Changeset 100625 in vbox for trunk

Timestamp:

Jul 18, 2023 10:10:57 AM (17 months ago)

Author:

vboxsync

Message:

CPUID: Expose AMD XSaveErPtr CPUID bit to guests. Eliminates fxsave_leak bug in Linux.

File:

• trunk/src/VBox/VMM/VMMR3/CPUMR3CpuId.cpp (modified) (4 diffs)

trunk/src/VBox/VMM/VMMR3/CPUMR3CpuId.cpp

@@ -2267 +2267 @@
 
     /* Cpuid 0x80000008:
-     * AMD:               EBX, EDX - reserved
-     *                    EAX: Virtual/Physical/Guest address Size
+     * AMD:               EAX: Long Mode Size Identifiers
+     *                    EBX: Extended Feature Identifiers
      *                    ECX: Number of cores + APICIdCoreIdSize
+     *                    EDX: RDPRU Register Identifier Range
      * Intel:             EAX: Virtual/Physical address Size
      *                    EBX, ECX, EDX - reserved
@@ -2277 +2278 @@
      * We only expose the virtual+pysical address size to the guest atm.
      * On AMD we set the core count, but not the apic id stuff as we're
-     * currently not doing the apic id assignments in a complatible manner.
+     * currently not doing the apic id assignments in a compatible manner.
      */
     uSubLeaf = 0;
@@ -2283 +2284 @@
     {
         pCurLeaf->uEax &= UINT32_C(0x0000ffff); /* Virtual & physical address sizes only. */
-        pCurLeaf->uEbx  = 0;  /* reserved - [12] == IBPB */
+        if (   pCpum->GuestFeatures.enmCpuVendor == CPUMCPUVENDOR_AMD
+            || pCpum->GuestFeatures.enmCpuVendor == CPUMCPUVENDOR_HYGON)
+        {
+            /* Expose XSaveErPtr aka RstrFpErrPtrs to guest. */
+            pCurLeaf->uEbx &= X86_CPUID_AMD_EFEID_EBX_XSAVE_ER_PTR;  /* reserved - [12] == IBPB */
+        }
+        else
+            pCurLeaf->uEbx  = 0;    /* reserved */
+
         pCurLeaf->uEdx  = 0;  /* reserved */
 
@@ -4994 +5003 @@
     DBGFREGSUBFIELD_RO("CLZERO\0"       "Clear zero instruction (cacheline)",            0, 1, 0),
     DBGFREGSUBFIELD_RO("IRPerf\0"       "Instructions retired count support",            1, 1, 0),
-    DBGFREGSUBFIELD_RO("XSaveErPtr\0"   "Save/restore error pointers (FXSAVE/RSTOR*)",   2, 1, 0),
+    DBGFREGSUBFIELD_RO("XSaveErPtr\0"   "Save/restore error pointers (FXSAVE/RSTOR)",    2, 1, 0),
     DBGFREGSUBFIELD_RO("RDPRU\0"        "RDPRU instruction",                             4, 1, 0),
     DBGFREGSUBFIELD_RO("MCOMMIT\0"      "MCOMMIT instruction",                           8, 1, 0),