[PATCH] arm64: kvm: Annotate guest entry/exit as a single function

[PATCH] arm64: kvm: Annotate guest entry/exit as a single function

[Mark Brown]

In an effort to clarify and simplify the annotations of assembly
functions in the kernel new macros have been introduced replacing ENTRY
and ENDPROC. There are separate annotations SYM_FUNC_ for normal C
functions and SYM_CODE_ for other code. Currently __guest_enter and
__guest_exit are annotated as standard functions but this is not
entirely correct as the former doesn't do a normal return and the latter
is not entered in a normal fashion. From the point of view of the
hypervisor the guest entry/exit may be viewed as a single
function which happens to have an eret in the middle of it so let's
annotate it as such.

Suggested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
 arch/arm64/kvm/hyp/entry.S | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kvm/hyp/entry.S b/arch/arm64/kvm/hyp/entry.S
index e5cc8d66bf53..5b76a89939b1 100644
--- a/arch/arm64/kvm/hyp/entry.S
+++ b/arch/arm64/kvm/hyp/entry.S
@@ -44,7 +44,7 @@
  * u64 __guest_enter(struct kvm_vcpu *vcpu,
  *		     struct kvm_cpu_context *host_ctxt);
  */
-ENTRY(__guest_enter)
+SYM_FUNC_START(__guest_enter)
 	// x0: vcpu
 	// x1: host context
 	// x2-x17: clobbered by macros
@@ -96,9 +96,8 @@ alternative_else_nop_endif
 	// Do not touch any register after this!
 	eret
 	sb
-ENDPROC(__guest_enter)
 
-ENTRY(__guest_exit)
+SYM_INNER_LABEL(__guest_exit, SYM_L_GLOBAL)
 	// x0: return code
 	// x1: vcpu
 	// x2-x29,lr: vcpu regs
@@ -192,4 +191,4 @@ abort_guest_exit_end:
 	msr	spsr_el2, x4
 	orr	x0, x0, x5
 1:	ret
-ENDPROC(__guest_exit)
+SYM_FUNC_END(__guest_enter)
-- 
2.20.1


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Re: [PATCH] arm64: kvm: Annotate guest entry/exit as a single function

[Will Deacon]

[+Marc Z]

On Mon, Jan 20, 2020 at 12:47:06PM +0000, Mark Brown wrote:
> In an effort to clarify and simplify the annotations of assembly
> functions in the kernel new macros have been introduced replacing ENTRY
> and ENDPROC. There are separate annotations SYM_FUNC_ for normal C
> functions and SYM_CODE_ for other code. Currently __guest_enter and
> __guest_exit are annotated as standard functions but this is not
> entirely correct as the former doesn't do a normal return and the latter
> is not entered in a normal fashion. From the point of view of the
> hypervisor the guest entry/exit may be viewed as a single
> function which happens to have an eret in the middle of it so let's
> annotate it as such.
> 
> Suggested-by: Mark Rutland <mark.rutland@arm.com>
> Signed-off-by: Mark Brown <broonie@kernel.org>
> ---
>  arch/arm64/kvm/hyp/entry.S | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/arm64/kvm/hyp/entry.S b/arch/arm64/kvm/hyp/entry.S
> index e5cc8d66bf53..5b76a89939b1 100644
> --- a/arch/arm64/kvm/hyp/entry.S
> +++ b/arch/arm64/kvm/hyp/entry.S
> @@ -44,7 +44,7 @@
>   * u64 __guest_enter(struct kvm_vcpu *vcpu,
>   *		     struct kvm_cpu_context *host_ctxt);
>   */
> -ENTRY(__guest_enter)
> +SYM_FUNC_START(__guest_enter)
>  	// x0: vcpu
>  	// x1: host context
>  	// x2-x17: clobbered by macros
> @@ -96,9 +96,8 @@ alternative_else_nop_endif
>  	// Do not touch any register after this!
>  	eret
>  	sb
> -ENDPROC(__guest_enter)
>  
> -ENTRY(__guest_exit)
> +SYM_INNER_LABEL(__guest_exit, SYM_L_GLOBAL)
>  	// x0: return code
>  	// x1: vcpu
>  	// x2-x29,lr: vcpu regs
> @@ -192,4 +191,4 @@ abort_guest_exit_end:
>  	msr	spsr_el2, x4
>  	orr	x0, x0, x5
>  1:	ret
> -ENDPROC(__guest_exit)
> +SYM_FUNC_END(__guest_enter)

