linux-kernel - Re: [PATCH] KVM: SVM: Fix offset computation bug in __sev_dbg

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Message-ID: <d9f6ac9b-0655-6403-aa4e-4dc70f519b28@redhat.com>
Date:   Mon, 16 Nov 2020 19:59:05 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Ashish Kalra <Ashish.Kalra@....com>
Cc:     tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
        joro@...tes.org, bp@...e.de, thomas.lendacky@....com,
        Brijesh.Singh@....com, x86@...nel.org, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, ssg.sos.patches@....com
Subject: Re: [PATCH] KVM: SVM: Fix offset computation bug in
 __sev_dbg_decrypt().

On 10/11/20 23:42, Ashish Kalra wrote:
> From: Ashish Kalra <ashish.kalra@....com>
> 
> Fix offset computation in __sev_dbg_decrypt() to include the
> source paddr before it is rounded down to be aligned to 16 bytes
> as required by SEV API. This fixes incorrect guest memory dumps
> observed when using qemu monitor.
> 
> Signed-off-by: Ashish Kalra <ashish.kalra@....com>
> ---
>   arch/x86/kvm/svm/sev.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
> index c0b14106258a..566f4d18185b 100644
> --- a/arch/x86/kvm/svm/sev.c
> +++ b/arch/x86/kvm/svm/sev.c
> @@ -642,8 +642,8 @@ static int __sev_dbg_decrypt(struct kvm *kvm, unsigned long src_paddr,
>   	 * Its safe to read more than we are asked, caller should ensure that
>   	 * destination has enough space.
>   	 */
> -	src_paddr = round_down(src_paddr, 16);
>   	offset = src_paddr & 15;
> +	src_paddr = round_down(src_paddr, 16);
>   	sz = round_up(sz + offset, 16);
>   
>   	return __sev_issue_dbg_cmd(kvm, src_paddr, dst_paddr, sz, err, false);
> 

I just missed it.  Queued now, thanks.

Paolo