Re: [PATCH 2/3] KVM: x86: use kvm_complete_insn_gp in emulating RDMSR/WRMSR
From: Tom Lendacky
Date: Mon Dec 14 2020 - 15:53:35 EST
On 12/14/20 12:32 PM, Paolo Bonzini wrote:
> Simplify the four functions that handle {kernel,user} {rd,wr}msr, there
> is still some repetition between the two instances of rdmsr but the
> whole business of calling kvm_inject_gp and kvm_skip_emulated_instruction
> can be unified nicely.
>
> Because complete_emulated_wrmsr now becomes essentially a call to
> kvm_complete_insn_gp, remove complete_emulated_msr.
>
> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Just two minor nits below.
Reviewed-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index a3fdc16cfd6f..2f1bc52e70c0 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -1634,27 +1634,20 @@ int kvm_set_msr(struct kvm_vcpu *vcpu, u32 index, u64 data)
> }
> EXPORT_SYMBOL_GPL(kvm_set_msr);
>
>
> /* MSR read failed? Inject a #GP */
This comment isn't accurate any more, maybe just delete it?
> - if (r) {
> + if (!r) {
> + trace_kvm_msr_read(ecx, data);
> +
> + kvm_rax_write(vcpu, data & -1u);
> + kvm_rdx_write(vcpu, (data >> 32) & -1u);
> + } else {
> trace_kvm_msr_read_ex(ecx);
> - kvm_inject_gp(vcpu, 0);
> - return 1;
> }
>
> - trace_kvm_msr_read(ecx, data);
> -
> - kvm_rax_write(vcpu, data & -1u);
> - kvm_rdx_write(vcpu, (data >> 32) & -1u);
> - return kvm_skip_emulated_instruction(vcpu);
> + return kvm_complete_insn_gp(vcpu, r);
> }
> EXPORT_SYMBOL_GPL(kvm_emulate_rdmsr);
>
> @@ -1750,14 +1742,12 @@ int kvm_emulate_wrmsr(struct kvm_vcpu *vcpu)
> return r;
>
> /* MSR write failed? Inject a #GP */
Ditto on this comment.
Thanks,
Tom
> - if (r > 0) {
> + if (!r)
> + trace_kvm_msr_write(ecx, data);
> + else
> trace_kvm_msr_write_ex(ecx, data);
> - kvm_inject_gp(vcpu, 0);
> - return 1;
> - }
>
> - trace_kvm_msr_write(ecx, data);
> - return kvm_skip_emulated_instruction(vcpu);
> + return kvm_complete_insn_gp(vcpu, r);
> }
> EXPORT_SYMBOL_GPL(kvm_emulate_wrmsr);
>
>