[PULL for-8.2 0/2] xenfv queue

[PULL for-8.2 0/2] xenfv queue

[David Woodhouse]

The following changes since commit af9264da80073435fd78944bc5a46e695897d7e5:

  Merge tag '20231119-xtensa-1' of https://github.com/OSLL/qemu-xtensa into staging (2023-11-20 05:25:19 -0500)

are available in the Git repository at:

  git://git.infradead.org/users/dwmw2/qemu.git tags/pull-xenfv-20231121

for you to fetch changes up to 6f7997e0047e57a9e4f6a0958569f480d07f6538:

  hw/xen: clean up xen_block_find_free_vdev() to avoid Coverity false positive (2023-11-21 11:45:06 +0000)

----------------------------------------------------------------
Xen fixes for 8.2-rc1

 • Disable default serial when xen-console is used
 • Fix Coverity warning in xen-block

----------------------------------------------------------------
David Woodhouse (2):
      vl: disable default serial when xen-console is enabled
      hw/xen: clean up xen_block_find_free_vdev() to avoid Coverity false positive

 hw/block/xen-block.c | 24 +++++++++++++++++++++---
 system/vl.c          |  1 +
 2 files changed, 22 insertions(+), 3 deletions(-)

[PULL for-8.2 1/2] vl: disable default serial when xen-console is enabled

[David Woodhouse]

From: David Woodhouse <dwmw@amazon.co.uk>

If a Xen console is configured on the command line, do not add a default
serial port.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Paul Durrant <paul@xen.org>
---
 system/vl.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/system/vl.c b/system/vl.c
index 5af7ced2a1..8109231834 100644
--- a/system/vl.c
+++ b/system/vl.c
@@ -198,6 +198,7 @@ static const struct {
     const char *driver;
     int *flag;
 } default_list[] = {
+    { .driver = "xen-console",          .flag = &default_serial    },
     { .driver = "isa-serial",           .flag = &default_serial    },
     { .driver = "isa-parallel",         .flag = &default_parallel  },
     { .driver = "isa-fdc",              .flag = &default_floppy    },
-- 
2.41.0

[PULL for-8.2 2/2] hw/xen: clean up xen_block_find_free_vdev() to avoid Coverity false positive

[David Woodhouse]

From: David Woodhouse <dwmw@amazon.co.uk>

Coverity couldn't see that nr_existing was always going to be zero when
qemu_xen_xs_directory() returned NULL in the ENOENT case (CID 1523906).

Perhaps more to the point, neither could Peter at first glance. Improve
the code to hopefully make it clearer to Coverity and human reviewers
alike.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>
---
 hw/block/xen-block.c | 24 +++++++++++++++++++++---
 1 file changed, 21 insertions(+), 3 deletions(-)

diff --git a/hw/block/xen-block.c b/hw/block/xen-block.c
index 6d64ede94f..aed1d5c330 100644
--- a/hw/block/xen-block.c
+++ b/hw/block/xen-block.c
@@ -91,9 +91,27 @@ static bool xen_block_find_free_vdev(XenBlockDevice *blockdev, Error **errp)
 
     existing_frontends = qemu_xen_xs_directory(xenbus->xsh, XBT_NULL, fe_path,
                                                &nr_existing);
-    if (!existing_frontends && errno != ENOENT) {
-        error_setg_errno(errp, errno, "cannot read %s", fe_path);
-        return false;
+    if (!existing_frontends) {
+        if (errno == ENOENT) {
+            /*
+             * If the frontend directory doesn't exist because there are
+             * no existing vbd devices, that's fine. Just ensure that we
+             * don't dereference the NULL existing_frontends pointer, by
+             * checking that nr_existing is zero so the loop below is not
+             * entered.
+             *
+             * In fact this is redundant since nr_existing is initialized
+             * to zero, but setting it again here makes it abundantly clear
+             * to Coverity, and to the human reader who doesn't know the
+             * semantics of qemu_xen_xs_directory() off the top of their
+             * head.
+             */
+            nr_existing = 0;
+        } else {
+            /* All other errors accessing the frontend directory are fatal. */
+            error_setg_errno(errp, errno, "cannot read %s", fe_path);
+            return false;
+        }
     }
 
     memset(used_devs, 0, sizeof(used_devs));
-- 
2.41.0

Re: [PULL for-8.2 0/2] xenfv queue

[Stefan Hajnoczi]

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Applied, thanks.

Please update the changelog at https://wiki.qemu.org/ChangeLog/8.2 for any user-visible changes.

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