[PATCH v16 12/20] KVM: selftests: Call KVM_TDX_INIT_VCPU when creating a new TDX vcpu

[Lisa Wang]

From: Sagi Shahar <sagis@xxxxxxxxxx>

TDX VMs need to issue the KVM_TDX_INIT_VCPU ioctl for each vcpu after
vcpu creation.

KVM_TDX_INIT_VCPU has a strict prerequisite for the CPUID state. To
satisfy this requirement, call KVM_TDX_GET_CPUID and KVM_SET_CPUID2 to
pull the CPUID configuration from the TDCS and commit it into KVM,
allowing KVM_TDX_INIT_VCPU to succeed.

Additionally, unlike tdx_vm_ioctl(), tdx_vcpu_ioctl() doesn't check
hw_error. KVM's vCPU-scoped TDX ioctl handlers don't propagate SEAMCALL
errors into hw_error: the error is handled in the kernel and only an
errno is returned. Checking the ioctl's return value and errno is
therefore sufficient.

Signed-off-by: Sagi Shahar <sagis@xxxxxxxxxx>
Signed-off-by: Lisa Wang <wyihan@xxxxxxxxxx>
---
 .../selftests/kvm/include/x86/tdx/tdx_util.h       | 22 ++++++++++++++++++
 tools/testing/selftests/kvm/lib/x86/processor.c    | 27 +++++++++++++++-------
 tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c | 11 +++++++++
 3 files changed, 52 insertions(+), 8 deletions(-)

diff --git a/tools/testing/selftests/kvm/include/x86/tdx/tdx_util.h b/tools/testing/selftests/kvm/include/x86/tdx/tdx_util.h
index 4330290d29e9..9d951f67b3b5 100644
--- a/tools/testing/selftests/kvm/include/x86/tdx/tdx_util.h
+++ b/tools/testing/selftests/kvm/include/x86/tdx/tdx_util.h
@@ -46,9 +46,31 @@ static inline bool is_tdx_vm(struct kvm_vm *vm)
 		    #cmd, ret, errno, strerror(errno), hw_error);	\
 })
 
+#define __tdx_vcpu_ioctl(vcpu, cmd, _flags, arg)			\
+({									\
+	union {								\
+		struct kvm_tdx_cmd c;					\
+		unsigned long raw;					\
+	} tdx_cmd = { .c = {						\
+		.id = (cmd),						\
+		.flags = (u32)(_flags),					\
+		.data = (u64)(arg),					\
+	} };								\
+									\
+	__vcpu_ioctl(vcpu, KVM_MEMORY_ENCRYPT_OP, &tdx_cmd.raw);	\
+})
+
+#define tdx_vcpu_ioctl(vcpu, cmd, flags, arg)				\
+({									\
+	int ret = __tdx_vcpu_ioctl(vcpu, cmd, flags, arg);		\
+									\
+	TEST_ASSERT(!ret, "%s failed, rc: %i errno: %i (%s)",		\
+		    #cmd, ret, errno, strerror(errno));			\
+})
 void tdx_init_vm(struct kvm_vm *vm);
 void tdx_vm_setup_boot_code_region(struct kvm_vm *vm);
 void tdx_vm_setup_boot_parameters_region(struct kvm_vm *vm, u32 nr_runnable_vcpus);
 void tdx_vm_load_common_boot_parameters(struct kvm_vm *vm);
+void tdx_vcpu_init(struct kvm_vcpu *vcpu);
 
 #endif /* SELFTESTS_TDX_TDX_UTIL_H */
diff --git a/tools/testing/selftests/kvm/lib/x86/processor.c b/tools/testing/selftests/kvm/lib/x86/processor.c
index a215ab6c2ea4..110d23e50bcc 100644
--- a/tools/testing/selftests/kvm/lib/x86/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86/processor.c
@@ -865,15 +865,26 @@ struct kvm_vcpu *vm_arch_vcpu_add(struct kvm_vm *vm, u32 vcpu_id)
 	struct kvm_vcpu *vcpu;
 
 	vcpu = __vm_vcpu_add(vm, vcpu_id);
-	vcpu_init_cpuid(vcpu, kvm_get_supported_cpuid());
-	vcpu_init_sregs(vm, vcpu);
-	vcpu_init_xcrs(vm, vcpu);
+	/*
+	 * Both kvm_get_supported_cpuid() (for legacy VMs) and KVM_TDX_GET_CPUID
+	 * (for TDX VMs) return VM-scoped CPUID, e.g. the APIC ID isn't
+	 * populated per vCPU. This is fine because KVM selftests don't
+	 * currently test CPUID topology enumeration.
+	 */
+	if (is_tdx_vm(vm)) {
+		tdx_vcpu_init(vcpu);
+	} else {
+		vcpu_init_cpuid(vcpu, kvm_get_supported_cpuid());
 
-	/* Setup guest general purpose registers */
-	vcpu_regs_get(vcpu, &regs);
-	regs.rflags = regs.rflags | X86_EFLAGS_FIXED;
-	regs.rsp = vm_alloc_stack(vm, DEFAULT_STACK_PGS);
-	vcpu_regs_set(vcpu, &regs);
+		vcpu_init_sregs(vm, vcpu);
+		vcpu_init_xcrs(vm, vcpu);
+
+		/* Setup guest general purpose registers */
+		vcpu_regs_get(vcpu, &regs);
+		regs.rflags = regs.rflags | X86_EFLAGS_FIXED;
+		regs.rsp = vm_alloc_stack(vm, DEFAULT_STACK_PGS);
+		vcpu_regs_set(vcpu, &regs);
+	}
 
 	/* Setup the MP state */
 	mp_state.mp_state = 0;
diff --git a/tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c b/tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c
index e8deef076f9a..1719dc1bb060 100644
--- a/tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c
+++ b/tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c
@@ -91,6 +91,17 @@ void tdx_vm_load_common_boot_parameters(struct kvm_vm *vm)
 	params->gdtr.limit = kvm_get_default_gdt_limit();
 }
 
+void tdx_vcpu_init(struct kvm_vcpu *vcpu)
+{
+	struct kvm_cpuid2 *cpuid;
+
+	cpuid = allocate_kvm_cpuid2(MAX_NR_CPUID_ENTRIES);
+	tdx_vcpu_ioctl(vcpu, KVM_TDX_GET_CPUID, 0, cpuid);
+	vcpu_init_cpuid(vcpu, cpuid);
+	free(cpuid);
+	tdx_vcpu_ioctl(vcpu, KVM_TDX_INIT_VCPU, 0, NULL);
+}
+
 static const struct kvm_tdx_capabilities *tdx_read_capabilities(struct kvm_vm *vm)
 {
 	static struct kvm_tdx_capabilities *tdx_cap;

-- 
2.56.0.455.g6c5a503b38-goog