[PATCH 19/27] KVM: arm64: nv: Add trap forwarding for CNTHCTL_EL2

[Eric Auger]

Hi Marc,

On 7/12/23 16:58, Marc Zyngier wrote:
> Describe the CNTHCTL_EL2 register, and associate it with all the sysregs
> it allows to trap.
>
> Signed-off-by: Marc Zyngier <maz at kernel.org>
> ---
>  arch/arm64/kvm/emulate-nested.c | 37 ++++++++++++++++++++++++++++++++-
>  1 file changed, 36 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/kvm/emulate-nested.c b/arch/arm64/kvm/emulate-nested.c
> index 25e4842ac334..c07c0f3361d7 100644
> --- a/arch/arm64/kvm/emulate-nested.c
> +++ b/arch/arm64/kvm/emulate-nested.c
> @@ -98,9 +98,11 @@ enum coarse_grain_trap_id {
>  
>  	/*
>  	 * Anything after this point requires a callback evaluating a
> -	 * complex trap condition. Hopefully we'll never need this...
> +	 * complex trap condition. Ugly stuff.
>  	 */
>  	__COMPLEX_CONDITIONS__,
> +	CGT_CNTHCTL_EL1PCTEN = __COMPLEX_CONDITIONS__,
> +	CGT_CNTHCTL_EL1PTEN,
>  };
>  
>  static const struct trap_bits coarse_trap_bits[] = {
> @@ -358,9 +360,37 @@ static const enum coarse_grain_trap_id *coarse_control_combo[] = {
>  
>  typedef enum trap_behaviour (*complex_condition_check)(struct kvm_vcpu *);
>  
> +static u64 get_sanitized_cnthctl(struct kvm_vcpu *vcpu)
> +{
> +	u64 val = __vcpu_sys_reg(vcpu, CNTHCTL_EL2);
> +
> +	if (!vcpu_el2_e2h_is_set(vcpu))
> +		val = (val & (CNTHCTL_EL1PCEN | CNTHCTL_EL1PCTEN)) << 10;
> +
> +	return val;
don't you want to return only bits 10 & 11 to match the other condition?

I would add a comment saying that When FEAT_VHE is implemented and
HCR_EL2.E2H == 1:

sanitized_cnthctl[11:10] = [EL1PTEN, EL1PCTEN]
otherwise
sanitized_cnthctl[11:10] = [EL1PCEN, EL1PCTEN]

> +}
> +
> +static enum trap_behaviour check_cnthctl_el1pcten(struct kvm_vcpu *vcpu)
> +{
> +	if (get_sanitized_cnthctl(vcpu) & (CNTHCTL_EL1PCTEN << 10))
> +		return BEHAVE_HANDLE_LOCALLY;
> +
> +	return BEHAVE_FORWARD_ANY;
> +}
> +
> +static enum trap_behaviour check_cnthctl_el1pten(struct kvm_vcpu *vcpu)
or pcen. This is a bit confusing to see EL1PCEN below. But this is due
to above sanitized CNTHCTL. Worth a comment to me.
> +{
> +	if (get_sanitized_cnthctl(vcpu) & (CNTHCTL_EL1PCEN << 10))
> +		return BEHAVE_HANDLE_LOCALLY;
> +
> +	return BEHAVE_FORWARD_ANY;
> +}
> +
>  #define CCC(id, fn)	[id - __COMPLEX_CONDITIONS__] = fn
>  
>  static const complex_condition_check ccc[] = {
> +	CCC(CGT_CNTHCTL_EL1PCTEN, check_cnthctl_el1pcten),
> +	CCC(CGT_CNTHCTL_EL1PTEN, check_cnthctl_el1pten),
>  };
>  
>  /*
> @@ -855,6 +885,11 @@ static const struct encoding_to_trap_config encoding_to_cgt[] __initdata = {
>  	SR_TRAP(SYS_TRBPTR_EL1, 	CGT_MDCR_E2TB),
>  	SR_TRAP(SYS_TRBSR_EL1, 		CGT_MDCR_E2TB),
>  	SR_TRAP(SYS_TRBTRG_EL1,		CGT_MDCR_E2TB),
> +	SR_TRAP(SYS_CNTP_TVAL_EL0,	CGT_CNTHCTL_EL1PTEN),
> +	SR_TRAP(SYS_CNTP_CVAL_EL0,	CGT_CNTHCTL_EL1PTEN),
> +	SR_TRAP(SYS_CNTP_CTL_EL0,	CGT_CNTHCTL_EL1PTEN),
> +	SR_TRAP(SYS_CNTPCT_EL0,		CGT_CNTHCTL_EL1PCTEN),
> +	SR_TRAP(SYS_CNTPCTSS_EL0,	CGT_CNTHCTL_EL1PCTEN),
>  };
>  
>  static DEFINE_XARRAY(sr_forward_xa);
Otherwise looks good to me
Reviewed-by: Eric Auger <eric.auger at redhat.com>


Eric