[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH v4] migration: do not rom_reset() during incomin
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [PATCH v4] migration: do not rom_reset() during incoming migration |
Date: |
Wed, 5 Jun 2019 19:31:22 +0100 |
User-agent: |
Mutt/1.11.4 (2019-03-13) |
Paolo, can you take this one please.
* Catherine Ho (address@hidden) 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 <address@hidden>
> Suggested-by: Peter Xu <address@hidden>
> Signed-off-by: Catherine Ho <address@hidden>
> ---
> hw/core/loader.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/hw/core/loader.c b/hw/core/loader.c
> index fe5cb24122..040109464b 100644
> --- a/hw/core/loader.c
> +++ b/hw/core/loader.c
> @@ -1087,6 +1087,15 @@ static void rom_reset(void *unused)
> {
> Rom *rom;
>
> + /*
> + * We don't need to fill in the RAM with ROM data because we'll fill
> + * the data in during the next incoming migration in all cases. Note
> + * that some of those RAMs can actually be modified by the guest on ARM
> + * so this is probably the only right thing to do here.
> + */
> + if (runstate_check(RUN_STATE_INMIGRATE))
> + return;
> +
> QTAILQ_FOREACH(rom, &roms, next) {
> if (rom->fw_file) {
> continue;
> --
> 2.17.1
>
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
[Prev in Thread] |
Current Thread |
[Next in Thread] |
- Re: [Qemu-devel] [PATCH v4] migration: do not rom_reset() during incoming migration,
Dr. David Alan Gilbert <=