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charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Patrick Roy =0A= =0A= Add a selftest that loads itself into guest_memfd (via=0A= GUEST_MEMFD_FLAG_MMAP) and triggers an MMIO exit when executed. This=0A= exercises x86 MMIO emulation code inside KVM for guest_memfd-backed=0A= memslots where the guest_memfd folios are direct map removed.=0A= Particularly, it validates that x86 MMIO emulation code (guest page=0A= table walks + instruction fetch) correctly accesses gmem through the VMA=0A= that's been reflected into the memslot's userspace_addr field (instead=0A= of trying to do direct map accesses).=0A= =0A= Signed-off-by: Patrick Roy =0A= Signed-off-by: Nikita Kalyazin =0A= ---=0A= .../selftests/kvm/set_memory_region_test.c | 52 +++++++++++++++++--=0A= 1 file changed, 48 insertions(+), 4 deletions(-)=0A= =0A= diff --git a/tools/testing/selftests/kvm/set_memory_region_test.c b/tools/t= esting/selftests/kvm/set_memory_region_test.c=0A= index 7fe427ff9b38..cb445d420e8c 100644=0A= --- a/tools/testing/selftests/kvm/set_memory_region_test.c=0A= +++ b/tools/testing/selftests/kvm/set_memory_region_test.c=0A= @@ -602,6 +602,41 @@ static void test_mmio_during_vectoring(void)=0A= =0A= kvm_vm_free(vm);=0A= }=0A= +=0A= +static void guest_code_trigger_mmio(void)=0A= +{=0A= + /*=0A= + * Read some GPA that is not backed by a memslot. KVM consider this=0A= + * as MMIO and tell userspace to emulate the read.=0A= + */=0A= + READ_ONCE(*((uint64_t *)MEM_REGION_GPA));=0A= +=0A= + GUEST_DONE();=0A= +}=0A= +=0A= +static void test_guest_memfd_mmio(void)=0A= +{=0A= + struct kvm_vm *vm;=0A= + struct kvm_vcpu *vcpu;=0A= + struct vm_shape shape =3D {=0A= + .mode =3D VM_MODE_DEFAULT,=0A= + .src_type =3D VM_MEM_SRC_GUEST_MEMFD_NO_DIRECT_MAP,=0A= + };=0A= + pthread_t vcpu_thread;=0A= +=0A= + pr_info("Testing MMIO emulation for instructions in gmem\n");=0A= +=0A= + vm =3D __vm_create_shape_with_one_vcpu(shape, &vcpu, 0, guest_code_trigge= r_mmio);=0A= +=0A= + virt_map(vm, MEM_REGION_GPA, MEM_REGION_GPA, 1);=0A= +=0A= + pthread_create(&vcpu_thread, NULL, vcpu_worker, vcpu);=0A= +=0A= + /* If the MMIO read was successfully emulated, the vcpu thread will exit = */=0A= + pthread_join(vcpu_thread, NULL);=0A= +=0A= + kvm_vm_free(vm);=0A= +}=0A= #endif=0A= =0A= int main(int argc, char *argv[])=0A= @@ -625,10 +660,19 @@ int main(int argc, char *argv[])=0A= test_add_max_memory_regions();=0A= =0A= #ifdef __x86_64__=0A= - if (kvm_has_cap(KVM_CAP_GUEST_MEMFD) &&=0A= - (kvm_check_cap(KVM_CAP_VM_TYPES) & BIT(KVM_X86_SW_PROTECTED_VM))) {= =0A= - test_add_private_memory_region();=0A= - test_add_overlapping_private_memory_regions();=0A= + if (kvm_has_cap(KVM_CAP_GUEST_MEMFD)) {=0A= + uint64_t valid_flags =3D kvm_check_cap(KVM_CAP_GUEST_MEMFD_FLAGS);=0A= +=0A= + if (kvm_check_cap(KVM_CAP_VM_TYPES) & BIT(KVM_X86_SW_PROTECTED_VM)) {=0A= + test_add_private_memory_region();=0A= + test_add_overlapping_private_memory_regions();=0A= + }=0A= +=0A= + if ((valid_flags & GUEST_MEMFD_FLAG_MMAP) &&=0A= + (valid_flags & GUEST_MEMFD_FLAG_NO_DIRECT_MAP))=0A= + test_guest_memfd_mmio();=0A= + else=0A= + pr_info("Skipping tests requiring GUEST_MEMFD_FLAG_MMAP | GUEST_MEMFD_F= LAG_NO_DIRECT_MAP");=0A= } else {=0A= pr_info("Skipping tests for KVM_MEM_GUEST_MEMFD memory regions\n");=0A= }=0A= -- =0A= 2.50.1=0A= =0A=