iommu/amd: Set exclusion range correctly

[ Upstream commit 3c677d206210f53a4be972211066c0f1cd47fe12 ]

The exlcusion range limit register needs to contain the
base-address of the last page that is part of the range, as
bits 0-11 of this register are treated as 0xfff by the
hardware for comparisons.

So correctly set the exclusion range in the hardware to the
last page which is _in_ the range.

Fixes: b2026aa2dce44 ('x86, AMD IOMMU: add functions for programming IOMMU MMIO space')
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/iommu/amd_iommu_init.c

@@ -356,7 +356,7 @@ static void iommu_write_l2(struct amd_iommu *iommu, u8 address, u32 val)
 static void iommu_set_exclusion_range(struct amd_iommu *iommu)
 {
 	u64 start = iommu->exclusion_start & PAGE_MASK;
-	u64 limit = (start + iommu->exclusion_length) & PAGE_MASK;
+	u64 limit = (start + iommu->exclusion_length - 1) & PAGE_MASK;
 	u64 entry;
 
 	if (!iommu->exclusion_start)