diff mbox series

[6/6] perf intel-pt: Add guest_code support

Message ID 20220513090237.10444-7-adrian.hunter@intel.com (mailing list archive)
State New, archived
Headers show
Series perf intel-pt: Add support for tracing KVM test programs | expand

Commit Message

Adrian Hunter May 13, 2022, 9:02 a.m. UTC 
A common case for KVM test programs is that the guest object code can be
found in the hypervisor process (i.e. the test program running on the
host). To support that, a new option "--guest-code" has been added in
previous patches.

In this patch, add support also to Intel PT.

In particular, ensure guest_code thread is set up before attempting to
walk object code or synthesize samples.

Example:

 # perf record --kcore -e intel_pt/cyc/ -- tools/testing/selftests/kselftest_install/kvm/tsc_msrs_test
 [ perf record: Woken up 1 times to write data ]
 [ perf record: Captured and wrote 0.280 MB perf.data ]
 # perf script --guest-code --itrace=bep --ns -F-period,+addr,+flags
 [SNIP]
   tsc_msrs_test 18436 [007] 10897.962087733:      branches:   call                   ffffffffc13b2ff5 __vmx_vcpu_run+0x15 (vmlinux) => ffffffffc13b2f50 vmx_update_host_rsp+0x0 (vmlinux)
   tsc_msrs_test 18436 [007] 10897.962087733:      branches:   return                 ffffffffc13b2f5d vmx_update_host_rsp+0xd (vmlinux) => ffffffffc13b2ffa __vmx_vcpu_run+0x1a (vmlinux)
   tsc_msrs_test 18436 [007] 10897.962087733:      branches:   call                   ffffffffc13b303b __vmx_vcpu_run+0x5b (vmlinux) => ffffffffc13b2f80 vmx_vmenter+0x0 (vmlinux)
   tsc_msrs_test 18436 [007] 10897.962087836:      branches:   vmentry                ffffffffc13b2f82 vmx_vmenter+0x2 (vmlinux) =>                0 [unknown] ([unknown])
   [guest/18436] 18436 [007] 10897.962087836:      branches:   vmentry                               0 [unknown] ([unknown]) =>           402c81 guest_code+0x131 (/home/ahunter/git/work/tools/testing/selftests/kselftest_install/kvm/tsc_msrs_test)
   [guest/18436] 18436 [007] 10897.962087836:      branches:   call                             402c81 guest_code+0x131 (/home/ahunter/git/work/tools/testing/selftests/kselftest_install/kvm/tsc_msrs_test) =>           40dba0 ucall+0x0 (/home/ahunter/git/work/tools/testing/selftests/kselftest_install/kvm/tsc_msrs_test)
   [guest/18436] 18436 [007] 10897.962088248:      branches:   vmexit                           40dba0 ucall+0x0 (/home/ahunter/git/work/tools/testing/selftests/kselftest_install/kvm/tsc_msrs_test) =>                0 [unknown] ([unknown])
   tsc_msrs_test 18436 [007] 10897.962088248:      branches:   vmexit                                0 [unknown] ([unknown]) => ffffffffc13b2fa0 vmx_vmexit+0x0 (vmlinux)
   tsc_msrs_test 18436 [007] 10897.962088248:      branches:   jmp                    ffffffffc13b2fa0 vmx_vmexit+0x0 (vmlinux) => ffffffffc13b2fd2 vmx_vmexit+0x32 (vmlinux)
   tsc_msrs_test 18436 [007] 10897.962088256:      branches:   return                 ffffffffc13b2fd2 vmx_vmexit+0x32 (vmlinux) => ffffffffc13b3040 __vmx_vcpu_run+0x60 (vmlinux)
   tsc_msrs_test 18436 [007] 10897.962088270:      branches:   return                 ffffffffc13b30b6 __vmx_vcpu_run+0xd6 (vmlinux) => ffffffffc13b2f2e vmx_vcpu_enter_exit+0x4e (vmlinux)
