[PATCH] KVM: selftests: fix steal_time for arm64

[PATCH] KVM: selftests: fix steal_time for arm64

[Sebastian Ott]

Fix the following failure to the steal_time test on arm64 by making
the timer address known to the guest.

==== Test Assertion Failure ====
  steal_time.c:229: !ret
  pid=18514 tid=18514 errno=22 - Invalid argument
     1  0x000000000040252f: check_steal_time_uapi at steal_time.c:229 (discriminator 20)
     2   (inlined by) main at steal_time.c:537 (discriminator 20)
     3  0x0000ffffa23d621b: ?? ??:0
     4  0x0000ffffa23d62fb: ?? ??:0
     5  0x0000000000402b6f: _start at ??:?
  KVM_SET_DEVICE_ATTR failed, rc: -1 errno: 22 (Invalid argument)

Fixes: 40351ed924dd ("KVM: selftests: Refactor UAPI tests into dedicated function")
Signed-off-by: Sebastian Ott <sebott@redhat.com>
---
 tools/testing/selftests/kvm/steal_time.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/testing/selftests/kvm/steal_time.c b/tools/testing/selftests/kvm/steal_time.c
index 7df2bc8eec02..76fcdd1fd3cb 100644
--- a/tools/testing/selftests/kvm/steal_time.c
+++ b/tools/testing/selftests/kvm/steal_time.c
@@ -220,6 +220,8 @@ static void check_steal_time_uapi(void)
 	};
 
 	vcpu_ioctl(vcpu, KVM_HAS_DEVICE_ATTR, &dev);
+	vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS, ST_GPA_BASE, 1, 1, 0);
+	virt_map(vm, ST_GPA_BASE, ST_GPA_BASE, 1);
 
 	st_ipa = (ulong)ST_GPA_BASE | 1;
 	ret = __vcpu_ioctl(vcpu, KVM_SET_DEVICE_ATTR, &dev);

base-commit: 6d35786de28116ecf78797a62b84e6bf3c45aa5a
-- 
2.52.0

Re: [PATCH] KVM: selftests: fix steal_time for arm64

[Marc Zyngier]

On Mon, 04 May 2026 13:28:08 +0200, Sebastian Ott wrote:
> Fix the following failure to the steal_time test on arm64 by making
> the timer address known to the guest.
> 
> ==== Test Assertion Failure ====
>   steal_time.c:229: !ret
>   pid=18514 tid=18514 errno=22 - Invalid argument
>      1  0x000000000040252f: check_steal_time_uapi at steal_time.c:229 (discriminator 20)
>      2   (inlined by) main at steal_time.c:537 (discriminator 20)
>      3  0x0000ffffa23d621b: ?? ??:0
>      4  0x0000ffffa23d62fb: ?? ??:0
>      5  0x0000000000402b6f: _start at ??:?
>   KVM_SET_DEVICE_ATTR failed, rc: -1 errno: 22 (Invalid argument)
> 
> [...]

Applied to fixes, thanks!

[1/1] KVM: selftests: fix steal_time for arm64
      commit: fc240715fc5003538ff530e3cfb985e7769b7171

Cheers,

	M.
-- 
Without deviation from the norm, progress is not possible.

Re: [PATCH] KVM: selftests: fix steal_time for arm64

[Zenghui Yu]

Hi Sebastian,

On 5/4/26 7:28 PM, Sebastian Ott wrote:
> Fix the following failure to the steal_time test on arm64 by making
> the timer address known to the guest.
> 
> ==== Test Assertion Failure ====
>   steal_time.c:229: !ret
>   pid=18514 tid=18514 errno=22 - Invalid argument
>      1  0x000000000040252f: check_steal_time_uapi at steal_time.c:229 (discriminator 20)
>      2   (inlined by) main at steal_time.c:537 (discriminator 20)
>      3  0x0000ffffa23d621b: ?? ??:0
>      4  0x0000ffffa23d62fb: ?? ??:0
>      5  0x0000000000402b6f: _start at ??:?
>   KVM_SET_DEVICE_ATTR failed, rc: -1 errno: 22 (Invalid argument)
> 
> Fixes: 40351ed924dd ("KVM: selftests: Refactor UAPI tests into dedicated function")
> Signed-off-by: Sebastian Ott <sebott@redhat.com>
> ---
>  tools/testing/selftests/kvm/steal_time.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/tools/testing/selftests/kvm/steal_time.c b/tools/testing/selftests/kvm/steal_time.c
> index 7df2bc8eec02..76fcdd1fd3cb 100644
> --- a/tools/testing/selftests/kvm/steal_time.c
> +++ b/tools/testing/selftests/kvm/steal_time.c
> @@ -220,6 +220,8 @@ static void check_steal_time_uapi(void)
>  	};
>  
>  	vcpu_ioctl(vcpu, KVM_HAS_DEVICE_ATTR, &dev);
> +	vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS, ST_GPA_BASE, 1, 1, 0);

