
iommu_pass_through)
swiotlb = 1;
if ((!iommu_detected && !no_iommu && max_pfn > MAX_DMA32_PFN))
swiotlb = 1;
#endif
if (swiotlb_force)
swiotlb = 1;
Expand Down
174 changes: 74 additions & 100 deletions drivers/pci/intel-iommu.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -251,7 +251,8 @@ static inline int first_pte_in_page(struct dma_pte *pte)
* 2. It maps to each iommu if successful.
* 3. Each iommu mapps to this domain if successful.
*/
struct dmar_domain *si_domain;
static struct dmar_domain *si_domain;
static int hw_pass_through = 1;

/* devices under the same p2p bridge are owned in one domain */
#define DOMAIN_FLAG_P2P_MULTIPLE_DEVICES (1 << 0)
Expand Down Expand Up @@ -1948,14 +1949,24 @@ static int iommu_prepare_identity_map(struct pci_dev *pdev,
struct dmar_domain *domain;
int ret;

printk(KERN_INFO
"IOMMU: Setting identity map for device %s [0x%Lx - 0x%Lx]\n",
pci_name(pdev), start, end);

domain = get_domain_for_dev(pdev, DEFAULT_DOMAIN_ADDRESS_WIDTH);
if (!domain)
return -ENOMEM;

/* For _hardware_ passthrough, don't bother. But for software
passthrough, we do it anyway -- it may indicate a memory
range which is reserved in E820, so which didn't get set
up to start with in si_domain */
if (domain == si_domain && hw_pass_through) {
printk("Ignoring identity map for HW passthrough device %s [0x%Lx - 0x%Lx]\n",
pci_name(pdev), start, end);
return 0;
}

printk(KERN_INFO
"IOMMU: Setting identity map for device %s [0x%Lx - 0x%Lx]\n",
pci_name(pdev), start, end);

ret = iommu_domain_identity_map(domain, start, end);
if (ret)
goto error;
Expand Down Expand Up @@ -2006,23 +2017,6 @@ static inline void iommu_prepare_isa(void)
}
#endif /* !CONFIG_DMAR_FLPY_WA */

/* Initialize each context entry as pass through.*/
static int __init init_context_pass_through(void)
{
struct pci_dev *pdev = NULL;
struct dmar_domain *domain;
int ret;

for_each_pci_dev(pdev) {
domain = get_domain_for_dev(pdev, DEFAULT_DOMAIN_ADDRESS_WIDTH);
ret = domain_context_mapping(domain, pdev,
CONTEXT_TT_PASS_THROUGH);
if (ret)
return ret;
}
return 0;
}

static int md_domain_init(struct dmar_domain *domain, int guest_width);

static int __init si_domain_work_fn(unsigned long start_pfn,
Expand All @@ -2037,7 +2031,7 @@ static int __init si_domain_work_fn(unsigned long start_pfn,

}

static int si_domain_init(void)
static int si_domain_init(int hw)
{
struct dmar_drhd_unit *drhd;
struct intel_iommu *iommu;
Expand All @@ -2064,6 +2058,9 @@ static int si_domain_init(void)

si_domain->flags = DOMAIN_FLAG_STATIC_IDENTITY;

if (hw)
return 0;

for_each_online_node(nid) {
work_with_active_regions(nid, si_domain_work_fn, &ret);
if (ret)
Expand Down Expand Up @@ -2155,24 +2152,26 @@ static int iommu_should_identity_map(struct pci_dev *pdev, int startup)
return 1;
}

static int iommu_prepare_static_identity_mapping(void)
static int iommu_prepare_static_identity_mapping(int hw)
{
struct pci_dev *pdev = NULL;
int ret;

ret = si_domain_init();
ret = si_domain_init(hw);
if (ret)
return -EFAULT;

for_each_pci_dev(pdev) {
if (iommu_should_identity_map(pdev, 1)) {
printk(KERN_INFO "IOMMU: identity mapping for device %s\n",
pci_name(pdev));
printk(KERN_INFO "IOMMU: %s identity mapping for device %s\n",
hw ? "hardware" : "software", pci_name(pdev));

ret = domain_context_mapping(si_domain, pdev,
hw ? CONTEXT_TT_PASS_THROUGH :
CONTEXT_TT_MULTI_LEVEL);
if (ret)
return ret;

ret = domain_add_dev_info(si_domain, pdev);
if (ret)
return ret;
Expand All @@ -2189,14 +2188,6 @@ int __init init_dmars(void)
struct pci_dev *pdev;
struct intel_iommu *iommu;
int i, ret;
int pass_through = 1;

/*
* In case pass through can not be enabled, iommu tries to use identity
* mapping.
*/
if (iommu_pass_through)
iommu_identity_mapping = 1;

