linux-kernel - Re: [PATCH 1/3] KVM: x86: move kvm_inject_gp up from kvm_set

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Date:   Tue, 2 Feb 2021 18:24:30 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: Re: [PATCH 1/3] KVM: x86: move kvm_inject_gp up from kvm_set_xcr to
 callers

On 02/02/21 18:19, Sean Christopherson wrote:
> On Tue, Feb 02, 2021, Paolo Bonzini wrote:
>> Push the injection of #GP up to the callers, so that they can just use
>> kvm_complete_insn_gp.
> 
> The SVM and VMX code is identical, IMO we should push all the code to x86.c
> instead of shuffling it around.
> 
> I'd also like to change svm_exit_handlers to take @vcpu instead of @svm so that
> SVM can invoke common handlers directly.
> 
> If you agree, I'll send a proper series to do the above, plus whatever other
> cleanups I find, e.g. INVD, WBINVD, etc...

Yes, why not.  There's a lot of things that are only slightly different 
between VMX and SVM for no particular reason.

Paolo

> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index fa7b2df6422b..bf917efde35c 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1530,7 +1530,7 @@ int kvm_get_dr(struct kvm_vcpu *vcpu, int dr, unsigned long *val);
>   unsigned long kvm_get_cr8(struct kvm_vcpu *vcpu);
>   void kvm_lmsw(struct kvm_vcpu *vcpu, unsigned long msw);
>   void kvm_get_cs_db_l_bits(struct kvm_vcpu *vcpu, int *db, int *l);
> -int kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr);
> +int kvm_emulate_xsetbv(struct kvm_vcpu *vcpu);
> 
>   int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr);
>   int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr);
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index 687876211ebe..842a74d88f1b 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -2334,14 +2334,7 @@ static int wbinvd_interception(struct vcpu_svm *svm)
> 
>   static int xsetbv_interception(struct vcpu_svm *svm)
>   {
> -       u64 new_bv = kvm_read_edx_eax(&svm->vcpu);
> -       u32 index = kvm_rcx_read(&svm->vcpu);
> -
> -       if (kvm_set_xcr(&svm->vcpu, index, new_bv) == 0) {
> -               return kvm_skip_emulated_instruction(&svm->vcpu);
> -       }
> -
> -       return 1;
> +       return kvm_emulate_xsetbv(&svm->vcpu);
>   }
> 
>   static int rdpru_interception(struct vcpu_svm *svm)
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index cf0c397dc3eb..474a169835de 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -5218,16 +5218,6 @@ static int handle_wbinvd(struct kvm_vcpu *vcpu)
>          return kvm_emulate_wbinvd(vcpu);
>   }
> 
> -static int handle_xsetbv(struct kvm_vcpu *vcpu)
> -{
> -       u64 new_bv = kvm_read_edx_eax(vcpu);
> -       u32 index = kvm_rcx_read(vcpu);
> -
> -       if (kvm_set_xcr(vcpu, index, new_bv) == 0)
> -               return kvm_skip_emulated_instruction(vcpu);
> -       return 1;
> -}
> -
>   static int handle_apic_access(struct kvm_vcpu *vcpu)
>   {
>          if (likely(fasteoi)) {
> @@ -5689,7 +5679,7 @@ static int (*kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu) = {
>          [EXIT_REASON_APIC_WRITE]              = handle_apic_write,
>          [EXIT_REASON_EOI_INDUCED]             = handle_apic_eoi_induced,
>          [EXIT_REASON_WBINVD]                  = handle_wbinvd,
> -       [EXIT_REASON_XSETBV]                  = handle_xsetbv,
> +       [EXIT_REASON_XSETBV]                  = kvm_emulate_xsetbv,
>          [EXIT_REASON_TASK_SWITCH]             = handle_task_switch,
>          [EXIT_REASON_MCE_DURING_VMENTRY]      = handle_machine_check,
>          [EXIT_REASON_GDTR_IDTR]               = handle_desc,
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 14fb8a138ec3..ef630f8d8bd2 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -984,16 +984,17 @@ static int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr)
>          return 0;
>   }
> 
> -int kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr)
> +int kvm_emulate_xsetbv(struct kvm_vcpu *vcpu)
>   {
>          if (static_call(kvm_x86_get_cpl)(vcpu) != 0 ||
> -           __kvm_set_xcr(vcpu, index, xcr)) {
> +           __kvm_set_xcr(vcpu, kvm_rcx_read(vcpu), kvm_read_edx_eax(vcpu))) {
>                  kvm_inject_gp(vcpu, 0);
>                  return 1;
>          }
> -       return 0;
> +
> +       return kvm_skip_emulated_instruction(vcpu);
>   }
> -EXPORT_SYMBOL_GPL(kvm_set_xcr);
> +EXPORT_SYMBOL_GPL(kvm_emulate_xsetbv);
> 
>   bool kvm_is_valid_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
>   {
> 
>