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Re: [Qemu-devel] [PATCH v9 00/22] legacy virtio support for cross-endian
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [PATCH v9 00/22] legacy virtio support for cross-endian targets |
Date: |
Sun, 29 Jun 2014 18:13:53 +0300 |
On Tue, Jun 24, 2014 at 07:06:58PM +0200, Greg Kurz wrote:
> The current legacy virtio devices have a fundamental flaw: they all share
> data between host and guest with guest endianness ordering. This is ok for
> nearly all architectures that have fixed endianness. Unfortunately, it breaks
> for recent PPC64 and ARM targets that can change endianness at runtime.
> The virtio-1.0 specification fixes the issue by enforcing little-endian
> ordering. It may take some time though until the code for 1.0 gets available
> and supported, and all the users can migrate. There have been discussions
> for some monthes about supporting such oddity: now we have little-endian
> PPC64 distros available, it is worth to propose something.
>
> This patch set brings legacy virtio support for cross-endian targets. The
> rationale is that we add a new device_endianness property to VirtIODevice.
> This property is used as a runtime indicator to decide wether we should
> do little-endian or big-endian conversion, as opposed to the compile time
> choice we have now with TARGTE_WORDS_BIGENDIAN. The choice was made to
> sample the device endianness out of the endianness mode of the guest
> CPU that does the reset. It is an evil but logical consequence of the
> initial flaw in the virtio specification, and it was agreed that the concept
> would be a good common base for ARM and PPC64 enablement at least. Please
> note also that this new property is state and must be preserved across
> migrations.
>
> There are several parts in the serie:
> - patches 1 and 2 are simple fixes
> - patches 3 to 9 introduce VMState based subsections in the virtio
> migration code. This is needed because we introduce a new property
> in VirtIODevice that we want to migrate without ruining compatibility
> efforts
> - patches 10 to 13 bring virtio device endianness and memory accessors
> to be used by the virtio code
> - patches 14 to 20 wire the new memory accessors everywhere accross the
> virtio code
> - patch 21 is the PPC64 enablement
> - patch 22 is a follow-up workaround to disable vhost-net acceleration
> in the case the host and guest have different endianness, because
> it is not supported for the moment
>
> Changes since v8 are provided in each patch.
>
> Cheers.
Applied, thanks everyone.
> ---
>
> Alexander Graf (1):
> virtio-serial: don't migrate the config space
>
> Cédric Le Goater (1):
> virtio-net: byteswap virtio-net header
>
> Greg Kurz (14):
> virtio: introduce device specific migration calls
> virtio-net: implement per-device migration calls
> virtio-blk: implement per-device migration calls
> virtio-serial: implement per-device migration calls
> virtio-balloon: implement per-device migration calls
> virtio-rng: implement per-device migration calls
> virtio: add subsections to the migration stream
> exec: introduce target_words_bigendian() helper
> cpu: introduce CPUClass::virtio_is_big_endian()
> virtio: add endian-ambivalent support to VirtIODevice
> virtio: memory accessors for endian-ambivalent targets
> virtio-9p: use virtio wrappers to access headers
> target-ppc: enable virtio endian ambivalent support
> vhost-net: disable when cross-endian
>
> Rusty Russell (6):
> virtio: allow byte swapping for vring
> virtio-net: use virtio wrappers to access headers
> virtio-balloon: use virtio wrappers to access page frame numbers
> virtio-blk: use virtio wrappers to access headers
> virtio-scsi: use virtio wrappers to access headers
> virtio-serial-bus: use virtio wrappers to access headers
>
>
> exec.c | 8 -
> hw/9pfs/virtio-9p-device.c | 3 -
> hw/block/virtio-blk.c | 62 ++++++-----
> hw/char/virtio-serial-bus.c | 94 ++++++++++------
> hw/net/vhost_net.c | 19 +++
> hw/net/virtio-net.c | 56 +++++++---
> hw/scsi/virtio-scsi.c | 40 ++++---
> hw/virtio/virtio-balloon.c | 33 +++---
> hw/virtio/virtio-pci.c | 11 +-
> hw/virtio/virtio-rng.c | 12 +-
> hw/virtio/virtio.c | 216
> ++++++++++++++++++++++++++++---------
> include/hw/virtio/virtio-access.h | 170 +++++++++++++++++++++++++++++
> include/hw/virtio/virtio.h | 17 +++
> include/qom/cpu.h | 1
> qom/cpu.c | 6 +
> target-ppc/cpu.h | 2
> target-ppc/translate_init.c | 15 +++
> 17 files changed, 583 insertions(+), 182 deletions(-)
> create mode 100644 include/hw/virtio/virtio-access.h
>
> --
> Greg
- [Qemu-devel] [PATCH v9 14/22] virtio: allow byte swapping for vring, (continued)
- [Qemu-devel] [PATCH v9 14/22] virtio: allow byte swapping for vring, Greg Kurz, 2014/06/24
- [Qemu-devel] [PATCH v9 15/22] virtio-net: use virtio wrappers to access headers, Greg Kurz, 2014/06/24
- [Qemu-devel] [PATCH v9 16/22] virtio-balloon: use virtio wrappers to access page frame numbers, Greg Kurz, 2014/06/24
- [Qemu-devel] [PATCH v9 17/22] virtio-blk: use virtio wrappers to access headers, Greg Kurz, 2014/06/24
- [Qemu-devel] [PATCH v9 18/22] virtio-scsi: use virtio wrappers to access headers, Greg Kurz, 2014/06/24
- [Qemu-devel] [PATCH v9 19/22] virtio-serial-bus: use virtio wrappers to access headers, Greg Kurz, 2014/06/24
- [Qemu-devel] [PATCH v9 20/22] virtio-9p: use virtio wrappers to access headers, Greg Kurz, 2014/06/24
- [Qemu-devel] [PATCH v9 21/22] target-ppc: enable virtio endian ambivalent support, Greg Kurz, 2014/06/24
- [Qemu-devel] [PATCH v9 22/22] vhost-net: disable when cross-endian, Greg Kurz, 2014/06/24
- Re: [Qemu-devel] [PATCH v9 00/22] legacy virtio support for cross-endian targets,
Michael S. Tsirkin <=