Re: [Part2 PATCH v4 01/29] Documentation/virtual/kvm: Add AMD Secure Encrypted Virtualization (SEV)

From: Borislav Petkov
Date: Fri Sep 29 2017 - 02:54:37 EST

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On Tue, Sep 19, 2017 at 03:45:59PM -0500, Brijesh Singh wrote:
> Create a Documentation entry to describe the AMD Secure Encrypted
> Virtualization (SEV) feature.
>
> 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: Jonathan Corbet <corbet@xxxxxxx>
> Cc: Borislav Petkov <bp@xxxxxxx>
> Cc: Tom Lendacky <thomas.lendacky@xxxxxxx>
> Cc: kvm@xxxxxxxxxxxxxxx
> Cc: x86@xxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx>
> ---
> Documentation/virtual/kvm/00-INDEX | 3 +
> .../virtual/kvm/amd-memory-encryption.txt | 210 +++++++++++++++++++++
> 2 files changed, 213 insertions(+)
> create mode 100644 Documentation/virtual/kvm/amd-memory-encryption.txt

Here's a diff which applies ontop of this one, it moves the KVM_SEV_*
commands to Documentation/virtual/kvm/api.txt where they're all together
in one place for obvious advantages.

Also I did some small cleanups while at it.

Notable is that the commands are a smaller number now and
KVM_SEV_RECEIVE_UPDATE_DATA, KVM_SEV_RECEIVE_START and a couple more are
missing.

On purpose?

---
diff --git a/Documentation/virtual/kvm/amd-memory-encryption.txt b/Documentation/virtual/kvm/amd-memory-encryption.txt
index 5b38b4feb9b7..2f17400f5720 100644
--- a/Documentation/virtual/kvm/amd-memory-encryption.txt
+++ b/Documentation/virtual/kvm/amd-memory-encryption.txt
@@ -1,16 +1,18 @@
Secure Encrypted Virtualization (SEV) is a feature found on AMD processors.

-SEV is an extension to the AMD-V architecture which supports running virtual
-machines (VMs) under the control of a hypervisor. When enabled, the memory
-contents of VM will be transparently encrypted with a key unique to the VM.
+SEV is an extension to the AMD-V architecture which supports running
+virtual machines (VMs) under the control of a hypervisor. When enabled,
+the memory contents of a VM will be transparently encrypted with a key
+unique to that VM.

-Hypervisor can determine the SEV support through the CPUID instruction. The CPUID
-function 0x8000001f reports information related to SEV:
+The hypervisor can determine the SEV support through the CPUID
+instruction. The CPUID function 0x8000001f reports information related
+to SEV:

0x8000001f[eax]:
Bit[1] indicates support for SEV
-
- 0x8000001f[ecx]:
+ ...
+ [ecx]:
Bits[31:0] Number of encrypted guests supported simultaneously

If support for SEV is present, MSR 0xc001_0010 (MSR_K8_SYSCFG) and MSR 0xc001_0015
@@ -24,8 +26,8 @@ If support for SEV is present, MSR 0xc001_0010 (MSR_K8_SYSCFG) and MSR 0xc001_00
Bit[0] 1 = memory encryption can be enabled
0 = memory encryption can not be enabled

-When SEV support is available, it can be enabled in a specific VM by setting SEV
-bit before executing VMRUN.
+When SEV support is available, it can be enabled in a specific VM by
+setting the SEV bit before executing VMRUN.

VMCB[0x90]:
Bit[1] 1 = SEV is enabled
@@ -45,182 +47,6 @@ more information, see SEV Key Management spec at

