[PATCH] arm/vgic-v3: Fix data abort in get_vcpu_from_rdist()

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

Just because vcpu_id is within d->max_vcpus doesn't mean d->vcpu[vcpu_id] is
non-NULL.  Use the proper accessor to look up a vcpu object.

Reported-by: Michal Orzel <michal.orzel@xxxxxxx>
Fixes: acf65e5a25a7 ("xen/arm: vgic-v3: Emulate correctly the re-distributor")
Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
CC: Julien Grall <julien@xxxxxxx>
CC: Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>
CC: Bertrand Marquis <bertrand.marquis@xxxxxxx>
CC: Michal Orzel <michal.orzel@xxxxxxx>
CC: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>

Untested.  This came from review discusson on a separate patch.
---
 xen/arch/arm/vgic-v3.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/xen/arch/arm/vgic-v3.c b/xen/arch/arm/vgic-v3.c
index c1c4d6f71ea8..c01cc596d593 100644
--- a/xen/arch/arm/vgic-v3.c
+++ b/xen/arch/arm/vgic-v3.c
@@ -1111,10 +1111,10 @@ static struct vcpu *get_vcpu_from_rdist(struct domain 
*d,
     unsigned int vcpu_id;
 
     vcpu_id = region->first_cpu + ((gpa - region->base) / GICV3_GICR_SIZE);
-    if ( unlikely(vcpu_id >= d->max_vcpus) )
-        return NULL;
 
-    v = d->vcpu[vcpu_id];
+    v = domain_vcpu(d, vcpu_id);
+    if ( !v )
+        return NULL;
 
     *offset = gpa - v->arch.vgic.rdist_base;
 

base-commit: c4bf5bc5f0edbcbc5965c924db069483b2cf6049
-- 
2.39.5