linux-kernel - [PATCH v3 7/7] selftests: KVM: Add test case for MMIO during vectoring

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Message-ID: <20241217181458.68690-8-iorlov@amazon.com>
Date: Tue, 17 Dec 2024 18:14:58 +0000
From: Ivan Orlov <iorlov@...zon.com>
To: <bp@...en8.de>, <dave.hansen@...ux.intel.com>, <mingo@...hat.com>,
	<pbonzini@...hat.com>, <seanjc@...gle.com>, <shuah@...nel.org>,
	<tglx@...utronix.de>
CC: Ivan Orlov <iorlov@...zon.com>, <hpa@...or.com>, <kvm@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <linux-kselftest@...r.kernel.org>,
	<x86@...nel.org>, <dwmw@...zon.co.uk>, <pdurrant@...zon.co.uk>,
	<jalliste@...zon.co.uk>
Subject: [PATCH v3 7/7] selftests: KVM: Add test case for MMIO during vectoring

Extend the 'set_memory_region_test' with a test case which covers the
MMIO during vectoring error handling. The test case

1) Sets an IDT descriptor base to point to an MMIO address
2) Generates a #GP in the guest
3) Verifies that we got a correct exit reason and suberror code
4) Verifies that we got a corrent reported GPA in internal.data[3]

Also, add a definition of non-canonical address to processor.h

Signed-off-by: Ivan Orlov <iorlov@...zon.com>
---
V1 -> V2:
- Get rid of pronouns, redundant comments and incorrect wording
- Define noncanonical address in processor.h
- Fix indentation and wrap lines at 80 columns
V2 -> V3:
- Move "NONCANONICAL" definition to the beginning of the file

 .../selftests/kvm/include/x86_64/processor.h  |  2 +
 .../selftests/kvm/set_memory_region_test.c    | 51 +++++++++++++++++++
 2 files changed, 53 insertions(+)

diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h
index 69938c649a5e..6b8d12f042a8 100644
--- a/tools/testing/selftests/kvm/include/x86_64/processor.h
+++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
@@ -29,6 +29,8 @@ extern uint64_t guest_tsc_khz;
 #define MAX_NR_CPUID_ENTRIES 100
 #endif
 
+#define NONCANONICAL 0xaaaaaaaaaaaaaaaaull
+
 /* Forced emulation prefix, used to invoke the emulator unconditionally. */
 #define KVM_FEP "ud2; .byte 'k', 'v', 'm';"
 
diff --git a/tools/testing/selftests/kvm/set_memory_region_test.c b/tools/testing/selftests/kvm/set_memory_region_test.c
index a1c53cc854a5..d65a9f20aa1a 100644
--- a/tools/testing/selftests/kvm/set_memory_region_test.c
+++ b/tools/testing/selftests/kvm/set_memory_region_test.c
@@ -553,6 +553,56 @@ static void test_add_overlapping_private_memory_regions(void)
 	close(memfd);
 	kvm_vm_free(vm);
 }
+
+static void guest_code_mmio_during_vectoring(void)
+{
+	const struct desc_ptr idt_desc = {
+		.address = MEM_REGION_GPA,
+		.size = 0xFFF,
+	};
+
+	set_idt(&idt_desc);
+
+	/* Generate a #GP by dereferencing a non-canonical address */
+	*((uint8_t *)NONCANONICAL) = 0x1;
+
+	GUEST_ASSERT(0);
+}
+
+/*
+ * This test points the IDT descriptor base to an MMIO address. It should cause
+ * a KVM internal error when an event occurs in the guest.
+ */
+static void test_mmio_during_vectoring(void)
+{
+	struct kvm_vcpu *vcpu;
+	struct kvm_run *run;
+	struct kvm_vm *vm;
+	u64 expected_gpa;
+
+	pr_info("Testing MMIO during vectoring error handling\n");
+
+	vm = vm_create_with_one_vcpu(&vcpu, guest_code_mmio_during_vectoring);
+	virt_map(vm, MEM_REGION_GPA, MEM_REGION_GPA, 1);
+
+	run = vcpu->run;
+
+	vcpu_run(vcpu);
+	TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_INTERNAL_ERROR);
+	TEST_ASSERT(run->internal.suberror == KVM_INTERNAL_ERROR_DELIVERY_EV,
+		    "Unexpected suberror = %d", vcpu->run->internal.suberror);
+	TEST_ASSERT(run->internal.ndata != 4, "Unexpected internal error data array size = %d",
+		    run->internal.ndata);
+
+	/* The reported GPA should be IDT base + offset of the GP vector */
+	expected_gpa = MEM_REGION_GPA + GP_VECTOR * sizeof(struct idt_entry);
+
+	TEST_ASSERT(run->internal.data[3] == expected_gpa,
+		    "Unexpected GPA = %llx (expected %lx)",
+		    vcpu->run->internal.data[3], expected_gpa);
+
+	kvm_vm_free(vm);
+}
 #endif
 
 int main(int argc, char *argv[])
@@ -568,6 +618,7 @@ int main(int argc, char *argv[])
 	 * KVM_RUN fails with ENOEXEC or EFAULT.
 	 */
 	test_zero_memory_regions();
+	test_mmio_during_vectoring();
 #endif
 
 	test_invalid_memory_region_flags();
-- 
2.43.0