On Fri, 2023-11-24 at 00:53 -0500, Yang Weijiang wrote:
> Tweak the code a bit to facilitate resetting more xstate components in
> the future, e.g., adding CET's xstate-managed MSRs.
>
> No functional change intended.
>
> Signed-off-by: Yang Weijiang <weijiang.yang@xxxxxxxxx>
> ---
> arch/x86/kvm/x86.c | 15 ++++++++++++---
> 1 file changed, 12 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index b9c2c0cd4cf5..16b4f2dd138a 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -12132,6 +12132,11 @@ void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
> static_branch_dec(&kvm_has_noapic_vcpu);
> }
>
> +static inline bool is_xstate_reset_needed(void)
> +{
> + return kvm_cpu_cap_has(X86_FEATURE_MPX);
> +}
> +
> void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
> {
> struct kvm_cpuid_entry2 *cpuid_0x1;
> @@ -12189,7 +12194,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
> kvm_async_pf_hash_reset(vcpu);
> vcpu->arch.apf.halted = false;
>
> - if (vcpu->arch.guest_fpu.fpstate && kvm_mpx_supported()) {
> + if (vcpu->arch.guest_fpu.fpstate && is_xstate_reset_needed()) {
> struct fpstate *fpstate = vcpu->arch.guest_fpu.fpstate;
>
> /*
> @@ -12199,8 +12204,12 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
> if (init_event)
> kvm_put_guest_fpu(vcpu);
>
> - fpstate_clear_xstate_component(fpstate, XFEATURE_BNDREGS);
> - fpstate_clear_xstate_component(fpstate, XFEATURE_BNDCSR);
> + if (kvm_cpu_cap_has(X86_FEATURE_MPX)) {
> + fpstate_clear_xstate_component(fpstate,
> + XFEATURE_BNDREGS);
> + fpstate_clear_xstate_component(fpstate,
> + XFEATURE_BNDCSR);
> + }
>
> if (init_event)
> kvm_load_guest_fpu(vcpu);
Reviewed-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
Best regards,
Maxim Levitsky
