KVM: MMU: Map device MMIO as UC in EPT

Software are not allow to access device MMIO using cacheable memory type, the
patch limit MMIO region with UC and WC(guest can select WC using PAT and
PCD/PWT).

Signed-off-by: Sheng Yang <sheng@linux.intel.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 7 insertions, 2 deletions

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 83f11c7474a1..2d4477c71473 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1698,8 +1698,13 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *shadow_pte,
         if (largepage)
                 spte |= PT_PAGE_SIZE_MASK;
         if (mt_mask) {
-                mt_mask = get_memory_type(vcpu, gfn) <<
-                          kvm_x86_ops->get_mt_mask_shift();
+                if (!kvm_is_mmio_pfn(pfn)) {
+                        mt_mask = get_memory_type(vcpu, gfn) <<
+                                kvm_x86_ops->get_mt_mask_shift();
+                        mt_mask |= VMX_EPT_IGMT_BIT;
+                } else
+                        mt_mask = MTRR_TYPE_UNCACHABLE <<
+                                kvm_x86_ops->get_mt_mask_shift();
                 spte |= mt_mask;
         }