iommu/vt-d: Don't read VCCAP register unless it exists (d76b42e9) · Commits · 戴 / test

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: ("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>

drivers/iommu/intel/dmar.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -986,6 +986,7 @@ static int map_iommu(struct intel_iommu *iommu, u64 phys_addr)
		warn_invalid_dmar(phys_addr, " returns all ones");
		goto unmap;
		}
		if (ecap_vcs(iommu->ecap))
		iommu->vccap = dmar_readq(iommu->reg + DMAR_VCCAP_REG);

		/* the registers might be more than one page */

drivers/iommu/intel/iommu.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -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");

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