linux-kernel - Re: [EXTERNAL] [PATCH] KVM: x86: revalidate steal time cache if MSR value changes

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Date:   Mon, 08 Aug 2022 13:42:58 +0100
From:   David Woodhouse <dwmw2@...radead.org>
To:     Paolo Bonzini <pbonzini@...hat.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, Metin Kaya <metikaya@...zon.co.uk>
Cc:     Dave Young <ruyang@...hat.com>, Xiaoying Yan <yiyan@...hat.com>,
        "Dr . David Alan Gilbert" <dgilbert@...hat.com>,
        stable@...r.kernel.org
Subject: Re: [EXTERNAL] [PATCH] KVM: x86: revalidate steal time cache if MSR
 value changes

On Thu, 2022-08-04 at 15:28 +0200, Paolo Bonzini wrote:
> @@ -3397,13 +3398,12 @@ static void record_steal_time(struct kvm_vcpu *vcpu)=
>         slots = kvm_memslots(vcpu->kvm);
> 
>         if (unlikely(slots->generation != ghc->generation ||
> +                    gpa != ghc->gpa ||
>                      kvm_is_error_hva(ghc->hva) || !ghc->memslot)) {

If we have to fix the same bug in two open-coded versions of the same
thing then surely it's time for something like...

static inline bool kvm_gfn_to_hva_cache_valid(struct kvm *kvm,
				              struct gfn_to_hva_cache *ghc,
					      gpa_t gpa)
{
	struct kvm_memslots *slots = kvm_memslots(kvm);

	return !unlikely(slots->generation != ghc->generation ||
			 gpa != ghc->gpa ||
			 kvm_is_error_hva(ghc->hva) || !ghc->memslot);
}

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