[PATCH 5.5 336/399] iommu/vt-d: Remove unnecessary WARN_ON_ONCE()

Greg Kroah-Hartman
2020-02-21T07:58:15Z

From: Lu Baolu <baolu.lu@linux.intel.com>

[ Upstream commit 857f081426e5aa38313426c13373730f1345fe95 ]

Address field in device TLB invalidation descriptor is qualified
by the S field. If S field is zero, a single page at page address
specified by address [63:12] is requested to be invalidated. If S
field is set, the least significant bit in the address field with
value 0b (say bit N) indicates the invalidation address range. The
spec doesn't require the address [N - 1, 0] to be cleared, hence
remove the unnecessary WARN_ON_ONCE().

Otherwise, the caller might set "mask = MAX_AGAW_PFN_WIDTH" in order
to invalidating all the cached mappings on an endpoint, and below
overflow error will be triggered.

[...]
UBSAN: Undefined behaviour in drivers/iommu/dmar.c:1354:3
shift exponent 64 is too large for 64-bit type 'long long unsigned int'
[...]

Reported-and-tested-by: Frank <fgndev@posteo.de>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/iommu/dmar.c | 1 -
1 file changed, 1 deletion(-)

diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
index 3acfa6a25fa29..fb66f717127d2 100644
--- a/drivers/iommu/dmar.c
+++ b/drivers/iommu/dmar.c
@@ -1354,7 +1354,6 @@ void qi_flush_dev_iotlb(struct intel_iommu *iommu, u16 sid, u16 pfsid,
struct qi_desc desc;

if (mask) {
- WARN_ON_ONCE(addr & ((1ULL << (VTD_PAGE_SHIFT + mask)) - 1));
addr |= (1ULL << (VTD_PAGE_SHIFT + mask - 1)) - 1;
desc.qw1 = QI_DEV_IOTLB_ADDR(addr) | QI_DEV_IOTLB_SIZE;
} else
--
2.20.1