The CPUID_EXTENDED_TOPOLOGY CPUID leaf takes a subleaf as input when
returning CPUID information. However, the AsmCpuid() function does not
zero out ECX before the CPUID instruction, so the input leaf is used as
the sub-leaf for the CPUID request and returns erroneous/invalid CPUID
data, since the intent of the request was to get data related to sub-leaf
0. Instead, use AsmCpuidEx() for the CPUID_EXTENDED_TOPOLOGY leaf.
Fixes: d4d7c9ad5fe5 ("UefiCpuPkg/MpInitLib: use BSP to do extended ...")
Signed-off-by: Tom Lendacky <thomas.lenda...@amd.com>
---
UefiCpuPkg/Library/MpInitLib/AmdSev.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/UefiCpuPkg/Library/MpInitLib/AmdSev.c
b/UefiCpuPkg/Library/MpInitLib/AmdSev.c
index bda4960f6fd3..d34f9513e002 100644
--- a/UefiCpuPkg/Library/MpInitLib/AmdSev.c
+++ b/UefiCpuPkg/Library/MpInitLib/AmdSev.c
@@ -256,7 +256,14 @@ FillExchangeInfoDataSevEs (
if (StdRangeMax >= CPUID_EXTENDED_TOPOLOGY) {
CPUID_EXTENDED_TOPOLOGY_EBX ExtTopoEbx;
- AsmCpuid (CPUID_EXTENDED_TOPOLOGY, NULL, &ExtTopoEbx.Uint32, NULL, NULL);
+ AsmCpuidEx (
+ CPUID_EXTENDED_TOPOLOGY,
+ 0,
+ NULL,
+ &ExtTopoEbx.Uint32,
+ NULL,
+ NULL
+ );
ExchangeInfo->ExtTopoAvail = !!ExtTopoEbx.Bits.LogicalProcessors;
}
}
--
2.42.0
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