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Subject[Part2 PATCH v9 08/38] KVM: Introduce KVM_MEMORY_ENCRYPT_{UN,}REG_REGION ioctl
Date
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>
---
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(+)

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index c8755be35543..c2ced6a44bbb 100644
--- 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 c87e214d55df..58b7cc30466b 100644
--- 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 7bbed0c0ba79..926f55cecf2e 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4287,6 +4287,30 @@ long kvm_arch_vm_ioctl(struct file *filp,
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 addd0cf4445f..c8c65190907d 100644
--- 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)
--
2.9.5
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