Currently in nVHE, KVM has to check if TRBE is enabled on every guest switch even if it was never used. Because it's a debug feature and is more likely to not be used than used, give KVM the TRBE buffer status to allow a much simpler and faster do-nothing path in the hyp.
Protected mode now disables trace regardless of TRBE (because trfcr_while_in_guest is always 0), which was not previously done. However, it continues to flush whenever the buffer is enabled regardless of the filter status. This avoids the hypothetical case of a host that had disabled the filter but not flushed which would arise if only doing the flush when the filter was enabled.
Signed-off-by: James Clark james.clark@linaro.org --- arch/arm64/include/asm/kvm_host.h | 9 +++ arch/arm64/kvm/debug.c | 32 +++++++++- arch/arm64/kvm/hyp/nvhe/debug-sr.c | 63 ++++++++++++-------- drivers/hwtracing/coresight/coresight-trbe.c | 3 + 4 files changed, 79 insertions(+), 28 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index fb252d540850..b244ec44bd3a 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -612,6 +612,8 @@ struct cpu_sve_state { struct kvm_host_data { #define KVM_HOST_DATA_FLAG_HAS_SPE 0 #define KVM_HOST_DATA_FLAG_HAS_TRBE 1 +#define KVM_HOST_DATA_FLAG_TRBE_ENABLED 2 +#define KVM_HOST_DATA_FLAG_EL1_TRACING_CONFIGURED 3 unsigned long flags;
struct kvm_cpu_context host_ctxt; @@ -657,6 +659,9 @@ struct kvm_host_data { u64 mdcr_el2; } host_debug_state;
+ /* Guest trace filter value */ + u64 trfcr_while_in_guest; + /* Number of programmable event counters (PMCR_EL0.N) for this CPU */ unsigned int nr_event_counters; }; @@ -1381,6 +1386,8 @@ static inline bool kvm_pmu_counter_deferred(struct perf_event_attr *attr) void kvm_set_pmu_events(u64 set, struct perf_event_attr *attr); void kvm_clr_pmu_events(u64 clr); bool kvm_set_pmuserenr(u64 val); +void kvm_enable_trbe(void); +void kvm_disable_trbe(void); #else static inline void kvm_set_pmu_events(u64 set, struct perf_event_attr *attr) {} static inline void kvm_clr_pmu_events(u64 clr) {} @@ -1388,6 +1395,8 @@ static inline bool kvm_set_pmuserenr(u64 val) { return false; } +static inline void kvm_enable_trbe(void) {} +static inline void kvm_disable_trbe(void) {} #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 1ee2fd765b62..e1ac3d2a65be 100644 --- a/arch/arm64/kvm/debug.c +++ b/arch/arm64/kvm/debug.c @@ -309,7 +309,33 @@ void kvm_init_host_debug_data(void) !(read_sysreg_s(SYS_PMBIDR_EL1) & PMBIDR_EL1_P)) host_data_set_flag(HAS_SPE);
- if (cpuid_feature_extract_unsigned_field(dfr0, ID_AA64DFR0_EL1_TraceBuffer_SHIFT) && - !(read_sysreg_s(SYS_TRBIDR_EL1) & TRBIDR_EL1_P)) - host_data_set_flag(HAS_TRBE); + if (cpuid_feature_extract_unsigned_field(dfr0, ID_AA64DFR0_EL1_TraceFilt_SHIFT)) { + /* Force disable trace in protected mode in case of no TRBE */ + if (is_protected_kvm_enabled()) + host_data_set_flag(EL1_TRACING_CONFIGURED); + + if (cpuid_feature_extract_unsigned_field(dfr0, ID_AA64DFR0_EL1_TraceBuffer_SHIFT) && + !(read_sysreg_s(SYS_TRBIDR_EL1) & TRBIDR_EL1_P)) + host_data_set_flag(HAS_TRBE); + } +} + +void kvm_enable_trbe(void) +{ + if (has_vhe() || is_protected_kvm_enabled() || + WARN_ON_ONCE(preemptible())) + return; + + host_data_set_flag(TRBE_ENABLED); +} +EXPORT_SYMBOL_GPL(kvm_enable_trbe); + +void kvm_disable_trbe(void) +{ + if (has_vhe() || is_protected_kvm_enabled() || + WARN_ON_ONCE(preemptible())) + return; + + host_data_clear_flag(TRBE_ENABLED); } +EXPORT_SYMBOL_GPL(kvm_disable_trbe); diff --git a/arch/arm64/kvm/hyp/nvhe/debug-sr.c b/arch/arm64/kvm/hyp/nvhe/debug-sr.c index 858bb38e273f..2f4a4f5036bb 100644 --- a/arch/arm64/kvm/hyp/nvhe/debug-sr.c +++ b/arch/arm64/kvm/hyp/nvhe/debug-sr.c @@ -51,32 +51,45 @@ static void __debug_restore_spe(u64 pmscr_el1) write_sysreg_el1(pmscr_el1, SYS_PMSCR); }
