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Date: Thu, 26 Aug 2021 17:57:18 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Will Deacon <will@...nel.org>, Mark Rutland <mark.rutland@....com>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Catalin Marinas <catalin.marinas@....com>,
Marc Zyngier <maz@...nel.org>, Guo Ren <guoren@...nel.org>,
Nick Hu <nickhu@...estech.com>,
Greentime Hu <green.hu@...il.com>,
Vincent Chen <deanbo422@...il.com>,
Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>,
Albert Ou <aou@...s.berkeley.edu>,
Thomas Gleixner <tglx@...utronix.de>,
Borislav Petkov <bp@...en8.de>, x86@...nel.org,
Paolo Bonzini <pbonzini@...hat.com>,
Boris Ostrovsky <boris.ostrovsky@...cle.com>,
Juergen Gross <jgross@...e.com>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...hat.com>,
Namhyung Kim <namhyung@...nel.org>,
James Morse <james.morse@....com>,
Alexandru Elisei <alexandru.elisei@....com>,
Suzuki K Poulose <suzuki.poulose@....com>,
"H. Peter Anvin" <hpa@...or.com>,
Sean Christopherson <seanjc@...gle.com>,
Vitaly Kuznetsov <vkuznets@...hat.com>,
Wanpeng Li <wanpengli@...cent.com>,
Jim Mattson <jmattson@...gle.com>,
Joerg Roedel <joro@...tes.org>,
Stefano Stabellini <sstabellini@...nel.org>,
linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
linux-csky@...r.kernel.org, linux-riscv@...ts.infradead.org,
kvm@...r.kernel.org, xen-devel@...ts.xenproject.org,
Artem Kashkanov <artem.kashkanov@...el.com>,
Like Xu <like.xu.linux@...il.com>,
Zhu Lingshan <lingshan.zhu@...el.com>
Subject: [PATCH 15/15] perf: KVM: Indicate "in guest" via NULL ->is_in_guest callback
Interpret a null ->is_in_guest callback as meaning "in guest" and use
the new semantics in KVM, which currently returns 'true' unconditionally
in its implementation of ->is_in_guest(). This avoids a retpoline on
the indirect call for PMIs that arrive in a KVM guest, and also provides
a handy excuse for a wrapper around retrieval of perf_get_guest_cbs,
e.g. to reduce the probability of an errant direct read of perf_guest_cbs.
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
arch/x86/events/core.c | 16 ++++++++--------
arch/x86/events/intel/core.c | 5 ++---
include/linux/perf_event.h | 17 +++++++++++++++++
virt/kvm/kvm_main.c | 9 ++-------
4 files changed, 29 insertions(+), 18 deletions(-)
diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index 34155a52e498..b60c339ae06b 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -2761,11 +2761,11 @@ static bool perf_hw_regs(struct pt_regs *regs)
void
perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
{
- struct perf_guest_info_callbacks *guest_cbs = this_cpu_read(perf_guest_cbs);
+ struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
struct unwind_state state;
unsigned long addr;
- if (guest_cbs && guest_cbs->is_in_guest()) {
+ if (guest_cbs) {
/* TODO: We don't support guest os callchain now */
return;
}
@@ -2865,11 +2865,11 @@ perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry_ctx *ent
void
perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
{
- struct perf_guest_info_callbacks *guest_cbs = this_cpu_read(perf_guest_cbs);
+ struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
struct stack_frame frame;
const struct stack_frame __user *fp;
- if (guest_cbs && guest_cbs->is_in_guest()) {
+ if (guest_cbs) {
/* TODO: We don't support guest os callchain now */
return;
}
@@ -2946,9 +2946,9 @@ static unsigned long code_segment_base(struct pt_regs *regs)
unsigned long perf_instruction_pointer(struct pt_regs *regs)
{
- struct perf_guest_info_callbacks *guest_cbs = this_cpu_read(perf_guest_cbs);
+ struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
- if (guest_cbs && guest_cbs->is_in_guest())
+ if (guest_cbs)
return guest_cbs->get_guest_ip();
return regs->ip + code_segment_base(regs);
@@ -2956,10 +2956,10 @@ 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 = this_cpu_read(perf_guest_cbs);
+ struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
int misc = 0;
- if (guest_cbs && guest_cbs->is_in_guest()) {
+ if (guest_cbs) {
if (guest_cbs->is_user_mode())
misc |= PERF_RECORD_MISC_GUEST_USER;
else
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 96001962c24d..9a8c18b51a96 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -2853,9 +2853,8 @@ static int handle_pmi_common(struct pt_regs *regs, u64 status)
*/
if (__test_and_clear_bit(GLOBAL_STATUS_TRACE_TOPAPMI_BIT, (unsigned long *)&status)) {
handled++;
- guest_cbs = this_cpu_read(perf_guest_cbs);
- if (unlikely(guest_cbs && guest_cbs->is_in_guest() &&
- guest_cbs->handle_intel_pt_intr))
+ guest_cbs = perf_get_guest_cbs();
+ if (unlikely(guest_cbs && guest_cbs->handle_intel_pt_intr))
guest_cbs->handle_intel_pt_intr();
else
intel_pt_interrupt();
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index db701409a62f..6e3a10784d24 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1241,6 +1241,23 @@ DECLARE_PER_CPU(struct perf_guest_info_callbacks *, perf_guest_cbs);
extern void perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs);
extern void perf_unregister_guest_info_callbacks(void);
extern void perf_register_guest_info_callbacks_all_cpus(struct perf_guest_info_callbacks *cbs);
+/*
+ * Returns guest callbacks for the current CPU if callbacks are registered and
+ * the PMI fired while a guest was running, otherwise returns NULL.
+ */
+static inline struct perf_guest_info_callbacks *perf_get_guest_cbs(void)
+{
+ struct perf_guest_info_callbacks *guest_cbs = this_cpu_read(perf_guest_cbs);
+
+ /*
+ * Implementing is_in_guest is optional if the callbacks are registered
+ * only when "in guest".
+ */
+ if (guest_cbs && (!guest_cbs->is_in_guest || guest_cbs->is_in_guest()))
+ return guest_cbs;
+
+ return NULL;
+}
#endif /* CONFIG_HAVE_GUEST_PERF_EVENTS */
extern void perf_event_exec(void);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 1bcc3eab510b..fa83d3846785 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -5461,12 +5461,6 @@ struct kvm_vcpu * __percpu *kvm_get_running_vcpus(void)
}
#ifdef __KVM_WANT_PERF_CALLBACKS
-static int kvm_is_in_guest(void)
-{
- /* Registration of KVM's callback signifies "in guest". */
- return true;
-}
-
static int kvm_is_user_mode(void)
{
struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
@@ -5488,7 +5482,8 @@ static unsigned long kvm_get_guest_ip(void)
}
static struct perf_guest_info_callbacks kvm_guest_cbs = {
- .is_in_guest = kvm_is_in_guest,
+ /* Registration of KVM's callback signifies "in guest". */
+ .is_in_guest = NULL,
.is_user_mode = kvm_is_user_mode,
.get_guest_ip = kvm_get_guest_ip,
.handle_intel_pt_intr = NULL,
--
2.33.0.259.gc128427fd7-goog
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