From 910170442944e1f8674fd5ddbeeb8ccd1877ea98 Mon Sep 17 00:00:00 2001 From: David Woodhouse Date: Mon, 12 Sep 2016 10:49:11 +0800 Subject: [PATCH] iommu/vt-d: Fix PASID table allocation MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 and also by Xunlei Pang 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 Cc: stable@vger.kernel.org --- drivers/iommu/intel-svm.c | 28 +++++++++++++++++----------- include/linux/intel-iommu.h | 1 + 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.*/ -- GitLab