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iommu/vt-d: Fix PASID table allocation

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Somehow I ended up with an off-by-three error in calculating the size of
the PASID and PASID State tables, which triggers allocations failures as
those tables unfortunately have to be physically contiguous.

In fact, even the *correct* maximum size of 8MiB is problematic and is
wont to lead to allocation failures. Since I have extracted a promise
that this *will* be fixed in hardware, I'm happy to limit it on the
current hardware to a maximum of 0x20000 PASIDs, which gives us 1MiB
tables — still not ideal, but better than before.

Reported by Mika Kuoppala <mika.kuoppala@linux.intel.com> and also by
Xunlei Pang <xlpang@redhat.com> who submitted a simpler patch to fix
only the allocation (and not the free) to the "correct" limit... which
was still problematic.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Cc: stable@vger.kernel.org
This commit is contained in:
David Woodhouse 2016-09-12 10:49:11 +08:00
parent 1c387188c6
commit 9101704429
2 changed files with 17 additions and 10 deletions
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26
drivers/iommu/intel-svm.c
View File

@ -39,10 +39,18 @@ int intel_svm_alloc_pasid_tables(struct intel_iommu *iommu)
struct page *pages;
int order;
order = ecap_pss(iommu->ecap) + 7 - PAGE_SHIFT;
if (order < 0)
order = 0;
/* Start at 2 because it's defined as 2^(1+PSS) */
iommu->pasid_max = 2 << ecap_pss(iommu->ecap);
/* Eventually I'm promised we will get a multi-level PASID table
* and it won't have to be physically contiguous. Until then,
* limit the size because 8MiB contiguous allocations can be hard
* to come by. The limit of 0x20000, which is 1MiB for each of
* the PASID and PASID-state tables, is somewhat arbitrary. */
if (iommu->pasid_max > 0x20000)
iommu->pasid_max = 0x20000;
order = get_order(sizeof(struct pasid_entry) * iommu->pasid_max);
pages = alloc_pages(GFP_KERNEL | __GFP_ZERO, order);
if (!pages) {
pr_warn("IOMMU: %s: Failed to allocate PASID table\n",
@ -53,6 +61,8 @@ int intel_svm_alloc_pasid_tables(struct intel_iommu *iommu)
pr_info("%s: Allocated order %d PASID table.\n", iommu->name, order);
if (ecap_dis(iommu->ecap)) {
/* Just making it explicit... */
BUILD_BUG_ON(sizeof(struct pasid_entry) != sizeof(struct pasid_state_entry));
pages = alloc_pages(GFP_KERNEL | __GFP_ZERO, order);
if (pages)
iommu->pasid_state_table = page_address(pages);
@ -68,11 +78,7 @@ int intel_svm_alloc_pasid_tables(struct intel_iommu *iommu)
int intel_svm_free_pasid_tables(struct intel_iommu *iommu)
{
int order;
order = ecap_pss(iommu->ecap) + 7 - PAGE_SHIFT;
if (order < 0)
order = 0;
int order = get_order(sizeof(struct pasid_entry) * iommu->pasid_max);
if (iommu->pasid_table) {
free_pages((unsigned long)iommu->pasid_table, order);
@ -371,8 +377,8 @@ int intel_svm_bind_mm(struct device *dev, int *pasid, int flags, struct svm_dev_
}
svm->iommu = iommu;
if (pasid_max > 2 << ecap_pss(iommu->ecap))
pasid_max = 2 << ecap_pss(iommu->ecap);
if (pasid_max > iommu->pasid_max)
pasid_max = iommu->pasid_max;
/* Do not use PASID 0 in caching mode (virtualised IOMMU) */
ret = idr_alloc(&iommu->pasid_idr, svm,

1
include/linux/intel-iommu.h
View File

@ -429,6 +429,7 @@ struct intel_iommu {
struct page_req_dsc *prq;
unsigned char prq_name[16]; /* Name for PRQ interrupt */
struct idr pasid_idr;
u32 pasid_max;
#endif
struct q_inval *qi; /* Queued invalidation info */
u32 *iommu_state; /* Store iommu states between suspend and resume.*/