 [SNIP]
   tsc_msrs_test 18436 [007] 10897.962089321:      branches:   call                   ffffffffc13b2ff5 __vmx_vcpu_run+0x15 (vmlinux) => ffffffffc13b2f50 vmx_update_host_rsp+0x0 (vmlinux)
   tsc_msrs_test 18436 [007] 10897.962089321:      branches:   return                 ffffffffc13b2f5d vmx_update_host_rsp+0xd (vmlinux) => ffffffffc13b2ffa __vmx_vcpu_run+0x1a (vmlinux)
   tsc_msrs_test 18436 [007] 10897.962089321:      branches:   call                   ffffffffc13b303b __vmx_vcpu_run+0x5b (vmlinux) => ffffffffc13b2f80 vmx_vmenter+0x0 (vmlinux)
   tsc_msrs_test 18436 [007] 10897.962089424:      branches:   vmentry                ffffffffc13b2f82 vmx_vmenter+0x2 (vmlinux) =>                0 [unknown] ([unknown])
   [guest/18436] 18436 [007] 10897.962089424:      branches:   vmentry                               0 [unknown] ([unknown]) =>           40dba0 ucall+0x0 (/home/ahunter/git/work/tools/testing/selftests/kselftest_install/kvm/tsc_msrs_test)
   [guest/18436] 18436 [007] 10897.962089701:      branches:   jmp                              40dc1b ucall+0x7b (/home/ahunter/git/work/tools/testing/selftests/kselftest_install/kvm/tsc_msrs_test) =>           40dc39 ucall+0x99 (/home/ahunter/git/work/tools/testing/selftests/kselftest_install/kvm/tsc_msrs_test)
   [guest/18436] 18436 [007] 10897.962089701:      branches:   jcc                              40dc3c ucall+0x9c (/home/ahunter/git/work/tools/testing/selftests/kselftest_install/kvm/tsc_msrs_test) =>           40dc20 ucall+0x80 (/home/ahunter/git/work/tools/testing/selftests/kselftest_install/kvm/tsc_msrs_test)
   [guest/18436] 18436 [007] 10897.962089701:      branches:   jcc                              40dc3c ucall+0x9c (/home/ahunter/git/work/tools/testing/selftests/kselftest_install/kvm/tsc_msrs_test) =>           40dc20 ucall+0x80 (/home/ahunter/git/work/tools/testing/selftests/kselftest_install/kvm/tsc_msrs_test)
   [guest/18436] 18436 [007] 10897.962089701:      branches:   jcc                              40dc37 ucall+0x97 (/home/ahunter/git/work/tools/testing/selftests/kselftest_install/kvm/tsc_msrs_test) =>           40dc50 ucall+0xb0 (/home/ahunter/git/work/tools/testing/selftests/kselftest_install/kvm/tsc_msrs_test)
   [guest/18436] 18436 [007] 10897.962089878:      branches:   vmexit                           40dc55 ucall+0xb5 (/home/ahunter/git/work/tools/testing/selftests/kselftest_install/kvm/tsc_msrs_test) =>                0 [unknown] ([unknown])
   tsc_msrs_test 18436 [007] 10897.962089878:      branches:   vmexit                                0 [unknown] ([unknown]) => ffffffffc13b2fa0 vmx_vmexit+0x0 (vmlinux)
   tsc_msrs_test 18436 [007] 10897.962089878:      branches:   jmp                    ffffffffc13b2fa0 vmx_vmexit+0x0 (vmlinux) => ffffffffc13b2fd2 vmx_vmexit+0x32 (vmlinux)
   tsc_msrs_test 18436 [007] 10897.962089887:      branches:   return                 ffffffffc13b2fd2 vmx_vmexit+0x32 (vmlinux) => ffffffffc13b3040 __vmx_vcpu_run+0x60 (vmlinux)
   tsc_msrs_test 18436 [007] 10897.962089901:      branches:   return                 ffffffffc13b30b6 __vmx_vcpu_run+0xd6 (vmlinux) => ffffffffc13b2f2e vmx_vcpu_enter_exit+0x4e (vmlinux)
 [SNIP]