/*
* for each drhd
Expand Down Expand Up @@ -2250,14 +2241,8 @@ int __init init_dmars(void)
goto error;
}
if (!ecap_pass_through(iommu->ecap))
pass_through = 0;
hw_pass_through = 0;
}
if (iommu_pass_through)
if (!pass_through) {
printk(KERN_INFO
"Pass Through is not supported by hardware.\n");
iommu_pass_through = 0;
}

/*
* Start from the sane iommu hardware state.
Expand Down Expand Up @@ -2312,64 +2297,57 @@ int __init init_dmars(void)
}
}

if (iommu_pass_through)
iommu_identity_mapping = 1;
#ifdef CONFIG_DMAR_BROKEN_GFX_WA
else
iommu_identity_mapping = 2;
#endif
/*
* If pass through is set and enabled, context entries of all pci
* devices are intialized by pass through translation type.
* If pass through is not set or not enabled, setup context entries for
* identity mappings for rmrr, gfx, and isa and may fall back to static
* identity mapping if iommu_identity_mapping is set.
*/
if (iommu_pass_through) {
ret = init_context_pass_through();
if (iommu_identity_mapping) {
ret = iommu_prepare_static_identity_mapping(hw_pass_through);
if (ret) {
printk(KERN_ERR "IOMMU: Pass through init failed.\n");
iommu_pass_through = 0;
printk(KERN_CRIT "Failed to setup IOMMU pass-through\n");
goto error;
}
}

/*
* If pass through is not set or not enabled, setup context entries for
* identity mappings for rmrr, gfx, and isa and may fall back to static
* identity mapping if iommu_identity_mapping is set.
* For each rmrr
* for each dev attached to rmrr
* do
* locate drhd for dev, alloc domain for dev
* allocate free domain
* allocate page table entries for rmrr
* if context not allocated for bus
* allocate and init context
* set present in root table for this bus
* init context with domain, translation etc
* endfor
* endfor
*/
if (!iommu_pass_through) {
#ifdef CONFIG_DMAR_BROKEN_GFX_WA
if (!iommu_identity_mapping)
iommu_identity_mapping = 2;
#endif
if (iommu_identity_mapping)
iommu_prepare_static_identity_mapping();
/*
* For each rmrr
* for each dev attached to rmrr
* do
* locate drhd for dev, alloc domain for dev
* allocate free domain
* allocate page table entries for rmrr
* if context not allocated for bus
* allocate and init context
* set present in root table for this bus
* init context with domain, translation etc
* endfor
* endfor
*/
printk(KERN_INFO "IOMMU: Setting RMRR:\n");
for_each_rmrr_units(rmrr) {
for (i = 0; i < rmrr->devices_cnt; i++) {
pdev = rmrr->devices[i];
/*
* some BIOS lists non-exist devices in DMAR
* table.
*/
if (!pdev)
continue;
ret = iommu_prepare_rmrr_dev(rmrr, pdev);
if (ret)
printk(KERN_ERR
"IOMMU: mapping reserved region failed\n");
}
printk(KERN_INFO "IOMMU: Setting RMRR:\n");
for_each_rmrr_units(rmrr) {
for (i = 0; i < rmrr->devices_cnt; i++) {
pdev = rmrr->devices[i];
/*
* some BIOS lists non-exist devices in DMAR
* table.
*/
if (!pdev)
continue;
ret = iommu_prepare_rmrr_dev(rmrr, pdev);
if (ret)
printk(KERN_ERR
"IOMMU: mapping reserved region failed\n");
}

iommu_prepare_isa();
}

iommu_prepare_isa();

/*
* for each drhd
* enable fault log
Expand Down Expand Up @@ -2536,7 +2514,10 @@ static int iommu_no_mapping(struct device *dev)
ret = domain_add_dev_info(si_domain, pdev);
if (ret)
return 0;
ret = domain_context_mapping(si_domain, pdev, CONTEXT_TT_MULTI_LEVEL);
ret = domain_context_mapping(si_domain, pdev,
hw_pass_through ?
CONTEXT_TT_PASS_THROUGH :
CONTEXT_TT_MULTI_LEVEL);
if (!ret) {
printk(KERN_INFO "64bit %s uses identity mapping\n",
pci_name(pdev));
Expand Down Expand Up @@ -3202,7 +3183,7 @@ int __init intel_iommu_init(void)
* Check the need for DMA-remapping initialization now.
* Above initialization will also be used by Interrupt-remapping.
*/
if (no_iommu || (swiotlb && !iommu_pass_through) || dmar_disabled)
if (no_iommu || swiotlb || dmar_disabled)
return -ENODEV;

iommu_init_mempool();
Expand All @@ -3222,14 +3203,7 @@ int __init intel_iommu_init(void)

init_timer(&unmap_timer);
force_iommu = 1;

if (!iommu_pass_through) {
printk(KERN_INFO
"Multi-level page-table translation for DMAR.\n");
dma_ops = &intel_dma_ops;
} else
printk(KERN_INFO
"DMAR: Pass through translation for DMAR.\n");
dma_ops = &intel_dma_ops;

init_iommu_sysfs();

Expand Down

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