This leads to the following failure when the host page size is greater than
the guest's:

[root@localhost kvm]# getconf PAGESIZE
16384
[root@localhost kvm]# ./steal_time 
Random seed: 0x6b8b4567
__vm_create: mode='PA-bits:40,  VA-bits:48,  4K pages' type='0', pages='672'
TAP version 13
1..4
__vm_create: mode='PA-bits:40,  VA-bits:48,  4K pages' type='0', pages='660'
==== Test Assertion Failure ====
  lib/kvm_util.c:991: vm_adjust_num_guest_pages(vm->mode, npages) == npages
  pid=873 tid=873 errno=0 - Success
     1	0x0000000000405a27: vm_mem_add at kvm_util.c:991
     2	0x000000000040241f: check_steal_time_uapi at steal_time.c:223 (discriminator 7)
     3	 (inlined by) main at steal_time.c:539 (discriminator 7)
     4	0x00007fff8b57af3b: ?? ??:0
     5	0x00007fff8b57b007: ?? ??:0
     6	0x0000000000402b6f: _start at ??:?
  Number of guest pages is not compatible with the host. Try npages=4

> +	virt_map(vm, ST_GPA_BASE, ST_GPA_BASE, 1);
>  
>  	st_ipa = (ulong)ST_GPA_BASE | 1;
>  	ret = __vcpu_ioctl(vcpu, KVM_SET_DEVICE_ATTR, &dev);

Thanks,
Zenghui

[PATCH] KVM: selftests: fix steal_time for arm64 with host page size > 4K

[Sebastian Ott]

Fix the following failure when running with 16K host page size:
==== Test Assertion Failure ====
   lib/kvm_util.c:991: vm_adjust_num_guest_pages(vm->mode, npages) == npages
   pid=873 tid=873 errno=0 - Success
      1  0x0000000000405a27: vm_mem_add at kvm_util.c:991
      2  0x000000000040241f: check_steal_time_uapi at steal_time.c:223 (discriminator 7)
      3   (inlined by) main at steal_time.c:539 (discriminator 7)
      4  0x00007fff8b57af3b: ?? ??:0
      5  0x00007fff8b57b007: ?? ??:0
      6  0x0000000000402b6f: _start at ??:?
   Number of guest pages is not compatible with the host. Try npages=4

Fixes: fc240715fc50 ("KVM: selftests: arm64: Fix steal_time test after UAPI refactoring")
Reported-by: Zenghui Yu <zenghui.yu@linux.dev>
Link: https://lore.kernel.org/kvmarm/7575a845-a542-4b16-b512-aec3126f97f3@linux.dev/T/#u
Signed-off-by: Sebastian Ott <sebott@redhat.com>
---
  tools/testing/selftests/kvm/steal_time.c | 6 ++++--
  1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/kvm/steal_time.c b/tools/testing/selftests/kvm/steal_time.c
index 76fcdd1fd3cb..cdb81f3ee4b2 100644
--- a/tools/testing/selftests/kvm/steal_time.c
+++ b/tools/testing/selftests/kvm/steal_time.c
@@ -208,6 +208,7 @@ static void check_steal_time_uapi(void)
  {
  	struct kvm_vm *vm;
  	struct kvm_vcpu *vcpu;
+	unsigned int gpages;
  	u64 st_ipa;
  	int ret;

