linux-kernel - Re: [PATCH] KVM: x86: Deplete Paolo's brown paper bag supply by one

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Message-ID: <02fd5a73-1120-6e43-cc5f-ecef331fcd8a@redhat.com>
Date:   Thu, 7 Apr 2022 09:07:35 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] KVM: x86: Deplete Paolo's brown paper bag supply by one

On 4/7/22 00:51, Sean Christopherson wrote:
> Fix an inverted check on CR0.PG when computing the cpu_role, the MMU is
> direct and all CR4 bits ignored if paging is disabled, not enabled.
> 
> Fixes: d73678dc11ec ("KVM: x86/mmu: split cpu_role from mmu_role")
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> ---
> 
> I haven't done much testing on the rest of the MMU role patches, this just
> popped up in very, very basic testing ;-)  I assume this will be squashed,
> hence the snarky shortlog.

It certainly got my attention... squashed, thanks. :)

Paolo

>   arch/x86/kvm/mmu/mmu.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index e41d7bba7a65..ab24fc161bac 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -4699,7 +4699,7 @@ kvm_calc_cpu_role(struct kvm_vcpu *vcpu, const struct kvm_mmu_role_regs *regs)
>   	role.base.smm = is_smm(vcpu);
>   	role.base.guest_mode = is_guest_mode(vcpu);
>   
> -	if (____is_cr0_pg(regs)) {
> +	if (!____is_cr0_pg(regs)) {
>   		role.base.direct = 1;
>   		return role;
>   	}
> 
> base-commit: 56ba4b488353a8925b30367d72e41d1996c23554