linux-kernel - [PATCH 5/7] KVM: nVMX: Allow nested guests to run with dirty debug registers

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Date:	Fri,  7 Mar 2014 12:42:49 +0100
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	linux-kernel@...r.kernel.org
Cc:	kvm@...r.kernel.org, alex.williamson@...hat.com,
	mtosatti@...hat.com, gleb@...nel.org, jan.kiszka@...mens.com
Subject: [PATCH 5/7] KVM: nVMX: Allow nested guests to run with dirty debug registers

When preparing the VMCS02, the CPU-based execution controls is computed
by vmx_exec_control.  Turn off DR access exits there, too, if the
KVM_DEBUGREG_WONT_EXIT bit is set in switch_db_regs.

Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/x86/kvm/vmx.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index e377522408b1..73ced6efc93e 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -4234,6 +4234,10 @@ static u32 vmx_pin_based_exec_ctrl(struct vcpu_vmx *vmx)
 static u32 vmx_exec_control(struct vcpu_vmx *vmx)
 {
 	u32 exec_control = vmcs_config.cpu_based_exec_ctrl;
+
+	if (vmx->vcpu.arch.switch_db_regs & KVM_DEBUGREG_WONT_EXIT)
+		exec_control &= ~CPU_BASED_MOV_DR_EXITING;
+
 	if (!vm_need_tpr_shadow(vmx->vcpu.kvm)) {
 		exec_control &= ~CPU_BASED_TPR_SHADOW;
 #ifdef CONFIG_X86_64
-- 
1.8.3.1


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