Re: [RFC PATCH 3/3] x86/cpu/amd, kvm: Satisfy guest kernel reads of IC_CFG MSR
On 14/11/2015 11:37, Borislav Petkov wrote:
> From: Borislav Petkov
>
> The kernel accesses IC_CFG MSR (0xc0011021) on AMD because it checks
> whether the way access filter is enabled on some F15h models, and, if
> so, disables it.
>
> kvm doesn't handle that MSR access and complains about it, which can
> get really noisy in dmesg when one starts kvm guests all the time for
> testing. And it is useless anyway - guest kernel shouldn't be doing such
> changes anyway so tell it that that filter is disabled.
>
> Signed-off-by: Borislav Petkov
> Cc: Paolo Bonzini
> ---
> arch/x86/include/asm/msr-index.h | 1 +
> arch/x86/kernel/cpu/amd.c| 4 ++--
> arch/x86/kvm/svm.c | 17 +
> 3 files changed, 20 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/include/asm/msr-index.h
> b/arch/x86/include/asm/msr-index.h
> index 9f3905697f12..5384485f8569 100644
> --- a/arch/x86/include/asm/msr-index.h
> +++ b/arch/x86/include/asm/msr-index.h
> @@ -322,6 +322,7 @@
> #define MSR_F15H_PERF_CTR0xc0010201
> #define MSR_F15H_NB_PERF_CTL 0xc0010240
> #define MSR_F15H_NB_PERF_CTR 0xc0010241
> +#define MSR_F15H_IC_CFG 0xc0011021
>
> /* Fam 10h MSRs */
> #define MSR_FAM10H_MMIO_CONF_BASE0xc0010058
> diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
> index 4a70fc6d400a..1d76dcdf7e55 100644
> --- a/arch/x86/kernel/cpu/amd.c
> +++ b/arch/x86/kernel/cpu/amd.c
> @@ -665,9 +665,9 @@ static void init_amd_bd(struct cpuinfo_x86 *c)
>* Disable it on the affected CPUs.
>*/
> if ((c->x86_model >= 0x02) && (c->x86_model < 0x20)) {
> - if (!rdmsrl_safe(0xc0011021, &value) && !(value & 0x1E)) {
> + if (!rdmsrl_safe(MSR_F15H_IC_CFG, &value) && !(value & 0x1E)) {
> value |= 0x1E;
> - wrmsrl_safe(0xc0011021, value);
> + wrmsrl_safe(MSR_F15H_IC_CFG, value);
> }
> }
> }
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index 83a1c643f9a5..58b64c17c4a8 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -3053,6 +3053,23 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, struct
> msr_data *msr_info)
> case MSR_IA32_UCODE_REV:
> msr_info->data = 0x0165;
> break;
> + case MSR_F15H_IC_CFG: {
> +
> + int family, model;
> +
> + family = guest_cpuid_family(vcpu);
> + model = guest_cpuid_model(vcpu);
> +
> + if (family < 0 || model < 0)
> + return kvm_get_msr_common(vcpu, msr_info);
> +
> + msr_info->data = 0;
> +
> + if (family == 0x15 &&
> + (model >= 0x2 && model < 0x20))
> + msr_info->data = 0x1E;
> + }
> + break;
> default:
> return kvm_get_msr_common(vcpu, msr_info);
> }
>
Reviewed-by: Paolo Bonzini
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[RFC PATCH 3/3] x86/cpu/amd, kvm: Satisfy guest kernel reads of IC_CFG MSR
From: Borislav Petkov
The kernel accesses IC_CFG MSR (0xc0011021) on AMD because it checks
whether the way access filter is enabled on some F15h models, and, if
so, disables it.
kvm doesn't handle that MSR access and complains about it, which can
get really noisy in dmesg when one starts kvm guests all the time for
testing. And it is useless anyway - guest kernel shouldn't be doing such
changes anyway so tell it that that filter is disabled.
Signed-off-by: Borislav Petkov
Cc: Paolo Bonzini
---
arch/x86/include/asm/msr-index.h | 1 +
arch/x86/kernel/cpu/amd.c| 4 ++--
arch/x86/kvm/svm.c | 17 +
3 files changed, 20 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index 9f3905697f12..5384485f8569 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -322,6 +322,7 @@
#define MSR_F15H_PERF_CTR 0xc0010201
#define MSR_F15H_NB_PERF_CTL 0xc0010240
#define MSR_F15H_NB_PERF_CTR 0xc0010241
+#define MSR_F15H_IC_CFG0xc0011021
/* Fam 10h MSRs */
#define MSR_FAM10H_MMIO_CONF_BASE 0xc0010058
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 4a70fc6d400a..1d76dcdf7e55 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -665,9 +665,9 @@ static void init_amd_bd(struct cpuinfo_x86 *c)
* Disable it on the affected CPUs.
*/
if ((c->x86_model >= 0x02) && (c->x86_model < 0x20)) {
- if (!rdmsrl_safe(0xc0011021, &value) && !(value & 0x1E)) {
+ if (!rdmsrl_safe(MSR_F15H_IC_CFG, &value) && !(value & 0x1E)) {
value |= 0x1E;
- wrmsrl_safe(0xc0011021, value);
+ wrmsrl_safe(MSR_F15H_IC_CFG, value);
}
}
}
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 83a1c643f9a5..58b64c17c4a8 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -3053,6 +3053,23 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, struct
msr_data *msr_info)
case MSR_IA32_UCODE_REV:
msr_info->data = 0x0165;
break;
+ case MSR_F15H_IC_CFG: {
+
+ int family, model;
+
+ family = guest_cpuid_family(vcpu);
+ model = guest_cpuid_model(vcpu);
+
+ if (family < 0 || model < 0)
+ return kvm_get_msr_common(vcpu, msr_info);
+
+ msr_info->data = 0;
+
+ if (family == 0x15 &&
+ (model >= 0x2 && model < 0x20))
+ msr_info->data = 0x1E;
+ }
+ break;
default:
return kvm_get_msr_common(vcpu, msr_info);
}
--
2.3.5
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