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

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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: David Woodhouse <David.Woodhouse@intel.com>
This commit is contained in:
David Woodhouse 2015-10-24 21:06:39 +02:00
parent 5d52f482eb
commit 5a10ba27d9
1 changed files with 18 additions and 5 deletions
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23
drivers/iommu/intel-svm.c
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@ -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);