[v7] Correct perf sampling with Guest VMs

[PATCH v7 4/5] x86: perf: Refactor misc flag assignments

Posted by Colton Lewis 2 weeks, 2 days ago

Break the assignment logic for misc flags into their own respective
functions to reduce the complexity of the nested logic.

Signed-off-by: Colton Lewis <coltonlewis@google.com>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
---
 arch/x86/events/core.c            | 32 +++++++++++++++++++++++--------
 arch/x86/include/asm/perf_event.h |  2 ++
 2 files changed, 26 insertions(+), 8 deletions(-)

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index d19e939f3998..9fdc5fa22c66 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -3011,16 +3011,35 @@ unsigned long perf_arch_instruction_pointer(struct pt_regs *regs)
 	return regs->ip + code_segment_base(regs);
 }
 
+static unsigned long common_misc_flags(struct pt_regs *regs)
+{
+	if (regs->flags & PERF_EFLAGS_EXACT)
+		return PERF_RECORD_MISC_EXACT_IP;
+
+	return 0;
+}
+
+unsigned long perf_arch_guest_misc_flags(struct pt_regs *regs)
+{
+	unsigned long guest_state = perf_guest_state();
+	unsigned long flags = common_misc_flags(regs);
+
+	if (!(guest_state & PERF_GUEST_ACTIVE))
+		return flags;
+
+	if (guest_state & PERF_GUEST_USER)
+		return flags & PERF_RECORD_MISC_GUEST_USER;
+	else
+		return flags & PERF_RECORD_MISC_GUEST_KERNEL;
+}
+
 unsigned long perf_arch_misc_flags(struct pt_regs *regs)
 {
 	unsigned int guest_state = perf_guest_state();
-	int misc = 0;
+	unsigned long misc = common_misc_flags(regs);
 
 	if (guest_state) {
-		if (guest_state & PERF_GUEST_USER)
-			misc |= PERF_RECORD_MISC_GUEST_USER;
-		else
-			misc |= PERF_RECORD_MISC_GUEST_KERNEL;
+		misc |= perf_arch_guest_misc_flags(regs);
 	} else {
 		if (user_mode(regs))
 			misc |= PERF_RECORD_MISC_USER;
@@ -3028,9 +3047,6 @@ unsigned long perf_arch_misc_flags(struct pt_regs *regs)
 			misc |= PERF_RECORD_MISC_KERNEL;
 	}
 
-	if (regs->flags & PERF_EFLAGS_EXACT)
-		misc |= PERF_RECORD_MISC_EXACT_IP;
-
 	return misc;
 }
 
diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h
index feb87bf3d2e9..d95f902acc52 100644
--- a/arch/x86/include/asm/perf_event.h
+++ b/arch/x86/include/asm/perf_event.h
@@ -538,7 +538,9 @@ struct x86_perf_regs {
 
 extern unsigned long perf_arch_instruction_pointer(struct pt_regs *regs);
 extern unsigned long perf_arch_misc_flags(struct pt_regs *regs);
+extern unsigned long perf_arch_guest_misc_flags(struct pt_regs *regs);
 #define perf_arch_misc_flags(regs)	perf_arch_misc_flags(regs)
+#define perf_arch_guest_misc_flags(regs)	perf_arch_guest_misc_flags(regs)
 
 #include <asm/stacktrace.h>
 
-- 
2.47.0.277.g8800431eea-goog

Re: [PATCH v7 4/5] x86: perf: Refactor misc flag assignments

Posted by Peter Zijlstra 2 weeks, 1 day ago

On Thu, Nov 07, 2024 at 07:03:35PM +0000, Colton Lewis wrote:
> Break the assignment logic for misc flags into their own respective
> functions to reduce the complexity of the nested logic.
> 
> Signed-off-by: Colton Lewis <coltonlewis@google.com>
> Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
> ---
>  arch/x86/events/core.c            | 32 +++++++++++++++++++++++--------
>  arch/x86/include/asm/perf_event.h |  2 ++
>  2 files changed, 26 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
> index d19e939f3998..9fdc5fa22c66 100644
> --- a/arch/x86/events/core.c
> +++ b/arch/x86/events/core.c
> @@ -3011,16 +3011,35 @@ unsigned long perf_arch_instruction_pointer(struct pt_regs *regs)
>  	return regs->ip + code_segment_base(regs);
>  }
>  
> +static unsigned long common_misc_flags(struct pt_regs *regs)
> +{
> +	if (regs->flags & PERF_EFLAGS_EXACT)
> +		return PERF_RECORD_MISC_EXACT_IP;
> +
> +	return 0;
> +}
> +
> +unsigned long perf_arch_guest_misc_flags(struct pt_regs *regs)
> +{
> +	unsigned long guest_state = perf_guest_state();
> +	unsigned long flags = common_misc_flags(regs);

