Re: [PATCH] target/arm: kvm: use RCU_READ_LOCK_GUARD() in kvm_arch_fixup_msi_route()

[Paolo Bonzini]

On 28/07/21 01:52, Hamza Mahfooz wrote:

As per commit 5626f8c6d468 ("rcu: Add automatically released rcu_read_lock
variants"), RCU_READ_LOCK_GUARD() should be used instead of
rcu_read_{un}lock().

Signed-off-by: Hamza Mahfooz <some...@effective-light.com>
---

Reviewed-by: Paolo Bonzini <pbonz...@redhat.com>

  target/arm/kvm.c | 17 ++++++++---------
  1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/target/arm/kvm.c b/target/arm/kvm.c
index d8381ba224..5d55de1a49 100644
--- a/target/arm/kvm.c
+++ b/target/arm/kvm.c
@@ -998,7 +998,6 @@ int kvm_arch_fixup_msi_route(struct kvm_irq_routing_entry 
*route,
      hwaddr xlat, len, doorbell_gpa;
      MemoryRegionSection mrs;
      MemoryRegion *mr;
-    int ret = 1;

if (as == &address_space_memory) {

          return 0;
@@ -1006,15 +1005,19 @@ int kvm_arch_fixup_msi_route(struct 
kvm_irq_routing_entry *route,

/* MSI doorbell address is translated by an IOMMU */ - rcu_read_lock();

+    RCU_READ_LOCK_GUARD();
+
      mr = address_space_translate(as, address, &xlat, &len, true,
                                   MEMTXATTRS_UNSPECIFIED);
+
      if (!mr) {
-        goto unlock;
+        return 1;
      }
+
      mrs = memory_region_find(mr, xlat, 1);
+
      if (!mrs.mr) {
-        goto unlock;
+        return 1;
      }

doorbell_gpa = mrs.offset_within_address_space;

@@ -1025,11 +1028,7 @@ int kvm_arch_fixup_msi_route(struct 
kvm_irq_routing_entry *route,

trace_kvm_arm_fixup_msi_route(address, doorbell_gpa); - ret = 0;

-
-unlock:
-    rcu_read_unlock();
-    return ret;
+    return 0;
  }

int kvm_arch_add_msi_route_post(struct kvm_irq_routing_entry *route,