[1/2] KVM: selftests: Implement ucall() for s390x
diff mbox series

Message ID 20190730100112.18205-2-thuth@redhat.com
State New
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Series
  • KVM: selftests: Enable ucall and dirty_log_test on s390x
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Commit Message

Thomas Huth July 30, 2019, 10:01 a.m. UTC
On s390x, we can neither exit via PIO nor MMIO, but have to use
an instruction like DIAGNOSE. While we're at it, rename UCALL_PIO
to UCALL_DEFAULT, since PIO only works on x86 anyway, and this
way we can re-use the "default" type for the DIAGNOSE exit on s390x.

Now that ucall() is implemented, we can use it in the sync_reg_test
on s390x, too.

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 .../testing/selftests/kvm/include/kvm_util.h  |  2 +-
 tools/testing/selftests/kvm/lib/ucall.c       | 34 +++++++++++++++----
 .../selftests/kvm/s390x/sync_regs_test.c      |  6 ++--
 3 files changed, 32 insertions(+), 10 deletions(-)

Comments

Andrew Jones July 30, 2019, 10:48 a.m. UTC | #1
On Tue, Jul 30, 2019 at 12:01:11PM +0200, Thomas Huth wrote:
> On s390x, we can neither exit via PIO nor MMIO, but have to use
> an instruction like DIAGNOSE. While we're at it, rename UCALL_PIO
> to UCALL_DEFAULT, since PIO only works on x86 anyway, and this
> way we can re-use the "default" type for the DIAGNOSE exit on s390x.
> 
> Now that ucall() is implemented, we can use it in the sync_reg_test
> on s390x, too.
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  .../testing/selftests/kvm/include/kvm_util.h  |  2 +-
>  tools/testing/selftests/kvm/lib/ucall.c       | 34 +++++++++++++++----
>  .../selftests/kvm/s390x/sync_regs_test.c      |  6 ++--
>  3 files changed, 32 insertions(+), 10 deletions(-)
> 
> diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
> index e0e66b115ef2..c37aea2e33e5 100644
> --- a/tools/testing/selftests/kvm/include/kvm_util.h
> +++ b/tools/testing/selftests/kvm/include/kvm_util.h
> @@ -167,7 +167,7 @@ int vm_create_device(struct kvm_vm *vm, struct kvm_create_device *cd);
>  
>  /* ucall implementation types */
>  typedef enum {
> -	UCALL_PIO,
> +	UCALL_DEFAULT,

I'd rather we keep explicit types defined; keep PIO and add DIAG. Then
we can have

/*  Set default ucall types */
#if defined(__x86_64__)
  ucall_type = UCALL_PIO;
#elif defined(__aarch64__)
  ucall_type = UCALL_MMIO;
  ucall_requires_init = true;
#elif defined(__s390x__)
  ucall_type = UCALL_DIAG;
#endif

And add an assert in get_ucall()

 assert(!ucall_requires_init || ucall_initialized);


