On Tue, 25 Jan 2022 00:11:01 +0000,
Mark Brown <[email protected]> wrote:
>
> SME defines two new traps which need to be enabled for guests to ensure
> that they can't use SME, one for the main SME operations which mirrors the
> traps for SVE and another for access to TPIDR2 in SCTLR_EL2.
>
> For VHE manage SMEN along with ZEN in activate_traps() and the FP state
> management callbacks.
>
> For nVHE the value to be used for CPTR_EL2 in the guest is stored in
> vcpu->arch.cptr_el2, set TSM there during initialisation. It will be
> cleared in __deactivate_traps_common() by virtue of not being set in
> CPTR_EL2_DEFAULT.
>
> For both VHE and nVHE cases handle SCTLR_EL2.EnTPIDR2 in the shared
> __active_traps_common() and __deactivate_traps_common(), there is no
> existing dynamic management of SCTLR_EL2.
>
> Signed-off-by: Mark Brown <[email protected]>
> ---
> arch/arm64/kvm/hyp/nvhe/switch.c | 30 ++++++++++++++++++++++++++++++
> arch/arm64/kvm/hyp/vhe/switch.c | 10 +++++++++-
> 2 files changed, 39 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c
> b/arch/arm64/kvm/hyp/nvhe/switch.c
> index 6410d21d8695..184bf6bd79b9 100644
> --- a/arch/arm64/kvm/hyp/nvhe/switch.c
> +++ b/arch/arm64/kvm/hyp/nvhe/switch.c
> @@ -47,10 +47,25 @@ static void __activate_traps(struct kvm_vcpu *vcpu)
> val |= CPTR_EL2_TFP | CPTR_EL2_TZ;
> __activate_traps_fpsimd32(vcpu);
> }
> + if (IS_ENABLED(CONFIG_ARM64_SME) && cpus_have_final_cap(ARM64_SME))
Please drop the IS_ENABLED(). We purposely avoid conditional
compilation in KVM in order to avoid bitrot, and the amount of code
you save isn't significant. Having a static key is more than enough to
avoid runtime costs.
> + val |= CPTR_EL2_TSM;
>
> write_sysreg(val, cptr_el2);
> write_sysreg(__this_cpu_read(kvm_hyp_vector), vbar_el2);
>
> + if (IS_ENABLED(CONFIG_ARM64_SME) && cpus_have_final_cap(ARM64_SME) &&
> + cpus_have_final_cap(ARM64_HAS_FGT)) {
> + val = read_sysreg_s(SYS_HFGRTR_EL2);
> + val &= ~(HFGxTR_EL2_nTPIDR_EL0_MASK |
> + HFGxTR_EL2_nSMPRI_EL1_MASK);
> + write_sysreg_s(val, SYS_HFGRTR_EL2);
> +
> + val = read_sysreg_s(SYS_HFGWTR_EL2);
> + val &= ~(HFGxTR_EL2_nTPIDR_EL0_MASK |
> + HFGxTR_EL2_nSMPRI_EL1_MASK);
> + write_sysreg_s(val, SYS_HFGWTR_EL2);
> + }
If the CPUs do not have FGT, what provides the equivalent trapping?
If FGT is mandatory when SME exists, then you should simplify the
condition.
M.
--
Without deviation from the norm, progress is not possible.
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