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 <someguy@effective-light.com>
> ---

Reviewed-by: Paolo Bonzini <pbonzini@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,