Changeset 74755 in vbox

Timestamp:

Oct 11, 2018 9:23:47 AM (6 years ago)

Author:

vboxsync

Message:

VMM/IEM: Nested VMX: bugref:9180 Initialize previous and first-pause loop tick records and ensure the required case for the
first execution of pause after VM-entry at CPL 0.

File:

• trunk/src/VBox/VMM/VMMAll/IEMAllCImplVmxInstr.cpp.h (modified) (2 diffs)

trunk/src/VBox/VMM/VMMAll/IEMAllCImplVmxInstr.cpp.h

@@ -3584 +3584 @@
     if (pVmcs->u32ProcCtls & VMX_PROC_CTLS_PAUSE_EXIT)
         fIntercept = true;
-    else if (pVmcs->u32ProcCtls2 & VMX_PROC_CTLS2_PAUSE_LOOP_EXIT)
+    else if (   (pVmcs->u32ProcCtls2 & VMX_PROC_CTLS2_PAUSE_LOOP_EXIT)
+             && pVCpu->iem.s.uCpl == 0)
     {
         IEM_CTX_IMPORT_RET(pVCpu, CPUMCTX_EXTRN_HWVIRT);
 
-        uint64_t      *puFirstPauseLoopTick = &pVCpu->cpum.GstCtx.hwvirt.vmx.uFirstPauseLoopTick;
-        uint64_t const uPrevPauseTick       = pVCpu->cpum.GstCtx.hwvirt.vmx.uPrevPauseTick;
-        uint32_t const uPleGap              = pVmcs->u32PleGap;
-        uint32_t const uPleWindow           = pVmcs->u32PleWindow;
-        uint64_t const uTick                = TMCpuTickGet(pVCpu);
-        if (uTick - uPrevPauseTick > uPleGap)
+        /*
+         * A previous-PAUSE-tick value of 0 is used to identify the first time
+         * execution of a PAUSE instruction after VM-entry at CPL 0. We must
+         * consider this to be the first execution of PAUSE in a loop according
+         * to the Intel.
+         *
+         * All subsequent records for the previous-PAUSE-tick we ensure that it
+         * cannot be zero by OR'ing 1 to rule out the TSC wrap-around cases at 0.
+         */
+        uint64_t *puFirstPauseLoopTick = &pVCpu->cpum.GstCtx.hwvirt.vmx.uFirstPauseLoopTick;
+        uint64_t *puPrevPauseTick      = &pVCpu->cpum.GstCtx.hwvirt.vmx.uPrevPauseTick;
+        uint64_t const  uTick          = TMCpuTickGet(pVCpu);
+        uint32_t const  uPleGap        = pVmcs->u32PleGap;
+        uint32_t const  uPleWindow     = pVmcs->u32PleWindow;
+        if (   *puPrevPauseTick == 0
+            || uTick - *puPrevPauseTick > uPleGap)
             *puFirstPauseLoopTick = uTick;
         else if (uTick - *puFirstPauseLoopTick > uPleWindow)
             fIntercept = true;
+
+        *puPrevPauseTick = uTick | 1;
     }
 
@@ -5748 +5761 @@
     pVCpu->cpum.GstCtx.rflags.u = pVmcs->u64GuestRFlags.u;
 
+    /* Initialize the PAUSE-loop controls as part of VM-entry. */
+    pVCpu->cpum.GstCtx.hwvirt.vmx.uFirstPauseLoopTick = 0;
+    pVCpu->cpum.GstCtx.hwvirt.vmx.uPrevPauseTick      = 0;
+
     iemVmxVmentryLoadGuestNonRegState(pVCpu);