From: Jason Andryuk <jandryuk@gmail.com>
Date: Tue, 7 Jun 2022 11:55:39 +0000 (+0200)
Subject: x86/irq: skip unmap_domain_pirq XSM during destruction
X-Git-Tag: archive/raspbian/4.16.2-1+rpi1^2~34^2~78
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=b58fb6e81bd55b6bd946abc3070770f7994c9ef9;p=xen.git

x86/irq: skip unmap_domain_pirq XSM during destruction

xsm_unmap_domain_irq was seen denying unmap_domain_pirq when called from
complete_domain_destroy as an RCU callback.  The source context was an
unexpected, random domain.  Since this is a xen-internal operation,
going through the XSM hook is inapproriate.

Check d->is_dying and skip the XSM hook when set since this is a cleanup
operation for a domain being destroyed.

Suggested-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: Jason Andryuk <jandryuk@gmail.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
master commit: 2e6f95a942d1927a53f077c301db0b799c54c05a
master date: 2022-04-08 14:51:52 +0200
---

diff --git a/xen/arch/x86/irq.c b/xen/arch/x86/irq.c
index 67cbf6b979..47b86af5dc 100644
--- a/xen/arch/x86/irq.c
+++ b/xen/arch/x86/irq.c
@@ -2342,8 +2342,14 @@ int unmap_domain_pirq(struct domain *d, int pirq)
         nr = msi_desc->msi.nvec;
     }
 
-    ret = xsm_unmap_domain_irq(XSM_HOOK, d, irq,
-                               msi_desc ? msi_desc->dev : NULL);
+    /*
+     * When called by complete_domain_destroy via RCU, current is a random
+     * domain.  Skip the XSM check since this is a Xen-initiated action.
+     */
+    if ( !d->is_dying )
+        ret = xsm_unmap_domain_irq(XSM_HOOK, d, irq,
+                                   msi_desc ? msi_desc->dev : NULL);
+
     if ( ret )
         goto done;