>  	UCALL_MMIO,
>  } ucall_type_t;
>  
> diff --git a/tools/testing/selftests/kvm/lib/ucall.c b/tools/testing/selftests/kvm/lib/ucall.c
> index dd9a66700f96..55534dd014dc 100644
> --- a/tools/testing/selftests/kvm/lib/ucall.c
> +++ b/tools/testing/selftests/kvm/lib/ucall.c
> @@ -30,7 +30,7 @@ void ucall_init(struct kvm_vm *vm, ucall_type_t type, void *arg)
>  	ucall_type = type;
>  	sync_global_to_guest(vm, ucall_type);
>  
> -	if (type == UCALL_PIO)
> +	if (type == UCALL_DEFAULT)
>  		return;
>  
>  	if (type == UCALL_MMIO) {
> @@ -84,11 +84,18 @@ void ucall_uninit(struct kvm_vm *vm)
>  	sync_global_to_guest(vm, ucall_exit_mmio_addr);
>  }
>  
> -static void ucall_pio_exit(struct ucall *uc)
> +static void ucall_default_exit(struct ucall *uc)
>  {
> -#ifdef __x86_64__
> +#if defined(__x86_64__)
> +	/* Exit via PIO */
>  	asm volatile("in %[port], %%al"
>  		: : [port] "d" (UCALL_PIO_PORT), "D" (uc) : "rax");
> +#elif defined(__s390x__)
> +	/* Exit via DIAGNOSE 0x501 (normally used for breakpoints) */
> +	asm volatile ("diag 0,%0,0x501" : : "a"(uc) : "memory");
> +#else
> +	fprintf(stderr, "No default ucall available on this architecture.\n");
> +	exit(1);
>  #endif
>  }
>  
> @@ -113,8 +120,8 @@ void ucall(uint64_t cmd, int nargs, ...)
>  	va_end(va);
>  
>  	switch (ucall_type) {
> -	case UCALL_PIO:
> -		ucall_pio_exit(&uc);
> +	case UCALL_DEFAULT:
> +		ucall_default_exit(&uc);
>  		break;
>  	case UCALL_MMIO:
>  		ucall_mmio_exit(&uc);
> @@ -128,15 +135,28 @@ uint64_t get_ucall(struct kvm_vm *vm, uint32_t vcpu_id, struct ucall *uc)
>  	struct ucall ucall = {};
>  	bool got_ucall = false;
>  
> -#ifdef __x86_64__
> -	if (ucall_type == UCALL_PIO && run->exit_reason == KVM_EXIT_IO &&
> +#if defined(__x86_64__)
> +	if (ucall_type == UCALL_DEFAULT && run->exit_reason == KVM_EXIT_IO &&
>  	    run->io.port == UCALL_PIO_PORT) {
>  		struct kvm_regs regs;
>  		vcpu_regs_get(vm, vcpu_id, &regs);
>  		memcpy(&ucall, addr_gva2hva(vm, (vm_vaddr_t)regs.rdi), sizeof(ucall));
>  		got_ucall = true;
>  	}
> +#elif defined(__s390x__)
> +	if (ucall_type == UCALL_DEFAULT &&
> +	    run->exit_reason == KVM_EXIT_S390_SIEIC &&
> +	    run->s390_sieic.icptcode == 4 &&
> +	    (run->s390_sieic.ipa >> 8) == 0x83 &&    /* 0x83 means DIAGNOSE */
> +	    (run->s390_sieic.ipb >> 16) == 0x501) {
> +		int reg = run->s390_sieic.ipa & 0xf;
> +
> +		memcpy(&ucall, addr_gva2hva(vm, run->s.regs.gprs[reg]),
> +		       sizeof(ucall));
> +		got_ucall = true;
> +	}
>  #endif
> +
>  	if (ucall_type == UCALL_MMIO && run->exit_reason == KVM_EXIT_MMIO &&
>  	    run->mmio.phys_addr == (uint64_t)ucall_exit_mmio_addr) {
>  		vm_vaddr_t gva;
> diff --git a/tools/testing/selftests/kvm/s390x/sync_regs_test.c b/tools/testing/selftests/kvm/s390x/sync_regs_test.c
> index e85ff0d69548..bbc93094519b 100644
> --- a/tools/testing/selftests/kvm/s390x/sync_regs_test.c
> +++ b/tools/testing/selftests/kvm/s390x/sync_regs_test.c
> @@ -25,9 +25,11 @@
>  
>  static void guest_code(void)
>  {
> +	register u64 stage asm("11") = 0;
> +
>  	for (;;) {
> -		asm volatile ("diag 0,0,0x501");
> -		asm volatile ("ahi 11,1");
> +		GUEST_SYNC(0);
> +		asm volatile ("ahi %0,1" : : "r"(stage));
>  	}
>  }
>  
> -- 
> 2.21.0
>

