[PATCH v3 06/16] perf/core: Rework guest callbacks to prepare for static_call support

Sean Christopherson
2021-09-22T00:06:08Z

From: Like Xu <like.xu@linux.intel.com>

To prepare for using static_calls to optimize perf's guest callbacks,
replace ->is_in_guest and ->is_user_mode with a new multiplexed hook
->state, tweak ->handle_intel_pt_intr to play nice with being called when
there is no active guest, and drop "guest" from ->is_in_guest.

Return '0' from ->state and ->handle_intel_pt_intr to indicate "not in
guest" so that DEFINE_STATIC_CALL_RET0 can be used to define the static
calls, i.e. no callback == !guest.

Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Originally-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Like Xu <like.xu@linux.intel.com>
Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
[sean: extracted from static_call patch, fixed get_ip() bug, wrote changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/arm64/kernel/perf_callchain.c | 13 +++++-----
arch/arm64/kvm/perf.c | 35 +++++++++++---------------
arch/x86/events/core.c | 13 +++++-----
arch/x86/events/intel/core.c | 5 +---
arch/x86/include/asm/kvm_host.h | 2 +-
arch/x86/kvm/pmu.c | 2 +-
arch/x86/kvm/x86.c | 40 ++++++++++++++++--------------
arch/x86/xen/pmu.c | 32 ++++++++++--------------
include/linux/perf_event.h | 10 +++++---
kernel/events/core.c | 1 +
10 files changed, 74 insertions(+), 79 deletions(-)

diff --git a/arch/arm64/kernel/perf_callchain.c b/arch/arm64/kernel/perf_callchain.c
index 86d9f2013172..274dc3e11b6d 100644
--- a/arch/arm64/kernel/perf_callchain.c
+++ b/arch/arm64/kernel/perf_callchain.c
@@ -104,7 +104,7 @@ void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
{
struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();

- if (guest_cbs && guest_cbs->is_in_guest()) {
+ if (guest_cbs && guest_cbs->state()) {
/* We don't support guest os callchain now */
return;
}
@@ -152,7 +152,7 @@ void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
struct stackframe frame;

- if (guest_cbs && guest_cbs->is_in_guest()) {
+ if (guest_cbs && guest_cbs->state()) {
/* We don't support guest os callchain now */
return;
}
@@ -165,8 +165,8 @@ unsigned long perf_instruction_pointer(struct pt_regs *regs)
{
struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();

- if (guest_cbs && guest_cbs->is_in_guest())
- return guest_cbs->get_guest_ip();
+ if (guest_cbs && guest_cbs->state())
+ return guest_cbs->get_ip();

return instruction_pointer(regs);
}
@@ -174,10 +174,11 @@ unsigned long perf_instruction_pointer(struct pt_regs *regs)
unsigned long perf_misc_flags(struct pt_regs *regs)
{
struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
+ unsigned int guest_state = guest_cbs ? guest_cbs->state() : 0;
int misc = 0;

- if (guest_cbs && guest_cbs->is_in_guest()) {
- if (guest_cbs->is_user_mode())
+ if (guest_state) {
+ if (guest_state & PERF_GUEST_USER)
misc |= PERF_RECORD_MISC_GUEST_USER;
else
misc |= PERF_RECORD_MISC_GUEST_KERNEL;
diff --git a/arch/arm64/kvm/perf.c b/arch/arm64/kvm/perf.c
index c37c0cf1bfe9..3e99ac4ab2d6 100644
--- a/arch/arm64/kvm/perf.c
+++ b/arch/arm64/kvm/perf.c
@@ -13,39 +13,34 @@

DEFINE_STATIC_KEY_FALSE(kvm_arm_pmu_available);

-static int kvm_is_in_guest(void)
+static unsigned int kvm_guest_state(void)
{
- return kvm_get_running_vcpu() != NULL;
-}
+ struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
+ unsigned int state;

-static int kvm_is_user_mode(void)
-{
- struct kvm_vcpu *vcpu;
-
- vcpu = kvm_get_running_vcpu();
+ if (!vcpu)
+ return 0;

- if (vcpu)
- return !vcpu_mode_priv(vcpu);
+ state = PERF_GUEST_ACTIVE;
+ if (!vcpu_mode_priv(vcpu))
+ state |= PERF_GUEST_USER;

- return 0;
+ return state;
}

static unsigned long kvm_get_guest_ip(void)
{
- struct kvm_vcpu *vcpu;
+ struct kvm_vcpu *vcpu = kvm_get_running_vcpu();

- vcpu = kvm_get_running_vcpu();
+ if (WARN_ON_ONCE(!vcpu))
+ return 0;

