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



From: Like Xu <like.xu@xxxxxxxxxxxxxxx>

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@xxxxxxxxxxxxx>
Originally-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Like Xu <like.xu@xxxxxxxxxxxxxxx>
Signed-off-by: Zhu Lingshan <lingshan.zhu@xxxxxxxxx>
[sean: extracted from static_call patch, fixed get_ip() bug, wrote changelog]
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
 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




 


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