linux-kernel - Re: [PATCH] vhost: disable metadata prefetch optimization

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Message-ID: <ccba99c1-7708-3e55-6fc9-7775415c77a8@redhat.com>
Date:   Fri, 26 Jul 2019 19:57:25 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     "Michael S. Tsirkin" <mst@...hat.com>, linux-kernel@...r.kernel.org
Cc:     kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org,
        netdev@...r.kernel.org
Subject: Re: [PATCH] vhost: disable metadata prefetch optimization


On 2019/7/26 下午7:51, Michael S. Tsirkin wrote:
> This seems to cause guest and host memory corruption.
> Disable for now until we get a better handle on that.
>
> Signed-off-by: Michael S. Tsirkin <mst@...hat.com>
> ---
>
> I put this in linux-next, we'll re-enable if we can fix
> the outstanding issues in a short order.


Btw, is this more suitable to e.g revert the 
842aa64eddacd23adc6ecdbc69cb2030bec47122 and let syzbot fuzz more on the 
current code?

I think we won't accept that patch eventually, so I suspect what syzbot 
reports today is a false positives.

Thanks


>
>   drivers/vhost/vhost.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
> index 819296332913..42a8c2a13ab1 100644
> --- a/drivers/vhost/vhost.h
> +++ b/drivers/vhost/vhost.h
> @@ -96,7 +96,7 @@ struct vhost_uaddr {
>   };
>   
>   #if defined(CONFIG_MMU_NOTIFIER) && ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE == 0
> -#define VHOST_ARCH_CAN_ACCEL_UACCESS 1
> +#define VHOST_ARCH_CAN_ACCEL_UACCESS 0
>   #else
>   #define VHOST_ARCH_CAN_ACCEL_UACCESS 0
>   #endif