- if (vcpu)
- return *vcpu_pc(vcpu);
-
- return 0;
+ return *vcpu_pc(vcpu);
}

static struct perf_guest_info_callbacks kvm_guest_cbs = {
- .is_in_guest = kvm_is_in_guest,
- .is_user_mode = kvm_is_user_mode,
- .get_guest_ip = kvm_get_guest_ip,
+ .state = kvm_guest_state,
+ .get_ip = kvm_get_guest_ip,
};

void kvm_perf_init(void)
diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index ffb3e6c0d367..3a7630fdd340 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -2765,7 +2765,7 @@ perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *re
struct unwind_state state;
unsigned long addr;

- if (guest_cbs && guest_cbs->is_in_guest()) {
+ if (guest_cbs && guest_cbs->state()) {
/* TODO: We don't support guest os callchain now */
return;
}
@@ -2869,7 +2869,7 @@ perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs
struct stack_frame frame;
const struct stack_frame __user *fp;

- if (guest_cbs && guest_cbs->is_in_guest()) {
+ if (guest_cbs && guest_cbs->state()) {
/* TODO: We don't support guest os callchain now */
return;
}
@@ -2948,8 +2948,8 @@ unsigned long perf_instruction_pointer(struct pt_regs *regs)
{
struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();

- if (guest_cbs && guest_cbs->is_in_guest())
- return guest_cbs->get_guest_ip();
+ if (guest_cbs && guest_cbs->state())
+ return guest_cbs->get_ip();

return regs->ip + code_segment_base(regs);
}
@@ -2957,10 +2957,11 @@ unsigned long perf_instruction_pointer(struct pt_regs *regs)
unsigned long perf_misc_flags(struct pt_regs *regs)
{
struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
+ unsigned int guest_state = guest_cbs ? guest_cbs->state() : 0;
int misc = 0;

- if (guest_cbs && guest_cbs->is_in_guest()) {
- if (guest_cbs->is_user_mode())
+ if (guest_state) {
+ if (guest_state & PERF_GUEST_USER)
misc |= PERF_RECORD_MISC_GUEST_USER;
else
misc |= PERF_RECORD_MISC_GUEST_KERNEL;
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 9baa46185d94..524ad1f747bd 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -2855,10 +2855,7 @@ static int handle_pmi_common(struct pt_regs *regs, u64 status)
handled++;

guest_cbs = perf_get_guest_cbs();
- if (unlikely(guest_cbs && guest_cbs->is_in_guest() &&
- guest_cbs->handle_intel_pt_intr))
- guest_cbs->handle_intel_pt_intr();
- else
+ if (likely(!guest_cbs || !guest_cbs->handle_intel_pt_intr()))
intel_pt_interrupt();
}

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 1ea4943a73d7..1080166fc0cf 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1874,7 +1874,7 @@ int kvm_skip_emulated_instruction(struct kvm_vcpu *vcpu);
int kvm_complete_insn_gp(struct kvm_vcpu *vcpu, int err);
void __kvm_request_immediate_exit(struct kvm_vcpu *vcpu);

-int kvm_is_in_guest(void);
+unsigned int kvm_guest_state(void);

void __user *__x86_set_memory_region(struct kvm *kvm, int id, gpa_t gpa,
u32 size);
diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index 0772bad9165c..5b68d4188de0 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -87,7 +87,7 @@ static void kvm_perf_overflow_intr(struct perf_event *perf_event,
* woken up. So we should wake it, but this is impossible from
* NMI context. Do it from irq work instead.
*/
- if (!kvm_is_in_guest())
+ if (!kvm_guest_state())
irq_work_queue(&pmc_to_pmu(pmc)->irq_work);
else
kvm_make_request(KVM_REQ_PMI, pmc->vcpu);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ffc6c2d73508..6cc66466f301 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8267,44 +8267,48 @@ static void kvm_timer_init(void)
DEFINE_PER_CPU(struct kvm_vcpu *, current_vcpu);
EXPORT_PER_CPU_SYMBOL_GPL(current_vcpu);

-int kvm_is_in_guest(void)
+unsigned int kvm_guest_state(void)
{
- return __this_cpu_read(current_vcpu) != NULL;
-}
+ struct kvm_vcpu *vcpu = __this_cpu_read(current_vcpu);
+ unsigned int state;

-static int kvm_is_user_mode(void)
-{
- int user_mode = 3;
+ if (!vcpu)
+ return 0;

- if (__this_cpu_read(current_vcpu))
- user_mode = static_call(kvm_x86_get_cpl)(__this_cpu_read(current_vcpu));
+ state = PERF_GUEST_ACTIVE;
+ if (static_call(kvm_x86_get_cpl)(vcpu))
+ state |= PERF_GUEST_USER;

- return user_mode != 0;
+ return state;
}

-static unsigned long kvm_get_guest_ip(void)
+static unsigned long kvm_guest_get_ip(void)
{
- unsigned long ip = 0;
+ struct kvm_vcpu *vcpu = __this_cpu_read(current_vcpu);

