On 8/21/2023 11:22 AM, Hao Xiang wrote:
For intel platform, The BzyMhz field of Turbostat shows zero
due to the missing of part msr bits of MSR_PLATFORM_INFO.
Acquire necessary msr bits, and expose following msr info to guest,
to make sure guest can get correct turbo frequency info.
MSR_PLATFORM_INFO bits
bit 15:8, Maximum Non-Turbo Ratio (MAX_NON_TURBO_LIM_RATIO)
bit 47:40, Maximum Efficiency Ratio (MAX_EFFICIENCY_RATIO)
I'm curious. How are they related to turbo frequency info?
bits 15:8, tell the Non-turbo frequency and bits 47:40 tells the min
frequency.
Signed-off-by: Hao Xiang <hao.xiang@xxxxxxxxxxxxxxxxx>
---
arch/x86/include/asm/msr-index.h | 4 ++++
arch/x86/kvm/x86.c | 25 ++++++++++++++++++++++++-
2 files changed, 28 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index 1d11135..1c8a276 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -68,6 +68,10 @@
#define MSR_PLATFORM_INFO 0x000000ce
#define MSR_PLATFORM_INFO_CPUID_FAULT_BIT 31
#define MSR_PLATFORM_INFO_CPUID_FAULT BIT_ULL(MSR_PLATFORM_INFO_CPUID_FAULT_BIT)
+/* MSR_PLATFORM_INFO bit 15:8, Maximum Non-Turbo Ratio (MAX_NON_TURBO_LIM_RATIO) */
+#define MSR_PLATFORM_INFO_MAX_NON_TURBO_LIM_RATIO 0x00000000ff00
+/* MSR_PLATFORM_INFO bit 47:40, Maximum Efficiency Ratio (MAX_EFFICIENCY_RATIO) */
+#define MSR_PLATFORM_INFO_MAX_EFFICIENCY_RATIO 0xff0000000000
They are mask not the value, please name them with _MASK suffix.
#define MSR_IA32_UMWAIT_CONTROL 0xe1
#define MSR_IA32_UMWAIT_CONTROL_C02_DISABLE BIT(0)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c381770..621c3e1 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1679,6 +1679,29 @@ static u64 kvm_get_arch_capabilities(void)
return data;
}
+
+static u64 kvm_get_msr_platform_info(void)
+{
+ u64 msr_platform_info = 0;
+
+ rdmsrl_safe(MSR_PLATFORM_INFO, &msr_platform_info);
+ /*
+ * MSR_PLATFORM_INFO bits:
+ * bit 15:8, Maximum Non-Turbo Ratio (MAX_NON_TURBO_LIM_RATIO)
+ * bit 31, CPUID Faulting Enabled (CPUID_FAULTING_EN)
+ * bit 47:40, Maximum Efficiency Ratio (MAX_EFFICIENCY_RATIO)
+ *
+ * Emulate part msr bits, expose above msr info to guest,
+ * to make sure guest can get correct turbo frequency info.
+ */
+
+ msr_platform_info &= (MSR_PLATFORM_INFO_MAX_NON_TURBO_RATIO |
+ MSR_PLATFORM_INFO_MAX_EFFICIENCY_RATIO);
+ msr_platform_info |= MSR_PLATFORM_INFO_CPUID_FAULT;
+
+ return msr_platform_info;
+}
+
static int kvm_get_msr_feature(struct kvm_msr_entry *msr)
{
switch (msr->index) {
@@ -11919,7 +11942,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
goto free_guest_fpu;
vcpu->arch.arch_capabilities = kvm_get_arch_capabilities();
- vcpu->arch.msr_platform_info = MSR_PLATFORM_INFO_CPUID_FAULT;
+ vcpu->arch.msr_platform_info = kvm_get_msr_platform_info();
kvm_xen_init_vcpu(vcpu);
kvm_vcpu_mtrr_init(vcpu);
vcpu_load(vcpu);
