@@ -617,6 +617,8 @@ struct kvm_host_data {
#define KVM_HOST_DATA_FLAG_HAS_TRBE 1
#define KVM_HOST_DATA_FLAG_HOST_SVE_ENABLED 2
#define KVM_HOST_DATA_FLAG_HOST_SME_ENABLED 3
+#define KVM_HOST_DATA_FLAG_TRBE_ENABLED 4
+#define KVM_HOST_DATA_FLAG_EL1_TRACING_CONFIGURED 5
unsigned long flags;
struct kvm_cpu_context host_ctxt;
@@ -662,6 +664,9 @@ 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;
@@ -1389,6 +1394,8 @@ 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) {}
@@ -1396,6 +1403,8 @@ 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);
@@ -81,9 +81,15 @@ 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);
+ }
}
/*
@@ -219,3 +225,23 @@ void kvm_debug_handle_oslar(struct kvm_vcpu *vcpu, u64 val)
kvm_arch_vcpu_load(vcpu, smp_processor_id());
preempt_enable();
}
+
+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);
@@ -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)
@@ -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();
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(-)