From ec1a78cee97001b0ed25b5866e92dae058eb5877 Mon Sep 17 00:00:00 2001 From: Jason Wang Date: Wed, 12 Apr 2023 15:35:10 +0800 Subject: [PATCH] intel_iommu: refine iotlb hash calculation Commit 1b2b12376c8 ("intel-iommu: PASID support") takes PASID into account when calculating iotlb hash like: static guint vtd_iotlb_hash(gconstpointer v) { const struct vtd_iotlb_key *key = v; return key->gfn | ((key->sid) << VTD_IOTLB_SID_SHIFT) | (key->level) << VTD_IOTLB_LVL_SHIFT | (key->pasid) << VTD_IOTLB_PASID_SHIFT; } This turns out to be problematic since: - the shift will lose bits if not converting to uint64_t - level should be off by one in order to fit into 2 bits - VTD_IOTLB_PASID_SHIFT is 30 but PASID is 20 bits which will waste some bits - the hash result is uint64_t so we will lose bits when converting to guint So this patch fixes them by - converting the keys into uint64_t before doing the shift - off level by one to make it fit into two bits - change the sid, lvl and pasid shift to 26, 42 and 44 in order to take the full width of uint64_t - perform an XOR to the top 32bit with the bottom 32bit for the final result to fit guint Fixes: Coverity CID 1508100 Fixes: 1b2b12376c8 ("intel-iommu: PASID support") Signed-off-by: Jason Wang Message-Id: <20230412073510.7158-1-jasowang@redhat.com> Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin Reviewed-by: Peter Xu --- hw/i386/intel_iommu.c | 9 +++++---- hw/i386/intel_iommu_internal.h | 6 +++--- 2 files changed, 8 insertions(+), 7 deletions(-) diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c index a62896759c..94d52f4205 100644 --- a/hw/i386/intel_iommu.c +++ b/hw/i386/intel_iommu.c @@ -64,8 +64,8 @@ struct vtd_as_key { struct vtd_iotlb_key { uint64_t gfn; uint32_t pasid; - uint32_t level; uint16_t sid; + uint8_t level; }; static void vtd_address_space_refresh_all(IntelIOMMUState *s); @@ -221,10 +221,11 @@ static gboolean vtd_iotlb_equal(gconstpointer v1, gconstpointer v2) static guint vtd_iotlb_hash(gconstpointer v) { const struct vtd_iotlb_key *key = v; + uint64_t hash64 = key->gfn | ((uint64_t)(key->sid) << VTD_IOTLB_SID_SHIFT) | + (uint64_t)(key->level - 1) << VTD_IOTLB_LVL_SHIFT | + (uint64_t)(key->pasid) << VTD_IOTLB_PASID_SHIFT; - return key->gfn | ((key->sid) << VTD_IOTLB_SID_SHIFT) | - (key->level) << VTD_IOTLB_LVL_SHIFT | - (key->pasid) << VTD_IOTLB_PASID_SHIFT; + return (guint)((hash64 >> 32) ^ (hash64 & 0xffffffffU)); } static gboolean vtd_as_equal(gconstpointer v1, gconstpointer v2) diff --git a/hw/i386/intel_iommu_internal.h b/hw/i386/intel_iommu_internal.h index f090e61e11..2e61eec2f5 100644 --- a/hw/i386/intel_iommu_internal.h +++ b/hw/i386/intel_iommu_internal.h @@ -114,9 +114,9 @@ VTD_INTERRUPT_ADDR_FIRST + 1) /* The shift of source_id in the key of IOTLB hash table */ -#define VTD_IOTLB_SID_SHIFT 20 -#define VTD_IOTLB_LVL_SHIFT 28 -#define VTD_IOTLB_PASID_SHIFT 30 +#define VTD_IOTLB_SID_SHIFT 26 +#define VTD_IOTLB_LVL_SHIFT 42 +#define VTD_IOTLB_PASID_SHIFT 44 #define VTD_IOTLB_MAX_SIZE 1024 /* Max size of the hash table */ /* IOTLB_REG */