[PATCH 01/11] KVM: x86: Introduce vm_type to differentiate normal VMs from confidential VMs

[Xiaoyao Li <xiaoyao.li@intel.com>]

From: Sean Christopherson <sean.j.christopherson@intel.com>

Unlike normal VMs, confidential VMs (Intel TDX and AMD SEV-ES) don't
allow some operations (e.g., memory read/write, register state acces, etc).

Introduce vm_type to track the type of the VM. Further, different policy
can be made based on vm_type.

Define KVM_X86_NORMAL_VM for normal VM as default and define
KVM_X86_TDX_VM for Intel TDX VM.

Add a capability KVM_CAP_VM_TYPES to effectively allow userspace to query
what VM types are supported by KVM.

Co-developed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 Documentation/virt/kvm/api.rst        | 15 +++++++++++++++
 arch/x86/include/asm/kvm-x86-ops.h    |  1 +
 arch/x86/include/asm/kvm_host.h       |  2 ++
 arch/x86/include/uapi/asm/kvm.h       |  3 +++
 arch/x86/kvm/svm/svm.c                |  6 ++++++
 arch/x86/kvm/vmx/vmx.c                |  6 ++++++
 arch/x86/kvm/x86.c                    |  9 ++++++++-
 include/uapi/linux/kvm.h              |  1 +
 tools/arch/x86/include/uapi/asm/kvm.h |  3 +++
 tools/include/uapi/linux/kvm.h        |  1 +
 10 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index 3b093d6dbe22..79b64cdb603b 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -147,15 +147,30 @@ described as 'basic' will be available.
 The new VM has no virtual cpus and no memory.
 You probably want to use 0 as machine type.
 
+X86:
+^^^^
+
+Supported vm type can be queried from KVM_CAP_VM_TYPES, which returns the
+bitmap of supported vm types. The 1-setting of bit @n means vm type with
+value @n is supported.
+
+S390:
+^^^^^
+
 In order to create user controlled virtual machines on S390, check
 KVM_CAP_S390_UCONTROL and use the flag KVM_VM_S390_UCONTROL as
 privileged user (CAP_SYS_ADMIN).
 
+MIPS:
+^^^^^
+
 To use hardware assisted virtualization on MIPS (VZ ASE) rather than
 the default trap & emulate implementation (which changes the virtual
 memory layout to fit in user mode), check KVM_CAP_MIPS_VZ and use the
 flag KVM_VM_MIPS_VZ.
 
+ARM64:
+^^^^^^
 
 On arm64, the physical address size for a VM (IPA Size limit) is limited
 to 40bits by default. The limit can be configured if the host supports the
diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h
index cefe1d81e2e8..4aa0a1c10b84 100644
--- a/arch/x86/include/asm/kvm-x86-ops.h
+++ b/arch/x86/include/asm/kvm-x86-ops.h
@@ -18,6 +18,7 @@ KVM_X86_OP_NULL(hardware_unsetup)
 KVM_X86_OP_NULL(cpu_has_accelerated_tpr)
 KVM_X86_OP(has_emulated_msr)
 KVM_X86_OP(vcpu_after_set_cpuid)
+KVM_X86_OP(is_vm_type_supported)
 KVM_X86_OP(vm_init)
 KVM_X86_OP_NULL(vm_destroy)
 KVM_X86_OP(vcpu_create)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 2acf37cc1991..a5e27111b198 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1036,6 +1036,7 @@ struct kvm_x86_msr_filter {
 #define APICV_INHIBIT_REASON_X2APIC	5
 
 struct kvm_arch {
+	unsigned long vm_type;
 	unsigned long n_used_mmu_pages;
 	unsigned long n_requested_mmu_pages;
 	unsigned long n_max_mmu_pages;
@@ -1310,6 +1311,7 @@ struct kvm_x86_ops {
 	bool (*has_emulated_msr)(struct kvm *kvm, u32 index);
 	void (*vcpu_after_set_cpuid)(struct kvm_vcpu *vcpu);
 
+	bool (*is_vm_type_supported)(unsigned long vm_type);
 	unsigned int vm_size;
 	int (*vm_init)(struct kvm *kvm);
 	void (*vm_destroy)(struct kvm *kvm);
diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
index 5a776a08f78c..102b71229f87 100644
--- a/arch/x86/include/uapi/asm/kvm.h
+++ b/arch/x86/include/uapi/asm/kvm.h
@@ -508,4 +508,7 @@ struct kvm_pmu_event_filter {
 #define KVM_VCPU_TSC_CTRL 0 /* control group for the timestamp counter (TSC) */
 #define   KVM_VCPU_TSC_OFFSET 0 /* attribute for the TSC offset */
 
