Commit 06f4b8d0 authored by Lu Baolu's avatar Lu Baolu Committed by Joerg Roedel
Browse files

iommu/vt-d: Remove unnecessary SVA data accesses in page fault path 



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: default avatarLu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: default avatarKevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20220914011821.400986-1-baolu.lu@linux.intel.com


Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
parent f76349cf

drivers/iommu/intel/iommu.h

+1 −1
Original line number Diff line number Diff line
@@ -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
@@ -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;

drivers/iommu/intel/svm.c

+7 −53
Original line number Diff line number Diff line
@@ -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)

{
@@ -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;



	/*
@@ -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;

		}
@@ -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;

	}
@@ -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;
@@ -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;
@@ -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)
@@ -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;

}