[PATCH v2] KVM: selftests: fix steal_time for arm64 with host page size > 4K

[PATCH v2] 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 | 30 ++++++++++++++++--------
 1 file changed, 20 insertions(+), 10 deletions(-)

diff --git a/tools/testing/selftests/kvm/steal_time.c b/tools/testing/selftests/kvm/steal_time.c
index bc3c62b72c58..785d19f9ee8f 100644
--- a/tools/testing/selftests/kvm/steal_time.c
+++ b/tools/testing/selftests/kvm/steal_time.c
@@ -27,6 +27,9 @@
 static void *st_gva[NR_VCPUS];
 static u64 guest_stolen_time[NR_VCPUS];
 
+static struct kvm_vm *vm_create_steal_time(u32 nr_vcpus, void *guest_code,
+					   struct kvm_vcpu *vcpus[]);
+
 #if defined(__x86_64__)
 
 /* steal_time must have 64-byte alignment */
@@ -210,17 +213,14 @@ static void check_steal_time_uapi(void)
 	u64 st_ipa;
 	int ret;
 
-	vm = vm_create_with_one_vcpu(&vcpu, NULL);
-
 	struct kvm_device_attr dev = {
 		.group = KVM_ARM_VCPU_PVTIME_CTRL,
 		.attr = KVM_ARM_VCPU_PVTIME_IPA,
 		.addr = (u64)&st_ipa,
 	};
 
+	vm = vm_create_steal_time(1, NULL, &vcpu);
 	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);
@@ -500,13 +500,27 @@ static void run_vcpu(struct kvm_vcpu *vcpu)
 	}
 }
 
+static struct kvm_vm *vm_create_steal_time(u32 nr_vcpus, void *guest_code,
+					   struct kvm_vcpu *vcpus[])
+{
+	unsigned int gpages;
+	struct kvm_vm *vm;
+
+	/* Create a VM and an identity mapped memslot for the steal time structure */
+	vm = vm_create_with_vcpus(nr_vcpus, guest_code, vcpus);
+	gpages = vm_calc_num_guest_pages(VM_MODE_DEFAULT, STEAL_TIME_SIZE * nr_vcpus);
+	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);
+
+	return vm;
+}
+
 int main(int ac, char **av)
 {
 	struct kvm_vcpu *vcpus[NR_VCPUS];
 	struct kvm_vm *vm;
 	pthread_t thread;
 	cpu_set_t cpuset;
-	unsigned int gpages;
 	long stolen_time;
 	long run_delay;
 	bool verbose;
@@ -517,11 +531,7 @@ int main(int ac, char **av)
 	/* Set CPU affinity so we can force preemption of the VCPU */
 	cpu = pin_self_to_any_cpu();
 
-	/* Create a VM and an identity mapped memslot for the steal time structure */
-	vm = vm_create_with_vcpus(NR_VCPUS, guest_code, vcpus);
-	gpages = vm_calc_num_guest_pages(VM_MODE_DEFAULT, STEAL_TIME_SIZE * NR_VCPUS);
-	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);
+	vm = vm_create_steal_time(NR_VCPUS, guest_code, vcpus);
 
 	ksft_print_header();
 	TEST_REQUIRE(is_steal_time_supported(vcpus[0]));
-- 
2.55.0

Re: [PATCH v2] KVM: selftests: fix steal_time for arm64 with host page size > 4K

[Zenghui Yu]

On 9/14/26 9:10 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 | 30 ++++++++++++++++--------
>  1 file changed, 20 insertions(+), 10 deletions(-)

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

Thanks,
Zenghui

Re: [PATCH v2] KVM: selftests: fix steal_time for arm64 with host page size > 4K

[Oliver Upton]

On Mon, 14 Sep 2026 15:10:13 +0200, 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
> 
> [...]

Applied to fixes, thanks!

[1/1] KVM: selftests: fix steal_time for arm64 with host page size > 4K
      https://git.kernel.org/kvmarm/kvmarm/c/96e6757cb067

--
Best,
Oliver