From: Paolo Bonzini <pbonzini@redhat.com>
To: Sean Christopherson <seanjc@google.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Will Deacon <will@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Marc Zyngier <maz@kernel.org>, Guo Ren <guoren@kernel.org>,
Nick Hu <nickhu@andestech.com>, Greentime Hu <green.hu@gmail.com>,
Vincent Chen <deanbo422@gmail.com>,
Paul Walmsley <paul.walmsley@sifive.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Albert Ou <aou@eecs.berkeley.edu>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Juergen Gross <jgross@suse.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
James Morse <james.morse@arm.com>,
Alexandru Elisei <alexandru.elisei@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
Stefano Stabellini <sstabellini@kernel.org>,
linux-arm-kernel@lists.infradead.org,
linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
kvmarm@lists.cs.columbia.edu, linux-csky@vger.kernel.org,
linux-riscv@lists.infradead.org, kvm@vger.kernel.org,
xen-devel@lists.xenproject.org,
Artem Kashkanov <artem.kashkanov@intel.com>,
Like Xu <like.xu.linux@gmail.com>,
Zhu Lingshan <lingshan.zhu@intel.com>
Subject: Re: [PATCH v3 07/16] perf: Add wrappers for invoking guest callbacks
Date: Wed, 22 Sep 2021 08:29:53 +0200 [thread overview]
Message-ID: <a67e5fde-8b96-47b9-f1dd-c8be8ea9da7f@redhat.com> (raw)
In-Reply-To: <20210922000533.713300-8-seanjc@google.com>
On 22/09/21 02:05, Sean Christopherson wrote:
> Add helpers for the guest callbacks to prepare for burying the callbacks
> behind a Kconfig (it's a lot easier to provide a few stubs than to #ifdef
> piles of code), and also to prepare for converting the callbacks to
> static_call(). perf_instruction_pointer() in particular will have subtle
> semantics with static_call(), as the "no callbacks" case will return 0 if
> the callbacks are unregistered between querying guest state and getting
> the IP. Implement the change now to avoid a functional change when adding
> static_call() support, and because the new helper needs to return
> _something_ in this case.
>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
> arch/arm64/kernel/perf_callchain.c | 16 +++++-----------
> arch/x86/events/core.c | 15 +++++----------
> arch/x86/events/intel/core.c | 5 +----
> include/linux/perf_event.h | 24 ++++++++++++++++++++++++
> 4 files changed, 35 insertions(+), 25 deletions(-)
>
> diff --git a/arch/arm64/kernel/perf_callchain.c b/arch/arm64/kernel/perf_callchain.c
> index 274dc3e11b6d..db04a55cee7e 100644
> --- a/arch/arm64/kernel/perf_callchain.c
> +++ b/arch/arm64/kernel/perf_callchain.c
> @@ -102,9 +102,7 @@ compat_user_backtrace(struct compat_frame_tail __user *tail,
> void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
> struct pt_regs *regs)
> {
> - struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
> -
> - if (guest_cbs && guest_cbs->state()) {
> + if (perf_guest_state()) {
> /* We don't support guest os callchain now */
> return;
> }
> @@ -149,10 +147,9 @@ static bool callchain_trace(void *data, unsigned long pc)
> void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
> struct pt_regs *regs)
> {
> - struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
> struct stackframe frame;
>
> - if (guest_cbs && guest_cbs->state()) {
> + if (perf_guest_state()) {
> /* We don't support guest os callchain now */
> return;
> }
> @@ -163,18 +160,15 @@ void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
>
> 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->state())
> - return guest_cbs->get_ip();
> + if (perf_guest_state())
> + return perf_guest_get_ip();
>
> return instruction_pointer(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;
> + unsigned int guest_state = perf_guest_state();
> int misc = 0;
>
> if (guest_state) {
> diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
> index 3a7630fdd340..d20e4f8d1aef 100644
> --- a/arch/x86/events/core.c
> +++ b/arch/x86/events/core.c
> @@ -2761,11 +2761,10 @@ 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 = perf_get_guest_cbs();
> struct unwind_state state;
> unsigned long addr;
>
> - if (guest_cbs && guest_cbs->state()) {
> + if (perf_guest_state()) {
> /* TODO: We don't support guest os callchain now */
> return;
> }
> @@ -2865,11 +2864,10 @@ 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 = perf_get_guest_cbs();
> struct stack_frame frame;
> const struct stack_frame __user *fp;
>
> - if (guest_cbs && guest_cbs->state()) {
> + if (perf_guest_state()) {
> /* TODO: We don't support guest os callchain now */
> return;
> }
> @@ -2946,18 +2944,15 @@ 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 = perf_get_guest_cbs();
> -
> - if (guest_cbs && guest_cbs->state())
> - return guest_cbs->get_ip();
> + if (perf_guest_state())
> + return perf_guest_get_ip();
>
> return regs->ip + code_segment_base(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;
> + unsigned int guest_state = perf_guest_state();
> int misc = 0;
>
> if (guest_state) {
> diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
> index 524ad1f747bd..f5b02017ba16 100644
> --- a/arch/x86/events/intel/core.c
> +++ b/arch/x86/events/intel/core.c
> @@ -2786,7 +2786,6 @@ static int handle_pmi_common(struct pt_regs *regs, u64 status)
> {
> struct perf_sample_data data;
> struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
> - struct perf_guest_info_callbacks *guest_cbs;
> int bit;
> int handled = 0;
> u64 intel_ctrl = hybrid(cpuc->pmu, intel_ctrl);
> @@ -2853,9 +2852,7 @@ 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 = perf_get_guest_cbs();
> - if (likely(!guest_cbs || !guest_cbs->handle_intel_pt_intr()))
> + if (!perf_guest_handle_intel_pt_intr())
> intel_pt_interrupt();
> }
>
> diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
> index f9be88a47434..c0a6eaf55fb1 100644
> --- a/include/linux/perf_event.h
> +++ b/include/linux/perf_event.h
> @@ -1247,6 +1247,30 @@ static inline struct perf_guest_info_callbacks *perf_get_guest_cbs(void)
> /* Prevent reloading between a !NULL check and dereferences. */
> return READ_ONCE(perf_guest_cbs);
> }
> +static inline unsigned int perf_guest_state(void)
> +{
> + struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
> +
> + return guest_cbs ? guest_cbs->state() : 0;
> +}
> +static inline unsigned long perf_guest_get_ip(void)
> +{
> + struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
> +
> + /*
> + * Arbitrarily return '0' in the unlikely scenario that the callbacks
> + * are unregistered between checking guest state and getting the IP.
