Changeset 71755 in vbox for trunk/src/VBox/VMM/VMMR0

Timestamp:

Apr 9, 2018 8:10:23 AM (7 years ago)

Author:

vboxsync

svn:sync-xref-src-repo-rev:

121857

Message:

VMM: Nested Hw.virt: Fix overriding SVM nested-guest PAT MSR while executing with nested-guest w/ shadow paging.
Also fixes loading, validating and restoring the PAT MSR when nested-paging is used by the nested-hypervisor.

File:

• trunk/src/VBox/VMM/VMMR0/HMSVMR0.cpp (modified) (5 diffs)

trunk/src/VBox/VMM/VMMR0/HMSVMR0.cpp

@@ -1001 +1001 @@
         /*
          * Setup the PAT MSR (applicable for Nested Paging only).
-         * The default value should be 0x0007040600070406ULL, but we want to treat all guest memory as WB,
-         * so choose type 6 for all PAT slots.
+         *
+         * While guests can modify and see the modified values throug the shadow values,
+         * we shall not honor any guest modifications of this MSR to ensure caching is always
+         * enabled similar to how we always run with CR0.CD and NW bits cleared.
          */
-        pVmcb->guest.u64GPAT = UINT64_C(0x0006060606060606);
+        pVmcb->guest.u64PAT = MSR_IA32_CR_PAT_INIT_VAL;
 
         /* Setup Nested Paging. This doesn't change throughout the execution time of the VM. */
@@ -1754 +1756 @@
     pVmcb->guest.u64SFMASK       = pCtx->msrSFMASK;
     pVmcb->guest.u64KernelGSBase = pCtx->msrKERNELGSBASE;
+
+    /* We don't honor guest modifications to its PAT MSR (similar to ignoring CR0.CD, NW bits). */
 }
 
@@ -2417 +2421 @@
         pVmcbNstGstCache->u64CR4            = pVmcbNstGstState->u64CR4;
         pVmcbNstGstCache->u64EFER           = pVmcbNstGstState->u64EFER;
+        pVmcbNstGstCache->u64PAT            = pVmcbNstGstState->u64PAT;
         pVmcbNstGstCache->u64DBGCTL         = pVmcbNstGstState->u64DBGCTL;
         pVmcbNstGstCache->u64IOPMPhysAddr   = pVmcbNstGstCtrl->u64IOPMPhysAddr;
@@ -2470 +2475 @@
         pVmcbNstGstCtrl->LbrVirt.n.u1LbrVirt = pVmcb->ctrl.LbrVirt.n.u1LbrVirt;
         pVmcbNstGst->guest.u64DBGCTL = pVmcb->guest.u64DBGCTL;
+
+        /* Override nested-guest PAT MSR, see @bugref{7243#c109}. */
+        pVmcbNstGst->guest.u64PAT = MSR_IA32_CR_PAT_INIT_VAL;
     }
     else
@@ -3919 +3927 @@
         Log4(("guest.u64SFMASK                   %#RX64\n",   pVmcb->guest.u64SFMASK));
         Log4(("guest.u64KernelGSBase             %#RX64\n",   pVmcb->guest.u64KernelGSBase));
-        Log4(("guest.u64GPAT                     %#RX64\n",   pVmcb->guest.u64GPAT));
+        Log4(("guest.u64PAT                      %#RX64\n",   pVmcb->guest.u64PAT));
         Log4(("guest.u64DBGCTL                   %#RX64\n",   pVmcb->guest.u64DBGCTL));
         Log4(("guest.u64BR_FROM                  %#RX64\n",   pVmcb->guest.u64BR_FROM));