@@ -641,6 +641,8 @@ struct kvm_host_data {
struct {
/* Host CPU features, set at init */
u8 feats;
+ /* Host CPU state */
+ u8 state;
} flags;
/*
@@ -941,6 +943,8 @@ struct kvm_vcpu_arch {
#define HOST_FEAT_HAS_TRBE __kvm_single_flag(feats, BIT(1))
/* CPU has Feat_TRF */
#define HOST_FEAT_HAS_TRF __kvm_single_flag(feats, BIT(2))
+/* PMBLIMITR_EL1_E is set (SPE profiling buffer enabled) */
+#define HOST_STATE_SPE_EN __kvm_single_flag(state, BIT(0))
/* Pointer to the vcpu's SVE FFR for sve_{save,load}_state() */
#define vcpu_sve_pffr(vcpu) (kern_hyp_va((vcpu)->arch.sve_state) + \
@@ -1382,6 +1386,7 @@ 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_set_pmblimitr(u64 pmblimitr);
#else
static inline void kvm_set_pmu_events(u64 set, struct perf_event_attr *attr) {}
static inline void kvm_clr_pmu_events(u64 clr) {}
@@ -1389,6 +1394,7 @@ static inline bool kvm_set_pmuserenr(u64 val)
{
return false;
}
+static inline void kvm_set_pmblimitr(u64 pmblimitr) {}
#endif
void kvm_vcpu_load_vhe(struct kvm_vcpu *vcpu);
@@ -335,3 +335,32 @@ void kvm_arm_clear_debug(struct kvm_vcpu *vcpu)
}
}
}
+
+static bool kvm_arm_skip_trace_state(void)
+{
+ /* pKVM hyp finds out the state for itself */
+ if (is_protected_kvm_enabled())
+ return true;
+
+ /* Make sure state gets there in one piece */
+ if (WARN_ON_ONCE(preemptible()))
+ return true;
+
+ return false;
+}
+
+void kvm_set_pmblimitr(u64 pmblimitr)
+{
+ /* Only read in nVHE */
+ if (has_vhe())
+ return;
+
+ if (kvm_arm_skip_trace_state())
+ return;
+
+ if (pmblimitr & PMBLIMITR_EL1_E)
+ host_data_set_flag(HOST_STATE_SPE_EN);
+ else
+ host_data_clear_flag(HOST_STATE_SPE_EN);
+}
+EXPORT_SYMBOL_GPL(kvm_set_pmblimitr);
@@ -23,6 +23,7 @@
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/kernel.h>
+#include <linux/kvm_host.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/of.h>
@@ -496,6 +497,12 @@ static u64 arm_spe_pmu_next_off(struct perf_output_handle *handle)
return limit;
}
+static void arm_spe_write_pmblimitr(u64 val)
+{
+ write_sysreg_s(val, SYS_PMBLIMITR_EL1);
+ kvm_set_pmblimitr(val);
+}
+
static void arm_spe_perf_aux_output_begin(struct perf_output_handle *handle,
struct perf_event *event)
{
@@ -524,7 +531,7 @@ static void arm_spe_perf_aux_output_begin(struct perf_output_handle *handle,
write_sysreg_s(base, SYS_PMBPTR_EL1);
out_write_limit:
- write_sysreg_s(limit, SYS_PMBLIMITR_EL1);
+ arm_spe_write_pmblimitr(limit);
}
static void arm_spe_perf_aux_output_end(struct perf_output_handle *handle)
@@ -552,7 +559,7 @@ static void arm_spe_pmu_disable_and_drain_local(void)
dsb(nsh);
/* Disable the profiling buffer */
- write_sysreg_s(0, SYS_PMBLIMITR_EL1);
+ arm_spe_write_pmblimitr(0);
isb();
}
@@ -1095,7 +1102,9 @@ static void __arm_spe_pmu_reset_local(void)
* This is probably overkill, as we have no idea where we're
* draining any buffered data to...
*/
+ preempt_disable();
arm_spe_pmu_disable_and_drain_local();
+ preempt_enable();
/* Reset the buffer base pointer */
write_sysreg_s(0, SYS_PMBPTR_EL1);
Currently in nVHE, KVM has to check if SPE 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 SPE buffer status to allow a much simpler and faster do-nothing path in the hyp. This is always called with preemption disabled except for probe/hotplug which gets wrapped with preempt_disable(). Signed-off-by: James Clark <james.clark@linaro.org> --- arch/arm64/include/asm/kvm_host.h | 6 ++++++ arch/arm64/kvm/debug.c | 29 +++++++++++++++++++++++++++++ drivers/perf/arm_spe_pmu.c | 13 +++++++++++-- 3 files changed, 46 insertions(+), 2 deletions(-)