- if (__this_cpu_read(current_vcpu))
- ip = kvm_rip_read(__this_cpu_read(current_vcpu));
+ if (WARN_ON_ONCE(!vcpu))
+ return 0;

- return ip;
+ return kvm_rip_read(vcpu);
}

-static void kvm_handle_intel_pt_intr(void)
+static unsigned int kvm_handle_intel_pt_intr(void)
{
struct kvm_vcpu *vcpu = __this_cpu_read(current_vcpu);

+ /* '0' on failure so that the !PT case can use a RET0 static call. */
+ if (!vcpu)
+ return 0;
+
kvm_make_request(KVM_REQ_PMI, vcpu);
__set_bit(MSR_CORE_PERF_GLOBAL_OVF_CTRL_TRACE_TOPA_PMI_BIT,
(unsigned long *)&vcpu->arch.pmu.global_status);
+ return 1;
}

static struct perf_guest_info_callbacks kvm_guest_cbs = {
- .is_in_guest = kvm_is_in_guest,
- .is_user_mode = kvm_is_user_mode,
- .get_guest_ip = kvm_get_guest_ip,
+ .state = kvm_guest_state,
+ .get_ip = kvm_guest_get_ip,
.handle_intel_pt_intr = NULL,
};

diff --git a/arch/x86/xen/pmu.c b/arch/x86/xen/pmu.c
index e13b0b49fcdf..89dd6b1708b0 100644
--- a/arch/x86/xen/pmu.c
+++ b/arch/x86/xen/pmu.c
@@ -413,34 +413,29 @@ int pmu_apic_update(uint32_t val)
}

/* perf callbacks */
-static int xen_is_in_guest(void)
+static unsigned int xen_guest_state(void)
{
const struct xen_pmu_data *xenpmu_data = get_xenpmu_data();
+ unsigned int state = 0;

if (!xenpmu_data) {
pr_warn_once("%s: pmudata not initialized\n", __func__);
- return 0;
+ return state;
}

if (!xen_initial_domain() || (xenpmu_data->domain_id >= DOMID_SELF))
- return 0;
+ return state;

- return 1;
-}
+ state |= PERF_GUEST_ACTIVE;

-static int xen_is_user_mode(void)
-{
- const struct xen_pmu_data *xenpmu_data = get_xenpmu_data();
-
- if (!xenpmu_data) {
- pr_warn_once("%s: pmudata not initialized\n", __func__);
- return 0;
+ if (xenpmu_data->pmu.pmu_flags & PMU_SAMPLE_PV) {
+ if (xenpmu_data->pmu.pmu_flags & PMU_SAMPLE_USER)
+ state |= PERF_GUEST_USER;
+ } else if (xenpmu_data->pmu.r.regs.cpl & 3) {
+ state |= PERF_GUEST_USER;
}

- if (xenpmu_data->pmu.pmu_flags & PMU_SAMPLE_PV)
- return (xenpmu_data->pmu.pmu_flags & PMU_SAMPLE_USER);
- else
- return !!(xenpmu_data->pmu.r.regs.cpl & 3);
+ return state;
}

static unsigned long xen_get_guest_ip(void)
@@ -456,9 +451,8 @@ static unsigned long xen_get_guest_ip(void)
}

static struct perf_guest_info_callbacks xen_guest_cbs = {
- .is_in_guest = xen_is_in_guest,
- .is_user_mode = xen_is_user_mode,
- .get_guest_ip = xen_get_guest_ip,
+ .state = xen_guest_state,
+ .get_ip = xen_get_guest_ip,
};

/* Convert registers from Xen's format to Linux' */
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 317d4658afe9..f9be88a47434 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -26,11 +26,13 @@
# include <asm/local64.h>
#endif

+#define PERF_GUEST_ACTIVE 0x01
+#define PERF_GUEST_USER 0x02
+
struct perf_guest_info_callbacks {
- int (*is_in_guest)(void);
- int (*is_user_mode)(void);
- unsigned long (*get_guest_ip)(void);
- void (*handle_intel_pt_intr)(void);
+ unsigned int (*state)(void);
+ unsigned long (*get_ip)(void);
+ unsigned int (*handle_intel_pt_intr)(void);
};

#ifdef CONFIG_HAVE_HW_BREAKPOINT
diff --git a/kernel/events/core.c b/kernel/events/core.c
index d90a43572400..2e3dc9fbd5d9 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6483,6 +6483,7 @@ static void perf_pending_event(struct irq_work *entry)
}

struct perf_guest_info_callbacks *perf_guest_cbs;
+
void perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
{
if (WARN_ON_ONCE(perf_guest_cbs))
--
2.33.0.464.g1972c5931b-goog