KVM: Introduce KVM_MEMORY_ENCRYPT_{UN,}REG_REGION ioctl

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>

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index c8755be..c2ced6a 100644 (file)
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -3410,6 +3410,40 @@ 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.
 
+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
 ------------------------
 

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index c87e214..58b7cc3 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1068,6 +1068,8 @@ 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 {

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 7bbed0c..926f55c 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4287,6 +4287,30 @@ 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;
        }

diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index addd0cf..c8c6519 100644 (file)
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1361,6 +1361,14 @@ 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)