Changeset 79144 in vbox

Timestamp:

Jun 14, 2019 5:01:07 AM (6 years ago)

Author:

vboxsync

Message:

VMM/HMVMXR0: Nested VMX: bugref:9180 Comments.

File:

• trunk/src/VBox/VMM/VMMR0/HMVMXR0.cpp (modified) (4 diffs)

trunk/src/VBox/VMM/VMMR0/HMVMXR0.cpp

@@ -5009 +5009 @@
             Assert(pVM->hm.s.fNestedPaging || (uXcptBitmap & RT_BIT(X86_XCPT_PF)));
 
-            /* Apply the fixed CR0 bits and enable caching. */
+            /* Apply the hardware specified fixed CR0 bits and enable caching. */
             u64GuestCr0 |= fSetCr0;
             u64GuestCr0 &= fZapCr0;
@@ -5037 +5037 @@
              * originally supplied. We must copy those bits from the nested-guest CR0 into
              * the nested-guest CR0 read-shadow.
-             *
-             * Note! We are zapping away any CR0 fixed bits of our VMX emulation and applying
-             *       the hardware's VMX CR0 fixed bits here.
              */
             HMVMX_CPUMCTX_ASSERT(pVCpu, CPUMCTX_EXTRN_CR0);
@@ -5047 +5044 @@
             Assert(u64GuestCr0 & X86_CR0_NE);
 
-            /* Apply the fixed CR0 bits and enable caching. */
+            /*
+             * Apply the hardware specified fixed CR0 bits and enable caching.
+             * Note! We could be altering our VMX emulation's fixed bits. We thus
+             *       need to re-apply them while importing CR0.
+             */
             u64GuestCr0 |= fSetCr0;
             u64GuestCr0 &= fZapCr0;
@@ -5285 +5286 @@
         }
 
-        /* Apply the fixed CR4 bits (mainly CR4.VMXE). */
+        /*
+         * Apply the hardware specified fixed CR4 bits (mainly CR4.VMXE).
+         * Note! For nested-guests, we could be altering our VMX emulation's
+         *       fixed bits. We thus need to re-apply them while importing CR4.
+         */
         u64GuestCr4 |= fSetCr4;
         u64GuestCr4 &= fZapCr4;