[Xen-devel] [PATCH 4/8] x86/EPT: relax treatment of APIC MFN

["Jan Beulich" <JBeulich@xxxxxxxx>]

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 <jbeulich@xxxxxxxx>

--- 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 )
     {

Attachment: EPT-relax-APIC-MFN.patch
Description: Text document

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