KVM: vmx: fix ept reserved bits for 1-GByte page

EPT misconfig handler in kvm will check which reason lead to EPT
misconfiguration after vmexit. One of the reasons is that an EPT
paging-structure entry is configured with settings reserved for
future functionality. However, the handler can't identify if
paging-structure entry of reserved bits for 1-GByte page are
configured, since PDPTE which point to 1-GByte page will reserve
bits 29:12 instead of bits 7:3 which are reserved for PDPTE that
references an EPT Page Directory. This patch fix it by reserve
bits 29:12 for 1-GByte page.

Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 12 insertions, 10 deletions

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index cad37d57cc47..286c2835e25c 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -5521,17 +5521,18 @@ static u64 ept_rsvd_mask(u64 spte, int level)
         for (i = 51; i > boot_cpu_data.x86_phys_bits; i--)
                 mask |= (1ULL << i);
 
-        if (level > 2)
+        if (level == 4)
                 /* bits 7:3 reserved */
                 mask |= 0xf8;
-        else if (level == 2) {
-                if (spte & (1ULL << 7))
-                        /* 2MB ref, bits 20:12 reserved */
-                        mask |= 0x1ff000;
-                else
-                        /* bits 6:3 reserved */
-                        mask |= 0x78;
-        }
+        else if (spte & (1ULL << 7))
+                /*
+                 * 1GB/2MB page, bits 29:12 or 20:12 reserved respectively,
+                 * level == 1 if the hypervisor is using the ignored bit 7.
+                 */
+                mask |= (PAGE_SIZE << ((level - 1) * 9)) - PAGE_SIZE;
+        else if (level > 1)
+                /* bits 6:3 reserved */
+                mask |= 0x78;
 
         return mask;
 }
@@ -5561,7 +5562,8 @@ static void ept_misconfig_inspect_spte(struct kvm_vcpu *vcpu, u64 spte,
                         WARN_ON(1);
                 }
 
-                if (level == 1 || (level == 2 && (spte & (1ULL << 7)))) {
+                /* bits 5:3 are _not_ reserved for large page or leaf page */
+                if ((rsvd_bits & 0x38) == 0) {
                         u64 ept_mem_type = (spte & 0x38) >> 3;
 
                         if (ept_mem_type == 2 || ept_mem_type == 3 ||