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@redhat.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index a9940ec9e215..f4e5aeda5edf 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -4242,6 +4242,10 @@ 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