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Subject[Part2 PATCH v5 08/31] KVM: Introduce KVM_MEMORY_ENCRYPT_REGISTER_REGION ioctl
Date
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@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
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
---
Documentation/virtual/kvm/api.txt | 34 ++++++++++++++++++++++++++++++++++
arch/x86/include/asm/kvm_host.h | 2 ++
arch/x86/kvm/x86.c | 36 ++++++++++++++++++++++++++++++++++++
include/uapi/linux/kvm.h | 10 ++++++++++
4 files changed, 82 insertions(+)

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index cc1aa76ee6cd..b007998c1403 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -3406,6 +3406,40 @@ 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_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).
+
+The ioctl is used in the SEV-enabled guest. When encryption is enabled, the
+guest memory region may contain the encrypted data. The SEV memory encryption
+engine uses a tweak such that two identical plaintext pages at different
+location will have different ciphertext. So swapping or moving ciphertext of
+two 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: 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_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 guest memory region registered with
+KVM_MEMORY_ENCRYPT_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 a68e8ca78dd8..95a95f24bcd7 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_ENCRYPT_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_ENCRYPT_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 4a39d99c5f99..d595d3970390 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1359,6 +1359,16 @@ 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_REGISTER_REGION _IOR(KVMIO, 0xbb,\
+ struct kvm_enc_region)
+#define KVM_MEMORY_ENCRYPT_UNREGISTER_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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