linux-kernel - Re: [PATCH 0/8] KVM: SEV-ES: fixes for string I/O emulation

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Date:   Thu, 21 Oct 2021 19:47:36 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     fwilhelm@...gle.com, seanjc@...gle.com, oupton@...gle.com
Subject: Re: [PATCH 0/8] KVM: SEV-ES: fixes for string I/O emulation

On 13/10/21 18:56, Paolo Bonzini wrote:
> This series, namely patches 1 and 8, fix two bugs in string I/O
> emulation for SEV-ES:
> 
> - first, the length is completely off for "rep ins" and "rep outs"
>    operation of size > 1.  After setup_vmgexit_scratch, svm->ghcb_sa_len
>    is in bytes, but kvm_sev_es_string_io expects the number of PIO
>    operations.
> 
> - second, the size of the GHCB buffer can exceed the size of
>    vcpu->arch.pio_data.  If that happens, we need to go over the GHCB
>    buffer in multiple passes.
> 
> The second bug was reported by Felix Wilhelm.  The first was found by
> me by code inspection; on one hand it seems *too* egregious so I'll be
> gladly proven wrong on this, on the other hand... I know I'm bad at code
> review, but not _that_ bad.

Ping.

Paolo