Thanks,
drew
Thomas Huth July 31, 2019, 9:43 a.m. UTC | #2
On 30/07/2019 12.48, Andrew Jones wrote:
> On Tue, Jul 30, 2019 at 12:01:11PM +0200, Thomas Huth wrote:
>> On s390x, we can neither exit via PIO nor MMIO, but have to use
>> an instruction like DIAGNOSE. While we're at it, rename UCALL_PIO
>> to UCALL_DEFAULT, since PIO only works on x86 anyway, and this
>> way we can re-use the "default" type for the DIAGNOSE exit on s390x.
>>
>> Now that ucall() is implemented, we can use it in the sync_reg_test
>> on s390x, too.
>>
>> Signed-off-by: Thomas Huth <thuth@redhat.com>
>> ---
>>  .../testing/selftests/kvm/include/kvm_util.h  |  2 +-
>>  tools/testing/selftests/kvm/lib/ucall.c       | 34 +++++++++++++++----
>>  .../selftests/kvm/s390x/sync_regs_test.c      |  6 ++--
>>  3 files changed, 32 insertions(+), 10 deletions(-)
>>
>> diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
>> index e0e66b115ef2..c37aea2e33e5 100644
>> --- a/tools/testing/selftests/kvm/include/kvm_util.h
>> +++ b/tools/testing/selftests/kvm/include/kvm_util.h
>> @@ -167,7 +167,7 @@ int vm_create_device(struct kvm_vm *vm, struct kvm_create_device *cd);
>>  
>>  /* ucall implementation types */
>>  typedef enum {
>> -	UCALL_PIO,
>> +	UCALL_DEFAULT,
> 
> I'd rather we keep explicit types defined; keep PIO and add DIAG. Then
> we can have
> 
> /*  Set default ucall types */
> #if defined(__x86_64__)
>   ucall_type = UCALL_PIO;
> #elif defined(__aarch64__)
>   ucall_type = UCALL_MMIO;
>   ucall_requires_init = true;
> #elif defined(__s390x__)
>   ucall_type = UCALL_DIAG;
> #endif
> 
> And add an assert in get_ucall()
> 
>  assert(!ucall_requires_init || ucall_initialized);

I'm not sure whether I really like that. It's yet another additional
#ifdef block, and yet another variable ...

What do you think about removing the enum completely and simply code it
directly, without the ucall_type indirection, i.e.:

void ucall(uint64_t cmd, int nargs, ...)
{
	struct ucall uc = {
		.cmd = cmd,
	};
	va_list va;
	int i;

	nargs = nargs <= UCALL_MAX_ARGS ? nargs : UCALL_MAX_ARGS;

	va_start(va, nargs);
	for (i = 0; i < nargs; ++i)
		uc.args[i] = va_arg(va, uint64_t);
	va_end(va);

#if defined(__x86_64__)

	/* Exit via PIO */
	asm volatile("in %[port], %%al"
		: : [port] "d" (UCALL_PIO_PORT), "D" (&uc) : "rax");

#elif defined(__aarch64__)

	*ucall_exit_mmio_addr = (vm_vaddr_t)&uc;

#elif defined(__s390x__)

	/* Exit via DIAGNOSE 0x501 (normally used for breakpoints) */
	asm volatile ("diag 0,%0,0x501" : : "a"(&uc) : "memory");

#endif
}

I think that's way less confusing than having to understand the meaning
of ucall_type etc. before...?