This is double common_misc and makes no sense

> +
> +	if (!(guest_state & PERF_GUEST_ACTIVE))
> +		return flags;
> +
> +	if (guest_state & PERF_GUEST_USER)
> +		return flags & PERF_RECORD_MISC_GUEST_USER;
> +	else
> +		return flags & PERF_RECORD_MISC_GUEST_KERNEL;

And this is just broken garbage, right?

> +}

Did you mean to write:

unsigned long perf_arch_guest_misc_flags(struct pt_regs *regs)
{
	unsigned long guest_state = perf_guest_state();
	unsigned long flags = 0;

	if (guest_state & PERF_GUEST_ACTIVE) {
		if (guest_state & PERF_GUEST_USER)
			flags |= PERF_RECORD_MISC_GUEST_USER;
		else
			flags |= PERF_RECORD_MISC_GUEST_KERNEL;
	}

	return flags;
}

>  unsigned long perf_arch_misc_flags(struct pt_regs *regs)
>  {
>  	unsigned int guest_state = perf_guest_state();
> -	int misc = 0;
> +	unsigned long misc = common_misc_flags(regs);

Because here you do the common thing..

>  
>  	if (guest_state) {
> -		if (guest_state & PERF_GUEST_USER)
> -			misc |= PERF_RECORD_MISC_GUEST_USER;
> -		else
> -			misc |= PERF_RECORD_MISC_GUEST_KERNEL;
> +		misc |= perf_arch_guest_misc_flags(regs);

And here you mix in the guest things.

>  	} else {
>  		if (user_mode(regs))
>  			misc |= PERF_RECORD_MISC_USER;

Re: [PATCH v7 4/5] x86: perf: Refactor misc flag assignments

Posted by Colton Lewis 2 weeks, 1 day ago

Peter Zijlstra <peterz@infradead.org> writes:

> On Thu, Nov 07, 2024 at 07:03:35PM +0000, Colton Lewis wrote:
>> Break the assignment logic for misc flags into their own respective
>> functions to reduce the complexity of the nested logic.

>> Signed-off-by: Colton Lewis <coltonlewis@google.com>
>> Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
>> ---
>>   arch/x86/events/core.c            | 32 +++++++++++++++++++++++--------
>>   arch/x86/include/asm/perf_event.h |  2 ++
>>   2 files changed, 26 insertions(+), 8 deletions(-)

>> diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
>> index d19e939f3998..9fdc5fa22c66 100644
>> --- a/arch/x86/events/core.c
>> +++ b/arch/x86/events/core.c
>> @@ -3011,16 +3011,35 @@ unsigned long  
>> perf_arch_instruction_pointer(struct pt_regs *regs)
>>   	return regs->ip + code_segment_base(regs);
>>   }

>> +static unsigned long common_misc_flags(struct pt_regs *regs)
>> +{
>> +	if (regs->flags & PERF_EFLAGS_EXACT)
>> +		return PERF_RECORD_MISC_EXACT_IP;
>> +
>> +	return 0;
>> +}
>> +
>> +unsigned long perf_arch_guest_misc_flags(struct pt_regs *regs)
>> +{
>> +	unsigned long guest_state = perf_guest_state();
>> +	unsigned long flags = common_misc_flags(regs);

> This is double common_misc and makes no sense

I'm confused what you mean. Are you referring to starting with
common_misc_flags in both perf_arch_misc_flags and
perf_arch_guest_misc_flags so possibly the common_msic_flags are set
twice?

That seems like a good thing that common flags are set wherever they
apply. You can't guarantee where perf_arch_guest_misc_flags may be
called in the future.
>> +
>> +	if (!(guest_state & PERF_GUEST_ACTIVE))
>> +		return flags;
>> +
>> +	if (guest_state & PERF_GUEST_USER)
>> +		return flags & PERF_RECORD_MISC_GUEST_USER;
>> +	else
>> +		return flags & PERF_RECORD_MISC_GUEST_KERNEL;

> And this is just broken garbage, right?

