[Part2 PATCH v8 07/38] KVM: Introduce KVM_MEMORY_ENCRYPT_OP ioctl

[Brijesh Singh]

If the hardware supports memory encryption then the
KVM_MEMORY_ENCRYPT_OP ioctl can be used by qemu to issue a platform
specific memory encryption commands.

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>
Reviewed-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Reviewed-by: Borislav Petkov <bp@xxxxxxx>
---
 Documentation/virtual/kvm/api.txt | 16 ++++++++++++++++
 arch/x86/include/asm/kvm_host.h   |  2 ++
 arch/x86/kvm/x86.c                |  6 ++++++
 include/uapi/linux/kvm.h          |  2 ++
 4 files changed, 26 insertions(+)

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index dd2dd96927b8..e3e29892167e 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -3394,6 +3394,22 @@ invalid, if invalid pages are written to (e.g. after the end of memory)
 or if no page table is present for the addresses (e.g. when using
 hugepages).
 
+4.109 KVM_MEMORY_ENCRYPT_OP
+
+Capability: basic
+Architectures: x86
+Type: system
+Parameters: an opaque platform specific structure (in/out)
+Returns: 0 on success; -1 on error
+
+If the platform supports creating encrypted VMs then this ioctl can be used
+for issuing platform-specific memory encryption commands to manage those
+encrypted VMs.
+
+Currently, this ioctl is used for issuing Secure Encrypted Virtualization
+(SEV) commands on AMD Processors. The SEV commands are defined in
+Documentation/virtual/kvm/amd-memory-encryption.txt.
+
 5. The kvm_run structure
 ------------------------
 
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 7233445a20bd..f7f68c1e6162 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1066,6 +1066,8 @@ struct kvm_x86_ops {
 	int (*pre_enter_smm)(struct kvm_vcpu *vcpu, char *smstate);
 	int (*pre_leave_smm)(struct kvm_vcpu *vcpu, u64 smbase);
 	int (*enable_smi_window)(struct kvm_vcpu *vcpu);
+
+	int (*mem_enc_op)(struct kvm *kvm, void __user *argp);
 };
 
 struct kvm_arch_async_pf {
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 34c85aa2e2d1..7bbed0c0ba79 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4281,6 +4281,12 @@ long kvm_arch_vm_ioctl(struct file *filp,
 		r = kvm_vm_ioctl_enable_cap(kvm, &cap);
 		break;
 	}
+	case KVM_MEMORY_ENCRYPT_OP: {
+		r = -ENOTTY;
+		if (kvm_x86_ops->mem_enc_op)
+			r = kvm_x86_ops->mem_enc_op(kvm, argp);
+		break;
+	}
 	default:
 		r = -ENOTTY;
 	}
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 838887587411..4a39d99c5f99 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1356,6 +1356,8 @@ struct kvm_s390_ucas_mapping {
 /* Available with KVM_CAP_S390_CMMA_MIGRATION */
 #define KVM_S390_GET_CMMA_BITS      _IOWR(KVMIO, 0xb8, struct kvm_s390_cmma_log)
 #define KVM_S390_SET_CMMA_BITS      _IOW(KVMIO, 0xb9, struct kvm_s390_cmma_log)
+/* Memory Encryption Commands */
+#define KVM_MEMORY_ENCRYPT_OP      _IOWR(KVMIO, 0xba, unsigned long)
 
 #define KVM_DEV_ASSIGN_ENABLE_IOMMU	(1 << 0)
 #define KVM_DEV_ASSIGN_PCI_2_3		(1 << 1)
-- 
2.9.5