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From: Juan Quintela <quintela@redhat.com>
In-Reply-To: <20110316100909.GA12895@redhat.com> (Michael S. Tsirkin's message
	of "Wed, 16 Mar 2011 12:09:10 +0200")
References: <20110316100909.GA12895@redhat.com>
Date: Wed, 16 Mar 2011 13:53:46 +0100
Message-ID: <m3vczjdy5h.fsf@trasno.org>
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Subject: [Qemu-devel] Re: [PATCH master,
	stable] vhost: fix dirty page handling
Reply-To: quintela@redhat.com
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To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>, Alex Williamson <alex.williamson@redhat.com>, jmforbes@linuxtx.org, qemu-devel@nongnu.org

"Michael S. Tsirkin" <mst@redhat.com> wrote:
> vhost was passing a physical address to cpu_physical_memory_set_dirty,
> which is wrong: we need to translate to ram address first.
>
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
>
> Note: this lead to crashes during migration, so the patch
> is needed on the stable branch too.

Reviewed-by: Juan Quintela <quintela@redhat.com>

We have been having strange migration corruptions for some time, this
can explain what was going on.

> ---
>  hw/vhost.c |    4 +++-
>  1 files changed, 3 insertions(+), 1 deletions(-)
>
> diff --git a/hw/vhost.c b/hw/vhost.c
> index aaa34e4..97a1299 100644
> --- a/hw/vhost.c
> +++ b/hw/vhost.c
> @@ -49,8 +49,10 @@ static void vhost_dev_sync_region(struct vhost_dev *dev,
>          log = __sync_fetch_and_and(from, 0);
>          while ((bit = sizeof(log) > sizeof(int) ?
>                  ffsll(log) : ffs(log))) {
> +            ram_addr_t ram_addr;
>              bit -= 1;
> -            cpu_physical_memory_set_dirty(addr + bit * VHOST_LOG_PAGE);
> +            ram_addr = cpu_get_physical_page_desc(addr + bit * VHOST_LOG_PAGE);
> +            cpu_physical_memory_set_dirty(ram_addr);
>              log &= ~(0x1ull << bit);
>          }
>          addr += VHOST_LOG_CHUNK;
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