@@ -220,8 +221,9 @@ static void check_steal_time_uapi(void)
  	};

  	vcpu_ioctl(vcpu, KVM_HAS_DEVICE_ATTR, &dev);
-	vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS, ST_GPA_BASE, 1, 1, 0);
-	virt_map(vm, ST_GPA_BASE, ST_GPA_BASE, 1);
+	gpages = vm_calc_num_guest_pages(VM_MODE_DEFAULT, 1);
+	vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS, ST_GPA_BASE, 1, gpages, 0);
+	virt_map(vm, ST_GPA_BASE, ST_GPA_BASE, gpages);

  	st_ipa = (ulong)ST_GPA_BASE | 1;
  	ret = __vcpu_ioctl(vcpu, KVM_SET_DEVICE_ATTR, &dev);
-- 
2.54.0

Re: [PATCH] KVM: selftests: fix steal_time for arm64 with host page size > 4K

[Zenghui Yu]

On 6/22/26 10:14 PM, Sebastian Ott wrote:
> 
> Fix the following failure when running with 16K host page size:
> ==== Test Assertion Failure ====
>   lib/kvm_util.c:991: vm_adjust_num_guest_pages(vm->mode, npages) == npages
>   pid=873 tid=873 errno=0 - Success
>      1  0x0000000000405a27: vm_mem_add at kvm_util.c:991
>      2  0x000000000040241f: check_steal_time_uapi at steal_time.c:223 (discriminator 7)
>      3   (inlined by) main at steal_time.c:539 (discriminator 7)
>      4  0x00007fff8b57af3b: ?? ??:0
>      5  0x00007fff8b57b007: ?? ??:0
>      6  0x0000000000402b6f: _start at ??:?
>   Number of guest pages is not compatible with the host. Try npages=4
> 
> Fixes: fc240715fc50 ("KVM: selftests: arm64: Fix steal_time test after UAPI refactoring")
> Reported-by: Zenghui Yu <zenghui.yu@linux.dev>
> Link: https://lore.kernel.org/kvmarm/7575a845-a542-4b16-b512-aec3126f97f3@linux.dev/T/#u
> Signed-off-by: Sebastian Ott <sebott@redhat.com>

Looks good to me,

Reviewed-by: Zenghui Yu <zenghui.yu@linux.dev>

Thanks,
Zenghui

Re: [PATCH] KVM: selftests: fix steal_time for arm64 with host page size > 4K

[Zenghui Yu]

On 6/22/26 10:14 PM, Sebastian Ott wrote:
> 
> Fix the following failure when running with 16K host page size:
> ==== Test Assertion Failure ====
>   lib/kvm_util.c:991: vm_adjust_num_guest_pages(vm->mode, npages) == npages
>   pid=873 tid=873 errno=0 - Success
>      1  0x0000000000405a27: vm_mem_add at kvm_util.c:991
>      2  0x000000000040241f: check_steal_time_uapi at steal_time.c:223 (discriminator 7)
>      3   (inlined by) main at steal_time.c:539 (discriminator 7)
>      4  0x00007fff8b57af3b: ?? ??:0
>      5  0x00007fff8b57b007: ?? ??:0
>      6  0x0000000000402b6f: _start at ??:?
>   Number of guest pages is not compatible with the host. Try npages=4
> 
> Fixes: fc240715fc50 ("KVM: selftests: arm64: Fix steal_time test after UAPI refactoring")
> Reported-by: Zenghui Yu <zenghui.yu@linux.dev>
> Link: https://lore.kernel.org/kvmarm/7575a845-a542-4b16-b512-aec3126f97f3@linux.dev/T/#u
> Signed-off-by: Sebastian Ott <sebott@redhat.com>
> ---
>  tools/testing/selftests/kvm/steal_time.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/testing/selftests/kvm/steal_time.c b/tools/testing/selftests/kvm/steal_time.c
> index 76fcdd1fd3cb..cdb81f3ee4b2 100644
> --- a/tools/testing/selftests/kvm/steal_time.c
> +++ b/tools/testing/selftests/kvm/steal_time.c
> @@ -208,6 +208,7 @@ static void check_steal_time_uapi(void)
>  {
>      struct kvm_vm *vm;
>      struct kvm_vcpu *vcpu;
> +    unsigned int gpages;
>      u64 st_ipa;
>      int ret;
> 
> @@ -220,8 +221,9 @@ static void check_steal_time_uapi(void)
>      };
> 
>      vcpu_ioctl(vcpu, KVM_HAS_DEVICE_ATTR, &dev);
> -    vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS, ST_GPA_BASE, 1, 1, 0);
> -    virt_map(vm, ST_GPA_BASE, ST_GPA_BASE, 1);
> +    gpages = vm_calc_num_guest_pages(VM_MODE_DEFAULT, 1);

