This is a note to let you know that I've just added the patch titled
hvc/xen: fix event channel handling for secondary consoles
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
hvc-xen-fix-event-channel-handling-for-secondary-consoles.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From ef5dd8ec88ac11e8e353164407d55b73c988b369 Mon Sep 17 00:00:00 2001
From: David Woodhouse <dwmw@xxxxxxxxxxxx>
Date: Fri, 20 Oct 2023 17:15:27 +0100
Subject: hvc/xen: fix event channel handling for secondary consoles
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From: David Woodhouse <dwmw@xxxxxxxxxxxx>
commit ef5dd8ec88ac11e8e353164407d55b73c988b369 upstream.
The xencons_connect_backend() function allocates a local interdomain
event channel with xenbus_alloc_evtchn(), then calls
bind_interdomain_evtchn_to_irq_lateeoi() to bind to that port# on the
*remote* domain.
That doesn't work very well:
(qemu) device_add xen-console,id=con1,chardev=pty0
[ 44.323872] xenconsole console-1: 2 xenbus_dev_probe on device/console/1
[ 44.323995] xenconsole: probe of console-1 failed with error -2
Fix it to use bind_evtchn_to_irq_lateeoi(), which does the right thing
by just binding that *local* event channel to an irq. The backend will
do the interdomain binding.
This didn't affect the primary console because the setup for that is
special — the toolstack allocates the guest event channel and the guest
discovers it with HVMOP_get_param.
Fixes: fe415186b43d ("xen/console: harden hvc_xen against event channel storms")
Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx>
Reviewed-by: Juergen Gross <jgross@xxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/20231020161529.355083-2-dwmw2@xxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/tty/hvc/hvc_xen.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/tty/hvc/hvc_xen.c
+++ b/drivers/tty/hvc/hvc_xen.c
@@ -436,7 +436,7 @@ static int xencons_connect_backend(struc
if (ret)
return ret;
info->evtchn = evtchn;
- irq = bind_interdomain_evtchn_to_irq_lateeoi(dev, evtchn);
+ irq = bind_evtchn_to_irq_lateeoi(evtchn);
if (irq < 0)
return irq;
info->irq = irq;
Patches currently in stable-queue which might be from dwmw@xxxxxxxxxxxx are
queue-5.15/hvc-xen-fix-event-channel-handling-for-secondary-consoles.patch
queue-5.15/hvc-xen-fix-console-unplug.patch
queue-5.15/hvc-xen-fix-error-path-in-xen_hvc_init-to-always-register-frontend-driver.patch