 # perf kvm --guest-code --guest --host report -i perf.data --stdio | head -20

 # To display the perf.data header info, please use --header/--header-only options.
 #
 #
 # Total Lost Samples: 0
 #
 # Samples: 12  of event 'instructions'
 # Event count (approx.): 2274583
 #
 # Children      Self  Command        Shared Object         Symbol
 # ........  ........  .............  ....................  ...........................................
 #
    54.70%     0.00%  tsc_msrs_test  [kernel.vmlinux]      [k] entry_SYSCALL_64_after_hwframe
            |
            ---entry_SYSCALL_64_after_hwframe
               do_syscall_64
               |
               |--29.44%--syscall_exit_to_user_mode
               |          exit_to_user_mode_prepare
               |          task_work_run
               |          __fput

For more information about Perf tools support for Intel® Processor Trace
refer:

  https://perf.wiki.kernel.org/index.php/Perf_tools_support_for_Intel%C2%AE_Processor_Trace

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
 tools/perf/Documentation/perf-intel-pt.txt | 67 ++++++++++++++++++++++
 tools/perf/util/intel-pt.c                 | 20 ++++++-
 2 files changed, 85 insertions(+), 2 deletions(-)

Comments

Andi Kleen May 13, 2022, 2:46 p.m. UTC | #1 
Adrian Hunter <adrian.hunter@intel.com> writes:

> A common case for KVM test programs is that the guest object code can be
> found in the hypervisor process (i.e. the test program running on the
> host). To support that, a new option "--guest-code" has been added in
> previous patches.
>
> In this patch, add support also to Intel PT.
>
> In particular, ensure guest_code thread is set up before attempting to
> walk object code or synthesize samples.

Can you make it clear in the documentation what parts runs on the host
and what parts on the guest? 

I'm still not fully sure how it exactly finds the code on the host,
how is the code transferred?

Other than that more support for this use case is very useful.

-Andi
Adrian Hunter May 13, 2022, 3:14 p.m. UTC | #2 
On 13/05/22 17:46, Andi Kleen wrote:
> Adrian Hunter <adrian.hunter@intel.com> writes:
> 
>> A common case for KVM test programs is that the guest object code can be
>> found in the hypervisor process (i.e. the test program running on the
>> host). To support that, a new option "--guest-code" has been added in
>> previous patches.
>>
>> In this patch, add support also to Intel PT.
>>
>> In particular, ensure guest_code thread is set up before attempting to
>> walk object code or synthesize samples.
> 
> Can you make it clear in the documentation what parts runs on the host
> and what parts on the guest? 

That is up to the test program.  All the host thread maps are
copied, so perf tools doesn't have to know.

> 
> I'm still not fully sure how it exactly finds the code on the host,
> how is the code transferred?

I don't know.  From a quick look at the code in
tools/testing/selftests/kvm/lib/kvm_util.c it seems to be using
KVM_SET_USER_MEMORY_REGION IOCTL.

> 
> Other than that more support for this use case is very useful.
> 
> -Andi
Andi Kleen May 13, 2022, 6:13 p.m. UTC | #3 
Adrian Hunter <adrian.hunter@intel.com> writes:
>> 
>> I'm still not fully sure how it exactly finds the code on the host,
>> how is the code transferred?
>
> I don't know.  From a quick look at the code in
> tools/testing/selftests/kvm/lib/kvm_util.c it seems to be using
> KVM_SET_USER_MEMORY_REGION IOCTL.

Okay so it assumes that the pages with code on the guest are still intact: that is
you cannot quit the traced program, or at least not do something that would
fill it with other data?. Is that correct?

It sounds like with that restriction it's more useful for kernel traces.

-Andi
Adrian Hunter May 15, 2022, 7:27 a.m. UTC | #4 
On 13/05/22 21:13, Andi Kleen wrote:
> Adrian Hunter <adrian.hunter@intel.com> writes:
>>>
>>> I'm still not fully sure how it exactly finds the code on the host,
>>> how is the code transferred?
>>
>> I don't know.  From a quick look at the code in
>> tools/testing/selftests/kvm/lib/kvm_util.c it seems to be using
>> KVM_SET_USER_MEMORY_REGION IOCTL.
> 
> Okay so it assumes that the pages with code on the guest are still intact: that is
> you cannot quit the traced program, or at least not do something that would
> fill it with other data?. Is that correct?
> 
> It sounds like with that restriction it's more useful for kernel traces.

