[PATCH v3 04/15] KVM: arm64: nv: Drop VCPU_HYP_CONTEXT flag

[Oliver Upton]

On Thu, Mar 21, 2024 at 03:53:45PM +0000, Marc Zyngier wrote:
> It has become obvious that HCR_EL2.NV serves the exact same use
> as VCPU_HYP_CONTEXT, only in an architectural way. So just drop
> the flag for good.
> 
> Reviewed-by: Joey Gouly <joey.gouly at arm.com>
> Signed-off-by: Marc Zyngier <maz at kernel.org>
> ---
>  arch/arm64/include/asm/kvm_host.h | 2 --
>  arch/arm64/kvm/hyp/vhe/switch.c   | 7 +------
>  2 files changed, 1 insertion(+), 8 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index 839c76529bb2..3f1c3c91e5c2 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -816,8 +816,6 @@ struct kvm_vcpu_arch {
>  #define DEBUG_STATE_SAVE_SPE	__vcpu_single_flag(iflags, BIT(5))
>  /* Save TRBE context if active  */
>  #define DEBUG_STATE_SAVE_TRBE	__vcpu_single_flag(iflags, BIT(6))
> -/* vcpu running in HYP context */
> -#define VCPU_HYP_CONTEXT	__vcpu_single_flag(iflags, BIT(7))
>  
>  /* SVE enabled for host EL0 */
>  #define HOST_SVE_ENABLED	__vcpu_single_flag(sflags, BIT(0))
> diff --git a/arch/arm64/kvm/hyp/vhe/switch.c b/arch/arm64/kvm/hyp/vhe/switch.c
> index 1581df6aec87..58415783fd53 100644
> --- a/arch/arm64/kvm/hyp/vhe/switch.c
> +++ b/arch/arm64/kvm/hyp/vhe/switch.c
> @@ -197,7 +197,7 @@ static void early_exit_filter(struct kvm_vcpu *vcpu, u64 *exit_code)
>  	 * If we were in HYP context on entry, adjust the PSTATE view
>  	 * so that the usual helpers work correctly.
>  	 */
> -	if (unlikely(vcpu_get_flag(vcpu, VCPU_HYP_CONTEXT))) {
> +	if (unlikely(read_sysreg(hcr_el2) & HCR_NV)) {

Can this be additionally predicated on vcpu_has_nv() so we condition on
the NV cpucap and avoid the sysreg read on non-nesting hardware?

-- 
Thanks,
Oliver