Would vm_calc_num_guest_pages(VM_MODE_DEFAULT, STEAL_TIME_SIZE) be better
to describe the number of pages we want to add?

> +    vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS, ST_GPA_BASE, 1, gpages, 0);
> +    virt_map(vm, ST_GPA_BASE, ST_GPA_BASE, gpages);
> 
>      st_ipa = (ulong)ST_GPA_BASE | 1;
>      ret = __vcpu_ioctl(vcpu, KVM_SET_DEVICE_ATTR, &dev);

Re: [PATCH] KVM: selftests: fix steal_time for arm64 with host page size > 4K

[Sebastian Ott]

On Sun, 28 Jun 2026, Zenghui Yu wrote:

> On 6/22/26 10:14 PM, Sebastian Ott wrote:
>>
>> Fix the following failure when running with 16K host page size:
>> ==== Test Assertion Failure ====
>>   lib/kvm_util.c:991: vm_adjust_num_guest_pages(vm->mode, npages) == npages
>>   pid=873 tid=873 errno=0 - Success
>>      1  0x0000000000405a27: vm_mem_add at kvm_util.c:991
>>      2  0x000000000040241f: check_steal_time_uapi at steal_time.c:223 (discriminator 7)
>>      3   (inlined by) main at steal_time.c:539 (discriminator 7)
>>      4  0x00007fff8b57af3b: ?? ??:0
>>      5  0x00007fff8b57b007: ?? ??:0
>>      6  0x0000000000402b6f: _start at ??:?
>>   Number of guest pages is not compatible with the host. Try npages=4
>>
>> Fixes: fc240715fc50 ("KVM: selftests: arm64: Fix steal_time test after UAPI refactoring")
>> Reported-by: Zenghui Yu <zenghui.yu@linux.dev>
>> Link: https://lore.kernel.org/kvmarm/7575a845-a542-4b16-b512-aec3126f97f3@linux.dev/T/#u
>> Signed-off-by: Sebastian Ott <sebott@redhat.com>
>> ---
>>  tools/testing/selftests/kvm/steal_time.c | 6 ++++--
>>  1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/tools/testing/selftests/kvm/steal_time.c b/tools/testing/selftests/kvm/steal_time.c
>> index 76fcdd1fd3cb..cdb81f3ee4b2 100644
>> --- a/tools/testing/selftests/kvm/steal_time.c
>> +++ b/tools/testing/selftests/kvm/steal_time.c
>> @@ -208,6 +208,7 @@ static void check_steal_time_uapi(void)
>>  {
>>      struct kvm_vm *vm;
>>      struct kvm_vcpu *vcpu;
>> +    unsigned int gpages;
>>      u64 st_ipa;
>>      int ret;
>>
>> @@ -220,8 +221,9 @@ static void check_steal_time_uapi(void)
>>      };
>>
>>      vcpu_ioctl(vcpu, KVM_HAS_DEVICE_ATTR, &dev);
>> -    vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS, ST_GPA_BASE, 1, 1, 0);
>> -    virt_map(vm, ST_GPA_BASE, ST_GPA_BASE, 1);
>> +    gpages = vm_calc_num_guest_pages(VM_MODE_DEFAULT, 1);
>
> Would vm_calc_num_guest_pages(VM_MODE_DEFAULT, STEAL_TIME_SIZE) be better
> to describe the number of pages we want to add?

Hm, I don't think we care. This is just for the uapi checker - the vm/vcpu
doesn't even run..

Thanks,
Sebastian