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Commit 5a10ba27 authored by David Woodhouse's avatar David Woodhouse
Browse files

iommu/vt-d: Handle Caching Mode implementations of SVM 



Not entirely clear why, but it seems we need to reserve PASID zero and
flush it when we make a PASID entry present.

Quite we we couldn't use the true PASID value, isn't clear.

Signed-off-by: default avatarDavid Woodhouse <David.Woodhouse@intel.com>
parent 5d52f482

drivers/iommu/intel-svm.c

+18 −5
Original line number Diff line number Diff line
@@ -236,12 +236,12 @@ static void intel_invalidate_range(struct mmu_notifier *mn, 
}





static void intel_flush_pasid_dev(struct intel_svm *svm, struct intel_svm_dev *sdev)

static void intel_flush_pasid_dev(struct intel_svm *svm, struct intel_svm_dev *sdev, int pasid)

{

	struct qi_desc desc;



	desc.high = 0;

	desc.low = QI_PC_TYPE | QI_PC_DID(sdev->did) | QI_PC_PASID_SEL | QI_PC_PASID(svm->pasid);

	desc.low = QI_PC_TYPE | QI_PC_DID(sdev->did) | QI_PC_PASID_SEL | QI_PC_PASID(pasid);



	qi_submit_sync(&desc, svm->iommu);

}
@@ -356,8 +356,10 @@ int intel_svm_bind_mm(struct device *dev, int *pasid, int flags, struct svm_dev_ 
		if (pasid_max > 2 << ecap_pss(iommu->ecap))

			pasid_max = 2 << ecap_pss(iommu->ecap);



		ret = idr_alloc(&iommu->pasid_idr, svm, 0, pasid_max - 1,

				GFP_KERNEL);

		/* Do not use PASID 0 in caching mode (virtualised IOMMU) */

		ret = idr_alloc(&iommu->pasid_idr, svm,

				!!cap_caching_mode(iommu->cap),

				pasid_max - 1, GFP_KERNEL);

		if (ret < 0) {

			kfree(svm);

			goto out;
@@ -381,6 +383,17 @@ int intel_svm_bind_mm(struct device *dev, int *pasid, int flags, struct svm_dev_ 
		} else

			iommu->pasid_table[svm->pasid].val = (u64)__pa(init_mm.pgd) | 1 | (1ULL << 11);

		wmb();

		/* In caching mode, we still have to flush with PASID 0 when

		 * a PASID table entry becomes present. Not entirely clear

		 * *why* that would be the case — surely we could just issue

		 * a flush with the PASID value that we've changed? The PASID

		 * is the index into the table, after all. It's not like domain

		 * IDs in the case of the equivalent context-entry change in

		 * caching mode. And for that matter it's not entirely clear why

		 * a VMM would be in the business of caching the PASID table

		 * anyway. Surely that can be left entirely to the guest? */

		if (cap_caching_mode(iommu->cap))

			intel_flush_pasid_dev(svm, sdev, 0);

	}

	list_add_rcu(&sdev->list, &svm->devs);
@@ -424,7 +437,7 @@ int intel_svm_unbind_mm(struct device *dev, int pasid) 
				 * to use. We have a *shared* PASID table, because it's

				 * large and has to be physically contiguous. So it's

				 * hard to be as defensive as we might like. */

				intel_flush_pasid_dev(svm, sdev);

				intel_flush_pasid_dev(svm, sdev, svm->pasid);

				intel_flush_svm_range_dev(svm, sdev, 0, -1, 0, !svm->mm);

				kfree_rcu(sdev, rcu);