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    SubjectRe: [PATCH 21/61] KVM: x86: Use supported_xcr0 to detect MPX support
    Date
    Sean Christopherson <sean.j.christopherson@intel.com> writes:

    > Query supported_xcr0 when checking for MPX support instead of invoking
    > ->mpx_supported() and drop ->mpx_supported() as kvm_mpx_supported() was
    > its last user. Rename vmx_mpx_supported() to cpu_has_vmx_mpx() to
    > better align with VMX/VMCS nomenclature.
    >
    > Modify VMX's adjustment of xcr0 to call cpus_has_vmx_mpx() (renamed from
    > vmx_mpx_supported()) directly to avoid reading supported_xcr0 before
    > it's fully configured.
    >
    > No functional change intended.
    >
    > Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
    > ---
    > arch/x86/include/asm/kvm_host.h | 2 +-
    > arch/x86/kvm/cpuid.c | 3 +--
    > arch/x86/kvm/svm.c | 6 ------
    > arch/x86/kvm/vmx/capabilities.h | 2 +-
    > arch/x86/kvm/vmx/vmx.c | 3 +--
    > 5 files changed, 4 insertions(+), 12 deletions(-)
    >
    > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
    > index 77d206a93658..85f0d96cfeb2 100644
    > --- a/arch/x86/include/asm/kvm_host.h
    > +++ b/arch/x86/include/asm/kvm_host.h
    > @@ -1163,7 +1163,7 @@ struct kvm_x86_ops {
    > enum x86_intercept_stage stage);
    > void (*handle_exit_irqoff)(struct kvm_vcpu *vcpu,
    > enum exit_fastpath_completion *exit_fastpath);
    > - bool (*mpx_supported)(void);
    > +
    > bool (*xsaves_supported)(void);
    > bool (*umip_emulated)(void);
    > bool (*pt_supported)(void);
    > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
    > index b9763eb711cb..84006cc4007c 100644
    > --- a/arch/x86/kvm/cpuid.c
    > +++ b/arch/x86/kvm/cpuid.c
    > @@ -47,8 +47,7 @@ static u32 xstate_required_size(u64 xstate_bv, bool compacted)
    >
    > bool kvm_mpx_supported(void)
    > {
    > - return ((host_xcr0 & (XFEATURE_MASK_BNDREGS | XFEATURE_MASK_BNDCSR))
    > - && kvm_x86_ops->mpx_supported());
    > + return supported_xcr0 & (XFEATURE_MASK_BNDREGS | XFEATURE_MASK_BNDCSR);
    > }
    > EXPORT_SYMBOL_GPL(kvm_mpx_supported);
    >
    > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
    > index af096c4f9c5f..3c7ddaff405d 100644
    > --- a/arch/x86/kvm/svm.c
    > +++ b/arch/x86/kvm/svm.c
    > @@ -6082,11 +6082,6 @@ static bool svm_invpcid_supported(void)
    > return false;
    > }
    >
    > -static bool svm_mpx_supported(void)
    > -{
    > - return false;
    > -}
    > -
    > static bool svm_xsaves_supported(void)
    > {
    > return boot_cpu_has(X86_FEATURE_XSAVES);
    > @@ -7468,7 +7463,6 @@ static struct kvm_x86_ops svm_x86_ops __ro_after_init = {
    >
    > .rdtscp_supported = svm_rdtscp_supported,
    > .invpcid_supported = svm_invpcid_supported,
    > - .mpx_supported = svm_mpx_supported,
    > .xsaves_supported = svm_xsaves_supported,
    > .umip_emulated = svm_umip_emulated,
    > .pt_supported = svm_pt_supported,
    > diff --git a/arch/x86/kvm/vmx/capabilities.h b/arch/x86/kvm/vmx/capabilities.h
    > index 1a6a99382e94..0a0b1494a934 100644
    > --- a/arch/x86/kvm/vmx/capabilities.h
    > +++ b/arch/x86/kvm/vmx/capabilities.h
    > @@ -100,7 +100,7 @@ static inline bool cpu_has_load_perf_global_ctrl(void)
    > (vmcs_config.vmexit_ctrl & VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL);
    > }
    >
    > -static inline bool vmx_mpx_supported(void)
    > +static inline bool cpu_has_vmx_mpx(void)
    > {
    > return (vmcs_config.vmexit_ctrl & VM_EXIT_CLEAR_BNDCFGS) &&
    > (vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_BNDCFGS);
    > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
    > index 32a84ec15064..98fd651f7f7e 100644
    > --- a/arch/x86/kvm/vmx/vmx.c
    > +++ b/arch/x86/kvm/vmx/vmx.c
    > @@ -7590,7 +7590,7 @@ static __init int hardware_setup(void)
    > WARN_ONCE(host_bndcfgs, "KVM: BNDCFGS in host will be lost");
    > }
    >
    > - if (!kvm_mpx_supported())
    > + if (!cpu_has_vmx_mpx())
    > supported_xcr0 &= ~(XFEATURE_MASK_BNDREGS |
    > XFEATURE_MASK_BNDCSR);
    >
    > @@ -7857,7 +7857,6 @@ static struct kvm_x86_ops vmx_x86_ops __ro_after_init = {
    >
    > .check_intercept = vmx_check_intercept,
    > .handle_exit_irqoff = vmx_handle_exit_irqoff,
    > - .mpx_supported = vmx_mpx_supported,
    > .xsaves_supported = vmx_xsaves_supported,
    > .umip_emulated = vmx_umip_emulated,
    > .pt_supported = vmx_pt_supported,

    Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>

    --
    Vitaly

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