 Thomas
Andrew Jones July 31, 2019, 10:28 a.m. UTC | #3
On Wed, Jul 31, 2019 at 11:43:16AM +0200, Thomas Huth wrote:
> On 30/07/2019 12.48, Andrew Jones wrote:
> > On Tue, Jul 30, 2019 at 12:01:11PM +0200, Thomas Huth wrote:
> >> On s390x, we can neither exit via PIO nor MMIO, but have to use
> >> an instruction like DIAGNOSE. While we're at it, rename UCALL_PIO
> >> to UCALL_DEFAULT, since PIO only works on x86 anyway, and this
> >> way we can re-use the "default" type for the DIAGNOSE exit on s390x.
> >>
> >> Now that ucall() is implemented, we can use it in the sync_reg_test
> >> on s390x, too.
> >>
> >> Signed-off-by: Thomas Huth <thuth@redhat.com>
> >> ---
> >>  .../testing/selftests/kvm/include/kvm_util.h  |  2 +-
> >>  tools/testing/selftests/kvm/lib/ucall.c       | 34 +++++++++++++++----
> >>  .../selftests/kvm/s390x/sync_regs_test.c      |  6 ++--
> >>  3 files changed, 32 insertions(+), 10 deletions(-)
> >>
> >> diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
> >> index e0e66b115ef2..c37aea2e33e5 100644
> >> --- a/tools/testing/selftests/kvm/include/kvm_util.h
> >> +++ b/tools/testing/selftests/kvm/include/kvm_util.h
> >> @@ -167,7 +167,7 @@ int vm_create_device(struct kvm_vm *vm, struct kvm_create_device *cd);
> >>  
> >>  /* ucall implementation types */
> >>  typedef enum {
> >> -	UCALL_PIO,
> >> +	UCALL_DEFAULT,
> > 
> > I'd rather we keep explicit types defined; keep PIO and add DIAG. Then
> > we can have
> > 
> > /*  Set default ucall types */
> > #if defined(__x86_64__)
> >   ucall_type = UCALL_PIO;
> > #elif defined(__aarch64__)
> >   ucall_type = UCALL_MMIO;
> >   ucall_requires_init = true;
> > #elif defined(__s390x__)
> >   ucall_type = UCALL_DIAG;
> > #endif
> > 
> > And add an assert in get_ucall()
> > 
> >  assert(!ucall_requires_init || ucall_initialized);
> 
> I'm not sure whether I really like that. It's yet another additional
> #ifdef block, and yet another variable ...
> 
> What do you think about removing the enum completely and simply code it
> directly, without the ucall_type indirection, i.e.:
> 
> void ucall(uint64_t cmd, int nargs, ...)
> {
> 	struct ucall uc = {
> 		.cmd = cmd,
> 	};
> 	va_list va;
> 	int i;
> 
> 	nargs = nargs <= UCALL_MAX_ARGS ? nargs : UCALL_MAX_ARGS;
> 
> 	va_start(va, nargs);
> 	for (i = 0; i < nargs; ++i)
> 		uc.args[i] = va_arg(va, uint64_t);
> 	va_end(va);
> 
> #if defined(__x86_64__)
> 
> 	/* Exit via PIO */
> 	asm volatile("in %[port], %%al"
> 		: : [port] "d" (UCALL_PIO_PORT), "D" (&uc) : "rax");
> 
> #elif defined(__aarch64__)
> 
> 	*ucall_exit_mmio_addr = (vm_vaddr_t)&uc;
> 
> #elif defined(__s390x__)
> 
> 	/* Exit via DIAGNOSE 0x501 (normally used for breakpoints) */
> 	asm volatile ("diag 0,%0,0x501" : : "a"(&uc) : "memory");
> 
> #endif
> }
> 
> I think that's way less confusing than having to understand the meaning
> of ucall_type etc. before...?
>

Sounds good to me.

