x86/EPT: relax treatment of APIC MFN There's no point in this being mapped UC by the guest due to using a respective PAT index - set the ignore-PAT flag to true. Signed-off-by: Jan Beulich --- a/xen/arch/x86/hvm/mtrr.c +++ b/xen/arch/x86/hvm/mtrr.c @@ -719,8 +719,12 @@ uint8_t epte_get_entry_emt(struct domain } if ( direct_mmio ) - return mfn_x(mfn) != d->arch.hvm_domain.vmx.apic_access_mfn - ? MTRR_TYPE_UNCACHABLE : MTRR_TYPE_WRBACK; + { + if ( mfn_x(mfn) != d->arch.hvm_domain.vmx.apic_access_mfn ) + return MTRR_TYPE_UNCACHABLE; + *ipat = 1; + return MTRR_TYPE_WRBACK; + } if ( iommu_snoop ) {