From: Like Xu <like.xu@linux.intel.com>
To: pbonzini@redhat.com, peterz@infradead.org, kvm@vger.kernel.org
Cc: like.xu@intel.com, linux-kernel@vger.kernel.org,
jmattson@google.com, sean.j.christopherson@intel.com,
wei.w.wang@intel.com, kan.liang@intel.com
Subject: [PATCH v3 1/6] perf/core: Provide a kernel-internal interface to recalibrate event period
Date: Tue, 22 Oct 2019 00:06:46 +0800 [thread overview]
Message-ID: <20191021160651.49508-2-like.xu@linux.intel.com> (raw)
In-Reply-To: <20191021160651.49508-1-like.xu@linux.intel.com>
Currently, perf_event_period() is used by user tools via ioctl. Based on
naming convention, exporting perf_event_period() for kernel users (such
as KVM) who may recalibrate the event period for their assigned counter
according to their requirements.
The perf_event_period() is an external accessor, just like the
perf_event_{en,dis}able() and should thus use perf_event_ctx_lock().
Suggested-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Like Xu <like.xu@linux.intel.com>
---
include/linux/perf_event.h | 5 +++++
kernel/events/core.c | 28 +++++++++++++++++++++-------
2 files changed, 26 insertions(+), 7 deletions(-)
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 61448c19a132..d601df36e671 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1336,6 +1336,7 @@ extern void perf_event_disable_local(struct perf_event *event);
extern void perf_event_disable_inatomic(struct perf_event *event);
extern void perf_event_task_tick(void);
extern int perf_event_account_interrupt(struct perf_event *event);
+extern int perf_event_period(struct perf_event *event, u64 value);
#else /* !CONFIG_PERF_EVENTS: */
static inline void *
perf_aux_output_begin(struct perf_output_handle *handle,
@@ -1415,6 +1416,10 @@ static inline void perf_event_disable(struct perf_event *event) { }
static inline int __perf_event_disable(void *info) { return -1; }
static inline void perf_event_task_tick(void) { }
static inline int perf_event_release_kernel(struct perf_event *event) { return 0; }
+static inline int perf_event_period(struct perf_event *event, u64 value)
+{
+ return -EINVAL;
+}
#endif
#if defined(CONFIG_PERF_EVENTS) && defined(CONFIG_CPU_SUP_INTEL)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 9ec0b0bfddbd..e1b83d2731da 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -5106,16 +5106,11 @@ static int perf_event_check_period(struct perf_event *event, u64 value)
return event->pmu->check_period(event, value);
}
-static int perf_event_period(struct perf_event *event, u64 __user *arg)
+static int _perf_event_period(struct perf_event *event, u64 value)
{
- u64 value;
-
if (!is_sampling_event(event))
return -EINVAL;
- if (copy_from_user(&value, arg, sizeof(value)))
- return -EFAULT;
-
if (!value)
return -EINVAL;
@@ -5133,6 +5128,19 @@ static int perf_event_period(struct perf_event *event, u64 __user *arg)
return 0;
}
+int perf_event_period(struct perf_event *event, u64 value)
+{
+ struct perf_event_context *ctx;
+ int ret;
+
+ ctx = perf_event_ctx_lock(event);
+ ret = _perf_event_period(event, value);
+ perf_event_ctx_unlock(event, ctx);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(perf_event_period);
+
static const struct file_operations perf_fops;
static inline int perf_fget_light(int fd, struct fd *p)
@@ -5176,8 +5184,14 @@ static long _perf_ioctl(struct perf_event *event, unsigned int cmd, unsigned lon
return _perf_event_refresh(event, arg);
case PERF_EVENT_IOC_PERIOD:
- return perf_event_period(event, (u64 __user *)arg);
+ {
+ u64 value;
+
+ if (copy_from_user(&value, (u64 __user *)arg, sizeof(value)))
+ return -EFAULT;
+ return _perf_event_period(event, value);
+ }
case PERF_EVENT_IOC_ID:
{
u64 id = primary_event_id(event);
--
2.21.0
next prev parent reply other threads:[~2019-10-22 8:12 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-21 16:06 [PATCH v3 0/6] KVM: x86/vPMU: Efficiency optimization by reusing last created perf_event Like Xu
2019-10-21 16:06 ` Like Xu [this message]
2019-10-21 16:06 ` [PATCH v3 2/6] perf/core: Provide a kernel-internal interface to pause perf_event Like Xu
2019-10-21 16:06 ` [PATCH v3 3/6] KVM: x86/vPMU: Rename pmu_ops callbacks from msr_idx to rdpmc_idx Like Xu
2019-10-23 17:55 ` Jim Mattson
2019-10-21 16:06 ` [PATCH v3 4/6] KVM: x86/vPMU: Introduce a new kvm_pmu_ops->msr_idx_to_pmc callback Like Xu
2019-10-26 5:28 ` [RFC PATCH] KVM: x86/vPMU: intel_msr_idx_to_pmc() can be static kbuild test robot
2019-10-26 5:28 ` [PATCH v3 4/6] KVM: x86/vPMU: Introduce a new kvm_pmu_ops->msr_idx_to_pmc callback kbuild test robot
2019-10-21 16:06 ` [PATCH v3 5/6] KVM: x86/vPMU: Reuse perf_event to avoid unnecessary pmc_reprogram_counter Like Xu
2019-10-21 16:06 ` [PATCH v3 6/6] KVM: x86/vPMU: Add lazy mechanism to release perf_event per vPMC Like Xu
2019-10-22 10:47 ` Paolo Bonzini
2019-10-22 12:00 ` Like Xu
2019-10-22 14:09 ` Paolo Bonzini
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20191021160651.49508-2-like.xu@linux.intel.com \
--to=like.xu@linux.intel.com \
--cc=jmattson@google.com \
--cc=kan.liang@intel.com \
--cc=kvm@vger.kernel.org \
--cc=like.xu@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=pbonzini@redhat.com \
--cc=peterz@infradead.org \
--cc=sean.j.christopherson@intel.com \
--cc=wei.w.wang@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).