linux-kernel - Re: [PATCH] x86/kvm: Remove unused virt to phys translation in kvm_guest_cpu

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Date:   Fri, 21 Oct 2022 13:32:27 +0200
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     Rafael Mendonca <rafaelmendsr@...il.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Wanpeng Li <wanpengli@...cent.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>, Andy Lutomirski <luto@...nel.org>
Subject: Re: [PATCH] x86/kvm: Remove unused virt to phys translation in
 kvm_guest_cpu_init()

Rafael Mendonca <rafaelmendsr@...il.com> writes:

> Presumably, this was introduced due to a conflict resolution with
> commit ef68017eb570 ("x86/kvm: Handle async page faults directly through
> do_page_fault()"), given that the last posted version [1] of the blamed
> commit was not based on the aforementioned commit.
>
> [1] https://lore.kernel.org/kvm/20200525144125.143875-9-vkuznets@redhat.com/
>
> Fixes: b1d405751cd5 ("KVM: x86: Switch KVM guest to using interrupts for page ready APF delivery")

Indeed, this looks like a mid-air collision happened upon commit/merge.

> Signed-off-by: Rafael Mendonca <rafaelmendsr@...il.com>
> ---
>  arch/x86/kernel/kvm.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
> index d4e48b4a438b..cf886f86038a 100644
> --- a/arch/x86/kernel/kvm.c
> +++ b/arch/x86/kernel/kvm.c
> @@ -349,7 +349,7 @@ static notrace void kvm_guest_apic_eoi_write(u32 reg, u32 val)
>  static void kvm_guest_cpu_init(void)
>  {
>  	if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) {
> -		u64 pa = slow_virt_to_phys(this_cpu_ptr(&apf_reason));
> +		u64 pa;
>  
>  		WARN_ON_ONCE(!static_branch_likely(&kvm_async_pf_enabled));

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

-- 
Vitaly