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-rw-r--r--src/VBox/VMM/VMMR3/CPUMR3CpuId.cpp47
1 files changed, 47 insertions, 0 deletions
diff --git a/src/VBox/VMM/VMMR3/CPUMR3CpuId.cpp b/src/VBox/VMM/VMMR3/CPUMR3CpuId.cpp
index a2288250..04d8ac3c 100644
--- a/src/VBox/VMM/VMMR3/CPUMR3CpuId.cpp
+++ b/src/VBox/VMM/VMMR3/CPUMR3CpuId.cpp
@@ -2233,6 +2233,53 @@ static int cpumR3CpuIdSanitize(PVM pVM, PCPUM pCpum, PCPUMCPUIDCONFIG pConfig)
* 0x80000006 L2 cache information
*/
+ uSubLeaf = 0;
+ while ((pCurLeaf = cpumR3CpuIdGetExactLeaf(pCpum, UINT32_C(0x80000006), uSubLeaf)) != NULL)
+ {
+ if ( pCpum->GuestFeatures.enmCpuVendor == CPUMCPUVENDOR_AMD
+ || pCpum->GuestFeatures.enmCpuVendor == CPUMCPUVENDOR_HYGON)
+ {
+ /*
+ * Some AMD CPUs (e.g. Ryzen 7940HS) report zero L3 cache line size here and refer
+ * to CPUID Fn8000_001D. This triggers division by zero in Linux if the
+ * TopologyExtensions aka TOPOEXT bit in Fn8000_0001_ECX is not set, or if the kernel
+ * is old enough (e.g. Linux 3.13) that it does not know about the topology extension
+ * CPUID leaves.
+ * We put a non-zero value in the cache line size here, if possible the actual value
+ * gleaned from Fn8000_001D, or worst case a made-up valid number.
+ */
+ PCPUMCPUIDLEAF pTopoLeaf;
+ uint32_t uTopoSubLeaf;
+ uint32_t uCacheLineSize;
+
+ if ((pCurLeaf->uEdx & 0xff) == 0)
+ {
+ uTopoSubLeaf = 0;
+
+ uCacheLineSize = 64; /* Use 64-byte line size as a fallback. */
+
+ /* Find L3 cache information. Have to check the cache level in EAX. */
+ while ((pTopoLeaf = cpumR3CpuIdGetExactLeaf(pCpum, UINT32_C(0x8000001d), uTopoSubLeaf)) != NULL)
+ {
+ if (((pTopoLeaf->uEax >> 5) & 0x07) == 3) {
+ uCacheLineSize = (pTopoLeaf->uEbx & 0xfff) + 1;
+ /* Fn8000_0006 can't report power of two line sizes greater than 128. */
+ if (uCacheLineSize > 128)
+ uCacheLineSize = 128;
+
+ break;
+ }
+ uTopoSubLeaf++;
+ }
+
+ Assert(uCacheLineSize < 256);
+ pCurLeaf->uEdx |= uCacheLineSize;
+ LogRel(("CPUM: AMD L3 cache line size in CPUID leaf 0x80000006 was zero, adjusting to %u\n", uCacheLineSize));
+ }
+ }
+ uSubLeaf++;
+ }
+
/* Cpuid 0x80000007: Advanced Power Management Information.
* AMD: EAX: Processor feedback capabilities.
* EBX: RAS capabilites.