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Thu, 28 Aug 2025 09:39:32 +0000 Received: from EX19D015EUB004.ant.amazon.com ([fe80::2dc9:7aa9:9cd3:fc8a]) by EX19D015EUB004.ant.amazon.com ([fe80::2dc9:7aa9:9cd3:fc8a%3]) with mapi id 15.02.2562.017; Thu, 28 Aug 2025 09:39:32 +0000 From: "Roy, Patrick" To: "david@redhat.com" , "seanjc@google.com" CC: "Roy, Patrick" , "tabba@google.com" , "ackerleytng@google.com" , "pbonzini@redhat.com" , "kvm@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "kvmarm@lists.linux.dev" , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "rppt@kernel.org" , "will@kernel.org" , "vbabka@suse.cz" , "Cali, Marco" , "Kalyazin, Nikita" , "Thomson, Jack" , "Manwaring, Derek" Subject: [PATCH v5 12/12] KVM: selftests: Test guest execution from direct map removed gmem Thread-Topic: [PATCH v5 12/12] KVM: selftests: Test guest execution from direct map removed gmem Thread-Index: AQHcF/+ov3wHy4Cyx0u9xmPfJ46Qpw== Date: Thu, 28 Aug 2025 09:39:32 +0000 Message-ID: <20250828093902.2719-13-roypat@amazon.co.uk> References: <20250828093902.2719-1-roypat@amazon.co.uk> In-Reply-To: <20250828093902.2719-1-roypat@amazon.co.uk> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [172.19.88.180] Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250828_023935_009914_962DB2AD X-CRM114-Status: GOOD ( 11.02 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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= ---=0A= .../selftests/kvm/set_memory_region_test.c | 50 +++++++++++++++++--=0A= 1 file changed, 46 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 ce3ac0fd6dfb..cb3bc642d376 100644=0A= --- a/tools/testing/selftests/kvm/set_memory_region_test.c=0A= +++ b/tools/testing/selftests/kvm/set_memory_region_test.c=0A= @@ -603,6 +603,41 @@ 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= @@ -626,10 +661,17 @@ 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= + 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 (kvm_has_cap(KVM_CAP_GUEST_MEMFD_MMAP) &&=0A= + kvm_has_cap(KVM_CAP_GUEST_MEMFD_NO_DIRECT_MAP))=0A= + test_guest_memfd_mmio();=0A= + else=0A= + pr_info("Skipping tests requiring KVM_CAP_GUEST_MEMFD_MMAP | KVM_CAP_GU= EST_MEMFD_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=