>> +}

> Did you mean to write:

> unsigned long perf_arch_guest_misc_flags(struct pt_regs *regs)
> {
> 	unsigned long guest_state = perf_guest_state();
> 	unsigned long flags = 0;

> 	if (guest_state & PERF_GUEST_ACTIVE) {
> 		if (guest_state & PERF_GUEST_USER)
> 			flags |= PERF_RECORD_MISC_GUEST_USER;
> 		else
> 			flags |= PERF_RECORD_MISC_GUEST_KERNEL;
> 	}

> 	return flags;
> }

Ok, my mistake was using & instead of |, but the branches are
functionally the same.

I'll use something closer to your suggestion.

>>   unsigned long perf_arch_misc_flags(struct pt_regs *regs)
>>   {
>>   	unsigned int guest_state = perf_guest_state();
>> -	int misc = 0;
>> +	unsigned long misc = common_misc_flags(regs);

> Because here you do the common thing..


>>   	if (guest_state) {
>> -		if (guest_state & PERF_GUEST_USER)
>> -			misc |= PERF_RECORD_MISC_GUEST_USER;
>> -		else
>> -			misc |= PERF_RECORD_MISC_GUEST_KERNEL;
>> +		misc |= perf_arch_guest_misc_flags(regs);

> And here you mix in the guest things.

>>   	} else {
>>   		if (user_mode(regs))
>>   			misc |= PERF_RECORD_MISC_USER;

Re: [PATCH v7 4/5] x86: perf: Refactor misc flag assignments

Posted by Peter Zijlstra 2 weeks, 1 day ago

On Fri, Nov 08, 2024 at 07:01:16PM +0000, Colton Lewis wrote:
> Peter Zijlstra <peterz@infradead.org> writes:
> 
> > On Thu, Nov 07, 2024 at 07:03:35PM +0000, Colton Lewis wrote:
> > > Break the assignment logic for misc flags into their own respective
> > > functions to reduce the complexity of the nested logic.
> 
> > > Signed-off-by: Colton Lewis <coltonlewis@google.com>
> > > Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
> > > ---
> > >   arch/x86/events/core.c            | 32 +++++++++++++++++++++++--------
> > >   arch/x86/include/asm/perf_event.h |  2 ++
> > >   2 files changed, 26 insertions(+), 8 deletions(-)
> 
> > > diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
> > > index d19e939f3998..9fdc5fa22c66 100644
> > > --- a/arch/x86/events/core.c
> > > +++ b/arch/x86/events/core.c
> > > @@ -3011,16 +3011,35 @@ unsigned long
> > > perf_arch_instruction_pointer(struct pt_regs *regs)
> > >   	return regs->ip + code_segment_base(regs);
> > >   }
> 
> > > +static unsigned long common_misc_flags(struct pt_regs *regs)
> > > +{
> > > +	if (regs->flags & PERF_EFLAGS_EXACT)
> > > +		return PERF_RECORD_MISC_EXACT_IP;
> > > +
> > > +	return 0;
> > > +}
> > > +
> > > +unsigned long perf_arch_guest_misc_flags(struct pt_regs *regs)
> > > +{
> > > +	unsigned long guest_state = perf_guest_state();
> > > +	unsigned long flags = common_misc_flags(regs);
> 
> > This is double common_misc and makes no sense
> 
> I'm confused what you mean. Are you referring to starting with
> common_misc_flags in both perf_arch_misc_flags and
> perf_arch_guest_misc_flags so possibly the common_msic_flags are set
> twice?
> 
> That seems like a good thing that common flags are set wherever they
> apply. You can't guarantee where perf_arch_guest_misc_flags may be
> called in the future.

I got confused by perf_arch_misc_flags() calling common_misc_flags()
twice. It is in fact worse, because afaict all of
perf_arch_guest_misc_flags() is 'common'.