Thanks,
drew
Thomas Huth July 31, 2019, 11:16 a.m. UTC | #4
On 31/07/2019 12.28, Andrew Jones wrote:
> On Wed, Jul 31, 2019 at 11:43:16AM +0200, Thomas Huth wrote:
>> On 30/07/2019 12.48, Andrew Jones wrote:
>>> On Tue, Jul 30, 2019 at 12:01:11PM +0200, Thomas Huth wrote:
>>>> On s390x, we can neither exit via PIO nor MMIO, but have to use
>>>> an instruction like DIAGNOSE. While we're at it, rename UCALL_PIO
>>>> to UCALL_DEFAULT, since PIO only works on x86 anyway, and this
>>>> way we can re-use the "default" type for the DIAGNOSE exit on s390x.
>>>>
>>>> Now that ucall() is implemented, we can use it in the sync_reg_test
>>>> on s390x, too.
>>>>
>>>> Signed-off-by: Thomas Huth <thuth@redhat.com>
>>>> ---
>>>>  .../testing/selftests/kvm/include/kvm_util.h  |  2 +-
>>>>  tools/testing/selftests/kvm/lib/ucall.c       | 34 +++++++++++++++----
>>>>  .../selftests/kvm/s390x/sync_regs_test.c      |  6 ++--
>>>>  3 files changed, 32 insertions(+), 10 deletions(-)
>>>>
>>>> diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
>>>> index e0e66b115ef2..c37aea2e33e5 100644
>>>> --- a/tools/testing/selftests/kvm/include/kvm_util.h
>>>> +++ b/tools/testing/selftests/kvm/include/kvm_util.h
>>>> @@ -167,7 +167,7 @@ int vm_create_device(struct kvm_vm *vm, struct kvm_create_device *cd);
>>>>  
>>>>  /* ucall implementation types */
>>>>  typedef enum {
>>>> -	UCALL_PIO,
>>>> +	UCALL_DEFAULT,
>>>
>>> I'd rather we keep explicit types defined; keep PIO and add DIAG. Then
>>> we can have
>>>
>>> /*  Set default ucall types */
>>> #if defined(__x86_64__)
>>>   ucall_type = UCALL_PIO;
>>> #elif defined(__aarch64__)
>>>   ucall_type = UCALL_MMIO;
>>>   ucall_requires_init = true;
>>> #elif defined(__s390x__)
>>>   ucall_type = UCALL_DIAG;
>>> #endif
>>>
>>> And add an assert in get_ucall()
>>>
>>>  assert(!ucall_requires_init || ucall_initialized);
>>
>> I'm not sure whether I really like that. It's yet another additional
>> #ifdef block, and yet another variable ...
>>
>> What do you think about removing the enum completely and simply code it
>> directly, without the ucall_type indirection, i.e.:
>>
>> void ucall(uint64_t cmd, int nargs, ...)
>> {
>> 	struct ucall uc = {
>> 		.cmd = cmd,
>> 	};
>> 	va_list va;
>> 	int i;
>>
>> 	nargs = nargs <= UCALL_MAX_ARGS ? nargs : UCALL_MAX_ARGS;
>>
>> 	va_start(va, nargs);
>> 	for (i = 0; i < nargs; ++i)
>> 		uc.args[i] = va_arg(va, uint64_t);
>> 	va_end(va);
>>
>> #if defined(__x86_64__)
>>
>> 	/* Exit via PIO */
>> 	asm volatile("in %[port], %%al"
>> 		: : [port] "d" (UCALL_PIO_PORT), "D" (&uc) : "rax");
>>
>> #elif defined(__aarch64__)
>>
>> 	*ucall_exit_mmio_addr = (vm_vaddr_t)&uc;
>>
>> #elif defined(__s390x__)
>>
>> 	/* Exit via DIAGNOSE 0x501 (normally used for breakpoints) */
>> 	asm volatile ("diag 0,%0,0x501" : : "a"(&uc) : "memory");
>>
>> #endif
>> }
>>
>> I think that's way less confusing than having to understand the meaning
>> of ucall_type etc. before...?
>>
> 
> Sounds good to me.

Or maybe even better: Let's move this file into lib/x86_64/ and
lib/aarch64/ instead, since there is more different code between the
architectures here than common code.

 Thomas
Paolo Bonzini July 31, 2019, 12:57 p.m. UTC | #5
On 31/07/19 13:16, Thomas Huth wrote:
> Or maybe even better: Let's move this file into lib/x86_64/ and
> lib/aarch64/ instead, since there is more different code between the
> architectures here than common code.

All good solutions, just choose one. :))

Paolo
Andrew Jones July 31, 2019, 1:05 p.m. UTC | #6
On Wed, Jul 31, 2019 at 02:57:38PM +0200, Paolo Bonzini wrote:
> On 31/07/19 13:16, Thomas Huth wrote:
> > Or maybe even better: Let's move this file into lib/x86_64/ and
> > lib/aarch64/ instead, since there is more different code between the
> > architectures here than common code.
> 
> All good solutions, just choose one. :))
>

Agreed, and I like this last solution (move to arch-code) the best.

Thanks,
drew

Patch
diff mbox series

diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
index e0e66b115ef2..c37aea2e33e5 100644
--- a/tools/testing/selftests/kvm/include/kvm_util.h
+++ b/tools/testing/selftests/kvm/include/kvm_util.h
@@ -167,7 +167,7 @@  int vm_create_device(struct kvm_vm *vm, struct kvm_create_device *cd);
 
 /* ucall implementation types */
 typedef enum {
-	UCALL_PIO,
+	UCALL_DEFAULT,
 	UCALL_MMIO,
 } ucall_type_t;
 
diff --git a/tools/testing/selftests/kvm/lib/ucall.c b/tools/testing/selftests/kvm/lib/ucall.c
index dd9a66700f96..55534dd014dc 100644
--- a/tools/testing/selftests/kvm/lib/ucall.c
+++ b/tools/testing/selftests/kvm/lib/ucall.c
@@ -30,7 +30,7 @@  void ucall_init(struct kvm_vm *vm, ucall_type_t type, void *arg)
 	ucall_type = type;
 	sync_global_to_guest(vm, ucall_type);
 
