[PULL 0/2] xen queue

[PULL 0/2] xen queue

[Anthony PERARD via]

The following changes since commit 60ca584b8af0de525656f959991a440f8c191f12:

  Merge tag 'pull-for-8.0-220323-1' of https://gitlab.com/stsquad/qemu into staging (2023-03-22 17:58:12 +0000)

are available in the Git repository at:

  https://xenbits.xen.org/git-http/people/aperard/qemu-dm.git tags/pull-xen-20230324

for you to fetch changes up to 670d8c6ebf7a2c425575bbd6fbaeb27d21edd6c6:

  hw/xenpv: Initialize Xen backend operations (2023-03-24 14:52:14 +0000)

----------------------------------------------------------------
Xen queue

- fix guest creation when -xen-domid-restrict is used.
- fix Xen PV guest creation.

----------------------------------------------------------------
David Woodhouse (2):
      accel/xen: Fix DM state change notification in dm_restrict mode
      hw/xenpv: Initialize Xen backend operations

 accel/xen/xen-all.c       | 27 ++++++++++-----------------
 hw/xenpv/xen_machine_pv.c |  2 ++
 2 files changed, 12 insertions(+), 17 deletions(-)

[PULL 1/2] accel/xen: Fix DM state change notification in dm_restrict mode

[Anthony PERARD via]

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

When dm_restrict is set, QEMU isn't permitted to update the XenStore node
to indicate its running status. Previously, the xs_write() call would fail
but the failure was ignored.

However, in refactoring to allow for emulated XenStore operations, a new
call to xs_open() was added. That one didn't fail gracefully, causing a
fatal error when running in dm_restrict mode.

Partially revert the offending patch, removing the additional call to
xs_open() because the global 'xenstore' variable is still available; it
just needs to be used with qemu_xen_xs_write() now instead of directly
with the xs_write() libxenstore function.

Also make the whole thing conditional on !xen_domid_restrict. There's no
point even registering the state change handler to attempt to update the
XenStore node when we know it's destined to fail.

Fixes: ba2a92db1ff6 ("hw/xen: Add xenstore operations to allow redirection to internal emulation")
Reported-by: Jason Andryuk <jandryuk@gmail.com>
Co-developed-by: Jason Andryuk <jandryuk@gmail.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>
Tested-by: Jason Andryuk <jandryuk@gmail.com>
Message-Id: <1f141995bb61af32c2867ef5559e253f39b0949c.camel@infradead.org>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
---
 accel/xen/xen-all.c | 27 ++++++++++-----------------
 1 file changed, 10 insertions(+), 17 deletions(-)

diff --git a/accel/xen/xen-all.c b/accel/xen/xen-all.c
index 00221e23c5..5ff0cb8bd9 100644
--- a/accel/xen/xen-all.c
+++ b/accel/xen/xen-all.c
@@ -32,28 +32,13 @@ xendevicemodel_handle *xen_dmod;
 
 static void xenstore_record_dm_state(const char *state)
 {
-    struct xs_handle *xs;
     char path[50];
 
-    /* We now have everything we need to set the xenstore entry. */
-    xs = xs_open(0);
-    if (xs == NULL) {
-        fprintf(stderr, "Could not contact XenStore\n");
-        exit(1);
-    }
-
     snprintf(path, sizeof (path), "device-model/%u/state", xen_domid);
-    /*
-     * This call may fail when running restricted so don't make it fatal in
-     * that case. Toolstacks should instead use QMP to listen for state changes.
-     */
-    if (!xs_write(xs, XBT_NULL, path, state, strlen(state)) &&
-            !xen_domid_restrict) {
+    if (!qemu_xen_xs_write(xenstore, XBT_NULL, path, state, strlen(state))) {
         error_report("error recording dm state");
         exit(1);
     }
-
-    xs_close(xs);
 }
 
 
@@ -111,7 +96,15 @@ static int xen_init(MachineState *ms)
         xc_interface_close(xen_xc);
         return -1;
     }
-    qemu_add_vm_change_state_handler(xen_change_state_handler, NULL);
+
+    /*
+     * The XenStore write would fail when running restricted so don't attempt
+     * it in that case. Toolstacks should instead use QMP to listen for state
+     * changes.
+     */
+    if (!xen_domid_restrict) {
+        qemu_add_vm_change_state_handler(xen_change_state_handler, NULL);
+    }
     /*
      * opt out of system RAM being allocated by generic code
      */
-- 
Anthony PERARD

[PULL 2/2] hw/xenpv: Initialize Xen backend operations

[Anthony PERARD via]

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

As the Xen backend operations were abstracted out into a function table to
allow for internally emulated Xen support, we missed the xen_init_pv()
code path which also needs to install the operations for the true Xen
libraries. Add the missing call to setup_xen_backend_ops().

Fixes: b6cacfea0b38 ("hw/xen: Add evtchn operations to allow redirection to internal emulation")
Reported-by: Anthony PERARD <anthony.perard@citrix.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>
Tested-by: Anthony PERARD <anthony.perard@citrix.com>
Message-Id: <5dfb65342d4502c1ce2f890c97cff20bf25b3860.camel@infradead.org>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
---
 hw/xenpv/xen_machine_pv.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/hw/xenpv/xen_machine_pv.c b/hw/xenpv/xen_machine_pv.c
index 2e759d0619..17cda5ec13 100644
--- a/hw/xenpv/xen_machine_pv.c
+++ b/hw/xenpv/xen_machine_pv.c
@@ -35,6 +35,8 @@ static void xen_init_pv(MachineState *machine)
     DriveInfo *dinfo;
     int i;
 
+    setup_xen_backend_ops();
+
     /* Initialize backend core & drivers */
     xen_be_init();
 
-- 
Anthony PERARD

Re: [PULL 0/2] xen queue

[Peter Maydell]

On Fri, 24 Mar 2023 at 14:56, Anthony PERARD <anthony.perard@citrix.com> wrote:
>
> The following changes since commit 60ca584b8af0de525656f959991a440f8c191f12:
>
>   Merge tag 'pull-for-8.0-220323-1' of https://gitlab.com/stsquad/qemu into staging (2023-03-22 17:58:12 +0000)
>
> are available in the Git repository at:
>
>   https://xenbits.xen.org/git-http/people/aperard/qemu-dm.git tags/pull-xen-20230324
>
> for you to fetch changes up to 670d8c6ebf7a2c425575bbd6fbaeb27d21edd6c6:
>
>   hw/xenpv: Initialize Xen backend operations (2023-03-24 14:52:14 +0000)
>
> ----------------------------------------------------------------
> Xen queue
>
> - fix guest creation when -xen-domid-restrict is used.
> - fix Xen PV guest creation.
>
> ----------------------------------------------------------------


Applied, thanks.

Please update the changelog at https://wiki.qemu.org/ChangeLog/8.0
for any user-visible changes.

-- PMM