| Message ID | 20130528101115.GA29353@redhat.com |
|---|---|
| State | New |
| Headers | show |
Il 28/05/2013 12:11, Michael S. Tsirkin ha scritto: > When a BE guest reads capacity from an LE host virtio-blk device or vice > versa, it will get the dwords of the qword field swapped. > As virtio-blk is the only one with such a quirk, > and as non-pci transports don't do byte-swaps at all, > solve this with a bit of device-specific hackery in > virtio-pci. > > Signed-off-by: Michael S. Tsirkin <mst@redhat.com> > --- > > I don't seem to be able to boot any big-endian > guests ATM, so this is only compile-tested - sending > this out for early feedback/flames. > Testing reports also wellcome! > > hw/virtio/virtio-pci.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c > index 9668b2b..0e9ae4c 100644 > --- a/hw/virtio/virtio-pci.c > +++ b/hw/virtio/virtio-pci.c > @@ -411,6 +411,15 @@ static uint64_t virtio_pci_config_read(void *opaque, hwaddr addr, > } > break; > case 4: > + /* Most devices don't have 64 bit config fields. > + * Block is an exception: first 8 bytes include > + * a 64 bit capacity field. > + */ > + if (virtio_is_big_endian() != defined(HOST_WORDS_BIGENDIAN) && I thought think this is not valid C? Paolo > + proxy->vdev->dev_id == VIRTIO_ID_BLOCK && addr < 8) { > + /* Swap first two words */ > + addr ^= 0x4; > + } > val = virtio_config_readl(proxy->vdev, addr); > if (virtio_is_big_endian()) { > val = bswap32(val); >
On Tue, May 28, 2013 at 12:14:59PM +0200, Paolo Bonzini wrote: > Il 28/05/2013 12:11, Michael S. Tsirkin ha scritto: > > When a BE guest reads capacity from an LE host virtio-blk device or vice > > versa, it will get the dwords of the qword field swapped. > > As virtio-blk is the only one with such a quirk, > > and as non-pci transports don't do byte-swaps at all, > > solve this with a bit of device-specific hackery in > > virtio-pci. > > > > Signed-off-by: Michael S. Tsirkin <mst@redhat.com> > > --- > > > > I don't seem to be able to boot any big-endian > > guests ATM, so this is only compile-tested - sending > > this out for early feedback/flames. > > Testing reports also wellcome! > > > > hw/virtio/virtio-pci.c | 9 +++++++++ > > 1 file changed, 9 insertions(+) > > > > diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c > > index 9668b2b..0e9ae4c 100644 > > --- a/hw/virtio/virtio-pci.c > > +++ b/hw/virtio/virtio-pci.c > > @@ -411,6 +411,15 @@ static uint64_t virtio_pci_config_read(void *opaque, hwaddr addr, > > } > > break; > > case 4: > > + /* Most devices don't have 64 bit config fields. > > + * Block is an exception: first 8 bytes include > > + * a 64 bit capacity field. > > + */ > > + if (virtio_is_big_endian() != defined(HOST_WORDS_BIGENDIAN) && > > I thought think this is not valid C? > > Paolo Yes, v2 I just sent fixes this. Thanks for paying attention. > > + proxy->vdev->dev_id == VIRTIO_ID_BLOCK && addr < 8) { > > + /* Swap first two words */ > > + addr ^= 0x4; > > + } > > val = virtio_config_readl(proxy->vdev, addr); > > if (virtio_is_big_endian()) { > > val = bswap32(val); > >
diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c index 9668b2b..0e9ae4c 100644 --- a/hw/virtio/virtio-pci.c +++ b/hw/virtio/virtio-pci.c @@ -411,6 +411,15 @@ static uint64_t virtio_pci_config_read(void *opaque, hwaddr addr, } break; case 4: + /* Most devices don't have 64 bit config fields. + * Block is an exception: first 8 bytes include + * a 64 bit capacity field. + */ + if (virtio_is_big_endian() != defined(HOST_WORDS_BIGENDIAN) && + proxy->vdev->dev_id == VIRTIO_ID_BLOCK && addr < 8) { + /* Swap first two words */ + addr ^= 0x4; + } val = virtio_config_readl(proxy->vdev, addr); if (virtio_is_big_endian()) { val = bswap32(val);
When a BE guest reads capacity from an LE host virtio-blk device or vice versa, it will get the dwords of the qword field swapped. As virtio-blk is the only one with such a quirk, and as non-pci transports don't do byte-swaps at all, solve this with a bit of device-specific hackery in virtio-pci. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> --- I don't seem to be able to boot any big-endian guests ATM, so this is only compile-tested - sending this out for early feedback/flames. Testing reports also wellcome! hw/virtio/virtio-pci.c | 9 +++++++++ 1 file changed, 9 insertions(+)