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iommu/vt-d: Remove unnecessary SVA data accesses in page fault path
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The existing I/O page fault handling code accesses the per-PASID SVA data
structures. This is unnecessary and makes the fault handling code only
suitable for SVA scenarios. This removes the SVA data accesses from the
I/O page fault reporting and responding code, so that the fault handling
code could be generic.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20220914011821.400986-1-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
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Lu Baolu authored and Joerg Roedel committed Sep 26, 2022
1 parent f76349c commit 06f4b8d
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Showing 2 changed files with 8 additions and 54 deletions.
2 changes: 1 addition & 1 deletion drivers/iommu/intel/iommu.h
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Original file line number Diff line number Diff line change
Expand Up @@ -586,6 +586,7 @@ struct intel_iommu {
#ifdef CONFIG_INTEL_IOMMU_SVM
struct page_req_dsc *prq;
unsigned char prq_name[16]; /* Name for PRQ interrupt */
unsigned long prq_seq_number;
struct completion prq_complete;
struct ioasid_allocator_ops pasid_allocator; /* Custom allocator for PASIDs */
#endif
Expand Down Expand Up @@ -761,7 +762,6 @@ struct intel_svm_dev {
struct device *dev;
struct intel_iommu *iommu;
struct iommu_sva sva;
unsigned long prq_seq_number;
u32 pasid;
int users;
u16 did;
Expand Down
60 changes: 7 additions & 53 deletions drivers/iommu/intel/svm.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -48,23 +48,6 @@ static void *pasid_private_find(ioasid_t pasid)
return xa_load(&pasid_private_array, pasid);
}

static struct intel_svm_dev *
svm_lookup_device_by_sid(struct intel_svm *svm, u16 sid)
{
struct intel_svm_dev *sdev = NULL, *t;

rcu_read_lock();
list_for_each_entry_rcu(t, &svm->devs, list) {
if (t->sid == sid) {
sdev = t;
break;
}
}
rcu_read_unlock();

return sdev;
}

static struct intel_svm_dev *
svm_lookup_device_by_dev(struct intel_svm *svm, struct device *dev)
{
Expand Down Expand Up @@ -706,11 +689,10 @@ static void handle_bad_prq_event(struct intel_iommu *iommu,

static irqreturn_t prq_event_thread(int irq, void *d)
{
struct intel_svm_dev *sdev = NULL;
struct intel_iommu *iommu = d;
struct intel_svm *svm = NULL;
struct page_req_dsc *req;
int head, tail, handled;
struct pci_dev *pdev;
u64 address;

/*
Expand All @@ -730,8 +712,6 @@ static irqreturn_t prq_event_thread(int irq, void *d)
pr_err("IOMMU: %s: Page request without PASID\n",
iommu->name);
bad_req:
svm = NULL;
sdev = NULL;
handle_bad_prq_event(iommu, req, QI_RESP_INVALID);
goto prq_advance;
}
Expand All @@ -758,34 +738,19 @@ static irqreturn_t prq_event_thread(int irq, void *d)
if (unlikely(req->lpig && !req->rd_req && !req->wr_req))
goto prq_advance;

if (!svm || svm->pasid != req->pasid) {
/*
* It can't go away, because the driver is not permitted
* to unbind the mm while any page faults are outstanding.
*/
svm = pasid_private_find(req->pasid);
if (IS_ERR_OR_NULL(svm) || (svm->flags & SVM_FLAG_SUPERVISOR_MODE))
goto bad_req;
}

if (!sdev || sdev->sid != req->rid) {
sdev = svm_lookup_device_by_sid(svm, req->rid);
if (!sdev)
goto bad_req;
}

sdev->prq_seq_number++;

pdev = pci_get_domain_bus_and_slot(iommu->segment,
PCI_BUS_NUM(req->rid),
req->rid & 0xff);
/*
* If prq is to be handled outside iommu driver via receiver of
* the fault notifiers, we skip the page response here.
*/
if (intel_svm_prq_report(iommu, sdev->dev, req))
if (!pdev || intel_svm_prq_report(iommu, &pdev->dev, req))
handle_bad_prq_event(iommu, req, QI_RESP_INVALID);

trace_prq_report(iommu, sdev->dev, req->qw_0, req->qw_1,
trace_prq_report(iommu, &pdev->dev, req->qw_0, req->qw_1,
req->priv_data[0], req->priv_data[1],
sdev->prq_seq_number);
iommu->prq_seq_number++);
prq_advance:
head = (head + sizeof(*req)) & PRQ_RING_MASK;
}
Expand Down Expand Up @@ -881,8 +846,6 @@ int intel_svm_page_response(struct device *dev,
struct iommu_page_response *msg)
{
struct iommu_fault_page_request *prm;
struct intel_svm_dev *sdev = NULL;
struct intel_svm *svm = NULL;
struct intel_iommu *iommu;
bool private_present;
bool pasid_present;
Expand All @@ -901,8 +864,6 @@ int intel_svm_page_response(struct device *dev,
if (!msg || !evt)
return -EINVAL;

mutex_lock(&pasid_mutex);

prm = &evt->fault.prm;
sid = PCI_DEVID(bus, devfn);
pasid_present = prm->flags & IOMMU_FAULT_PAGE_REQUEST_PASID_VALID;
Expand All @@ -919,12 +880,6 @@ int intel_svm_page_response(struct device *dev,
goto out;
}

ret = pasid_to_svm_sdev(dev, prm->pasid, &svm, &sdev);
if (ret || !sdev) {
ret = -ENODEV;
goto out;
}

/*
* Per VT-d spec. v3.0 ch7.7, system software must respond
* with page group response if private data is present (PDP)
Expand Down Expand Up @@ -954,6 +909,5 @@ int intel_svm_page_response(struct device *dev,
qi_submit_sync(iommu, &desc, 1, 0);
}
out:
mutex_unlock(&pasid_mutex);
return ret;
}

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