These patches are to support tracing of test programs that
 *are* the hypervisor, creating, populating, and destroying the VM.
The VM is not running an OS.

Like:
	https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/testing/selftests/kvm/x86_64/tsc_msrs_test.c
	
guest_code() gets mapped into the VM at the same virtual address as the host,
so the Intel PT decoder, which wants to walk the object code, can find the
object code in the host program.
diff mbox series

Patch

diff --git a/tools/perf/Documentation/perf-intel-pt.txt b/tools/perf/Documentation/perf-intel-pt.txt
index 92532d0d3618..14cc61b254db 100644
--- a/tools/perf/Documentation/perf-intel-pt.txt
+++ b/tools/perf/Documentation/perf-intel-pt.txt
@@ -1398,6 +1398,73 @@  There were none.
           :17006 17006 [001] 11500.262869216:  ffffffff8220116e error_entry+0xe ([guest.kernel.kallsyms])               pushq  %rax
 
 
+Tracing Virtual Machines - Guest Code
+-------------------------------------
+
+A common case for KVM test programs is that the guest object code can be
+found in the hypervisor process (i.e. the test program running on the
+host). To support that, option "--guest-code" has been added to perf script
+and perf kvm report.
+
+Here is an example tracing a test program from the kernel's KVM selftests:
+
+ # perf record --kcore -e intel_pt/cyc/ -- tools/testing/selftests/kselftest_install/kvm/tsc_msrs_test
+ [ perf record: Woken up 1 times to write data ]
+ [ perf record: Captured and wrote 0.280 MB perf.data ]
+ # perf script --guest-code --itrace=bep --ns -F-period,+addr,+flags
+ [SNIP]
+   tsc_msrs_test 18436 [007] 10897.962087733:      branches:   call                   ffffffffc13b2ff5 __vmx_vcpu_run+0x15 (vmlinux) => ffffffffc13b2f50 vmx_update_host_rsp+0x0 (vmlinux)
+   tsc_msrs_test 18436 [007] 10897.962087733:      branches:   return                 ffffffffc13b2f5d vmx_update_host_rsp+0xd (vmlinux) => ffffffffc13b2ffa __vmx_vcpu_run+0x1a (vmlinux)
+   tsc_msrs_test 18436 [007] 10897.962087733:      branches:   call                   ffffffffc13b303b __vmx_vcpu_run+0x5b (vmlinux) => ffffffffc13b2f80 vmx_vmenter+0x0 (vmlinux)
+   tsc_msrs_test 18436 [007] 10897.962087836:      branches:   vmentry                ffffffffc13b2f82 vmx_vmenter+0x2 (vmlinux) =>                0 [unknown] ([unknown])
+   [guest/18436] 18436 [007] 10897.962087836:      branches:   vmentry                               0 [unknown] ([unknown]) =>           402c81 guest_code+0x131 (/home/user/git/work/tools/testing/selftests/kselftest_install/kvm/tsc_msrs_test)
+   [guest/18436] 18436 [007] 10897.962087836:      branches:   call                             402c81 guest_code+0x131 (/home/user/git/work/tools/testing/selftests/kselftest_install/kvm/tsc_msrs_test) =>           40dba0 ucall+0x0 (/home/user/git/work/tools/testing/selftests/kselftest_install/kvm/tsc_msrs_test)
+   [guest/18436] 18436 [007] 10897.962088248:      branches:   vmexit                           40dba0 ucall+0x0 (/home/user/git/work/tools/testing/selftests/kselftest_install/kvm/tsc_msrs_test) =>                0 [unknown] ([unknown])
+   tsc_msrs_test 18436 [007] 10897.962088248:      branches:   vmexit                                0 [unknown] ([unknown]) => ffffffffc13b2fa0 vmx_vmexit+0x0 (vmlinux)
+   tsc_msrs_test 18436 [007] 10897.962088248:      branches:   jmp                    ffffffffc13b2fa0 vmx_vmexit+0x0 (vmlinux) => ffffffffc13b2fd2 vmx_vmexit+0x32 (vmlinux)
+   tsc_msrs_test 18436 [007] 10897.962088256:      branches:   return                 ffffffffc13b2fd2 vmx_vmexit+0x32 (vmlinux) => ffffffffc13b3040 __vmx_vcpu_run+0x60 (vmlinux)
+   tsc_msrs_test 18436 [007] 10897.962088270:      branches:   return                 ffffffffc13b30b6 __vmx_vcpu_run+0xd6 (vmlinux) => ffffffffc13b2f2e vmx_vcpu_enter_exit+0x4e (vmlinux)
+ [SNIP]
+   tsc_msrs_test 18436 [007] 10897.962089321:      branches:   call                   ffffffffc13b2ff5 __vmx_vcpu_run+0x15 (vmlinux) => ffffffffc13b2f50 vmx_update_host_rsp+0x0 (vmlinux)
