From: "Michael S. Tsirkin" <mst@redhat.com>
To: Guenter Roeck <linux@roeck-us.net>
Cc: Jason Wang <jasowang@redhat.com>,
kvm@vger.kernel.org, virtualization@lists.linux-foundation.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH] vhost: Fix compile time error
Date: Sat, 14 Sep 2019 15:38:39 -0400 [thread overview]
Message-ID: <20190914153325-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <1568450697-16775-1-git-send-email-linux@roeck-us.net>
On Sat, Sep 14, 2019 at 01:44:57AM -0700, Guenter Roeck wrote:
> Building vhost on 32-bit targets results in the following error.
>
> drivers/vhost/vhost.c: In function 'translate_desc':
> include/linux/compiler.h:549:38: error:
> call to '__compiletime_assert_1879' declared with attribute error:
> BUILD_BUG_ON failed: sizeof(_s) > sizeof(long)
>
> Fixes: a89db445fbd7 ("vhost: block speculation of translated descriptors")
> Cc: Michael S. Tsirkin <mst@redhat.com>
> Cc: Jason Wang <jasowang@redhat.com>
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
> ---
> drivers/vhost/vhost.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> index acabf20b069e..102a0c877007 100644
> --- a/drivers/vhost/vhost.c
> +++ b/drivers/vhost/vhost.c
> @@ -2074,7 +2074,7 @@ static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
> _iov->iov_base = (void __user *)
> ((unsigned long)node->userspace_addr +
> array_index_nospec((unsigned long)(addr - node->start),
> - node->size));
> + (unsigned long)node->size));
Unfortunately this does not fix the case where size is actually 64 bit,
e.g. a single node with VA 0, size 2^32 is how
you cover the whole virtual address space.
this is not how qemu uses it, but it's valid.
I think it's best to just revert the patch for now.
> s += size;
> addr += size;
> ++ret;
> --
> 2.7.4
prev parent reply other threads:[~2019-09-14 19:38 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-14 8:44 [PATCH] vhost: Fix compile time error Guenter Roeck
2019-09-14 19:38 ` Michael S. Tsirkin [this message]
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