From: Vladislav Yaroshchuk <yaroshchuk2000@gmail.com>
Some guests (ex. Darwin-XNU) can attemp to read this MSR to retrieve and
validate CPU topology comparing it to ACPI MADT content
MSR description from Intel Manual:
35H: MSR_CORE_THREAD_COUNT: Configured State of Enabled Processor Core
Count and Logical Processor Count
Bits 15:0 THREAD_COUNT The number of logical processors that are
currently enabled in the physical package
Bits 31:16 Core_COUNT The number of processor cores that are currently
enabled in the physical package
Bits 63:32 Reserved
Signed-off-by: Vladislav Yaroshchuk <yaroshchuk2000@gmail.com>
---
target/i386/cpu.h | 2 ++
target/i386/hvf/x86_emu.c | 5 +++++
2 files changed, 7 insertions(+)
diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index d23a5b340a..cc35676b50 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -371,6 +371,8 @@ typedef enum X86Seg {
#define MSR_MTRRcap_FIXRANGE_SUPPORT (1 << 8)
#define MSR_MTRRcap_WC_SUPPORTED (1 << 10)
+#define MSR_CORE_THREAD_COUNT 0x35
+
#define MSR_IA32_SYSENTER_CS 0x174
#define MSR_IA32_SYSENTER_ESP 0x175
#define MSR_IA32_SYSENTER_EIP 0x176
diff --git a/target/i386/hvf/x86_emu.c b/target/i386/hvf/x86_emu.c
index da570e352b..2d362763fb 100644
--- a/target/i386/hvf/x86_emu.c
+++ b/target/i386/hvf/x86_emu.c
@@ -668,6 +668,7 @@ void simulate_rdmsr(struct CPUState *cpu)
{
X86CPU *x86_cpu = X86_CPU(cpu);
CPUX86State *env = &x86_cpu->env;
+ CPUState *cs = env_cpu(env);
uint32_t msr = ECX(env);
uint64_t val = 0;
@@ -745,6 +746,10 @@ void simulate_rdmsr(struct CPUState *cpu)
case MSR_MTRRdefType:
val = env->mtrr_deftype;
break;
+ case MSR_CORE_THREAD_COUNT:
+ val = cs->nr_threads * cs->nr_cores; /* thread count, bits 15..0 */
+ val |= ((uint32_t)cs->nr_cores << 16u); /* core count, bits 31..16 */
+ break;
default:
/* fprintf(stderr, "%s: unknown msr 0x%x\n", __func__, msr); */
val = 0;
--
2.28.0