> + */
> + return guest_cbs ? guest_cbs->get_ip() : 0;
> +}
> +static inline unsigned int perf_guest_handle_intel_pt_intr(void)
> +{
> + struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
> +
> + if (guest_cbs && guest_cbs->handle_intel_pt_intr)
> + return guest_cbs->handle_intel_pt_intr();
> + return 0;
> +}
> extern void perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs);
> extern void perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs);
>
>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
next prev parent reply other threads:[~2021-09-22 6:30 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-22 0:05 [PATCH v3 00/16] perf: KVM: Fix, optimize, and clean up callbacks Sean Christopherson
2021-09-22 0:05 ` [PATCH v3 01/16] perf: Ensure perf_guest_cbs aren't reloaded between !NULL check and deref Sean Christopherson
2021-11-04 9:32 ` Like Xu
2021-11-04 14:18 ` Sean Christopherson
2021-11-10 11:07 ` Paolo Bonzini
2021-11-11 0:39 ` Sean Christopherson
2021-09-22 0:05 ` [PATCH v3 02/16] KVM: x86: Register perf callbacks after calling vendor's hardware_setup() Sean Christopherson
2021-09-22 6:23 ` Paolo Bonzini
2021-09-22 0:05 ` [PATCH v3 03/16] KVM: x86: Register Processor Trace interrupt hook iff PT enabled in guest Sean Christopherson
2021-09-22 6:24 ` Paolo Bonzini
2021-09-22 0:05 ` [PATCH v3 04/16] perf: Stop pretending that perf can handle multiple guest callbacks Sean Christopherson
2021-09-22 6:25 ` Paolo Bonzini
2021-09-22 0:05 ` [PATCH v3 05/16] perf: Drop dead and useless guest "support" from arm, csky, nds32 and riscv Sean Christopherson
2021-09-22 6:26 ` Paolo Bonzini
2021-09-22 0:05 ` [PATCH v3 06/16] perf/core: Rework guest callbacks to prepare for static_call support Sean Christopherson
2021-09-22 6:28 ` Paolo Bonzini
2021-09-22 18:31 ` Boris Ostrovsky
2021-09-22 0:05 ` [PATCH v3 07/16] perf: Add wrappers for invoking guest callbacks Sean Christopherson
2021-09-22 6:29 ` Paolo Bonzini [this message]
2021-09-22 0:05 ` [PATCH v3 08/16] perf: Force architectures to opt-in to " Sean Christopherson
2021-09-22 6:32 ` Paolo Bonzini
2021-09-22 14:48 ` Sean Christopherson
2021-11-09 23:46 ` Sean Christopherson
2021-09-22 0:05 ` [PATCH v3 09/16] perf/core: Use static_call to optimize perf_guest_info_callbacks Sean Christopherson
2021-09-22 6:33 ` Paolo Bonzini
2021-09-22 0:05 ` [PATCH v3 10/16] KVM: x86: Drop current_vcpu for kvm_running_vcpu + kvm_arch_vcpu variable Sean Christopherson
2021-09-22 6:40 ` Paolo Bonzini
2021-09-22 0:05 ` [PATCH v3 11/16] KVM: x86: More precisely identify NMI from guest when handling PMI Sean Christopherson
2021-09-22 6:38 ` Paolo Bonzini
2021-09-22 0:05 ` [PATCH v3 12/16] KVM: Move x86's perf guest info callbacks to generic KVM Sean Christopherson
2021-09-22 6:41 ` Paolo Bonzini
2021-10-11 9:35 ` Marc Zyngier
2021-10-11 14:46 ` Sean Christopherson
2021-10-11 15:33 ` Marc Zyngier
2021-09-22 0:05 ` [PATCH v3 13/16] KVM: x86: Move Intel Processor Trace interrupt handler to vmx.c Sean Christopherson
2021-09-22 0:05 ` [PATCH v3 14/16] KVM: arm64: Convert to the generic perf callbacks Sean Christopherson
2021-10-11 9:38 ` Marc Zyngier
2021-09-22 0:05 ` [PATCH v3 15/16] KVM: arm64: Drop perf.c and fold its tiny bits of code into arm.c / pmu.c Sean Christopherson
2021-10-11 9:44 ` Marc Zyngier
2021-11-09 23:16 ` Sean Christopherson
2021-09-22 0:05 ` [PATCH v3 16/16] perf: Drop guest callback (un)register stubs Sean Christopherson
2021-09-22 6:29 ` Paolo Bonzini
2021-09-22 6:42 ` [PATCH v3 00/16] perf: KVM: Fix, optimize, and clean up callbacks Paolo Bonzini
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