[PATCH] xen/arm: vpl011: record the virq only once it is reserved

[Stefano Stabellini <stefano.stabellini@xxxxxxx>]

domain_vpl011_init() sets vpl011->virq before vgic_reserve_virq() claims
it, and both a refused reservation and a failed
alloc_unbound_xen_event_channel() take the out1 error path into
domain_vpl011_deinit(), which frees vpl011->virq. That clears the
allocation bit of an interrupt the vPL011 never reserved, so an
interrupt held by another user can be handed out a second time.

Record the virq only after the reservation succeeds.

Fixes: 08bbc1c02d38 ("xen/arm: vpl011: Fix domain_vpl011_init error path")
Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxx>
---
CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>,
CC: Julien Grall <julien@xxxxxxx>,
CC: Bertrand Marquis <bertrand.marquis@xxxxxxx>,
CC: Michal Orzel <michal.orzel@xxxxxxx>,
CC: Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>

 xen/arch/arm/vpl011.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/xen/arch/arm/vpl011.c b/xen/arch/arm/vpl011.c
index d0d17c76b7..a37e88a8b4 100644
--- a/xen/arch/arm/vpl011.c
+++ b/xen/arch/arm/vpl011.c
@@ -640,6 +640,7 @@ static void vpl011_notification(struct vcpu *v, unsigned 
int port)
 int domain_vpl011_init(struct domain *d, struct vpl011_init_info *info)
 {
     int rc;
+    unsigned int virq;
     struct vpl011 *vpl011 = &d->arch.vpl011;
 
     if ( vpl011->backend.dom.ring_buf )
@@ -659,7 +660,7 @@ int domain_vpl011_init(struct domain *d, struct 
vpl011_init_info *info)
         if ( (uart != NULL) && (vpl011_irq > 0) )
         {
             vpl011->base_addr = uart->base_addr;
-            vpl011->virq = vpl011_irq;
+            virq = vpl011_irq;
         }
         else
         {
@@ -685,7 +686,7 @@ int domain_vpl011_init(struct domain *d, struct 
vpl011_init_info *info)
     else
     {
         vpl011->base_addr = GUEST_PL011_BASE;
-        vpl011->virq = GUEST_VPL011_SPI;
+        virq = GUEST_VPL011_SPI;
     }
 
     /*
@@ -724,12 +725,12 @@ int domain_vpl011_init(struct domain *d, struct 
vpl011_init_info *info)
         }
     }
 
-    rc = vgic_reserve_virq(d, vpl011->virq);
-    if ( !rc )
+    if ( !vgic_reserve_virq(d, virq) )
     {
         rc = -EINVAL;
         goto out1;
     }
+    vpl011->virq = virq;
 
     vpl011->uartfr = TXFE | RXFE;
 
-- 
2.47.3