-	if (type == UCALL_PIO)
+	if (type == UCALL_DEFAULT)
 		return;
 
 	if (type == UCALL_MMIO) {
@@ -84,11 +84,18 @@  void ucall_uninit(struct kvm_vm *vm)
 	sync_global_to_guest(vm, ucall_exit_mmio_addr);
 }
 
-static void ucall_pio_exit(struct ucall *uc)
+static void ucall_default_exit(struct ucall *uc)
 {
-#ifdef __x86_64__
+#if defined(__x86_64__)
+	/* Exit via PIO */
 	asm volatile("in %[port], %%al"
 		: : [port] "d" (UCALL_PIO_PORT), "D" (uc) : "rax");
+#elif defined(__s390x__)
+	/* Exit via DIAGNOSE 0x501 (normally used for breakpoints) */
+	asm volatile ("diag 0,%0,0x501" : : "a"(uc) : "memory");
+#else
+	fprintf(stderr, "No default ucall available on this architecture.\n");
+	exit(1);
 #endif
 }
 
@@ -113,8 +120,8 @@  void ucall(uint64_t cmd, int nargs, ...)
 	va_end(va);
 
 	switch (ucall_type) {
-	case UCALL_PIO:
-		ucall_pio_exit(&uc);
+	case UCALL_DEFAULT:
+		ucall_default_exit(&uc);
 		break;
 	case UCALL_MMIO:
 		ucall_mmio_exit(&uc);
@@ -128,15 +135,28 @@  uint64_t get_ucall(struct kvm_vm *vm, uint32_t vcpu_id, struct ucall *uc)
 	struct ucall ucall = {};
 	bool got_ucall = false;
 
-#ifdef __x86_64__
-	if (ucall_type == UCALL_PIO && run->exit_reason == KVM_EXIT_IO &&
+#if defined(__x86_64__)
+	if (ucall_type == UCALL_DEFAULT && run->exit_reason == KVM_EXIT_IO &&
 	    run->io.port == UCALL_PIO_PORT) {
 		struct kvm_regs regs;
 		vcpu_regs_get(vm, vcpu_id, &regs);
 		memcpy(&ucall, addr_gva2hva(vm, (vm_vaddr_t)regs.rdi), sizeof(ucall));
 		got_ucall = true;
 	}
+#elif defined(__s390x__)
+	if (ucall_type == UCALL_DEFAULT &&
+	    run->exit_reason == KVM_EXIT_S390_SIEIC &&
+	    run->s390_sieic.icptcode == 4 &&
+	    (run->s390_sieic.ipa >> 8) == 0x83 &&    /* 0x83 means DIAGNOSE */
+	    (run->s390_sieic.ipb >> 16) == 0x501) {
+		int reg = run->s390_sieic.ipa & 0xf;
+
+		memcpy(&ucall, addr_gva2hva(vm, run->s.regs.gprs[reg]),
+		       sizeof(ucall));
+		got_ucall = true;
+	}
 #endif
+
 	if (ucall_type == UCALL_MMIO && run->exit_reason == KVM_EXIT_MMIO &&
 	    run->mmio.phys_addr == (uint64_t)ucall_exit_mmio_addr) {
 		vm_vaddr_t gva;
diff --git a/tools/testing/selftests/kvm/s390x/sync_regs_test.c b/tools/testing/selftests/kvm/s390x/sync_regs_test.c
index e85ff0d69548..bbc93094519b 100644
--- a/tools/testing/selftests/kvm/s390x/sync_regs_test.c
+++ b/tools/testing/selftests/kvm/s390x/sync_regs_test.c
@@ -25,9 +25,11 @@ 
 
 static void guest_code(void)
 {
+	register u64 stage asm("11") = 0;
+
 	for (;;) {
-		asm volatile ("diag 0,0,0x501");
-		asm volatile ("ahi 11,1");
+		GUEST_SYNC(0);
+		asm volatile ("ahi %0,1" : : "r"(stage));
 	}
 }