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File xsa360.patch of Package xen (Revision 686b93194c114de60c54d272df5b73bb)

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From: Roger Pau Monne <roger.pau@citrix.com>
Subject: x86/dpci: do not remove pirqs from domain tree on unbind

A fix for a previous issue removed the pirqs from the domain tree when
they are unbound in order to prevent shared pirqs from triggering a
BUG_ON in __pirq_guest_unbind if they are unbound multiple times. That
caused free_domain_pirqs to no longer unmap the pirqs because they
are gone from the domain pirq tree, thus leaving stale unbound pirqs
after domain destruction if the domain had mapped dpci pirqs after
shutdown.

Take a different approach to fix the original issue, instead of
removing the pirq from d->pirq_tree clear the flags of the dpci pirq
struct to signal that the pirq is now unbound. This prevents calling
pirq_guest_unbind multiple times for the same pirq without having to
remove it from the domain pirq tree.

This is XSA-360.

Fixes: 5b58dad089 ('x86/pass-through: avoid double IRQ unbind during domain cleanup')
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

--- a/xen/arch/x86/irq.c
+++ b/xen/arch/x86/irq.c
@@ -1331,7 +1331,7 @@ void (pirq_cleanup_check)(struct pirq *p
     }
 
     if ( radix_tree_delete(&d->pirq_tree, pirq->pirq) != pirq )
-        BUG_ON(!d->is_dying);
+        BUG();
 }
 
 /* Flush all ready EOIs from the top of this CPU's pending-EOI stack. */
--- a/xen/drivers/passthrough/pci.c
+++ b/xen/drivers/passthrough/pci.c
@@ -862,6 +862,10 @@ static int pci_clean_dpci_irq(struct dom
 {
     struct dev_intx_gsi_link *digl, *tmp;
 
+    if ( !pirq_dpci->flags )
+        /* Already processed. */
+        return 0;
+
     pirq_guest_unbind(d, dpci_pirq(pirq_dpci));
 
     if ( pt_irq_need_timer(pirq_dpci->flags) )
@@ -872,15 +876,10 @@ static int pci_clean_dpci_irq(struct dom
         list_del(&digl->list);
         xfree(digl);
     }
+    /* Note the pirq is now unbound. */
+    pirq_dpci->flags = 0;
 
-    radix_tree_delete(&d->pirq_tree, dpci_pirq(pirq_dpci)->pirq);
-
-    if ( !pt_pirq_softirq_active(pirq_dpci) )
-        return 0;
-
-    domain_get_irq_dpci(d)->pending_pirq_dpci = pirq_dpci;
-
-    return -ERESTART;
+    return pt_pirq_softirq_active(pirq_dpci) ? -ERESTART : 0;
 }
 
 static int pci_clean_dpci_irqs(struct domain *d)
@@ -897,18 +896,8 @@ static int pci_clean_dpci_irqs(struct do
     hvm_irq_dpci = domain_get_irq_dpci(d);
     if ( hvm_irq_dpci != NULL )
     {
-        int ret = 0;
-
-        if ( hvm_irq_dpci->pending_pirq_dpci )
-        {
-            if ( pt_pirq_softirq_active(hvm_irq_dpci->pending_pirq_dpci) )
-                 ret = -ERESTART;
-            else
-                 hvm_irq_dpci->pending_pirq_dpci = NULL;
-        }
+        int ret = pt_pirq_iterate(d, pci_clean_dpci_irq, NULL);
 
-        if ( !ret )
-            ret = pt_pirq_iterate(d, pci_clean_dpci_irq, NULL);
         if ( ret )
         {
             spin_unlock(&d->event_lock);
--- a/xen/include/asm-x86/hvm/irq.h
+++ b/xen/include/asm-x86/hvm/irq.h
@@ -160,8 +160,6 @@ struct hvm_irq_dpci {
     DECLARE_BITMAP(isairq_map, NR_ISAIRQS);
     /* Record of mapped Links */
     uint8_t link_cnt[NR_LINK];
-    /* Clean up: Entry with a softirq invocation pending / in progress. */
-    struct hvm_pirq_dpci *pending_pirq_dpci;
 };
 
 /* Machine IRQ to guest device/intx mapping. */

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File xsa360.patch of Package xen (Revision 686b93194c114de60c54d272df5b73bb)

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