Isn't the below more or less what you want?

static unsigned long misc_flags(struct pt_regs *regs)
{
	unsigned long flags = 0;

	if (regs->flags & PERF_EFLAGS_EXACT)
		flags |= PERF_RECORD_MISC_EXACT_IP;

	return flags;
}

static unsigned long native_flags(struct pt_regs *regs)
{
	unsigned long flags = 0;

	if (user_mode(regs))
		flags |= PERF_RECORD_MISC_USER;
	else
		flags |= PERF_RECORD_MISC_KERNEL;

	return flags;
}

static unsigned long guest_flags(struct pt_regs *regs)
{
	unsigned long guest_state = perf_guest_state();
	unsigned long flags = 0;

	if (guest_state & PERF_GUEST_ACTIVE) {
		if (guest_state & PERF_GUEST_USER)
			flags |= PERF_RECORD_MISC_GUEST_USER;
		else
			flags |= PERF_RECORD_MISC_GUEST_KERNEL;
	}

	return flags;
}

unsigned long perf_arch_guest_misc_flags(struct pt_regs *regs)
{
	unsigned long flags;

	flags = misc_flags(regs);
	flags |= guest_flags(regs);

	return flags;
}

unsigned long perf_arch_misc_flags(struct pt_regs *regs)
{
	unsigned long flags;
	unsigned long guest;

	flags = misc_flags(regs);
	guest = guest_flags(regs);
	if (guest)
		flags |= guest;
	else
		flags |= native_flags(regs);

	return flags;
}

Note how both perf_arch*() functions end up calling both misc and guest.

Re: [PATCH v7 4/5] x86: perf: Refactor misc flag assignments

Posted by Peter Zijlstra 2 weeks, 1 day ago

On Fri, Nov 08, 2024 at 08:20:44PM +0100, Peter Zijlstra wrote:

> Isn't the below more or less what you want?
> 
> static unsigned long misc_flags(struct pt_regs *regs)
> {
> 	unsigned long flags = 0;
> 
> 	if (regs->flags & PERF_EFLAGS_EXACT)
> 		flags |= PERF_RECORD_MISC_EXACT_IP;
> 
> 	return flags;
> }
> 
> static unsigned long native_flags(struct pt_regs *regs)
> {
> 	unsigned long flags = 0;
> 
> 	if (user_mode(regs))
> 		flags |= PERF_RECORD_MISC_USER;
> 	else
> 		flags |= PERF_RECORD_MISC_KERNEL;
> 
> 	return flags;
> }
> 
> static unsigned long guest_flags(struct pt_regs *regs)
> {
> 	unsigned long guest_state = perf_guest_state();
> 	unsigned long flags = 0;
> 
> 	if (guest_state & PERF_GUEST_ACTIVE) {
> 		if (guest_state & PERF_GUEST_USER)
> 			flags |= PERF_RECORD_MISC_GUEST_USER;
> 		else
> 			flags |= PERF_RECORD_MISC_GUEST_KERNEL;
> 	}
> 
> 	return flags;
> }
> 
> unsigned long perf_arch_guest_misc_flags(struct pt_regs *regs)
> {
> 	unsigned long flags;
> 
> 	flags = misc_flags(regs);
> 	flags |= guest_flags(regs);
> 
> 	return flags;
> }
> 
> unsigned long perf_arch_misc_flags(struct pt_regs *regs)
> {
> 	unsigned long flags;
> 	unsigned long guest;
> 
> 	flags = misc_flags(regs);
> 	guest = guest_flags(regs);
> 	if (guest)
> 		flags |= guest;
> 	else
> 		flags |= native_flags(regs);
> 
> 	return flags;
> }

This last can be written more concise:

unsigned long perf_arch_misc_flags(struct pt_regs *regs)
{
	unsigned long flags;

	flags = guest_flags(regs);
	if (!flags)
		flags |= native_flags(regs);

	flgs |= misc_flags(regs);

	return flags;
}

Re: [PATCH v7 4/5] x86: perf: Refactor misc flag assignments

Posted by Colton Lewis 1 week, 3 days ago

Peter Zijlstra <peterz@infradead.org> writes:

> On Fri, Nov 08, 2024 at 08:20:44PM +0100, Peter Zijlstra wrote:

>> Isn't the below more or less what you want?

