From: Peter Xu <peterx@redhat.com>
To: Catherine Ho <catherine.hecx@gmail.com>
Cc: Juan Quintela <quintela@redhat.com>,
Markus Armbruster <armbru@redhat.com>,
qemu-devel@nongnu.org,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Richard Henderson <rth@twiddle.net>
Subject: Re: [Qemu-devel] [PATCH v4] migration: do not rom_reset() during incoming migration
Date: Tue, 16 Apr 2019 10:51:47 +0800 [thread overview]
Message-ID: <20190416025147.GA20550@xz-x1> (raw)
Message-ID: <20190416025147.G0zZQcpqbvfyNF-_Er-21tLAKz6exz0C6eTicCVU52Q@z> (raw)
In-Reply-To: <1554712933-18682-1-git-send-email-catherine.hecx@gmail.com>
On Mon, Apr 08, 2019 at 04:42:13AM -0400, Catherine Ho wrote:
> Commit 18269069c310 ("migration: Introduce ignore-shared capability")
> addes ignore-shared capability to bypass the shared ramblock (e,g,
> membackend + numa node). It does good to live migration.
>
> As told by Yury,this commit expectes that QEMU doesn't write to guest RAM
> until VM starts, but it does on aarch64 qemu:
> Backtrace:
> 1 0x000055f4a296dd84 in address_space_write_rom_internal () at
> exec.c:3458
> 2 0x000055f4a296de3a in address_space_write_rom () at exec.c:3479
> 3 0x000055f4a2d519ff in rom_reset () at hw/core/loader.c:1101
> 4 0x000055f4a2d475ec in qemu_devices_reset () at hw/core/reset.c:69
> 5 0x000055f4a2c90a28 in qemu_system_reset () at vl.c:1675
> 6 0x000055f4a2c9851d in main () at vl.c:4552
>
> Actually, on arm64 virt marchine, ramblock "dtb" will be filled into ram
> druing rom_reset. In ignore-shared incoming case, this rom filling
> is not required since all the data has been stored in memory backend
> file.
>
> Further more, as suggested by Peter Xu, if we do rom_reset() now with
> these ROMs then the RAM data should be re-filled again too with the
> migration stream coming in.
>
> Fixes: commit 18269069c310 ("migration: Introduce ignore-shared
> capability")
> Suggested-by: Yury Kotov <yury-kotov@yandex-team.ru>
> Suggested-by: Peter Xu <peterx@redhat.com>
> Signed-off-by: Catherine Ho <catherine.hecx@gmail.com>
Acked-by: Peter Xu <peterx@redhat.com>
--
Peter Xu
next prev parent reply other threads:[~2019-04-16 2:52 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-08 1:56 [Qemu-devel] [PATCH v3] migration: do not rom_reset() during incoming migration Catherine Ho
2019-04-08 1:56 ` Catherine Ho
2019-04-08 3:31 ` Peter Xu
2019-04-08 3:31 ` Peter Xu
2019-04-08 8:42 ` [Qemu-devel] [PATCH v4] " Catherine Ho
2019-04-08 8:42 ` Catherine Ho
2019-04-16 1:46 ` Catherine Ho
2019-04-16 1:46 ` Catherine Ho
2019-04-16 2:51 ` Peter Xu [this message]
2019-04-16 2:51 ` Peter Xu
2019-05-13 3:00 ` Catherine Ho
2019-06-05 18:31 ` Dr. David Alan Gilbert
2019-08-14 10:40 ` Catherine Ho
2019-08-14 12:34 ` Paolo Bonzini
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