The following changes since commit 346ed3151f1c43e72c40cb55b392a1d4cface62c:

Merge remote-tracking branch 'remotes/awilliam/tags/vfio-update-20200206.0' into staging (2020-02-07 11:52:15 +0000)

https://github.com/stefanha/qemu.git tags/block-pull-request

for you to fetch changes up to 11a18c84db4a71497d3d40769688a01b6f64b2ad:

hw/core: Allow setting 'virtio-blk-device.scsi' property on OSX host (2020-02-07 16:49:39 +0000)

Pull request

hw/core: Allow setting 'virtio-blk-device.scsi' property on OSX host

block: fix crash on zero-length unaligned write and read

block/io.c | 28 +++++++++++++++++++++++++++-

hw/core/machine.c | 3 ++-

2 files changed, 29 insertions(+), 2 deletions(-)

2.24.1

Commit ed65fd1a2750 ("virtio-blk: switch off scsi-passthrough by

default") changed the default value of the 'scsi' property of

virtio-blk, which is only available on Linux hosts. It also added

an unconditional compat entry for 2.4 or earlier machines.

Trying to set this property on a pre-2.5 machine on OSX, we get:

Unexpected error in object_property_find() at qom/object.c:1201:

qemu-system-x86_64: -device virtio-blk-pci,id=scsi0,drive=drive0: can't apply global virtio-blk-device.scsi=true: Property '.scsi' not found

Fix this error by marking the property optional.

Fixes: ed65fd1a27 ("virtio-blk: switch off scsi-passthrough by default")

Suggested-by: Cornelia Huck <cohuck@redhat.com>

Reviewed-by: Cornelia Huck <cohuck@redhat.com>

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>

Reviewed-by: Michael S. Tsirkin <mst@redhat.com>

Message-id: 20200207001404.1739-1-philmd@redhat.com

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

---

hw/core/machine.c | 3 ++-

1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/hw/core/machine.c b/hw/core/machine.c

--- a/hw/core/machine.c

+++ b/hw/core/machine.c

@@ -XXX,XX +XXX,XX @@ GlobalProperty hw_compat_2_5[] = {

const size_t hw_compat_2_5_len = G_N_ELEMENTS(hw_compat_2_5);

GlobalProperty hw_compat_2_4[] = {

- { "virtio-blk-device", "scsi", "true" },

+ /* Optional because the 'scsi' property is Linux-only */

+ { "virtio-blk-device", "scsi", "true", .optional = true },

{ "e1000", "extra_mac_registers", "off" },

{ "virtio-pci", "x-disable-pcie", "on" },

{ "virtio-pci", "migrate-extra", "off" },

2.24.1

Commit 7a3f542fbd "block/io: refactor padding" occasionally dropped

aligning for zero-length request: bdrv_init_padding() blindly return

false if bytes == 0, like there is nothing to align.

This leads the following command to crash:

./qemu-io --image-opts -c 'write 1 0' \

driver=blkdebug,align=512,image.driver=null-co,image.size=512

>> qemu-io: block/io.c:1955: bdrv_aligned_pwritev: Assertion

`(offset & (align - 1)) == 0' failed.

>> Aborted (core dumped)

Prior to 7a3f542fbd we does aligning of such zero requests. Instead of

recovering this behavior let's just do nothing on such requests as it

is useless.

Note that driver may have special meaning of zero-length reqeusts, like

qcow2_co_pwritev_compressed_part, so we can't skip any zero-length

operation. But for unaligned ones, we can't pass it to driver anyway.

This commit also fixes crash in iotest 80 running with -nocache:

./check -nocache -qcow2 80

which crashes on same assertion due to trying to read empty extra data

in qcow2_do_read_snapshots().

Cc: qemu-stable@nongnu.org # v4.2

Fixes: 7a3f542fbd

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

Reviewed-by: Max Reitz <mreitz@redhat.com>

Message-id: 20200206164245.17781-1-vsementsov@virtuozzo.com

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

---

block/io.c | 28 +++++++++++++++++++++++++++-

1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/block/io.c b/block/io.c

--- a/block/io.c

+++ b/block/io.c

@@ -XXX,XX +XXX,XX @@ static bool bdrv_init_padding(BlockDriverState *bs,

pad->tail = align - pad->tail;

}

- if ((!pad->head && !pad->tail) || !bytes) {

+ if (!pad->head && !pad->tail) {

return false;

}

+ assert(bytes); /* Nothing good in aligning zero-length requests */

+

sum = pad->head + bytes + pad->tail;

pad->buf_len = (sum > align && pad->head && pad->tail) ? 2 * align : align;

pad->buf = qemu_blockalign(bs, pad->buf_len);

@@ -XXX,XX +XXX,XX @@ int coroutine_fn bdrv_co_preadv_part(BdrvChild *child,

return ret;

}

+ if (bytes == 0 && !QEMU_IS_ALIGNED(offset, bs->bl.request_alignment)) {

+ /*

+ * Aligning zero request is nonsense. Even if driver has special meaning

+ * of zero-length (like qcow2_co_pwritev_compressed_part), we can't pass

+ * it to driver due to request_alignment.

+ *

+ * Still, no reason to return an error if someone do unaligned

+ * zero-length read occasionally.

+ */

+ return 0;

+ }

+

bdrv_inc_in_flight(bs);

/* Don't do copy-on-read if we read data before write operation */

@@ -XXX,XX +XXX,XX @@ int coroutine_fn bdrv_co_pwritev_part(BdrvChild *child,

return -ENOTSUP;

}

+ if (bytes == 0 && !QEMU_IS_ALIGNED(offset, bs->bl.request_alignment)) {

+ /*

+ * Aligning zero request is nonsense. Even if driver has special meaning

+ * of zero-length (like qcow2_co_pwritev_compressed_part), we can't pass

+ * it to driver due to request_alignment.

+ *

+ * Still, no reason to return an error if someone do unaligned

+ * zero-length write occasionally.

+ */

+ return 0;

+ }

+

bdrv_inc_in_flight(bs);

/*

* Align write if necessary by performing a read-modify-write cycle.

2.24.1