From: Peter Xu <peterx@redhat.com>
To: David Hildenbrand <david@redhat.com>
Cc: "Eduardo Habkost" <ehabkost@redhat.com>,
"Juan Quintela" <quintela@redhat.com>,
"Michael S. Tsirkin" <mst@redhat.com>,
"Richard Henderson" <richard.henderson@linaro.org>,
qemu-devel@nongnu.org,
"Dr . David Alan Gilbert" <dgilbert@redhat.com>,
"Shannon Zhao" <shannon.zhao@linaro.org>,
"Igor Mammedov" <imammedo@redhat.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Alex Bennée" <alex.bennee@linaro.org>,
"Richard Henderson" <rth@twiddle.net>
Subject: Re: [PATCH v2 05/13] migration/ram: Handle RAM block resizes during precopy
Date: Mon, 24 Feb 2020 17:27:22 -0500 [thread overview]
Message-ID: <20200224222722.GB113102@xz-x1> (raw)
In-Reply-To: <20200221164204.105570-6-david@redhat.com>
On Fri, Feb 21, 2020 at 05:41:56PM +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.
>
> In the case of precopy, the ram block size must not change on the source,
> after syncing the RAM block list in ram_save_setup(), so as long as the
> guest is still running on the source.
>
> 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()
>
> Use the ram block notifier to get notified about resizes. Let's simply
> cancel migration and indicate the reason. We'll continue running on the
> source. No harm done.
>
> Update the documentation. Postcopy will be handled separately.
>
> Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> Cc: Juan Quintela <quintela@redhat.com>
> Cc: Eduardo Habkost <ehabkost@redhat.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Igor Mammedov <imammedo@redhat.com>
> Cc: "Michael S. Tsirkin" <mst@redhat.com>
> Cc: Richard Henderson <richard.henderson@linaro.org>
> Cc: Shannon Zhao <shannon.zhao@linaro.org>
> Cc: Alex Bennée <alex.bennee@linaro.org>
> Cc: Peter Xu <peterx@redhat.com>
> Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
--
Peter Xu
next prev parent reply other threads:[~2020-02-24 22:38 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-21 16:41 [PATCH v2 00/13] migrate/ram: Fix resizing RAM blocks while migrating David Hildenbrand
2020-02-21 16:41 ` [PATCH v2 01/13] util: vfio-helpers: Factor out and fix processing of existing ram blocks David Hildenbrand
2020-02-21 16:41 ` [PATCH v2 02/13] stubs/ram-block: Remove stubs that are no longer needed David Hildenbrand
2020-02-21 16:41 ` [PATCH v2 03/13] numa: Teach ram block notifiers about resizeable ram blocks David Hildenbrand
2020-02-21 16:41 ` [Xen-devel] " David Hildenbrand
2020-02-21 16:41 ` [PATCH v2 04/13] numa: Make all callbacks of ram block notifiers optional David Hildenbrand
2020-02-21 16:41 ` [PATCH v2 05/13] migration/ram: Handle RAM block resizes during precopy David Hildenbrand
2020-02-24 22:27 ` Peter Xu [this message]
2020-02-21 16:41 ` [PATCH v2 06/13] exec: Relax range check in ram_block_discard_range() David Hildenbrand
2020-02-24 22:27 ` Peter Xu
2020-02-21 16:41 ` [PATCH v2 07/13] migration/ram: Discard RAM when growing RAM blocks after ram_postcopy_incoming_init() David Hildenbrand
2020-02-24 22:28 ` Peter Xu
2020-02-21 16:41 ` [PATCH v2 08/13] migration/ram: Simplify host page handling in ram_load_postcopy() David Hildenbrand
2020-02-21 16:42 ` [PATCH v2 09/13] migration/ram: Consolidate variable reset after placement " David Hildenbrand
2020-02-21 16:42 ` [PATCH v2 10/13] migration/ram: Handle RAM block resizes during postcopy David Hildenbrand
2020-02-24 22:26 ` Peter Xu
2020-02-25 7:28 ` David Hildenbrand
2020-02-25 16:11 ` Peter Xu
2020-02-21 16:42 ` [PATCH v2 11/13] migration/multifd: Print used_length of memory block David Hildenbrand
2020-02-21 16:42 ` [PATCH v2 12/13] migration/ram: Use offset_in_ramblock() in range checks David Hildenbrand
2020-02-21 16:42 ` [PATCH v2 13/13] migration/ram: Tolerate partially changed mappings in postcopy code David Hildenbrand
2020-02-24 22:49 ` Peter Xu
2020-02-25 7:44 ` David Hildenbrand
2020-02-25 14:27 ` Peter Xu
2020-02-25 15:37 ` Peter Xu
2020-02-21 18:04 ` [PATCH v2 00/13] migrate/ram: Fix resizing RAM blocks while migrating Peter Xu
2020-02-24 9:09 ` David Hildenbrand
2020-02-24 17:45 ` Peter Xu
2020-02-24 18:44 ` David Hildenbrand
2020-02-24 18:59 ` David Hildenbrand
2020-02-24 19:18 ` Peter Xu
2020-02-24 19:34 ` David Hildenbrand
2020-02-24 20:04 ` Peter Xu
2020-02-24 20:54 ` David Hildenbrand
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