From: David Woodhouse <d...@amazon.co.uk> 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 <d...@amazon.co.uk>
Reviewed-by: Liu Yi L <yi.l....@intel.com>
Cc: sta...@vger.kernel.org # v5.7+
---
drivers/iommu/intel/dmar.c | 3 ++-
drivers/iommu/intel/iommu.c | 4 ++--
2 files changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/iommu/intel/dmar.c b/drivers/iommu/intel/dmar.c
index 404b40af31cb..38d1d40cfe34 100644
--- a/drivers/iommu/intel/dmar.c
+++ b/drivers/iommu/intel/dmar.c
@@ -967,7 +967,8 @@ 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),
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 8651f6d4dfa0..0823761f3a7c 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -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
@@ -3209,7 +3209,7 @@ 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");
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