Re: [PATCH v5 08/14] KVM: ARM: Emulation framework and CP15 emulation

Christoffer Dall
2013-01-14T17:38:18Z

On Mon, Jan 14, 2013 at 11:36 AM, Russell King - ARM Linux
<linux@arm.linux.org.uk> wrote:
> On Tue, Jan 08, 2013 at 01:39:31PM -0500, Christoffer Dall wrote:
>> + /*
>> + * Check whether this vcpu requires the cache to be flushed on
>> + * this physical CPU. This is a consequence of doing dcache
>> + * operations by set/way on this vcpu. We do it here to be in
>> + * a non-preemptible section.
>> + */
>> + if (cpumask_test_cpu(cpu, &vcpu->arch.require_dcache_flush)) {
>> + cpumask_clear_cpu(cpu, &vcpu->arch.require_dcache_flush);
>
> There is cpumask_test_and_clear_cpu() which may be better for this.

nice:

commit d31686fadb74ad564f6a5acabdebe411de86d77d
Author: Christoffer Dall <c.dall@virtualopensystems.com>
Date: Mon Jan 14 12:36:53 2013 -0500

KVM: ARM: Use cpumask_test_and_clear_cpu

Nicer shorter cleaner code. Ahhhh.

Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: Christoffer Dall <c.dall@virtualopensystems.com>

diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index b5c6ab1..fdd4a7c 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -352,10 +352,8 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
* operations by set/way on this vcpu. We do it here to be in
* a non-preemptible section.
*/
- if (cpumask_test_cpu(cpu, &vcpu->arch.require_dcache_flush)) {
- cpumask_clear_cpu(cpu, &vcpu->arch.require_dcache_flush);
+ if (cpumask_test_and_clear_cpu(cpu, &vcpu->arch.require_dcache_flush))
flush_cache_all(); /* We'd really want v7_flush_dcache_all() */
- }

kvm_arm_set_running_vcpu(vcpu);
}

--

Thanks,
-Christoffer