[Part2 PATCH v4 12/29] KVM: Introduce KVM_MEMORY_ENCRYPT_REGISTER_REGION ioctl

[Brijesh Singh]

If hardware supports memory encryption then KVM_MEMORY_ENCRYPT_REGISTER_REGION
and KVM_MEMORY_ENCRYPT_UNREGISTER_REGION ioctl's can be used by userspace to
register/unregister the guest memory regions which may contain the encrypted
data (e.g guest RAM, PCI BAR, SMRAM etc).

Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: "Radim KrÄmÃÅ" <rkrcmar@xxxxxxxxxx>
Cc: Joerg Roedel <joro@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Cc: Tom Lendacky <thomas.lendacky@xxxxxxx>
Cc: x86@xxxxxxxxxx
Cc: kvm@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx>
---
 Documentation/virtual/kvm/api.txt | 22 ++++++++++++++++++++++
 arch/x86/include/asm/kvm_host.h   |  2 ++
 arch/x86/kvm/x86.c                | 36 ++++++++++++++++++++++++++++++++++++
 include/uapi/linux/kvm.h          |  9 +++++++++
 4 files changed, 69 insertions(+)

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index 3f0dc33d8a8b..f07b7b87cba9 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -3405,6 +3405,28 @@ VMs.
 Currently, this ioctl is used for issuing Secure Encrypted Virtualization (SEV)
 commands on AMD Processors.
 
+4.110 KVM_MEMORY_ENCRYPTION_REGISTER_REGION
+
+Capability: basic
+Architectures: x86
+Type: system
+Parameters: struct kvm_enc_region (in)
+Returns: 0 on success; -1 on error
+
+This ioctl can be used to register the guest memory region which may contain the
+encrypted data (e.g guest RAM, SMRAM etc).
+
+4.111 KVM_MEMORY_ENCRYPTION_UNREGISTER_REGION
+
+Capability: basic
+Architectures: x86
+Type: system
+Parameters: struct kvm_enc_region (in)
+Returns: 0 on success; -1 on error
+
+This ioctl can be used to unregister the memory region registered with
+KVM_MEMORY_ENCRYPTION_REGISTER_REGION ioctl.
+
 5. The kvm_run structure
 ------------------------
 
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 48001ca48c14..20fba8bfa727 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1063,6 +1063,8 @@ struct kvm_x86_ops {
 	void (*setup_mce)(struct kvm_vcpu *vcpu);
 
 	int (*mem_enc_op)(struct kvm *kvm, void __user *argp);
+	int (*mem_enc_register_region)(struct kvm *kvm, struct kvm_enc_region *argp);
+	int (*mem_enc_unregister_region)(struct kvm *kvm, struct kvm_enc_region *argp);
 };
 
 struct kvm_arch_async_pf {
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ec9f634b75f0..b00035488569 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4018,6 +4018,24 @@ static int kvm_vm_ioctl_mem_enc_op(struct kvm *kvm, void __user *argp)
 	return -ENOTTY;
 }
 
+static int kvm_vm_ioctl_mem_enc_register_region(struct kvm *kvm,
+						struct kvm_enc_region *region)
+{
+	if (kvm_x86_ops->mem_enc_register_region)
+		return kvm_x86_ops->mem_enc_register_region(kvm, region);
+
+	return -ENOTTY;
+}
+
+static int kvm_vm_ioctl_mem_enc_unregister_region(struct kvm *kvm,
+						  struct kvm_enc_region *region)
+{
+	if (kvm_x86_ops->mem_enc_unregister_region)
+		return kvm_x86_ops->mem_enc_unregister_region(kvm, region);
+
+	return -ENOTTY;
+}
+
 long kvm_arch_vm_ioctl(struct file *filp,
 		       unsigned int ioctl, unsigned long arg)
 {
@@ -4282,6 +4300,24 @@ long kvm_arch_vm_ioctl(struct file *filp,
 		r = kvm_vm_ioctl_mem_enc_op(kvm, argp);
 		break;
 	}
+	case KVM_MEMORY_ENCRYPTION_REGISTER_REGION: {
+		struct kvm_enc_region region;
+
+		r = -EFAULT;
+		if (copy_from_user(&region, argp, sizeof(region)))
+			goto out;
+		r = kvm_vm_ioctl_mem_enc_register_region(kvm, &region);
+		break;
+	}
+	case KVM_MEMORY_ENCRYPTION_UNREGISTER_REGION: {
+		struct kvm_enc_region region;
+
+		r = -EFAULT;
+		if (copy_from_user(&region, argp, sizeof(region)))
+			goto out;
+		r = kvm_vm_ioctl_mem_enc_unregister_region(kvm, &region);
+		break;
+	}
 	default:
 		r = -ENOTTY;
 	}
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 23028a78f12f..fc1825440a14 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1358,6 +1358,15 @@ struct kvm_s390_ucas_mapping {
 #define KVM_S390_SET_CMMA_BITS      _IOW(KVMIO, 0xb9, struct kvm_s390_cmma_log)
 /* Memory Encryption Commands */
 #define KVM_MEMORY_ENCRYPTION_OP  _IOWR(KVMIO, 0xba, unsigned long)
+#define KVM_MEMORY_ENCRYPTION_REGISTER_REGION   _IOR(KVMIO, 0xbb,\
+						     struct kvm_enc_region)
+#define KVM_MEMORY_ENCRYPTION_UNREGISTER_REGION _IOR(KVMIO, 0xbc,\
+						     struct kvm_enc_region)
+
+struct kvm_enc_region {
+	__u64 addr;
+	__u64 size;
+};
 
 #define KVM_DEV_ASSIGN_ENABLE_IOMMU	(1 << 0)
 #define KVM_DEV_ASSIGN_PCI_2_3		(1 << 1)
-- 
2.9.5