From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:53877) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UhGrv-0008Hl-6e for qemu-devel@nongnu.org; Tue, 28 May 2013 06:11:06 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UhGrq-0003If-MT for qemu-devel@nongnu.org; Tue, 28 May 2013 06:11:02 -0400 Received: from mx1.redhat.com ([209.132.183.28]:47011) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UhGrq-0003IO-Ej for qemu-devel@nongnu.org; Tue, 28 May 2013 06:10:58 -0400 Date: Tue, 28 May 2013 13:11:15 +0300 From: "Michael S. Tsirkin" Message-ID: <20130528101115.GA29353@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Subject: [Qemu-devel] [PATCH RFC] virtio-pci: fix LE host/BE guest capacity for blk List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Peter Maydell , Anthony Liguori , agraf@suse.de, blauwirbel@gmail.com, Paolo Bonzini , KONRAD Frederic 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 --- 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) && + 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); -- MST