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authorDavid Woodhouse <dwmw2@infradead.org>2016-09-12 10:49:11 +0800
committerDavid Woodhouse <dwmw2@infradead.org>2016-11-19 09:42:35 -0800
commit910170442944e1f8674fd5ddbeeb8ccd1877ea98 (patch)
tree0d3b866ec62df63888e0c747e724ccd6f4b6efdf
parent1c387188c60f53b338c20eee32db055dfe022a9b (diff)
downloadlinux-stericsson-910170442944e1f8674fd5ddbeeb8ccd1877ea98.tar.gz
iommu/vt-d: Fix PASID table allocation
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
-rw-r--r--drivers/iommu/intel-svm.c28
-rw-r--r--include/linux/intel-iommu.h1
2 files changed, 18 insertions, 11 deletions
diff --git a/drivers/iommu/intel-svm.c b/drivers/iommu/intel-svm.c
index 8ebb3530afa7..cb72e0011310 100644
--- a/drivers/iommu/intel-svm.c
+++ b/drivers/iommu/intel-svm.c
@@ -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,
diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
index 2d9b650047a5..d49e26c6cdc7 100644
--- a/include/linux/intel-iommu.h
+++ b/include/linux/intel-iommu.h
@@ -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.*/