Changeset 103659 in vbox for trunk/src/VBox/VMM

Timestamp:

Mar 4, 2024 10:43:32 AM (12 months ago)

Author:

vboxsync

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

162019

Message:

VMM/IEM: Flush the current program counter to CPUMCTX when in the TLB-miss branch but restore it after the function call to avoid unnecessarily writing CPUMCTX::rip in the TLB-hit path, bugref:10373

Location:

trunk/src/VBox/VMM

Files:

• VMMAll/IEMAllN8veRecompiler.cpp (modified) (4 diffs)
• include/IEMN8veRecompiler.h (modified) (1 diff)

trunk/src/VBox/VMM/VMMAll/IEMAllN8veRecompiler.cpp

@@ -5135 +5135 @@
  * RIP updates, since these are the most common ones.
  */
-DECL_HIDDEN_THROW(uint32_t) iemNativeRegFlushPendingWrites(PIEMRECOMPILERSTATE pReNative, uint32_t off)
+DECL_HIDDEN_THROW(uint32_t) iemNativeRegFlushPendingWrites(PIEMRECOMPILERSTATE pReNative, uint32_t off, uint64_t fGstShwExcept /*= 0*/)
 {
 #ifdef IEMNATIVE_WITH_DELAYED_PC_UPDATING
-    off = iemNativeEmitPcWriteback(pReNative, off);
-#else
-    RT_NOREF(pReNative);
+    if (!(fGstShwExcept & kIemNativeGstReg_Pc))
+        off = iemNativeEmitPcWriteback(pReNative, off);
+#else
+    RT_NOREF(pReNative, fGstShwExcept);
 #endif
 
@@ -11703 +11704 @@
      * registers after returning from the call. Not sure if that's sensible or
      * not, though. */
+#ifndef IEMNATIVE_WITH_INSTRUCTION_COUNTING
     off = iemNativeRegFlushPendingWrites(pReNative, off);
+#else
+    /* The program counter is treated differently for now. */
+    off = iemNativeRegFlushPendingWrites(pReNative, off, RT_BIT_64(kIemNativeGstReg_Pc));
+#endif
 
 #ifdef IEMNATIVE_WITH_FREE_AND_FLUSH_VOLATILE_REGS_AT_TLB_LOOKUP
@@ -11754 +11760 @@
 #endif
 
+#ifdef IEMNATIVE_WITH_DELAYED_PC_UPDATING
+    if (pReNative->Core.offPc)
+    {
+        /*
+         * Update the program counter but restore it at the end of the TlbMiss branch.
+         * This should allow delaying more program counter updates for the TlbLookup and hit paths
+         * which are hopefully much more frequent, reducing the amount of memory accesses.
+         */
+        /* Allocate a temporary PC register. */
+        uint8_t const idxPcReg = iemNativeRegAllocTmpForGuestReg(pReNative, &off, kIemNativeGstReg_Pc, kIemNativeGstRegUse_ForUpdate);
+
+        /* Perform the addition and store the result. */
+        off = iemNativeEmitAddGprImm(pReNative, off, idxPcReg, pReNative->Core.offPc);
+        off = iemNativeEmitStoreGprToVCpuU64(pReNative, off, idxPcReg, RT_UOFFSETOF(VMCPU, cpum.GstCtx.rip));
+
+        /* Free and flush the PC register. */
+        iemNativeRegFreeTmp(pReNative, idxPcReg);
+        iemNativeRegFlushGuestShadowsByHostMask(pReNative, RT_BIT_32(idxPcReg));
+    }
+#endif
+
 #ifndef IEMNATIVE_WITH_FREE_AND_FLUSH_VOLATILE_REGS_AT_TLB_LOOKUP
     /* Save variables in volatile registers. */
@@ -11811 +11838 @@
     off = iemNativeVarRestoreVolatileRegsPostHlpCall(pReNative, off, fHstRegsNotToSave);
     off = iemNativeRegRestoreGuestShadowsInVolatileRegs(pReNative, off, TlbState.getActiveRegsWithShadows());
+#endif
+
+#ifdef IEMNATIVE_WITH_DELAYED_PC_UPDATING
+    if (pReNative->Core.offPc)
+    {
+        /*
+         * Time to restore the program counter to its original value.
+         */
+        /* Allocate a temporary PC register. */
+        uint8_t const idxPcReg = iemNativeRegAllocTmpForGuestReg(pReNative, &off, kIemNativeGstReg_Pc, kIemNativeGstRegUse_ForUpdate);
+
+        /* Restore the original value. */
+        off = iemNativeEmitSubGprImm(pReNative, off, idxPcReg, pReNative->Core.offPc);
+        off = iemNativeEmitStoreGprToVCpuU64(pReNative, off, idxPcReg, RT_UOFFSETOF(VMCPU, cpum.GstCtx.rip));
+
+        /* Free and flush the PC register. */
+        iemNativeRegFreeTmp(pReNative, idxPcReg);
+        iemNativeRegFlushGuestShadowsByHostMask(pReNative, RT_BIT_32(idxPcReg));
+    }
 #endif
 

trunk/src/VBox/VMM/include/IEMN8veRecompiler.h

@@ -1232 +1232 @@
 DECLHIDDEN(void)            iemNativeRegFreeVar(PIEMRECOMPILERSTATE pReNative, uint8_t idxHstReg, bool fFlushShadows) RT_NOEXCEPT;
 DECLHIDDEN(void)            iemNativeRegFreeAndFlushMask(PIEMRECOMPILERSTATE pReNative, uint32_t fHstRegMask) RT_NOEXCEPT;
-DECL_HIDDEN_THROW(uint32_t) iemNativeRegFlushPendingWrites(PIEMRECOMPILERSTATE pReNative, uint32_t off);
+DECL_HIDDEN_THROW(uint32_t) iemNativeRegFlushPendingWrites(PIEMRECOMPILERSTATE pReNative, uint32_t off, uint64_t fGstShwExept = 0);
 DECL_HIDDEN_THROW(uint32_t) iemNativeRegMoveAndFreeAndFlushAtCall(PIEMRECOMPILERSTATE pReNative, uint32_t off, uint8_t cArgs,
                                                                   uint32_t fKeepVars = 0);