[PATCH 3/6] KVM: PPC: Book3E: Increase FPU laziness

[Alexander Graf]

On 03.07.2013, at 20:37, Scott Wood wrote:

> On 07/03/2013 07:42:36 AM, Mihai Caraman wrote:
>> Increase FPU laziness by calling kvmppc_load_guest_fp() just before
>> returning to guest instead of each sched in. Without this improvement
>> an interrupt may also claim floting point corrupting guest state.
>> Signed-off-by: Mihai Caraman <mihai.caraman at freescale.com>
>> ---
>> arch/powerpc/kvm/booke.c  |    1 +
>> arch/powerpc/kvm/e500mc.c |    2 --
>> 2 files changed, 1 insertions(+), 2 deletions(-)
>> diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
>> index 113961f..3cae2e3 100644
>> --- a/arch/powerpc/kvm/booke.c
>> +++ b/arch/powerpc/kvm/booke.c
>> @@ -1204,6 +1204,7 @@ int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu,
>> 			r = (s << 2) | RESUME_HOST | (r & RESUME_FLAG_NV);
>> 		} else {
>> 			kvmppc_lazy_ee_enable();
>> +			kvmppc_load_guest_fp(vcpu);
>> 		}
>> 	}
>> diff --git a/arch/powerpc/kvm/e500mc.c b/arch/powerpc/kvm/e500mc.c
>> index 19c8379..09da1ac 100644
>> --- a/arch/powerpc/kvm/e500mc.c
>> +++ b/arch/powerpc/kvm/e500mc.c
>> @@ -143,8 +143,6 @@ void kvmppc_core_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
>> 		kvmppc_e500_tlbil_all(vcpu_e500);
>> 		__get_cpu_var(last_vcpu_on_cpu) = vcpu;
>> 	}
>> -
>> -	kvmppc_load_guest_fp(vcpu);
>> }
>> void kvmppc_core_vcpu_put(struct kvm_vcpu *vcpu)
> 
> Can we now remove vcpu->fpu_active, and the comment that says "Kernel usage of FP (via
> enable_kernel_fp()) in this thread must not occur while vcpu->fpu_active is set."?

I think so, yes.


Alex