KVM: selftests: Extend nested_invalid_cr3_test to cover SVM

Add SVM L1 code to run the nested guest, and allow the test to run with
SVM as well as VMX.

Signed-off-by: Yosry Ahmed <yosry.ahmed@linux.dev>
Link: https://patch.msgid.link/20251021074736.1324328-7-yosry.ahmed@linux.dev
Signed-off-by: Sean Christopherson <seanjc@google.com>

Author: yosrym93

tools/testing/selftests/kvm/x86/nested_invalid_cr3_test.c

@@ -7,6 +7,7 @@
  */
 #include "kvm_util.h"
 #include "vmx.h"
+#include "svm_util.h"
 #include "kselftest.h"
 
 
@@ -17,6 +18,28 @@ static void l2_guest_code(void)
 	vmcall();
 }
 
+static void l1_svm_code(struct svm_test_data *svm)
+{
+	unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
+	uintptr_t save_cr3;
+
+	generic_svm_setup(svm, l2_guest_code,
+			  &l2_guest_stack[L2_GUEST_STACK_SIZE]);
+
+	/* Try to run L2 with invalid CR3 and make sure it fails */
+	save_cr3 = svm->vmcb->save.cr3;
+	svm->vmcb->save.cr3 = -1ull;
+	run_guest(svm->vmcb, svm->vmcb_gpa);
+	GUEST_ASSERT(svm->vmcb->control.exit_code == SVM_EXIT_ERR);
+
+	/* Now restore CR3 and make sure L2 runs successfully */
+	svm->vmcb->save.cr3 = save_cr3;
+	run_guest(svm->vmcb, svm->vmcb_gpa);
+	GUEST_ASSERT(svm->vmcb->control.exit_code == SVM_EXIT_VMMCALL);
+
+	GUEST_DONE();
+}
+
 static void l1_vmx_code(struct vmx_pages *vmx_pages)
 {
 	unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
@@ -43,16 +66,30 @@ static void l1_vmx_code(struct vmx_pages *vmx_pages)
 	GUEST_DONE();
 }
 
+static void l1_guest_code(void *data)
+{
+	if (this_cpu_has(X86_FEATURE_VMX))
+		l1_vmx_code(data);
+	else
+		l1_svm_code(data);
+}
+
 int main(int argc, char *argv[])
 {
 	struct kvm_vcpu *vcpu;
 	struct kvm_vm *vm;
 	vm_vaddr_t guest_gva = 0;
 
-	TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_VMX));
+	TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_VMX) ||
+		     kvm_cpu_has(X86_FEATURE_SVM));
+
+	vm = vm_create_with_one_vcpu(&vcpu, l1_guest_code);
+
+	if (kvm_cpu_has(X86_FEATURE_VMX))
+		vcpu_alloc_vmx(vm, &guest_gva);
+	else
+		vcpu_alloc_svm(vm, &guest_gva);
 
-	vm = vm_create_with_one_vcpu(&vcpu, l1_vmx_code);
-	vcpu_alloc_vmx(vm, &guest_gva);
 	vcpu_args_set(vcpu, 1, guest_gva);
 
 	for (;;) {