From: Peter Xu <peterx@redhat.com>
To: David Hildenbrand <david@redhat.com>
Cc: "Eduardo Habkost" <ehabkost@redhat.com>,
"Michael S. Tsirkin" <mst@redhat.com>,
"Juan Quintela" <quintela@redhat.com>,
"Richard Henderson" <richard.henderson@linaro.org>,
qemu-devel@nongnu.org,
"Shameerali Kolothum Thodi"
<shameerali.kolothum.thodi@huawei.com>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
"Shannon Zhao" <shannon.zhao@linaro.org>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Igor Mammedov" <imammedo@redhat.com>,
"Alex Bennée" <alex.bennee@linaro.org>
Subject: Re: [PATCH RFC] memory: Don't allow to resize RAM while migrating
Date: Thu, 13 Feb 2020 13:32:21 -0500 [thread overview]
Message-ID: <20200213183221.GD1103216@xz-x1> (raw)
In-Reply-To: <20200213172016.196609-1-david@redhat.com>
On Thu, Feb 13, 2020 at 06:20:16PM +0100, David Hildenbrand wrote:
> Resizing while migrating is dangerous and does not work as expected.
> The whole migration code works on the usable_length of ram blocks and does
> not expect this to change at random points in time.
>
> Precopy: The ram block size must not change on the source, after
> ram_save_setup(), so as long as the guest is still running on the source.
>
> Postcopy: The ram block size must not change on the target, after
> synchronizing the RAM block list (ram_load_precopy()).
>
> AFAIKS, resizing can be trigger *after* (but not during) a reset in
> ACPI code by the guest
> - hw/arm/virt-acpi-build.c:acpi_ram_update()
> - hw/i386/acpi-build.c:acpi_ram_update()
What can be the pre-condition of triggering this after reset? I'm
thinking whether QEMU can be aware of this "resizing can happen"
condition, then we could simply stop the migration from happening even
before the resizing happens. Thanks,
--
Peter Xu
next prev parent reply other threads:[~2020-02-13 18:36 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-13 17:20 [PATCH RFC] memory: Don't allow to resize RAM while migrating David Hildenbrand
2020-02-13 18:32 ` Peter Xu [this message]
2020-02-13 19:42 ` David Hildenbrand
2020-02-13 20:56 ` Peter Xu
2020-02-14 9:17 ` David Hildenbrand
2020-02-14 15:56 ` Peter Xu
2020-02-14 16:45 ` David Hildenbrand
2020-02-13 19:09 ` Juan Quintela
2020-02-13 19:38 ` David Hildenbrand
2020-02-14 10:25 ` Dr. David Alan Gilbert
2020-02-14 10:32 ` David Hildenbrand
2020-02-14 10:42 ` Dr. David Alan Gilbert
2020-02-14 10:46 ` David Hildenbrand
2020-02-14 11:02 ` Dr. David Alan Gilbert
2020-02-14 11:08 ` David Hildenbrand
2020-02-14 12:02 ` David Hildenbrand
2020-02-14 12:46 ` Juan Quintela
2020-02-14 14:00 ` David Hildenbrand
2020-02-14 15:14 ` Dr. David Alan Gilbert
2020-02-14 17:29 ` Peter Xu
2020-02-14 17:32 ` David Hildenbrand
2020-02-14 18:11 ` Peter Xu
2020-02-14 18:26 ` David Hildenbrand
2020-02-14 19:44 ` Peter Xu
2020-02-14 20:04 ` David Hildenbrand
2020-02-14 20:38 ` Peter Xu
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