http://support.amd.com/TechDocs/55766_SEV-KM%20API_Specification.pdf

-KVM implements the following commands to support SEV guests common lifecycle
-events such as launching, running, snapshotting, migrating and decommissioning
-guests.
-
-1. KVM_SEV_INIT
-
-Returns: 0 on success, -negative on error
-
-The KVM_SEV_INIT command is used by the hypervisor to initialize the SEV platform
-context. In a typical workflow, this command should be the first command issued.
-
-2. KVM_SEV_LAUNCH_START
-
-Parameters: struct kvm_sev_launch_start (in/out)
-Returns: 0 on success, -negative on error
-
-The KVM_SEV_LAUNCH_START command is used for creating the memory encryption
-context. To create the encryption context, user must provide a guest policy,
-the owner's public Diffie-Hellman (PDH) key and session information.
-
-struct kvm_sev_launch_start {
- /* if zero then firmware creates a new handle */
- __u32 handle;
-
- /* guest's policy */
- __u32 policy;
-
- /* userspace address pointing to the guest owner's PDH key */
- __u64 dh_uaddr;
- __u32 dh_len;
-
- /* userspace address which points to the guest session information */
- __u64 session_addr;
- __u32 session_len;
-};
-
-On success, the 'handle' field contain a new handle and on error, a negative value.
-
-For more details, see SEV spec Section 6.2.
-
-3. KVM_SEV_LAUNCH_UPDATE_DATA
-
-Parameters (in): struct kvm_sev_launch_update_data
-Returns: 0 on success, -negative on error
-
-The KVM_SEV_LAUNCH_UPDATE_DATA is used for encrypting the memory region. It also
-calculates a measurement of the memory contents. The measurement is a signature
-of the memory contents that can be sent to the guest owners as an attestation
-that the memory was encrypted correctly by the firmware.
-
-struct kvm_sev_launch_update {
- /* userspace address need to be encrypted (must be 16-byte aligned) */
- __u64 uaddr;
-
- /* length of the data to be encrypted (must be 16-byte aligned) */
- __u32 len;
-};
-
-For more details, see SEV spec Section 6.3.
-
-4. KVM_SEV_LAUNCH_MEASURE
-
-Parameters (in): struct kvm_sev_launch_measure
-Returns: 0 on success, -negative on error
-
-The KVM_SEV_LAUNCH_MEASURE command is used to retrieve the measurement of the
-data encrypted by the KVM_SEV_LAUNCH_UPDATE_DATA. The guest owner may wait to
-provide the guest with confidential information until it can verify the measurement.
-Since the guest owner knows the initial contents of the guest at boot, the
-measurement can be verified by comparing it to what the guest owner expect.
-
-struct kvm_sev_launch_measure {
- /* where to copy the measurement */
- __u64 uaddr;
-
- /* length of measurement blob */
- __u32 len;
-};
-
-For more details on the measurement verification flow, see SEV spec Section 6.4
-
-5. KVM_SEV_LAUNCH_FINISH
-
-Returns: 0 on success, -negative on error
-
-After completion of the launch flow, the KVM_SEV_LAUNCH_FINISH command can be
-issued to make the guest ready for the execution.
-
-6. KVM_SEV_GUEST_STATUS
-
-Parameters (out): struct kvm_sev_guest_status
-Returns: 0 on success, -negative on error
-
-The KVM_SEV_GUEST_STATUS command is used to retrieve status information about an
-SEV-enabled guest..
-
-struct kvm_sev_guest_status {
- /* guest handle */
- __u32 handle;
-
- /* guest policy */
- __u32 policy;
-
- /* guest state (see below) */
- __u8 state;
-};
-
-SEV guest state:
-
-enum {
- SEV_STATE_INVALID = 0;
- SEV_STATE_LAUNCHING, /* guest is currently being launched */
- SEV_STATE_SECRET, /* guest is being launched and ready to accept the ciphertext data */
- SEV_STATE_RUNNING, /* guest is fully launched and running */
- SEV_STATE_RECEIVING, /* guest is being migrated in from another SEV machine */
- SEV_STATE_SENDING /* guest is getting migrated out to another SEV machine */
-};
-
-7. KVM_SEV_DBG_DECRYPT
-
-Parameters (in): struct kvm_sev_dbg
-Returns: 0 on success, -negative on error
-
-The KVM_SEV_DEBUG_DECRYPT command can be used by the hypervisor to request the
-firmware to decrypt the data at the given memory region.
-
-struct kvm_sev_dbg {
- /* userspace address of data to decrypt */
- __u64 src_uaddr;
- /* userspace address of destination */
- __u64 dst_uaddr;
-
- /* length of memory region to decrypt */
- __u32 len;
-};
-
-The command returns an error if guest policy does not allow debugging.
-
-8. KVM_SEV_DBG_ENCRYPT
-
-Parameters (in): struct kvm_sev_dbg
-Returns: 0 on success, -negative on error
-
-The KVM_SEV_DEBUG_ENCRYPT command can be used by the hypervisor to request the
-firmware to encrypt the data at the given memory region.
-
-struct kvm_sev_dbg {
- /* userspace address of data to encrypt */
- __u64 src_uaddr;
- /* userspace address of destination */
- __u64 dst_uaddr;
-
- /* length of memory region to encrypt */
- __u32 len;
-};
-
-The command returns an error if guest policy does not allow debugging.
-
-9. KVM_SEV_LAUNCH_SECRET
-
-Parameters (in): struct kvm_sev_launch_secret
-Returns: 0 on success, -negative on error
-
-Te KVM_SEV_LAUNCH_SECRET command can be used by the hypevisor to inject a secret
-data after the measurement has been validated by the guest owner.
-
-struct kvm_sev_launch_secret {
- /* userspace address containing the packet header */
- __u64 hdr_uaddr;
- __u32 hdr_len;
-
- /* the guest memory region where the secret should be injected */
- __u64 guest_uaddr;
- __u32 guest_len;
-
- /* the hypervisor memory region which contains the secret */
- __u64 trans_uaddr;
- __u32 trans_len;
-};
+See Documentation/virtual/kvm/api.txt for the commands KVM implements to
+support common lifecycle events of SEV guests such as launching, running,
