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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: 3375303e82 ("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>
zero-sugar-mainline-defconfig
David Woodhouse 2020-11-26 11:13:51 +00:00 committed by Will Deacon
parent e2be2a833a
commit d76b42e927
2 changed files with 4 additions and 3 deletions
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3
drivers/iommu/intel/dmar.c
View File

@ -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),

4
drivers/iommu/intel/iommu.c
View File

@ -1833,7 +1833,7 @@ static void free_dmar_iommu(struct intel_iommu *iommu)
if (ecap_prs(iommu->ecap))
intel_svm_finish_prq(iommu);
}
if (ecap_vcs(iommu->ecap) && vccap_pasid(iommu->vccap))
if (vccap_pasid(iommu->vccap))
ioasid_unregister_allocator(&iommu->pasid_allocator);
#endif
@ -3212,7 +3212,7 @@ static void register_pasid_allocator(struct intel_iommu *iommu)
* is active. All vIOMMU allocators will eventually be calling the same
* host allocator.
*/
if (!ecap_vcs(iommu->ecap) || !vccap_pasid(iommu->vccap))
if (!vccap_pasid(iommu->vccap))
return;
pr_info("Register custom PASID allocator\n");