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
diff --git a/drivers/iommu/intel-svm.c b/drivers/iommu/intel-svm.c
index 8ebb353..cb72e00 100644
--- a/drivers/iommu/intel-svm.c
+++ b/drivers/iommu/intel-svm.c
@@ -39,10 +39,18 @@
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 @@
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_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 @@
}
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,