+   tsc_msrs_test 18436 [007] 10897.962089321:      branches:   return                 ffffffffc13b2f5d vmx_update_host_rsp+0xd (vmlinux) => ffffffffc13b2ffa __vmx_vcpu_run+0x1a (vmlinux)
+   tsc_msrs_test 18436 [007] 10897.962089321:      branches:   call                   ffffffffc13b303b __vmx_vcpu_run+0x5b (vmlinux) => ffffffffc13b2f80 vmx_vmenter+0x0 (vmlinux)
+   tsc_msrs_test 18436 [007] 10897.962089424:      branches:   vmentry                ffffffffc13b2f82 vmx_vmenter+0x2 (vmlinux) =>                0 [unknown] ([unknown])
+   [guest/18436] 18436 [007] 10897.962089424:      branches:   vmentry                               0 [unknown] ([unknown]) =>           40dba0 ucall+0x0 (/home/user/git/work/tools/testing/selftests/kselftest_install/kvm/tsc_msrs_test)
+   [guest/18436] 18436 [007] 10897.962089701:      branches:   jmp                              40dc1b ucall+0x7b (/home/user/git/work/tools/testing/selftests/kselftest_install/kvm/tsc_msrs_test) =>           40dc39 ucall+0x99 (/home/user/git/work/tools/testing/selftests/kselftest_install/kvm/tsc_msrs_test)
+   [guest/18436] 18436 [007] 10897.962089701:      branches:   jcc                              40dc3c ucall+0x9c (/home/user/git/work/tools/testing/selftests/kselftest_install/kvm/tsc_msrs_test) =>           40dc20 ucall+0x80 (/home/user/git/work/tools/testing/selftests/kselftest_install/kvm/tsc_msrs_test)
+   [guest/18436] 18436 [007] 10897.962089701:      branches:   jcc                              40dc3c ucall+0x9c (/home/user/git/work/tools/testing/selftests/kselftest_install/kvm/tsc_msrs_test) =>           40dc20 ucall+0x80 (/home/user/git/work/tools/testing/selftests/kselftest_install/kvm/tsc_msrs_test)
+   [guest/18436] 18436 [007] 10897.962089701:      branches:   jcc                              40dc37 ucall+0x97 (/home/user/git/work/tools/testing/selftests/kselftest_install/kvm/tsc_msrs_test) =>           40dc50 ucall+0xb0 (/home/user/git/work/tools/testing/selftests/kselftest_install/kvm/tsc_msrs_test)
+   [guest/18436] 18436 [007] 10897.962089878:      branches:   vmexit                           40dc55 ucall+0xb5 (/home/user/git/work/tools/testing/selftests/kselftest_install/kvm/tsc_msrs_test) =>                0 [unknown] ([unknown])
+   tsc_msrs_test 18436 [007] 10897.962089878:      branches:   vmexit                                0 [unknown] ([unknown]) => ffffffffc13b2fa0 vmx_vmexit+0x0 (vmlinux)
+   tsc_msrs_test 18436 [007] 10897.962089878:      branches:   jmp                    ffffffffc13b2fa0 vmx_vmexit+0x0 (vmlinux) => ffffffffc13b2fd2 vmx_vmexit+0x32 (vmlinux)
+   tsc_msrs_test 18436 [007] 10897.962089887:      branches:   return                 ffffffffc13b2fd2 vmx_vmexit+0x32 (vmlinux) => ffffffffc13b3040 __vmx_vcpu_run+0x60 (vmlinux)
+   tsc_msrs_test 18436 [007] 10897.962089901:      branches:   return                 ffffffffc13b30b6 __vmx_vcpu_run+0xd6 (vmlinux) => ffffffffc13b2f2e vmx_vcpu_enter_exit+0x4e (vmlinux)
+ [SNIP]
+
+ # perf kvm --guest-code --guest --host report -i perf.data --stdio | head -20
+
+ # To display the perf.data header info, please use --header/--header-only options.
+ #
+ #
+ # Total Lost Samples: 0
+ #
+ # Samples: 12  of event 'instructions'
+ # Event count (approx.): 2274583
+ #
+ # Children      Self  Command        Shared Object         Symbol
+ # ........  ........  .............  ....................  ...........................................
+ #
+    54.70%     0.00%  tsc_msrs_test  [kernel.vmlinux]      [k] entry_SYSCALL_64_after_hwframe
+            |
+            ---entry_SYSCALL_64_after_hwframe
+               do_syscall_64
+               |
+               |--29.44%--syscall_exit_to_user_mode
+               |          exit_to_user_mode_prepare
+               |          task_work_run
+               |          __fput
+
+
 Event Trace
 -----------
 
diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index ec43d364d0de..66f23006cfff 100644
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -192,6 +192,7 @@  struct intel_pt_queue {
 	pid_t next_tid;
 	struct thread *thread;
 	struct machine *guest_machine;
+	struct thread *guest_thread;
 	struct thread *unknown_guest_thread;
 	pid_t guest_machine_pid;
 	bool exclude_kernel;
@@ -688,6 +689,11 @@  static int intel_pt_get_guest(struct intel_pt_queue *ptq)
 	ptq->guest_machine = NULL;
 	thread__zput(ptq->unknown_guest_thread);
 
+	if (symbol_conf.guest_code) {
+		thread__zput(ptq->guest_thread);
+		ptq->guest_thread = machines__findnew_guest_code(machines, pid);
+	}
+
 	machine = machines__find_guest(machines, pid);
 	if (!machine)
 		return -1;
@@ -729,11 +735,16 @@  static int intel_pt_walk_next_insn(struct intel_pt_insn *intel_pt_insn,
 	cpumode = intel_pt_nr_cpumode(ptq, *ip, nr);
 
 	if (nr) {
-		if (cpumode != PERF_RECORD_MISC_GUEST_KERNEL ||
+		if ((!symbol_conf.guest_code && cpumode != PERF_RECORD_MISC_GUEST_KERNEL) ||
 		    intel_pt_get_guest(ptq))
 			return -EINVAL;
 		machine = ptq->guest_machine;
-		thread = ptq->unknown_guest_thread;
+		thread = ptq->guest_thread;
+		if (!thread) {
+			if (cpumode != PERF_RECORD_MISC_GUEST_KERNEL)
+				return -EINVAL;
+			thread = ptq->unknown_guest_thread;
+		}
 	} else {
 		thread = ptq->thread;
 		if (!thread) {
@@ -1300,6 +1311,7 @@  static void intel_pt_free_queue(void *priv)
 	if (!ptq)
 		return;
 	thread__zput(ptq->thread);
+	thread__zput(ptq->guest_thread);
 	thread__zput(ptq->unknown_guest_thread);
 	intel_pt_decoder_free(ptq->decoder);
 	zfree(&ptq->event_buf);
@@ -2372,6 +2384,10 @@  static int intel_pt_sample(struct intel_pt_queue *ptq)
 		ptq->sample_ipc = ptq->state->flags & INTEL_PT_SAMPLE_IPC;
 	}
 
+	/* Ensure guest code maps are set up */
+	if (symbol_conf.guest_code && (state->from_nr || state->to_nr))
+		intel_pt_get_guest(ptq);
+
 	/*
 	 * Do PEBS first to allow for the possibility that the PEBS timestamp
 	 * precedes the current timestamp.