Re: [PATCH] KVM: nVMX: Add support for activity state HLT

[Paolo Bonzini <pbonzini@redhat.com>]

Il 04/12/2013 08:58, Jan Kiszka ha scritto:
> We can easily emulate the HLT activity state for L1: If it decides that
> L2 shall be halted on entry, just invoke the normal emulation of halt
> after switching to L2. We do not depend on specific host features to
> provide this, so we can expose the capability unconditionally.
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> ---
> 
> Jailhouse would like to use this. Experimental code works fine so far,
> both on patched KVM and real HW.

Nice. :)

Do you have a testcase for kvm-unit-tests?

Paolo

>  arch/x86/include/asm/vmx.h | 1 +
>  arch/x86/kvm/vmx.c         | 7 ++++++-
>  2 files changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
> index 966502d..2067264 100644
> --- a/arch/x86/include/asm/vmx.h
> +++ b/arch/x86/include/asm/vmx.h
> @@ -100,6 +100,7 @@
>  
>  #define VMX_MISC_PREEMPTION_TIMER_RATE_MASK	0x0000001f
>  #define VMX_MISC_SAVE_EFER_LMA			0x00000020
> +#define VMX_MISC_ACTIVITY_HLT			0x00000040
>  
>  /* VMCS Encodings */
>  enum vmcs_field {
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index b2fe1c2..00faf1f 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -2279,6 +2279,7 @@ static __init void nested_vmx_setup_ctls_msrs(void)
>  	rdmsr(MSR_IA32_VMX_MISC, nested_vmx_misc_low, nested_vmx_misc_high);
>  	nested_vmx_misc_low &= VMX_MISC_PREEMPTION_TIMER_RATE_MASK |
>  		VMX_MISC_SAVE_EFER_LMA;
> +	nested_vmx_misc_low |= VMX_MISC_ACTIVITY_HLT;
>  	nested_vmx_misc_high = 0;
>  }
>  
> @@ -7882,7 +7883,8 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
>  		return 1;
>  	}
>  
> -	if (vmcs12->guest_activity_state != GUEST_ACTIVITY_ACTIVE) {
> +	if (vmcs12->guest_activity_state != GUEST_ACTIVITY_ACTIVE &&
> +	    vmcs12->guest_activity_state != GUEST_ACTIVITY_HLT) {
>  		nested_vmx_failValid(vcpu, VMXERR_ENTRY_INVALID_CONTROL_FIELD);
>  		return 1;
>  	}
> @@ -8011,6 +8013,9 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
>  
>  	prepare_vmcs02(vcpu, vmcs12);
>  
> +	if (vmcs12->guest_activity_state == GUEST_ACTIVITY_HLT)
> +		return kvm_emulate_halt(vcpu);
> +
>  	/*
>  	 * Note no nested_vmx_succeed or nested_vmx_fail here. At this point
>  	 * we are no longer running L1, and VMLAUNCH/VMRESUME has not yet
>