-static void __debug_save_trace(u64 *trfcr_el1) +static void __trace_do_switch(u64 *saved_trfcr, u64 new_trfcr) { - *trfcr_el1 = 0; + *saved_trfcr = read_sysreg_el1(SYS_TRFCR); + write_sysreg_el1(new_trfcr, SYS_TRFCR); +}
- /* Check if the TRBE is enabled */ - if (!(read_sysreg_s(SYS_TRBLIMITR_EL1) & TRBLIMITR_EL1_E)) - return; - /* - * Prohibit trace generation while we are in guest. - * Since access to TRFCR_EL1 is trapped, the guest can't - * modify the filtering set by the host. - */ - *trfcr_el1 = read_sysreg_el1(SYS_TRFCR); - write_sysreg_el1(0, SYS_TRFCR); - isb(); - /* Drain the trace buffer to memory */ - tsb_csync(); +static bool __trace_needs_drain(void) +{ + if (is_protected_kvm_enabled() && host_data_test_flag(HAS_TRBE)) + return read_sysreg_s(SYS_TRBLIMITR_EL1) & TRBLIMITR_EL1_E; + + return host_data_test_flag(TRBE_ENABLED); }
-static void __debug_restore_trace(u64 trfcr_el1) +static bool __trace_needs_switch(void) { - if (!trfcr_el1) - return; + return host_data_test_flag(TRBE_ENABLED) || + host_data_test_flag(EL1_TRACING_CONFIGURED); +} + +static void __trace_switch_to_guest(void) +{ + /* Unsupported with TRBE so disable */ + if (host_data_test_flag(TRBE_ENABLED)) + *host_data_ptr(trfcr_while_in_guest) = 0; + + __trace_do_switch(host_data_ptr(host_debug_state.trfcr_el1), + *host_data_ptr(trfcr_while_in_guest));
- /* Restore trace filter controls */ - write_sysreg_el1(trfcr_el1, SYS_TRFCR); + if (__trace_needs_drain()) { + isb(); + tsb_csync(); + } +} + +static void __trace_switch_to_host(void) +{ + __trace_do_switch(host_data_ptr(trfcr_while_in_guest), + *host_data_ptr(host_debug_state.trfcr_el1)); }
void __debug_save_host_buffers_nvhe(struct kvm_vcpu *vcpu) @@ -84,9 +97,9 @@ void __debug_save_host_buffers_nvhe(struct kvm_vcpu *vcpu) /* Disable and flush SPE data generation */ if (host_data_test_flag(HAS_SPE)) __debug_save_spe(host_data_ptr(host_debug_state.pmscr_el1)); - /* Disable and flush Self-Hosted Trace generation */ - if (host_data_test_flag(HAS_TRBE)) - __debug_save_trace(host_data_ptr(host_debug_state.trfcr_el1)); + + if (__trace_needs_switch()) + __trace_switch_to_guest(); }
void __debug_switch_to_guest(struct kvm_vcpu *vcpu) @@ -98,8 +111,8 @@ void __debug_restore_host_buffers_nvhe(struct kvm_vcpu *vcpu) { if (host_data_test_flag(HAS_SPE)) __debug_restore_spe(*host_data_ptr(host_debug_state.pmscr_el1)); - if (host_data_test_flag(HAS_TRBE)) - __debug_restore_trace(*host_data_ptr(host_debug_state.trfcr_el1)); + if (__trace_needs_switch()) + __trace_switch_to_host(); }
void __debug_switch_to_host(struct kvm_vcpu *vcpu) diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c index 03d3695ba5aa..a728802d2206 100644 --- a/drivers/hwtracing/coresight/coresight-trbe.c +++ b/drivers/hwtracing/coresight/coresight-trbe.c @@ -17,6 +17,7 @@
#include <asm/barrier.h> #include <asm/cpufeature.h> +#include <linux/kvm_host.h> #include <linux/vmalloc.h>
#include "coresight-self-hosted-trace.h" @@ -221,6 +222,7 @@ static inline void set_trbe_enabled(struct trbe_cpudata *cpudata, u64 trblimitr) */ trblimitr |= TRBLIMITR_EL1_E; write_sysreg_s(trblimitr, SYS_TRBLIMITR_EL1); + kvm_enable_trbe();
/* Synchronize the TRBE enable event */ isb(); @@ -239,6 +241,7 @@ static inline void set_trbe_disabled(struct trbe_cpudata *cpudata) */ trblimitr &= ~TRBLIMITR_EL1_E; write_sysreg_s(trblimitr, SYS_TRBLIMITR_EL1); + kvm_disable_trbe();
if (trbe_needs_drain_after_disable(cpudata)) trbe_drain_buffer();