>> static unsigned long misc_flags(struct pt_regs *regs)
>> {
>> 	unsigned long flags = 0;

>> 	if (regs->flags & PERF_EFLAGS_EXACT)
>> 		flags |= PERF_RECORD_MISC_EXACT_IP;

>> 	return flags;
>> }

>> static unsigned long native_flags(struct pt_regs *regs)
>> {
>> 	unsigned long flags = 0;

>> 	if (user_mode(regs))
>> 		flags |= PERF_RECORD_MISC_USER;
>> 	else
>> 		flags |= PERF_RECORD_MISC_KERNEL;

>> 	return flags;
>> }

>> static unsigned long guest_flags(struct pt_regs *regs)
>> {
>> 	unsigned long guest_state = perf_guest_state();
>> 	unsigned long flags = 0;

>> 	if (guest_state & PERF_GUEST_ACTIVE) {
>> 		if (guest_state & PERF_GUEST_USER)
>> 			flags |= PERF_RECORD_MISC_GUEST_USER;
>> 		else
>> 			flags |= PERF_RECORD_MISC_GUEST_KERNEL;
>> 	}

>> 	return flags;
>> }

>> unsigned long perf_arch_guest_misc_flags(struct pt_regs *regs)
>> {
>> 	unsigned long flags;

>> 	flags = misc_flags(regs);
>> 	flags |= guest_flags(regs);

>> 	return flags;
>> }

>> unsigned long perf_arch_misc_flags(struct pt_regs *regs)
>> {
>> 	unsigned long flags;
>> 	unsigned long guest;

>> 	flags = misc_flags(regs);
>> 	guest = guest_flags(regs);
>> 	if (guest)
>> 		flags |= guest;
>> 	else
>> 		flags |= native_flags(regs);

>> 	return flags;
>> }

> This last can be written more concise:

> unsigned long perf_arch_misc_flags(struct pt_regs *regs)
> {
> 	unsigned long flags;

> 	flags = guest_flags(regs);
> 	if (!flags)
> 		flags |= native_flags(regs);

> 	flgs |= misc_flags(regs);

> 	return flags;
> }

This isn't right because it is choosing to return guest or native
flags depending on the presence of guest flags, but that's not what we
want.

See perf_misc_flags in kernel/events/core.c which chooses to return
perf_arch_guest_misc_flags or perf_arch_misc_flags depending on
should_sample_guest which depends on more than current guest state.

But I will take some of your suggestions to split the functions out
more.

Re: [PATCH v7 4/5] x86: perf: Refactor misc flag assignments

Posted by Colton Lewis 1 week, 3 days ago

Colton Lewis <coltonlewis@google.com> writes:

> Peter Zijlstra <peterz@infradead.org> writes:

>> On Fri, Nov 08, 2024 at 08:20:44PM +0100, Peter Zijlstra wrote:

>>> Isn't the below more or less what you want?

>>> static unsigned long misc_flags(struct pt_regs *regs)
>>> {
>>> 	unsigned long flags = 0;

>>> 	if (regs->flags & PERF_EFLAGS_EXACT)
>>> 		flags |= PERF_RECORD_MISC_EXACT_IP;

>>> 	return flags;
>>> }

>>> static unsigned long native_flags(struct pt_regs *regs)
>>> {
>>> 	unsigned long flags = 0;

>>> 	if (user_mode(regs))
>>> 		flags |= PERF_RECORD_MISC_USER;
>>> 	else
>>> 		flags |= PERF_RECORD_MISC_KERNEL;

>>> 	return flags;
>>> }

>>> static unsigned long guest_flags(struct pt_regs *regs)
>>> {
>>> 	unsigned long guest_state = perf_guest_state();
>>> 	unsigned long flags = 0;

>>> 	if (guest_state & PERF_GUEST_ACTIVE) {
>>> 		if (guest_state & PERF_GUEST_USER)
>>> 			flags |= PERF_RECORD_MISC_GUEST_USER;
>>> 		else
>>> 			flags |= PERF_RECORD_MISC_GUEST_KERNEL;
>>> 	}

>>> 	return flags;
>>> }

>>> unsigned long perf_arch_guest_misc_flags(struct pt_regs *regs)
>>> {
>>> 	unsigned long flags;

>>> 	flags = misc_flags(regs);
>>> 	flags |= guest_flags(regs);

>>> 	return flags;
>>> }

>>> unsigned long perf_arch_misc_flags(struct pt_regs *regs)
>>> {
>>> 	unsigned long flags;
>>> 	unsigned long guest;

>>> 	flags = misc_flags(regs);
>>> 	guest = guest_flags(regs);
>>> 	if (guest)
>>> 		flags |= guest;
>>> 	else
>>> 		flags |= native_flags(regs);

>>> 	return flags;
>>> }

>> This last can be written more concise:

>> unsigned long perf_arch_misc_flags(struct pt_regs *regs)
>> {
>> 	unsigned long flags;

>> 	flags = guest_flags(regs);
>> 	if (!flags)
>> 		flags |= native_flags(regs);

>> 	flgs |= misc_flags(regs);

>> 	return flags;
>> }

> This isn't right because it is choosing to return guest or native
> flags depending on the presence of guest flags, but that's not what we
> want.

