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

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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@xxxxxxxxxxxxx>
---
 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."?

-Scott
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