[PATCH 20/25] KVM: arm64: Streamline save/restore of HFG[RW]TR_EL2

[Joey Gouly]

On Mon, Jan 22, 2024 at 08:18:47PM +0000, Marc Zyngier wrote:
> The way we save/restore HFG[RW]TR_EL2 can now be simplified, and
> the Ampere erratum hack is the only thing that still stands out.
> 
> Signed-off-by: Marc Zyngier <maz at kernel.org>
> ---
>  arch/arm64/kvm/hyp/include/hyp/switch.h | 42 ++++++-------------------
>  1 file changed, 9 insertions(+), 33 deletions(-)
> 
> diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h
> index 245f9c1ca666..2d5891518006 100644
> --- a/arch/arm64/kvm/hyp/include/hyp/switch.h
> +++ b/arch/arm64/kvm/hyp/include/hyp/switch.h
> @@ -157,8 +157,6 @@ static inline void __activate_traps_hfgxtr(struct kvm_vcpu *vcpu)
>  {
>  	struct kvm_cpu_context *hctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt;
>  	struct kvm *kvm = kern_hyp_va(vcpu->kvm);
> -	u64 r_clr = 0, w_clr = 0, r_set = 0, w_set = 0;
> -	u64 r_val, w_val;
>  
>  	CHECK_FGT_MASKS(HFGRTR_EL2);
>  	CHECK_FGT_MASKS(HFGWTR_EL2);
> @@ -171,34 +169,10 @@ static inline void __activate_traps_hfgxtr(struct kvm_vcpu *vcpu)
>  	if (!cpus_have_final_cap(ARM64_HAS_FGT))
>  		return;
>  
> -	ctxt_sys_reg(hctxt, HFGRTR_EL2) = read_sysreg_s(SYS_HFGRTR_EL2);
> -	ctxt_sys_reg(hctxt, HFGWTR_EL2) = read_sysreg_s(SYS_HFGWTR_EL2);
> -
> -	/*
> -	 * Trap guest writes to TCR_EL1 to prevent it from enabling HA or HD.
> -	 */
> -	if (cpus_have_final_cap(ARM64_WORKAROUND_AMPERE_AC03_CPU_38))
> -		w_set |= HFGxTR_EL2_TCR_EL1_MASK;
> -
> -	if (vcpu_has_nv(vcpu) && !is_hyp_ctxt(vcpu)) {
> -		compute_clr_set(vcpu, HFGRTR_EL2, r_clr, r_set);
> -		compute_clr_set(vcpu, HFGWTR_EL2, w_clr, w_set);
> -	}
> -
> -	compute_undef_clr_set(vcpu, kvm, HFGRTR_EL2, r_clr, r_set);
> -	compute_undef_clr_set(vcpu, kvm, HFGWTR_EL2, w_clr, w_set);
> -
> -	r_val = __HFGRTR_EL2_nMASK;
> -	r_val |= r_set;
> -	r_val &= ~r_clr;
> -
> -	w_val = __HFGWTR_EL2_nMASK;
> -	w_val |= w_set;
> -	w_val &= ~w_clr;
> -
> -	write_sysreg_s(r_val, SYS_HFGRTR_EL2);
> -	write_sysreg_s(w_val, SYS_HFGWTR_EL2);
> -
> +	update_fgt_traps(hctxt, vcpu, kvm, HFGRTR_EL2);
> +	update_fgt_traps_cs(hctxt, vcpu, kvm, HFGWTR_EL2, 0,
> +			    cpus_have_final_cap(ARM64_WORKAROUND_AMPERE_AC03_CPU_38) ?
> +			    HFGxTR_EL2_TCR_EL1_MASK : 0);
>  	update_fgt_traps(hctxt, vcpu, kvm, HFGITR_EL2);
>  	update_fgt_traps(hctxt, vcpu, kvm, HDFGRTR_EL2);
>  	update_fgt_traps(hctxt, vcpu, kvm, HDFGWTR_EL2);
> @@ -223,9 +197,11 @@ static inline void __deactivate_traps_hfgxtr(struct kvm_vcpu *vcpu)
>  	if (!cpus_have_final_cap(ARM64_HAS_FGT))
>  		return;
>  
> -	write_sysreg_s(ctxt_sys_reg(hctxt, HFGRTR_EL2), SYS_HFGRTR_EL2);
> -	write_sysreg_s(ctxt_sys_reg(hctxt, HFGWTR_EL2), SYS_HFGWTR_EL2);
> -
> +	__deactivate_fgt(hctxt, vcpu, kvm, HFGRTR_EL2);
> +	if (cpus_have_final_cap(ARM64_WORKAROUND_AMPERE_AC03_CPU_38))
> +		write_sysreg_s(ctxt_sys_reg(hctxt, HFGWTR_EL2), SYS_HFGWTR_EL2);
> +	else
> +		__deactivate_fgt(hctxt, vcpu, kvm, HFGWTR_EL2);
>  	__deactivate_fgt(hctxt, vcpu, kvm, HFGITR_EL2);
>  	__deactivate_fgt(hctxt, vcpu, kvm, HDFGRTR_EL2);
>  	__deactivate_fgt(hctxt, vcpu, kvm, HDFGWTR_EL2);

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

Thanks,
Joey