> See perf_misc_flags in kernel/events/core.c which chooses to return
> perf_arch_guest_misc_flags or perf_arch_misc_flags depending on
> should_sample_guest which depends on more than current guest state.

This is in the next patch. Excuse me for not clarifying.

> But I will take some of your suggestions to split the functions out
> more.

Re: [PATCH v7 4/5] x86: perf: Refactor misc flag assignments

Posted by Liang, Kan 2 weeks, 2 days ago


On 2024-11-07 2:03 p.m., Colton Lewis wrote:
> Break the assignment logic for misc flags into their own respective
> functions to reduce the complexity of the nested logic.
> 
> Signed-off-by: Colton Lewis <coltonlewis@google.com>
> Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
> ---

Acked-by: Kan Liang <kan.liang@linux.intel.com>

Thanks,
Kan
>  arch/x86/events/core.c            | 32 +++++++++++++++++++++++--------
>  arch/x86/include/asm/perf_event.h |  2 ++
>  2 files changed, 26 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
> index d19e939f3998..9fdc5fa22c66 100644
> --- a/arch/x86/events/core.c
> +++ b/arch/x86/events/core.c
> @@ -3011,16 +3011,35 @@ unsigned long perf_arch_instruction_pointer(struct pt_regs *regs)
>  	return regs->ip + code_segment_base(regs);
>  }
>  
> +static unsigned long common_misc_flags(struct pt_regs *regs)
> +{
> +	if (regs->flags & PERF_EFLAGS_EXACT)
> +		return PERF_RECORD_MISC_EXACT_IP;
> +
> +	return 0;
> +}
> +
> +unsigned long perf_arch_guest_misc_flags(struct pt_regs *regs)
> +{
> +	unsigned long guest_state = perf_guest_state();
> +	unsigned long flags = common_misc_flags(regs);
> +
> +	if (!(guest_state & PERF_GUEST_ACTIVE))
> +		return flags;
> +
> +	if (guest_state & PERF_GUEST_USER)
> +		return flags & PERF_RECORD_MISC_GUEST_USER;
> +	else
> +		return flags & PERF_RECORD_MISC_GUEST_KERNEL;
> +}
> +
>  unsigned long perf_arch_misc_flags(struct pt_regs *regs)
>  {
>  	unsigned int guest_state = perf_guest_state();
> -	int misc = 0;
> +	unsigned long misc = common_misc_flags(regs);
>  
>  	if (guest_state) {
> -		if (guest_state & PERF_GUEST_USER)
> -			misc |= PERF_RECORD_MISC_GUEST_USER;
> -		else
> -			misc |= PERF_RECORD_MISC_GUEST_KERNEL;
> +		misc |= perf_arch_guest_misc_flags(regs);
>  	} else {
>  		if (user_mode(regs))
>  			misc |= PERF_RECORD_MISC_USER;
> @@ -3028,9 +3047,6 @@ unsigned long perf_arch_misc_flags(struct pt_regs *regs)
>  			misc |= PERF_RECORD_MISC_KERNEL;
>  	}
>  
> -	if (regs->flags & PERF_EFLAGS_EXACT)
> -		misc |= PERF_RECORD_MISC_EXACT_IP;
> -
>  	return misc;
>  }
>  
> diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h
> index feb87bf3d2e9..d95f902acc52 100644
> --- a/arch/x86/include/asm/perf_event.h
> +++ b/arch/x86/include/asm/perf_event.h
> @@ -538,7 +538,9 @@ struct x86_perf_regs {
>  
>  extern unsigned long perf_arch_instruction_pointer(struct pt_regs *regs);
>  extern unsigned long perf_arch_misc_flags(struct pt_regs *regs);
> +extern unsigned long perf_arch_guest_misc_flags(struct pt_regs *regs);
>  #define perf_arch_misc_flags(regs)	perf_arch_misc_flags(regs)
> +#define perf_arch_guest_misc_flags(regs)	perf_arch_guest_misc_flags(regs)
>  
>  #include <asm/stacktrace.h>
>