+snapshotting, migrating and decommissioning.
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index e63a35fafef0..d48f338b67e0 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -3390,6 +3390,183 @@ 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_SEV_INIT
+
+Returns: 0 on success, -negative on error
+
+The KVM_SEV_INIT command is used by the hypervisor to initialize the SEV platform
+context. In a typical workflow, this command should be the first command issued.
+
+4.110 KVM_SEV_LAUNCH_START
+
+Parameters: struct kvm_sev_launch_start (in/out)
+Returns: 0 on success, -negative on error
+
+The KVM_SEV_LAUNCH_START command is used for creating the memory encryption
+context. To create the encryption context, user must provide a guest policy,
+the owner's public Diffie-Hellman (PDH) key and session information.
+
+struct kvm_sev_launch_start {
+ /* if zero then firmware creates a new handle */
+ __u32 handle;
+
+ /* guest's policy */
+ __u32 policy;
+
+ /* userspace address pointing to the guest owner's PDH key */
+ __u64 dh_uaddr;
+ __u32 dh_len;
+
+ /* userspace address which points to the guest session information */
+ __u64 session_addr;
+ __u32 session_len;
+};
+
+On success, the 'handle' field contain a new handle and on error, a negative value.
+
+For more details, see SEV spec Section 6.2.
+
+4.111 KVM_SEV_LAUNCH_UPDATE_DATA
+
+Parameters (in): struct kvm_sev_launch_update_data
+Returns: 0 on success, -negative on error
+
+The KVM_SEV_LAUNCH_UPDATE_DATA is used for encrypting the memory region. It also
+calculates a measurement of the memory contents. The measurement is a signature
+of the memory contents that can be sent to the guest owner as an attestation
+that the memory was encrypted correctly by the firmware.
+
+struct kvm_sev_launch_update {
+ /* userspace address need to be encrypted (must be 16-byte aligned) */
+ __u64 uaddr;
+
+ /* length of the data to be encrypted (must be 16-byte aligned) */
+ __u32 len;
+};
+
+For more details, see SEV spec Section 6.3.
+
+4.112 KVM_SEV_LAUNCH_MEASURE
+
+Parameters (in): struct kvm_sev_launch_measure
+Returns: 0 on success, -negative on error
+
+The KVM_SEV_LAUNCH_MEASURE command is used to retrieve the measurement
+of the data encrypted by the KVM_SEV_LAUNCH_UPDATE_DATA. The guest owner
+may wait to provide the guest with confidential information until it can
+verify the measurement. Since the guest owner knows the initial contents
+of the guest at boot, the measurement can be verified by comparing it to
+what the guest owner expects.
+
+struct kvm_sev_launch_measure {
+ /* where to copy the measurement */
+ __u64 uaddr;
+
+ /* length of measurement blob */
+ __u32 len;
+};
+
+For more details on the measurement verification flow, see SEV spec Section 6.4
+
+4.113 KVM_SEV_LAUNCH_FINISH
+
+Returns: 0 on success, -negative on error
+
+After completion of the launch flow, the KVM_SEV_LAUNCH_FINISH command can be
+issued to make the guest ready for the execution.
+
+4.114 KVM_SEV_GUEST_STATUS
+
+Parameters (out): struct kvm_sev_guest_status
+Returns: 0 on success, -negative on error
+
+The KVM_SEV_GUEST_STATUS command is used to retrieve status information about a
+SEV-enabled guest.
+
+struct kvm_sev_guest_status {
+ /* guest handle */
+ __u32 handle;
+
+ /* guest policy */
+ __u32 policy;
+
+ /* guest state (see below) */
+ __u8 state;
+};
+
+SEV guest state:
+
+enum {
+ SEV_STATE_INVALID = 0;
+ SEV_STATE_LAUNCHING, /* guest is currently being launched */
+ SEV_STATE_SECRET, /* guest is being launched and ready to accept the ciphertext data */
+ SEV_STATE_RUNNING, /* guest is fully launched and running */
+ SEV_STATE_RECEIVING, /* guest is being migrated in from another SEV machine */
+ SEV_STATE_SENDING /* guest is getting migrated out to another SEV machine */
+};
+
+4.115 KVM_SEV_DBG_DECRYPT
+
+Parameters (in): struct kvm_sev_dbg
+Returns: 0 on success, -negative on error
+
+The KVM_SEV_DEBUG_DECRYPT command can be used by the hypervisor to request the
+firmware to decrypt the data at the given memory region.
+
+struct kvm_sev_dbg {
+ /* userspace address of data to decrypt */
+ __u64 src_uaddr;
+ /* userspace address of destination */
+ __u64 dst_uaddr;
+
+ /* length of memory region to decrypt */
+ __u32 len;
+};
+
+The command returns an error if guest policy does not allow debugging.
+
+4.116 KVM_SEV_DBG_ENCRYPT
+
+Parameters (in): struct kvm_sev_dbg
+Returns: 0 on success, -negative on error
+
+The KVM_SEV_DEBUG_ENCRYPT command can be used by the hypervisor to request the
+firmware to encrypt the data at the given memory region.
+
+struct kvm_sev_dbg {
+ /* userspace address of data to encrypt */
+ __u64 src_uaddr;
+ /* userspace address of destination */
+ __u64 dst_uaddr;
+
+ /* length of memory region to encrypt */
+ __u32 len;
+};
+
+The command returns an error if guest policy does not allow debugging.
+
+4.117 KVM_SEV_LAUNCH_SECRET
+
+Parameters (in): struct kvm_sev_launch_secret
+Returns: 0 on success, -negative on error
+
+Te KVM_SEV_LAUNCH_SECRET command can be used by the hypervisor to inject a secret
+data after the measurement has been validated by the guest owner.
+
+struct kvm_sev_launch_secret {
+ /* userspace address containing the packet header */
+ __u64 hdr_uaddr;
+ __u32 hdr_len;
+
+ /* the guest memory region where the secret should be injected */
+ __u64 guest_uaddr;
+ __u32 guest_len;
+
+ /* the hypervisor memory region which contains the secret */
+ __u64 trans_uaddr;
+ __u32 trans_len;
+};
+
5. The kvm_run structure
------------------------

