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Date: Wed, 13 Mar 2019 09:15:18 +0100
From: Paolo Bonzini <pbonzini@...hat.com>
To: Fenghua Yu <fenghua.yu@...el.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, H Peter Anvin <hpa@...or.com>,
Dave Hansen <dave.hansen@...el.com>,
Ashok Raj <ashok.raj@...el.com>,
Peter Zijlstra <peterz@...radead.org>,
Xiaoyao Li <xiaoyao.li@...el.com>,
Michael Chan <michael.chan@...adcom.com>,
Ravi V Shankar <ravi.v.shankar@...el.com>
Cc: linux-kernel <linux-kernel@...r.kernel.org>, x86 <x86@...nel.org>,
linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
kvm@...r.kernel.org, Xiaoyao Li <xiaoyao.li@...ux.intel.com>
Subject: Re: [PATCH v5 10/18] kvm/x86: Emulate MSR IA32_CORE_CAPABILITY
On 13/03/19 00:00, Fenghua Yu wrote:
> From: Xiaoyao Li <xiaoyao.li@...ux.intel.com>
>
> MSR IA32_CORE_CAPABILITY is a feature-enumerating MSR, bit 5 of which
> reports the capability of enabling detection of split locks (will be
> supported on future processors based on Tremont microarchitecture and
> later).
>
> CPUID.(EAX=7H,ECX=0):EDX[30] will enumerate the presence of the
> IA32_CORE_CAPABILITY MSR.
>
> Please check the latest Intel 64 and IA-32 Architectures Software
> Developer's Manual for more detailed information on the MSR and
> the split lock bit.
>
> Since MSR_IA32_CORE_CAPABILITY is a feature-enumerating MSR, we can
> emulate it in software regardless of host's capability. What we need to
> do is to set the right value of it to report the capability of guest.
>
> In this patch we just set the guest's core_capability as 0, because we
> haven't added support of the features it indicates to guest. It's for
> bisectability.
>
> Signed-off-by: Xiaoyao Li <xiaoyao.li@...ux.intel.com>
> Signed-off-by: Fenghua Yu <fenghua.yu@...el.com>
> ---
> arch/x86/include/asm/kvm_host.h | 2 ++
> arch/x86/kvm/cpuid.c | 6 ++++++
> arch/x86/kvm/x86.c | 24 ++++++++++++++++++++++++
> 3 files changed, 32 insertions(+)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 180373360e34..2c53df4a5a2a 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -570,6 +570,7 @@ struct kvm_vcpu_arch {
> bool tpr_access_reporting;
> u64 ia32_xss;
> u64 microcode_version;
> + u64 core_capability;
>
> /*
> * Paging state of the vcpu
> @@ -1527,6 +1528,7 @@ int kvm_pv_send_ipi(struct kvm *kvm, unsigned long ipi_bitmap_low,
> unsigned long icr, int op_64_bit);
>
> u64 kvm_get_arch_capabilities(void);
> +u64 kvm_get_core_capability(void);
> void kvm_define_shared_msr(unsigned index, u32 msr);
> int kvm_set_shared_msr(unsigned index, u64 val, u64 mask);
>
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index c07958b59f50..b7fb1822a1e5 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -505,6 +505,12 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
> * if the host doesn't support it.
> */
> entry->edx |= F(ARCH_CAPABILITIES);
> + /*
> + * Since we emulate MSR IA32_CORE_CAPABILITY in
> + * software, we can always enable it for guest
> + * regardless of host's capability.
> + */
> + entry->edx |= F(CORE_CAPABILITY);
> } else {
> entry->ebx = 0;
> entry->ecx = 0;
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 941f932373d0..e20cbb8c2b74 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -1158,6 +1158,7 @@ static u32 emulated_msrs[] = {
>
> MSR_IA32_TSC_ADJUST,
> MSR_IA32_TSCDEADLINE,
> + MSR_IA32_CORE_CAPABILITY,
> MSR_IA32_MISC_ENABLE,
> MSR_IA32_MCG_STATUS,
> MSR_IA32_MCG_CTL,
> @@ -1197,6 +1198,7 @@ static u32 msr_based_features[] = {
>
> MSR_F10H_DECFG,
> MSR_IA32_UCODE_REV,
> + MSR_IA32_CORE_CAPABILITY,
> MSR_IA32_ARCH_CAPABILITIES,
> };
>
> @@ -1224,9 +1226,18 @@ u64 kvm_get_arch_capabilities(void)
> }
> EXPORT_SYMBOL_GPL(kvm_get_arch_capabilities);
>
> +u64 kvm_get_core_capability(void)
> +{
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(kvm_get_core_capability);
> +
> static int kvm_get_msr_feature(struct kvm_msr_entry *msr)
> {
> switch (msr->index) {
> + case MSR_IA32_CORE_CAPABILITY:
> + msr->data = kvm_get_core_capability();
> + break;
> case MSR_IA32_ARCH_CAPABILITIES:
> msr->data = kvm_get_arch_capabilities();
> break;
> @@ -2445,6 +2456,12 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
> break;
> case MSR_EFER:
> return set_efer(vcpu, data);
> + case MSR_IA32_CORE_CAPABILITY:
> + if (!msr_info->host_initiated)
> + return 1;
> +
> + vcpu->arch.core_capability = data;
> + break;
> case MSR_K7_HWCR:
> data &= ~(u64)0x40; /* ignore flush filter disable */
> data &= ~(u64)0x100; /* ignore ignne emulation enable */
> @@ -2750,6 +2767,12 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
> case MSR_IA32_TSC:
> msr_info->data = kvm_scale_tsc(vcpu, rdtsc()) + vcpu->arch.tsc_offset;
> break;
> + case MSR_IA32_CORE_CAPABILITY:
> + if (!msr_info->host_initiated &&
> + !guest_cpuid_has(vcpu, X86_FEATURE_CORE_CAPABILITY))
> + return 1;
> + msr_info->data = vcpu->arch.core_capability;
> + break;
> case MSR_MTRRcap:
> case 0x200 ... 0x2ff:
> return kvm_mtrr_get_msr(vcpu, msr_info->index, &msr_info->data);
> @@ -8725,6 +8748,7 @@ struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm,
>
> int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
> {
> + vcpu->arch.core_capability = kvm_get_core_capability();
> vcpu->arch.msr_platform_info = MSR_PLATFORM_INFO_CPUID_FAULT;
> kvm_vcpu_mtrr_init(vcpu);
> vcpu_load(vcpu);
>
Acked-by: Paolo Bonzini <pbonzini@...hat.com>
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