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    SubjectRe: [PATCH v4 16/17] kvm: x86: Add support IA32_CORE_CAPABILITY MSR
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    On Mon, 2019-03-04 at 09:42 +0100, Paolo Bonzini wrote:
    > On 02/03/19 03:45, Fenghua Yu wrote:
    > > From: Xiaoyao Li <xiaoyao.li@linux.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).
    > >
    > > Please check the latest Intel Architecture Instruction Set Extensions
    > > and Future Features Programming Reference for more detailed information
    > > on the MSR and the split lock bit.
    > >
    > > 1. Expose it to user space as a feature-enumerating MSR, so that user
    > > space can query it.
    > >
    > > 2. Emualte MSR_IA32_CORE_CAPABILITY with vmx->core_capability. And add the
    > > get and set handler of MSR_IA32_CORE_CAPABILITY.
    > > For uesrspace, it can set this MSR when customizing features of guest,
    > > also it can read the value of this MSR of guest.
    > > For guest, as it's a feature-enumerating MSR, guest only can read it.
    > >
    > > Signed-off-by: Xiaoyao Li <xiaoyao.li@linux.intel.com>
    > > Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
    > > ---
    > > arch/x86/include/asm/kvm_host.h | 1 +
    > > arch/x86/kvm/vmx/vmx.c | 23 +++++++++++++++++++++++
    > > arch/x86/kvm/vmx/vmx.h | 1 +
    > > arch/x86/kvm/x86.c | 17 ++++++++++++++++-
    > > 4 files changed, 41 insertions(+), 1 deletion(-)
    > >
    > > diff --git a/arch/x86/include/asm/kvm_host.h
    > > b/arch/x86/include/asm/kvm_host.h
    > > index 180373360e34..208f15570d17 100644
    > > --- a/arch/x86/include/asm/kvm_host.h
    > > +++ b/arch/x86/include/asm/kvm_host.h
    > > @@ -1527,6 +1527,7 @@ 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/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
    > > index 30a6bcd735ec..3e03c6e1e558 100644
    > > --- a/arch/x86/kvm/vmx/vmx.c
    > > +++ b/arch/x86/kvm/vmx/vmx.c
    > > @@ -1679,6 +1679,12 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, struct
    > > msr_data *msr_info)
    > >
    > > msr_info->data = to_vmx(vcpu)->spec_ctrl;
    > > break;
    > > + case MSR_IA32_CORE_CAPABILITY:
    > > + if (!msr_info->host_initiated &&
    > > + !guest_cpuid_has(vcpu, X86_FEATURE_CORE_CAPABILITY))
    > > + return 1;
    > > + msr_info->data = vmx->core_capability;
    > > + break;
    > > case MSR_IA32_ARCH_CAPABILITIES:
    > > if (!msr_info->host_initiated &&
    > > !guest_cpuid_has(vcpu, X86_FEATURE_ARCH_CAPABILITIES))
    > > @@ -1891,6 +1897,21 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct
    > > msr_data *msr_info)
    > > vmx_disable_intercept_for_msr(vmx->vmcs01.msr_bitmap,
    > > MSR_IA32_PRED_CMD,
    > > MSR_TYPE_W);
    > > break;
    > > + case MSR_IA32_CORE_CAPABILITY:
    > > + if (!msr_info->host_initiated)
    > > + return 1;
    > > + if (data & ~CORE_CAP_SPLIT_LOCK_DETECT)
    > > + return 1;
    > > +
    > > + /*
    > > + * Since AC split lock is a hardware feature, and there is no
    > > + * software emulation yet, we cannot enable it for guest if
