diff options
| author | David Woodhouse <dwmw@amazon.co.uk> | 2020-11-26 11:13:51 +0000 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2020-11-26 14:50:24 +0000 |
| commit | d76b42e92780c3587c1a998a3a943b501c137553 (patch) | |
| tree | 17299f741bc4c68f792f2d6ddfe8d0bcd1cdd1ff /drivers/iommu/intel/dmar.c | |
| parent | e2be2a833ab5338fa5b8b99ba622b911d96f1795 (diff) | |
| download | linux-d76b42e92780c3587c1a998a3a943b501c137553.tar.bz2 | |
iommu/vt-d: Don't read VCCAP register unless it exists
My virtual IOMMU implementation is whining that the guest is reading a
register that doesn't exist. Only read the VCCAP_REG if the corresponding
capability is set in ECAP_REG to indicate that it actually exists.
Fixes: 3375303e8287 ("iommu/vt-d: Add custom allocator for IOASID")
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Liu Yi L <yi.l.liu@intel.com>
Cc: stable@vger.kernel.org # v5.7+
Acked-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/de32b150ffaa752e0cff8571b17dfb1213fbe71c.camel@infradead.org
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'drivers/iommu/intel/dmar.c')
| -rw-r--r-- | drivers/iommu/intel/dmar.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/iommu/intel/dmar.c b/drivers/iommu/intel/dmar.c index 11319e4dce4a..b46dbfa6d0ed 100644 --- a/drivers/iommu/intel/dmar.c +++ b/drivers/iommu/intel/dmar.c @@ -986,7 +986,8 @@ static int map_iommu(struct intel_iommu *iommu, u64 phys_addr) warn_invalid_dmar(phys_addr, " returns all ones"); goto unmap; } - iommu->vccap = dmar_readq(iommu->reg + DMAR_VCCAP_REG); + if (ecap_vcs(iommu->ecap)) + iommu->vccap = dmar_readq(iommu->reg + DMAR_VCCAP_REG); /* the registers might be more than one page */ map_size = max_t(int, ecap_max_iotlb_offset(iommu->ecap), |