linux-kernel - Re: [PATCH 17/22] KVM: x86: Check EMULTYPE_WRITE_PF_TO

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Message-ID: <aede9ea1-099a-47db-a133-28ad22206858@redhat.com>
Date: Wed, 14 Aug 2024 19:53:53 +0200
From: Paolo Bonzini <pbonzini@...hat.com>
To: Sean Christopherson <seanjc@...gle.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
 Peter Gonda <pgonda@...gle.com>, Michael Roth <michael.roth@....com>,
 Vishal Annapurve <vannapurve@...gle.com>,
 Ackerly Tng <ackerleytng@...gle.com>
Subject: Re: [PATCH 17/22] KVM: x86: Check EMULTYPE_WRITE_PF_TO_SP before
 unprotecting gfn

On 8/9/24 21:03, Sean Christopherson wrote:
> +	 * Retry even if _this_ vCPU didn't unprotect the gfn, as it's possible
> +	 * all SPTEs were already zapped by a different task.  The alternative
> +	 * is to report the error to userspace and likely terminate the guest,
> +	 * and the infinite loop detection logic will prevent retrying the page
> +	 * fault indefinitely, i.e. there's nothing to lose by retrying.

Putting myself in the shoes of someone unfamiliar with the code, I might 
prefer "the last_retry_eip/last_retry_addr checks" to "the infinite loop 
detection logic"; after all, you're saying in the same sentence that 
it's preventing an infinite loop.

Thanks,

Paolo