    > > + * host hardware doesn't support it.
    > > + */
    > > + if (!boot_cpu_has(X86_FEATURE_SPLIT_LOCK_DETECT))
    > > + data &= ~CORE_CAP_SPLIT_LOCK_DETECT;
    > > + vmx->core_capability = data;
    > > + break;
    > > case MSR_IA32_ARCH_CAPABILITIES:
    > > if (!msr_info->host_initiated)
    > > return 1;
    > > @@ -4083,6 +4104,8 @@ static void vmx_vcpu_setup(struct vcpu_vmx *vmx)
    > > ++vmx->nmsrs;
    > > }
    > >
    > > + vmx->core_capability = kvm_get_core_capability();
    > > +
    > > vmx->arch_capabilities = kvm_get_arch_capabilities();
    > >
    > > vm_exit_controls_init(vmx, vmx_vmexit_ctrl());
    > > diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
    > > index 0ac0a64c7790..cc22379991f3 100644
    > > --- a/arch/x86/kvm/vmx/vmx.h
    > > +++ b/arch/x86/kvm/vmx/vmx.h
    > > @@ -191,6 +191,7 @@ struct vcpu_vmx {
    > > u64 msr_guest_kernel_gs_base;
    > > #endif
    > >
    > > + u64 core_capability;
    > > u64 arch_capabilities;
    > > u64 spec_ctrl;
    > >
    > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
    > > index 941f932373d0..c3c9e3f2d08a 100644
    > > --- a/arch/x86/kvm/x86.c
    > > +++ b/arch/x86/kvm/x86.c
    > > @@ -1125,7 +1125,8 @@ static u32 msrs_to_save[] = {
    > > #endif
    > > MSR_IA32_TSC, MSR_IA32_CR_PAT, MSR_VM_HSAVE_PA,
    > > MSR_IA32_FEATURE_CONTROL, MSR_IA32_BNDCFGS, MSR_TSC_AUX,
    > > - MSR_IA32_SPEC_CTRL, MSR_IA32_ARCH_CAPABILITIES,
    > > + MSR_IA32_SPEC_CTRL, MSR_IA32_CORE_CAPABILITY,
    > > + MSR_IA32_ARCH_CAPABILITIES,
    > > MSR_IA32_RTIT_CTL, MSR_IA32_RTIT_STATUS, MSR_IA32_RTIT_CR3_MATCH,
    > > MSR_IA32_RTIT_OUTPUT_BASE, MSR_IA32_RTIT_OUTPUT_MASK,
    > > MSR_IA32_RTIT_ADDR0_A, MSR_IA32_RTIT_ADDR0_B,
    > > @@ -1197,11 +1198,22 @@ static u32 msr_based_features[] = {
    > >
    > > MSR_F10H_DECFG,
    > > MSR_IA32_UCODE_REV,
    > > + MSR_IA32_CORE_CAPABILITY,
    > > MSR_IA32_ARCH_CAPABILITIES,
    > > };
    > >
    > > static unsigned int num_msr_based_features;
    > >
    > > +u64 kvm_get_core_capability(void)
    > > +{
    > > + u64 data;
    > > +
    > > + rdmsrl_safe(MSR_IA32_CORE_CAPABILITY, &data);
    >
    > This patch should be merged with the previous patch. Also here you
    > should add:
    >
    > data &= CORE_CAP_SPLIT_LOCK_DETECT;
    >
    > so that non-virtualizable features are hidden and
    >
    > if (boot_cpu_has(X86_FEATURE_SPLIT_LOCK_DETECT))
    > data |= CORE_CAP_SPLIT_LOCK_DETECT;
    >
    > so that userspace gets "for free" the FMS list that will be added
    > later to the kernel.
    >
    > Thanks,
    >
    > Paolo

    You are right. I'll correct it in next version.

    > > +
    > > + return data;
    > > +}
    > > +EXPORT_SYMBOL_GPL(kvm_get_core_capability);
    > > +
    > > u64 kvm_get_arch_capabilities(void)
    > > {
    > > u64 data;
    > > @@ -1227,6 +1239,9 @@ EXPORT_SYMBOL_GPL(kvm_get_arch_capabilities);
    > > 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;
    > >
    >
    >

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