[Qemu-devel] [PATCH] kvm: run cpu state synchronization on target vcpu thread

[Qemu-devel] [PATCH] kvm: run cpu state synchronization on target vcpu thread

[David Hildenbrand]

As already done for kvm_cpu_synchronize_state(), let's trigger
kvm_arch_put_registers() via run_on_cpu() for kvm_cpu_synchronize_post_reset()
and kvm_cpu_synchronize_post_init().

This way, we make sure that the register synchronizing ioctls are
called from the proper vcpu thread; this avoids calls to
synchronize_rcu() in the kernel.

Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
---
 kvm-all.c | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/kvm-all.c b/kvm-all.c
index 1402f4f..b240bf8 100644
--- a/kvm-all.c
+++ b/kvm-all.c
@@ -1669,18 +1669,32 @@ void kvm_cpu_synchronize_state(CPUState *cpu)
     }
 }
 
-void kvm_cpu_synchronize_post_reset(CPUState *cpu)
+static void do_kvm_cpu_synchronize_post_reset(void *arg)
 {
+    CPUState *cpu = arg;
+
     kvm_arch_put_registers(cpu, KVM_PUT_RESET_STATE);
     cpu->kvm_vcpu_dirty = false;
 }
 
-void kvm_cpu_synchronize_post_init(CPUState *cpu)
+void kvm_cpu_synchronize_post_reset(CPUState *cpu)
+{
+    run_on_cpu(cpu, do_kvm_cpu_synchronize_post_reset, cpu);
+}
+
+static void do_kvm_cpu_synchronize_post_init(void *arg)
 {
+    CPUState *cpu = arg;
+
     kvm_arch_put_registers(cpu, KVM_PUT_FULL_STATE);
     cpu->kvm_vcpu_dirty = false;
 }
 
+void kvm_cpu_synchronize_post_init(CPUState *cpu)
+{
+    run_on_cpu(cpu, do_kvm_cpu_synchronize_post_init, cpu);
+}
+
 int kvm_cpu_exec(CPUState *cpu)
 {
     struct kvm_run *run = cpu->kvm_run;
-- 
1.8.5.5

Re: [Qemu-devel] [PATCH] kvm: run cpu state synchronization on target vcpu thread

[Christian Borntraeger]

On 20/08/14 14:55, David Hildenbrand wrote:
> As already done for kvm_cpu_synchronize_state(), let's trigger
> kvm_arch_put_registers() via run_on_cpu() for kvm_cpu_synchronize_post_reset()
> and kvm_cpu_synchronize_post_init().
> 
> This way, we make sure that the register synchronizing ioctls are
> called from the proper vcpu thread; this avoids calls to
> synchronize_rcu() in the kernel.
> 
> Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
> Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>

Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>

Paolo, will you take that via the kvm tree? 
Otherwise I can queue that via the s390 tree together with the other patches that move our vcpu ioctls to the vcpu thread. I need your ACK in that case.


Christian
> ---
>  kvm-all.c | 18 ++++++++++++++++--
>  1 file changed, 16 insertions(+), 2 deletions(-)
> 
> diff --git a/kvm-all.c b/kvm-all.c
> index 1402f4f..b240bf8 100644
> --- a/kvm-all.c
> +++ b/kvm-all.c
> @@ -1669,18 +1669,32 @@ void kvm_cpu_synchronize_state(CPUState *cpu)
>      }
>  }
> 
> -void kvm_cpu_synchronize_post_reset(CPUState *cpu)
> +static void do_kvm_cpu_synchronize_post_reset(void *arg)
>  {
> +    CPUState *cpu = arg;
> +
>      kvm_arch_put_registers(cpu, KVM_PUT_RESET_STATE);
>      cpu->kvm_vcpu_dirty = false;
>  }
> 
> -void kvm_cpu_synchronize_post_init(CPUState *cpu)
> +void kvm_cpu_synchronize_post_reset(CPUState *cpu)
> +{
> +    run_on_cpu(cpu, do_kvm_cpu_synchronize_post_reset, cpu);
> +}
> +
> +static void do_kvm_cpu_synchronize_post_init(void *arg)
>  {
> +    CPUState *cpu = arg;
> +
>      kvm_arch_put_registers(cpu, KVM_PUT_FULL_STATE);
>      cpu->kvm_vcpu_dirty = false;
>  }
> 
> +void kvm_cpu_synchronize_post_init(CPUState *cpu)
> +{
> +    run_on_cpu(cpu, do_kvm_cpu_synchronize_post_init, cpu);
> +}
> +
>  int kvm_cpu_exec(CPUState *cpu)
>  {
>      struct kvm_run *run = cpu->kvm_run;
> 

Re: [Qemu-devel] [PATCH] kvm: run cpu state synchronization on target vcpu thread

[Paolo Bonzini]

Il 26/08/2014 14:43, Christian Borntraeger ha scritto:
> Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
> 
> Paolo, will you take that via the kvm tree? 

Yes, I will.

Paolo