linux-kernel - [PATCH 37/54] KVM: VMX: Avoid exit when setting cr8 if the local apic is in the kernel

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Date:	Tue,  1 Jan 2008 17:36:03 +0200
From:	Avi Kivity <avi@...ranet.com>
To:	linux-kernel@...r.kernel.org, kvm-devel@...ts.sourceforge.net
Subject: [PATCH 37/54] KVM: VMX: Avoid exit when setting cr8 if the local apic is in the kernel

With apic in userspace, we must exit to userspace after a cr8 write in order
to update the tpr.  But if the apic is in the kernel, the exit is unnecessary.

Noticed by Joerg Roedel.

Signed-off-by: Avi Kivity <avi@...ranet.com>
---
 drivers/kvm/vmx.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index aa6bf2b..548e3a5 100644
--- a/drivers/kvm/vmx.c
+++ b/drivers/kvm/vmx.c
@@ -1973,6 +1973,8 @@ static int handle_cr(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 			vcpu_load_rsp_rip(vcpu);
 			set_cr8(vcpu, vcpu->regs[reg]);
 			skip_emulated_instruction(vcpu);
+			if (irqchip_in_kernel(vcpu->kvm))
+				return 1;
 			kvm_run->exit_reason = KVM_EXIT_SET_TPR;
 			return 0;
 		};
-- 
1.5.3.7

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