From 17c1559139d6a58794944901f84dd4e8cd1f5335 Mon Sep 17 00:00:00 2001

From: Connor Kuehl <ckuehl@redhat.com>

Date: Tue, 22 Jun 2021 20:00:20 -0400

Subject: [PATCH 08/12] doc: Fix some mistakes in the SEV documentation

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RH-Author: Miroslav Rezanina <mrezanin@redhat.com>

RH-MergeRequest: 16: Synchronize with RHEL-AV 8.5 release 21 to RHEL 9

RH-Commit: [6/8] ce828f81de1320a1833241700cb13dfdcf7d82e7 (mrezanin/centos-src-qemu-kvm)

RH-Bugzilla: 1957194

RH-Acked-by: Vitaly Kuznetsov <vkuznets@redhat.com>

RH-Acked-by: Daniel P. Berrangé <berrange@redhat.com>

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

Fix some spelling and grammar mistakes in the amd-memory-encryption.txt

file. No new information added.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>

Reviewed-by: Laszlo Ersek <lersek@redhat.com>

Reviewed-by: Connor Kuehl <ckuehl@redhat.com>

Message-Id: <a7c5ee6c056d840f46028f4a817c16a9862bdd9e.1619208498.git.thomas.lendacky@amd.com>

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>

(cherry picked from commit f538adeccf4554e6402fe661a0a51bcc8d6bd227)

Signed-off-by: Connor Kuehl <ckuehl@redhat.com>

Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

---

 docs/amd-memory-encryption.txt | 59 +++++++++++++++++-----------------

 1 file changed, 29 insertions(+), 30 deletions(-)

diff --git a/docs/amd-memory-encryption.txt b/docs/amd-memory-encryption.txt

index 145896aec7..ed85159ea7 100644

--- a/docs/amd-memory-encryption.txt

+++ b/docs/amd-memory-encryption.txt

@@ -1,38 +1,38 @@

 Secure Encrypted Virtualization (SEV) is a feature found on AMD processors.

 SEV is an extension to the AMD-V architecture which supports running encrypted

-virtual machine (VMs) under the control of KVM. Encrypted VMs have their pages

+virtual machines (VMs) under the control of KVM. Encrypted VMs have their pages

 (code and data) secured such that only the guest itself has access to the

 unencrypted version. Each encrypted VM is associated with a unique encryption

-key; if its data is accessed to a different entity using a different key the

+key; if its data is accessed by a different entity using a different key the

 encrypted guests data will be incorrectly decrypted, leading to unintelligible

 data.

-The key management of this feature is handled by separate processor known as

-AMD secure processor (AMD-SP) which is present in AMD SOCs. Firmware running

-inside the AMD-SP provide commands to support common VM lifecycle. This

+Key management for this feature is handled by a separate processor known as the

+AMD secure processor (AMD-SP), which is present in AMD SOCs. Firmware running

+inside the AMD-SP provides commands to support a common VM lifecycle. This

 includes commands for launching, snapshotting, migrating and debugging the

-encrypted guest. Those SEV command can be issued via KVM_MEMORY_ENCRYPT_OP

+encrypted guest. These SEV commands can be issued via KVM_MEMORY_ENCRYPT_OP

 ioctls.

 Launching

 ---------

-Boot images (such as bios) must be encrypted before guest can be booted.

-MEMORY_ENCRYPT_OP ioctl provides commands to encrypt the images :LAUNCH_START,

+Boot images (such as bios) must be encrypted before a guest can be booted. The

+MEMORY_ENCRYPT_OP ioctl provides commands to encrypt the images: LAUNCH_START,

 LAUNCH_UPDATE_DATA, LAUNCH_MEASURE and LAUNCH_FINISH. These four commands

 together generate a fresh memory encryption key for the VM, encrypt the boot

-images and provide a measurement than can be used as an attestation of the

+images and provide a measurement than can be used as an attestation of a

 successful launch.

 LAUNCH_START is called first to create a cryptographic launch context within

-the firmware. To create this context, guest owner must provides guest policy,

+the firmware. To create this context, guest owner must provide a guest policy,

 its public Diffie-Hellman key (PDH) and session parameters. These inputs

-should be treated as binary blob and must be passed as-is to the SEV firmware.

+should be treated as a binary blob and must be passed as-is to the SEV firmware.

-The guest policy is passed as plaintext and hypervisor may able to read it

+The guest policy is passed as plaintext. A hypervisor may choose to read it,

 but should not modify it (any modification of the policy bits will result

 in bad measurement). The guest policy is a 4-byte data structure containing

-several flags that restricts what can be done on running SEV guest.

+several flags that restricts what can be done on a running SEV guest.

 See KM Spec section 3 and 6.2 for more details.

 The guest policy can be provided via the 'policy' property (see below)

@@ -40,31 +40,30 @@ The guest policy can be provided via the 'policy' property (see below)

 # ${QEMU} \

    sev-guest,id=sev0,policy=0x1...\

-Guest owners provided DH certificate and session parameters will be used to

+The guest owner provided DH certificate and session parameters will be used to

 establish a cryptographic session with the guest owner to negotiate keys used

 for the attestation.

-The DH certificate and session blob can be provided via 'dh-cert-file' and

-'session-file' property (see below

+The DH certificate and session blob can be provided via the 'dh-cert-file' and

+'session-file' properties (see below)

 # ${QEMU} \

      sev-guest,id=sev0,dh-cert-file=<file1>,session-file=<file2>

 LAUNCH_UPDATE_DATA encrypts the memory region using the cryptographic context

-created via LAUNCH_START command. If required, this command can be called

+created via the LAUNCH_START command. If required, this command can be called

 multiple times to encrypt different memory regions. The command also calculates

 the measurement of the memory contents as it encrypts.

-LAUNCH_MEASURE command can be used to retrieve the measurement of encrypted

-memory. This 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. The guest owner may wait to provide the guest

-confidential information until it can verify the attestation measurement.

-Since the guest owner knows the initial contents of the guest at boot, the

-attestation measurement can be verified by comparing it to what the guest owner

-expects.

+LAUNCH_MEASURE can be used to retrieve the measurement of encrypted memory.

+This 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. The guest owner may wait to provide the guest confidential information

+until it can verify the attestation measurement. Since the guest owner knows the

+initial contents of the guest at boot, the attestation measurement can be

+verified by comparing it to what the guest owner expects.

-LAUNCH_FINISH command finalizes the guest launch and destroy's the cryptographic

+LAUNCH_FINISH finalizes the guest launch and destroys the cryptographic

 context.

 See SEV KM API Spec [1] 'Launching a guest' usage flow (Appendix A) for the

@@ -78,10 +77,10 @@ To launch a SEV guest

 Debugging

 -----------

-Since memory contents of SEV guest is encrypted hence hypervisor access to the

-guest memory will get a cipher text. If guest policy allows debugging, then

-hypervisor can use DEBUG_DECRYPT and DEBUG_ENCRYPT commands access the guest

-memory region for debug purposes.  This is not supported in QEMU yet.

+Since the memory contents of a SEV guest are encrypted, hypervisor access to

+the guest memory will return cipher text. If the guest policy allows debugging,

+then a hypervisor can use the DEBUG_DECRYPT and DEBUG_ENCRYPT commands to access

+the guest memory region for debug purposes.  This is not supported in QEMU yet.

 Snapshot/Restore

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

-- 

2.27.0