I wondered what the INNER_LABEL thing was for! Looks good:

Acked-by: Will Deacon <will@kernel.org>

Assuming this is going via the kvm tree.

Will

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Re: [PATCH] arm64: kvm: Annotate guest entry/exit as a single function

[Marc Zyngier]

On 2020-01-20 16:45, Will Deacon wrote:
> [+Marc Z]

Thanks for the heads up!

> On Mon, Jan 20, 2020 at 12:47:06PM +0000, Mark Brown wrote:
>> In an effort to clarify and simplify the annotations of assembly
>> functions in the kernel new macros have been introduced replacing 
>> ENTRY
>> and ENDPROC. There are separate annotations SYM_FUNC_ for normal C
>> functions and SYM_CODE_ for other code. Currently __guest_enter and
>> __guest_exit are annotated as standard functions but this is not
>> entirely correct as the former doesn't do a normal return and the 
>> latter
>> is not entered in a normal fashion. From the point of view of the
>> hypervisor the guest entry/exit may be viewed as a single
>> function which happens to have an eret in the middle of it so let's
>> annotate it as such.
>> 
>> Suggested-by: Mark Rutland <mark.rutland@arm.com>
>> Signed-off-by: Mark Brown <broonie@kernel.org>
>> ---
>>  arch/arm64/kvm/hyp/entry.S | 7 +++----
>>  1 file changed, 3 insertions(+), 4 deletions(-)
>> 
>> diff --git a/arch/arm64/kvm/hyp/entry.S b/arch/arm64/kvm/hyp/entry.S
>> index e5cc8d66bf53..5b76a89939b1 100644
>> --- a/arch/arm64/kvm/hyp/entry.S
>> +++ b/arch/arm64/kvm/hyp/entry.S
>> @@ -44,7 +44,7 @@
>>   * u64 __guest_enter(struct kvm_vcpu *vcpu,
>>   *		     struct kvm_cpu_context *host_ctxt);
>>   */
>> -ENTRY(__guest_enter)
>> +SYM_FUNC_START(__guest_enter)
>>  	// x0: vcpu
>>  	// x1: host context
>>  	// x2-x17: clobbered by macros
>> @@ -96,9 +96,8 @@ alternative_else_nop_endif
>>  	// Do not touch any register after this!
>>  	eret
>>  	sb
>> -ENDPROC(__guest_enter)
>> 
>> -ENTRY(__guest_exit)
>> +SYM_INNER_LABEL(__guest_exit, SYM_L_GLOBAL)
>>  	// x0: return code
>>  	// x1: vcpu
>>  	// x2-x29,lr: vcpu regs
>> @@ -192,4 +191,4 @@ abort_guest_exit_end:
>>  	msr	spsr_el2, x4
>>  	orr	x0, x0, x5
>>  1:	ret
>> -ENDPROC(__guest_exit)
>> +SYM_FUNC_END(__guest_enter)
> 
> I wondered what the INNER_LABEL thing was for! Looks good:
> 
> Acked-by: Will Deacon <will@kernel.org>
> 
> Assuming this is going via the kvm tree.

Yup, I've now picked it up.

Thanks,

         M.
-- 
Jazz is not dead. It just smells funny...

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Re: [PATCH] arm64: kvm: Annotate guest entry/exit as a single function

[Mark Brown]

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On Mon, Jan 20, 2020 at 04:45:23PM +0000, Will Deacon wrote:
> [+Marc Z]

Ugh, sorry - guess there's some limit in my mind on the number of
recipients for a mail and KVM just has one too many reviewers!

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