On Fri, 13 Jun 2014 14:41:30 +0200 Alexander Graf <ag...@suse.de> wrote:
> > On 13.06.14 14:14, Greg Kurz wrote: > > On Fri, 13 Jun 2014 13:46:39 +0200 > > Alexander Graf <ag...@suse.de> wrote: > > > >> On 13.06.14 13:23, Greg Kurz wrote: > >>> Some CPU families can dynamically change their endianness. This means we > >>> can have little endian ppc or big endian arm guests for example. This has > >>> an impact on legacy virtio data structures since they are target endian. > >>> We hence introduce a new property to track the endianness of each virtio > >>> device. It is reasonnably assumed that endianness won't change while the > >>> device is in use : we hence capture the device endianness when it gets > >>> reset. > >>> > >>> We migrate this property in a subsection, after the device descriptor. > >>> This > >>> means the load code must not rely on it until it is restored. As a > >>> consequence, > >>> the vring sanity checks had to be moved after the call to > >>> vmstate_load_state(). > >>> We enforce paranoia by poisoning the property at the begining of > >>> virtio_load(). > >>> > >>> Signed-off-by: Greg Kurz <gk...@linux.vnet.ibm.com> > >>> --- > >>> > >>> Changes since last version (virtio migration RFC): > >>> - endianness cached at device reset time > >>> - reworked migration support > >>> > >>> hw/virtio/virtio-pci.c | 8 ++-- > >>> hw/virtio/virtio.c | 100 > >>> +++++++++++++++++++++++++++++++++++++++----- > >>> include/hw/virtio/virtio.h | 12 ++++- > >>> 3 files changed, 102 insertions(+), 18 deletions(-) > >>> > >>> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c > >>> index 390c8d2..2ffceb8 100644 > >>> --- a/hw/virtio/virtio-pci.c > >>> +++ b/hw/virtio/virtio-pci.c > >>> @@ -406,13 +406,13 @@ static uint64_t virtio_pci_config_read(void > >>> *opaque, hwaddr addr, > >>> break; > >>> case 2: > >>> val = virtio_config_readw(vdev, addr); > >>> - if (virtio_is_big_endian()) { > >>> + if (virtio_is_big_endian(vdev)) { > >>> val = bswap16(val); > >>> } > >>> break; > >>> case 4: > >>> val = virtio_config_readl(vdev, addr); > >>> - if (virtio_is_big_endian()) { > >>> + if (virtio_is_big_endian(vdev)) { > >>> val = bswap32(val); > >>> } > >>> break; > >>> @@ -440,13 +440,13 @@ static void virtio_pci_config_write(void *opaque, > >>> hwaddr addr, > >>> virtio_config_writeb(vdev, addr, val); > >>> break; > >>> case 2: > >>> - if (virtio_is_big_endian()) { > >>> + if (virtio_is_big_endian(vdev)) { > >>> val = bswap16(val); > >>> } > >>> virtio_config_writew(vdev, addr, val); > >>> break; > >>> case 4: > >>> - if (virtio_is_big_endian()) { > >>> + if (virtio_is_big_endian(vdev)) { > >>> val = bswap32(val); > >>> } > >>> virtio_config_writel(vdev, addr, val); > >>> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c > >>> index 16b73d9..6235df8 100644 > >>> --- a/hw/virtio/virtio.c > >>> +++ b/hw/virtio/virtio.c > >>> @@ -545,6 +545,24 @@ void virtio_set_status(VirtIODevice *vdev, uint8_t > >>> val) > >>> vdev->status = val; > >>> } > >>> > >>> +static void virtio_set_endian_target_default(VirtIODevice *vdev) > >>> +{ > >>> +#ifdef TARGET_WORDS_BIGENDIAN > >>> + vdev->device_endian = VIRTIO_DEVICE_ENDIAN_BIG; > >>> +#else > >>> + vdev->device_endian = VIRTIO_DEVICE_ENDIAN_LITTLE; > >>> +#endif > >>> +} > >>> + > >>> +static void virtio_set_endian_cpu(VirtIODevice *vdev, CPUState *cpu) > >>> +{ > >>> + if (cpu_virtio_is_big_endian(cpu)) { > >>> + vdev->device_endian = VIRTIO_DEVICE_ENDIAN_BIG; > >>> + } else { > >>> + vdev->device_endian = VIRTIO_DEVICE_ENDIAN_LITTLE; > >>> + } > >>> +} > >>> + > >>> void virtio_reset(void *opaque) > >>> { > >>> VirtIODevice *vdev = opaque; > >>> @@ -552,6 +570,13 @@ void virtio_reset(void *opaque) > >>> int i; > >>> > >>> virtio_set_status(vdev, 0); > >>> + if (current_cpu) { > >>> + /* Guest initiated reset */ > >>> + virtio_set_endian_cpu(vdev, current_cpu); > >>> + } else { > >>> + /* System reset */ > >>> + virtio_set_endian_target_default(vdev); > >>> + } > >>> > >>> if (k->reset) { > >>> k->reset(vdev); > >>> @@ -840,6 +865,28 @@ void virtio_notify_config(VirtIODevice *vdev) > >>> virtio_notify_vector(vdev, vdev->config_vector); > >>> } > >>> > >>> +static bool virtio_device_endian_needed(void *opaque) > >>> +{ > >>> + VirtIODevice *vdev = opaque; > >>> + > >>> + assert(vdev->device_endian != VIRTIO_DEVICE_ENDIAN_UNKNOWN); > >>> +#ifdef TARGET_WORDS_BIGENDIAN > >>> + return vdev->device_endian == VIRTIO_DEVICE_ENDIAN_LITTLE; > >>> +#else > >>> + return vdev->device_endian == VIRTIO_DEVICE_ENDIAN_BIG; > >>> +#endif > >> if (target_words_bigendian()) { > >> return virtio_is_big_endian(); > >> } else { > >> return !virtio_is_big_endian(); > >> } > >> > >> Then we have one less dependency on TARGET_WORDS_BIGENDIAN which means a > >> step towards compiling virtio once ;). > >> > >> > >> Alex > >> > > Heh ! It used to be target_words_bigendian() in the first place and I turned > > it into TARGET_WORDS_BIGENDIAN to avoid "hey virtio isn't soon to be common > > why don't you sort this out at compile time?" remarks. :) > > > > Since we are definitely not on a fastpath here, I'll gladly fix this. > > Yeah, just combine it with virtio_set_endian_target_default. > > static enum foo virtio_default_endian(vdev) > { > if (target_words_bigendian()) { > return VIRTIO_DEVICE_ENDIAN_BIG; > .... > } > > Instead of calling virtio_set_endian_target_default, you do > > vdev->device_endian = virtio_default_endian(vdev); > > and > > static bool virtio_biendian_section_needed(vdev) > { > assert(unknown); > return vdev->device_endian != virtio_default_endian(vdev); > } > > > Alex > It sure looks better. Thanks ! -- Gregory Kurz kurzg...@fr.ibm.com gk...@linux.vnet.ibm.com Software Engineer @ IBM/Meiosys http://www.ibm.com Tel +33 (0)562 165 496 "Anarchy is about taking complete responsibility for yourself." Alan Moore.