Re: [PATCH 2/2] KVM: selftests: Test that KVM_RUN fails for unresolvable host faults

[Christian Borntraeger <borntraeger@linux.ibm.com>]

Am 20.10.26 um 16:40 schrieb sashiko-bot@kernel.org:
> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> - [Medium] KVM: selftests: missing gmem_flags argument to vm_mem_add() in main()
> --
> 
> commit 3a1c0f90404979b6638dbd3c2769d7b78633b104
> Author: Christian Borntraeger <borntraeger@linux.ibm.com>
> 
> KVM: selftests: Test that KVM_RUN fails for unresolvable host faults
> 
> This commit adds a selftest in which a guest writes to a shmem-backed
> memslot beyond the end of the file to verify that KVM_RUN fails with
> -EFAULT rather than retrying an asynchronous page fault indefinitely.
> 
>> diff --git a/tools/testing/selftests/kvm/faultin_sigbus_test.c b/tools/testing/selftests/kvm/faultin_sigbus_test.c
>> new file mode 100644
>> index 0000000000000..b9d673260ed5a
>> --- /dev/null
>> +++ b/tools/testing/selftests/kvm/faultin_sigbus_test.c
>> @@ -0,0 +1,168 @@
> 
> [ ... ]
> 
>> +int main(void)
>> +{
>> +	struct sigaction sa = { .sa_handler = sig_alarm };	/* no SA_RESTART */
>> +	struct userspace_mem_region *region;
>> +	struct kvm_vcpu *vcpu;
>> +	struct kvm_vm *vm;
>> +	struct ucall uc;
>> +	gpa_t gpa;
>> +	gva_t gva;
>> +	u64 npages;
>> +	int r;
>> +
>> +	vm = vm_create_with_one_vcpu(&vcpu, guest_code);
>> +
>> +	/* After slot 0 and the page that some architectures use for ucalls. */
>> +	region = memslot2region(vm, 0);
>> +	gpa = align_up(region->region.guest_phys_addr +
>> +		       region->region.memory_size + vm->page_size, TEST_SIZE);
>> +	npages = TEST_SIZE / vm->page_size;
>> +
>> +	vm_mem_add(vm, VM_MEM_SRC_SHMEM, gpa, TEST_SLOT, npages, 0, -1, 0);
> 
> [Severity: Medium]
> Does this fail to build when compiling KVM selftests?
> 
> In tools/testing/selftests/kvm/include/kvm_util.h (and
> tools/testing/selftests/kvm/lib/kvm_util.c), vm_mem_add() takes 9
> arguments following commit ee455183c92be7:
> 
> void vm_mem_add(struct kvm_vm *vm, enum vm_mem_backing_src_type src_type,
> 		gpa_t gpa, u32 slot, u64 npages, u32 flags,
> 		int gmem_fd, u64 gmem_offset, u64 gmem_flags);
> 
> Calling vm_mem_add() in main() with only 8 arguments omits the final
> gmem_flags parameter and fails compilation with too few arguments to
> function vm_mem_add. Should this pass the 9th argument (0), or use the
> 6-argument helper vm_userspace_mem_region_add(vm, VM_MEM_SRC_SHMEM, gpa,
> TEST_SLOT, npages, 0) instead?

Yes, this works on 7.3 but fails on next