linux-kernel - [PATCH] kvm/fpu: Enable eager restore kvm FPU for MPX

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Date:	Wed, 20 May 2015 22:35:39 +0800
From:	Liang Li <liang.z.li@...el.com>
To:	kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:	gleb@...nel.or, pbonzini@...hat.com, tglx@...utronix.de,
	mingo@...hat.com, hpa@...or.com, x86@...nel.org,
	yang.z.zhang@...el.com, Liang Li <liang.z.li@...el.com>
Subject: [PATCH] kvm/fpu: Enable eager restore kvm FPU for MPX

The MPX feature requires eager KVM FPU restore support. We have verified
that MPX cannot work correctly with the current lazy KVM FPU restore
mechanism. Eager KVM FPU restore should be enabled if the MPX feature is
exposed to VM.

Signed-off-by: Liang Li <liang.z.li@...el.com>
---
 arch/x86/kvm/vmx.c | 2 ++
 arch/x86/kvm/x86.c | 3 ++-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index f7b6168..e2cccbe 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -8445,6 +8445,8 @@ static struct kvm_vcpu *vmx_create_vcpu(struct kvm *kvm, unsigned int id)
 			goto free_vmcs;
 	}
 
+	if (vmx_mpx_supported())
+		vmx_fpu_activate(&vmx->vcpu);
 	return &vmx->vcpu;
 
 free_vmcs:
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 5f38188..5993f5f 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -7060,7 +7060,8 @@ void kvm_put_guest_fpu(struct kvm_vcpu *vcpu)
 	fpu_save_init(&vcpu->arch.guest_fpu);
 	__kernel_fpu_end();
 	++vcpu->stat.fpu_reload;
-	kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu);
+	if (!kvm_x86_ops->mpx_supported())
+		kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu);
 	trace_kvm_fpu(0);
 }
 
-- 
1.9.1

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