Messages in this thread | | | Date | Thu, 5 Oct 2023 17:58:53 +0100 | Subject | Re: [PATCH v2 4/6] arm64: KVM: Add interface to set guest value for TRFCR register | From | Suzuki K Poulose <> |
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On 05/10/2023 13:57, 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, TRFCR_EL1 is written immediately. Because guest writes
minor nit: May be it would be clearer to say:
For VHE, the host trace is controlled by TRFCR_EL2 and thus we can write to the TRFCR_EL1 immediately. Because, ...
> to the register are trapped, the value will persist and can't be > modified. > > The settings must be copied to the vCPU before each run in the same > way that PMU events are because the per-cpu struct isn't accessible in
super minor nit:
way that PMU events are, because ...
> protected mode. > > Now that both guest and host values are saved, rename trfcr_el1 to > host_trfcr_el1 to make it clear that's the value that should be restored
This seems obsolete ? I couldn't find any reference to host_trfcr_el1 anywhere ?
Otherwise looks good to me.
Suzuki
> on return to the host. > > Signed-off-by: James Clark <james.clark@arm.com> > --- > arch/arm64/include/asm/kvm_host.h | 3 +++ > arch/arm64/kvm/arm.c | 1 + > arch/arm64/kvm/debug.c | 26 ++++++++++++++++++++++++++ > 3 files changed, 30 insertions(+) > > diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h > index b5200f199692..8f2b4ec8ea61 100644 > --- a/arch/arm64/include/asm/kvm_host.h > +++ b/arch/arm64/include/asm/kvm_host.h > @@ -1123,6 +1123,8 @@ 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); > +void kvm_etm_update_vcpu_events(struct kvm_vcpu *vcpu); > #else > static inline void kvm_set_pmu_events(u32 set, struct perf_event_attr *attr) {} > static inline void kvm_clr_pmu_events(u32 clr) {} > @@ -1130,6 +1132,7 @@ 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_sysregs_vhe(struct kvm_vcpu *vcpu); > diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c > index 78b0970eb8e6..22fab356b88f 100644 > --- a/arch/arm64/kvm/arm.c > +++ b/arch/arm64/kvm/arm.c > @@ -1012,6 +1012,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu) > kvm_vgic_flush_hwstate(vcpu); > > kvm_pmu_update_vcpu_events(vcpu); > + kvm_etm_update_vcpu_events(vcpu); > > /* > * Ensure we set mode to IN_GUEST_MODE after we disable > diff --git a/arch/arm64/kvm/debug.c b/arch/arm64/kvm/debug.c > index 6a1bad1a921b..19e722359154 100644 > --- a/arch/arm64/kvm/debug.c > +++ b/arch/arm64/kvm/debug.c > @@ -23,6 +23,12 @@ > > static DEFINE_PER_CPU(u64, mdcr_el2); > > +/* > + * Per CPU value for TRFCR that should be applied to any guest vcpu that may > + * run on that core in the future. > + */ > +static DEFINE_PER_CPU(u64, guest_trfcr); > + > /** > * save/restore_guest_debug_regs > * > @@ -342,3 +348,23 @@ void kvm_arch_vcpu_put_debug_state_flags(struct kvm_vcpu *vcpu) > vcpu_clear_flag(vcpu, DEBUG_STATE_SAVE_SPE); > vcpu_clear_flag(vcpu, DEBUG_STATE_SAVE_TRFCR); > } > + > +void kvm_etm_set_guest_trfcr(u64 trfcr_guest) > +{ > + if (has_vhe()) > + write_sysreg_s(trfcr_guest, SYS_TRFCR_EL12); > + else > + *this_cpu_ptr(&guest_trfcr) = trfcr_guest; > +} > +EXPORT_SYMBOL_GPL(kvm_etm_set_guest_trfcr); > + > +/* > + * Updates the vcpu's view of the etm events for this cpu. Must be > + * called before every vcpu run after disabling interrupts, to ensure > + * that an interrupt cannot fire and update the structure. > + */ > +void kvm_etm_update_vcpu_events(struct kvm_vcpu *vcpu) > +{ > + if (!has_vhe() && vcpu_get_flag(vcpu, DEBUG_STATE_SAVE_TRFCR)) > + ctxt_sys_reg(&vcpu->arch.ctxt, TRFCR_EL1) = *this_cpu_ptr(&guest_trfcr); > +}
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