Re: [PATCH 03/13] KVM: arm64: nv: Drop VCPU_HYP_CONTEXT flag

[Joey Gouly <joey.gouly@arm.com>]

On Mon, Feb 19, 2024 at 09:20:04AM +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.
> 
> Signed-off-by: Marc Zyngier <maz@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 a5ec4c7d3966..75eb8e170515 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)) {
>  		u64 mode = *vcpu_cpsr(vcpu) & (PSR_MODE_MASK | PSR_MODE32_BIT);
>  
>  		switch (mode) {
> @@ -240,11 +240,6 @@ static int __kvm_vcpu_run_vhe(struct kvm_vcpu *vcpu)
>  	sysreg_restore_guest_state_vhe(guest_ctxt);
>  	__debug_switch_to_guest(vcpu);
>  
> -	if (is_hyp_ctxt(vcpu))
> -		vcpu_set_flag(vcpu, VCPU_HYP_CONTEXT);
> -	else
> -		vcpu_clear_flag(vcpu, VCPU_HYP_CONTEXT);
> -
>  	do {
>  		/* Jump in the fire! */
>  		exit_code = __guest_enter(vcpu);

Makes sense to me.

Reviewed-by: Joey Gouly <joey.gouly@arm.com>

Thanks,
Joey