From: Brijesh Singh <brijesh.singh@amd.com>

Date: Mon, 4 Dec 2017 10:57:26 -0600

Subject: KVM: Introduce KVM_MEMORY_ENCRYPT_{UN,}REG_REGION ioctl

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Git-commit: 69eaedee411c1fc1cf123520897a96b7cf04d8a0

Patch-mainline: v4.16-rc1

References: bsc#1063068

If hardware supports memory encryption then KVM_MEMORY_ENCRYPT_REG_REGION

and KVM_MEMORY_ENCRYPT_UNREG_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@linutronix.de>

Cc: Ingo Molnar <mingo@redhat.com>

Cc: "H. Peter Anvin" <hpa@zytor.com>

Cc: Paolo Bonzini <pbonzini@redhat.com>

Cc: "Radim Krčmář" <rkrcmar@redhat.com>

Cc: Joerg Roedel <joro@8bytes.org>

Cc: Borislav Petkov <bp@suse.de>

Cc: Tom Lendacky <thomas.lendacky@amd.com>

Cc: x86@kernel.org

Cc: kvm@vger.kernel.org

Cc: linux-kernel@vger.kernel.org

Improvements-by: Borislav Petkov <bp@suse.de>

Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>

Reviewed-by: Borislav Petkov <bp@suse.de>

Acked-by: Borislav Petkov <bp@suse.de>

---

 Documentation/virtual/kvm/api.txt |   34 ++++++++++++++++++++++++++++++++++

 arch/x86/include/asm/kvm_host.h   |    2 ++

 arch/x86/kvm/x86.c                |   24 ++++++++++++++++++++++++

 include/uapi/linux/kvm.h          |    8 ++++++++

 4 files changed, 68 insertions(+)

--- a/arch/x86/include/asm/kvm_host.h

+++ b/arch/x86/include/asm/kvm_host.h

@@ -1082,6 +1082,8 @@ struct kvm_x86_ops {

 	int (*enable_smi_window)(struct kvm_vcpu *vcpu);

 	int (*mem_enc_op)(struct kvm *kvm, void __user *argp);

+	int (*mem_enc_reg_region)(struct kvm *kvm, struct kvm_enc_region *argp);

+	int (*mem_enc_unreg_region)(struct kvm *kvm, struct kvm_enc_region *argp);

 };

 struct kvm_arch_async_pf {

--- a/arch/x86/kvm/x86.c

+++ b/arch/x86/kvm/x86.c

@@ -4301,6 +4301,30 @@ set_identity_unlock:

 			r = kvm_x86_ops->mem_enc_op(kvm, argp);

 		break;

 	}

+	case KVM_MEMORY_ENCRYPT_REG_REGION: {

+		struct kvm_enc_region region;

+

+		r = -EFAULT;

+		if (copy_from_user(&region, argp, sizeof(region)))

+			goto out;

+

+		r = -ENOTTY;

+		if (kvm_x86_ops->mem_enc_reg_region)

+			r = kvm_x86_ops->mem_enc_reg_region(kvm, &region);

+		break;

+	}

+	case KVM_MEMORY_ENCRYPT_UNREG_REGION: {

+		struct kvm_enc_region region;

+

+		r = -EFAULT;

+		if (copy_from_user(&region, argp, sizeof(region)))

+			goto out;

+

+		r = -ENOTTY;

+		if (kvm_x86_ops->mem_enc_unreg_region)

+			r = kvm_x86_ops->mem_enc_unreg_region(kvm, &region);

+		break;

+	}

 	default:

 		r = -ENOTTY;

 	}

--- a/Documentation/virtual/kvm/api.txt

+++ b/Documentation/virtual/kvm/api.txt

@@ -3462,6 +3462,40 @@ Currently, this ioctl is used for issuin

 (SEV) commands on AMD Processors. The SEV commands are defined in

 Documentation/virtual/kvm/amd-memory-encryption.txt.

+4.110 KVM_MEMORY_ENCRYPT_REG_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 a guest memory region which may

+contain encrypted data (e.g. guest RAM, SMRAM etc).

+

+It is used in the SEV-enabled guest. When encryption is enabled, a guest

+memory region may contain encrypted data. The SEV memory encryption

+engine uses a tweak such that two identical plaintext pages, each at

+different locations will have differing ciphertexts. So swapping or

+moving ciphertext of those pages will not result in plaintext being

+swapped. So relocating (or migrating) physical backing pages for the SEV

+guest will require some additional steps.

+

+Note: The current SEV key management spec does not provide commands to

+swap or migrate (move) ciphertext pages. Hence, for now we pin the guest

+memory region registered with the ioctl.

+

+4.111 KVM_MEMORY_ENCRYPT_UNREG_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 guest memory region registered

+with KVM_MEMORY_ENCRYPT_REG_REGION ioctl above.

+

 5. The kvm_run structure

 ------------------------

--- a/include/uapi/linux/kvm.h

+++ b/include/uapi/linux/kvm.h

@@ -1364,6 +1364,14 @@ struct kvm_s390_ucas_mapping {

 /* Memory Encryption Commands */

 #define KVM_MEMORY_ENCRYPT_OP      _IOWR(KVMIO, 0xba, unsigned long)

+struct kvm_enc_region {

+	__u64 addr;

+	__u64 size;

+};

+

+#define KVM_MEMORY_ENCRYPT_REG_REGION    _IOR(KVMIO, 0xbb, struct kvm_enc_region)

+#define KVM_MEMORY_ENCRYPT_UNREG_REGION  _IOR(KVMIO, 0xbc, struct kvm_enc_region)

+

 #define KVM_DEV_ASSIGN_ENABLE_IOMMU	(1 << 0)

 #define KVM_DEV_ASSIGN_PCI_2_3		(1 << 1)

 #define KVM_DEV_ASSIGN_MASK_INTX	(1 << 2)