[PATCH v4 5/7] arm64: KVM: Add interface to set guest value for TRFCR register
Suzuki K Poulose
suzuki.poulose at arm.com
Fri Jan 5 01:20:39 PST 2024
On 04/01/2024 16:27, James Clark wrote:
> Add an interface for the Coresight driver to use to set the value of the
> TRFCR register for the guest. This register controls the exclude
> settings for trace at different exception levels, and is used to honor
> the exclude_host and exclude_guest parameters from the Perf session.
> This will be used to later write TRFCR_EL1 on nVHE at guest switch. For
> VHE, the host trace is controlled by TRFCR_EL2 and thus we can write to
> the TRFCR_EL1 immediately. Because guest writes to the register are
> trapped, the value will persist and can't be modified.
>
> Signed-off-by: James Clark <james.clark at arm.com>
> ---
> arch/arm64/include/asm/kvm_host.h | 3 +++
> arch/arm64/kvm/debug.c | 24 ++++++++++++++++++++++++
> 2 files changed, 27 insertions(+)
>
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index 4864a1fcdf89..ee6cba7ee6ee 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -471,6 +471,7 @@ struct kvm_host_global_state {
> u32 events_host;
> u32 events_guest;
> } pmu_events;
> + u64 guest_trfcr_el1;
> } ____cacheline_aligned;
> extern struct kvm_host_global_state kvm_host_global_state[NR_CPUS];
>
> @@ -1145,6 +1146,7 @@ void kvm_arch_vcpu_put_debug_state_flags(struct kvm_vcpu *vcpu);
> void kvm_set_pmu_events(u32 set, struct perf_event_attr *attr);
> void kvm_clr_pmu_events(u32 clr);
> bool kvm_set_pmuserenr(u64 val);
> +void kvm_etm_set_guest_trfcr(u64 trfcr_guest);
> #else
> static inline void kvm_set_pmu_events(u32 set, struct perf_event_attr *attr) {}
> static inline void kvm_clr_pmu_events(u32 clr) {}
> @@ -1152,6 +1154,7 @@ static inline bool kvm_set_pmuserenr(u64 val)
> {
> return false;
> }
> +static inline void kvm_etm_set_guest_trfcr(u64 trfcr_guest) {}
> #endif
>
> void kvm_vcpu_load_vhe(struct kvm_vcpu *vcpu);
> diff --git a/arch/arm64/kvm/debug.c b/arch/arm64/kvm/debug.c
> index f86cbfae60f3..d69a0b9d9575 100644
> --- a/arch/arm64/kvm/debug.c
> +++ b/arch/arm64/kvm/debug.c
> @@ -358,3 +358,27 @@ void kvm_arch_vcpu_put_debug_state_flags(struct kvm_vcpu *vcpu)
> vcpu_clear_flag(vcpu, DEBUG_STATE_SAVE_TRBE);
> vcpu_clear_flag(vcpu, DEBUG_STATE_SAVE_TRFCR);
> }
> +
> +/*
> + * Interface for the Coresight driver to use to set the value of the TRFCR
> + * register for the guest. This register controls the exclude settings for trace
> + * at different exception levels, and is used to honor the exclude_host and
> + * exclude_guest parameters from the Perf session.
> + *
> + * This will be used to later write TRFCR_EL1 on nVHE at guest switch. For VHE,
> + * the host trace is controlled by TRFCR_EL2 and thus we can write to the
> + * TRFCR_EL1 immediately. Because guest writes to the register are trapped, the
> + * value will persist and can't be modified.
> + */
> +void kvm_etm_set_guest_trfcr(u64 trfcr_guest)
> +{
> + if (!cpuid_feature_extract_unsigned_field(read_sysreg(id_aa64dfr0_el1),
> + ID_AA64DFR0_EL1_TraceFilt_SHIFT))
Perhaps WARN_ON_ONCE() ?
Otherwise,
Reviewed-by: Suzuki K Poulose <suzuki.poulose at arm.com>
> + return;
> +
> + if (has_vhe())
> + write_sysreg_s(trfcr_guest, SYS_TRFCR_EL12);
> + else
> + kvm_host_global_state[smp_processor_id()].guest_trfcr_el1 = trfcr_guest;
> +}
> +EXPORT_SYMBOL_GPL(kvm_etm_set_guest_trfcr);
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