+#define KVM_X86_NORMAL_VM	0
+#define KVM_X86_TDX_VM		1
+
 #endif /* _ASM_X86_KVM_H */
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index b36ca4e476c2..1c7a7e1f56f8 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4567,6 +4567,11 @@ static void svm_vm_destroy(struct kvm *kvm)
 	sev_vm_destroy(kvm);
 }
 
+static bool svm_is_vm_type_supported(unsigned long type)
+{
+	return type == KVM_X86_NORMAL_VM;
+}
+
 static int svm_vm_init(struct kvm *kvm)
 {
 	if (!pause_filter_count || !pause_filter_thresh)
@@ -4594,6 +4599,7 @@ static struct kvm_x86_ops svm_x86_ops __initdata = {
 	.vcpu_free = svm_free_vcpu,
 	.vcpu_reset = svm_vcpu_reset,
 
+	.is_vm_type_supported = svm_is_vm_type_supported,
 	.vm_size = sizeof(struct kvm_svm),
 	.vm_init = svm_vm_init,
 	.vm_destroy = svm_vm_destroy,
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 76861b66bbcf..41513ae18f22 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6925,6 +6925,11 @@ static int vmx_create_vcpu(struct kvm_vcpu *vcpu)
 	return err;
 }
 
+static bool vmx_is_vm_type_supported(unsigned long type)
+{
+	return type == KVM_X86_NORMAL_VM;
+}
+
 #define L1TF_MSG_SMT "L1TF CPU bug present and SMT on, data leak possible. See CVE-2018-3646 and https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/l1tf.html for details.\n"
 #define L1TF_MSG_L1D "L1TF CPU bug present and virtualization mitigation disabled, data leak possible. See CVE-2018-3646 and https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/l1tf.html for details.\n"
 
@@ -7578,6 +7583,7 @@ static struct kvm_x86_ops vmx_x86_ops __initdata = {
 	.cpu_has_accelerated_tpr = report_flexpriority,
 	.has_emulated_msr = vmx_has_emulated_msr,
 
+	.is_vm_type_supported = vmx_is_vm_type_supported,
 	.vm_size = sizeof(struct kvm_vmx),
 	.vm_init = vmx_vm_init,
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c1c4e2b05a63..c080c68e4386 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4183,6 +4183,11 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 		else
 			r = 0;
 		break;
+	case KVM_CAP_VM_TYPES:
+		r = BIT(KVM_X86_NORMAL_VM);
+		if (static_call(kvm_x86_is_vm_type_supported)(KVM_X86_TDX_VM))
+			r |= BIT(KVM_X86_TDX_VM);
+		break;
 	default:
 		break;
 	}
@@ -11231,9 +11236,11 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 	int ret;
 	unsigned long flags;
 
-	if (type)
+	if (!static_call(kvm_x86_is_vm_type_supported)(type))
 		return -EINVAL;
 
+	kvm->arch.vm_type = type;
+
 	ret = kvm_page_track_init(kvm);
 	if (ret)
 		return ret;
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 78f0719cc2a3..91f75704ef6a 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1130,6 +1130,7 @@ struct kvm_ppc_resize_hpt {
 #define KVM_CAP_BINARY_STATS_FD 203
 #define KVM_CAP_EXIT_ON_EMULATION_FAILURE 204
 #define KVM_CAP_ARM_MTE 205
+#define KVM_CAP_VM_TYPES 206
 
 #ifdef KVM_CAP_IRQ_ROUTING
 
diff --git a/tools/arch/x86/include/uapi/asm/kvm.h b/tools/arch/x86/include/uapi/asm/kvm.h
index 2ef1f6513c68..69851dfd5085 100644
--- a/tools/arch/x86/include/uapi/asm/kvm.h
+++ b/tools/arch/x86/include/uapi/asm/kvm.h
@@ -504,4 +504,7 @@ struct kvm_pmu_event_filter {
 #define KVM_PMU_EVENT_ALLOW 0
 #define KVM_PMU_EVENT_DENY 1
 
+#define KVM_X86_NORMAL_VM	0
+#define KVM_X86_TDX_VM		1
+
 #endif /* _ASM_X86_KVM_H */
diff --git a/tools/include/uapi/linux/kvm.h b/tools/include/uapi/linux/kvm.h
index a067410ebea5..e7616e64fb4e 100644
--- a/tools/include/uapi/linux/kvm.h
+++ b/tools/include/uapi/linux/kvm.h
@@ -1112,6 +1112,7 @@ struct kvm_ppc_resize_hpt {
 #define KVM_CAP_BINARY_STATS_FD 203
 #define KVM_CAP_EXIT_ON_EMULATION_FAILURE 204
 #define KVM_CAP_ARM_MTE 205
+#define KVM_CAP_VM_TYPES 206
 
 #ifdef KVM_CAP_IRQ_ROUTING
 
-- 
2.27.0