diff --git a/Documentation/x86/amd-memory-encryption.txt b/Documentation/x86/amd-memory-encryption.txt
index afc41f544dab..b6b64b01692a 100644
--- a/Documentation/x86/amd-memory-encryption.txt
+++ b/Documentation/x86/amd-memory-encryption.txt
@@ -39,7 +39,7 @@ CPUID function 0x8000001f reports information related to SME:
0x8000001f[eax]:
Bit[0] indicates support for SME
Bit[1] indicates support for SEV
- 0x8000001f[ebx]:
+ ... [ebx]:
Bits[5:0] pagetable bit number used to activate memory
encryption
Bits[11:6] reduction in physical address space, in bits, when
@@ -50,14 +50,14 @@ CPUID function 0x8000001f reports information related to SME:
If support for SME is present, MSR 0xc00100010 (MSR_K8_SYSCFG) can be used to
determine if SME is enabled and/or to enable memory encryption:

- 0xc0010010:
+ 0xc001_0010:
Bit[23] 0 = memory encryption features are disabled
1 = memory encryption features are enabled

If SEV is supported, MSR 0xc0010131 (MSR_AMD64_SEV) can be used to determine if
SEV is active:

- 0xc0010131:
+ 0xc001_0131:
Bit[0] 0 = memory encryption is not active
1 = memory encryption is active

--
Regards/Gruss,
Boris.

SUSE Linux GmbH, GF: Felix ImendÃrffer, Jane Smithard, Graham Norton, HRB 21284 (AG NÃrnberg)
--

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