672f70aa3d
Update to 2.11.1, plus a few other fixes. OBS-URL: https://build.opensuse.org/request/show/579209 OBS-URL: https://build.opensuse.org/package/show/Virtualization/qemu?expand=0&rev=392
116 lines
4.9 KiB
Diff
116 lines
4.9 KiB
Diff
From 23745abd0c79cea6c85622263a46a33c3a96fefb Mon Sep 17 00:00:00 2001
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From: Brijesh Singh <brijesh.singh@amd.com>
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Date: Thu, 15 Feb 2018 09:03:20 -0600
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Subject: [PATCH] docs: add AMD Secure Encrypted Virtualization (SEV)
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Create a documentation entry to describe the AMD Secure Encrypted
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Virtualization (SEV) feature.
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Cc: Paolo Bonzini <pbonzini@redhat.com>
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Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
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[BR: FATE#322124]
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Signed-off-by: Bruce Rogers <brogers@suse.com>
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---
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docs/amd-memory-encryption.txt | 92 ++++++++++++++++++++++++++++++++++++++++++
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1 file changed, 92 insertions(+)
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create mode 100644 docs/amd-memory-encryption.txt
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diff --git a/docs/amd-memory-encryption.txt b/docs/amd-memory-encryption.txt
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new file mode 100644
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index 0000000000..72a92b6c63
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--- /dev/null
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+++ b/docs/amd-memory-encryption.txt
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@@ -0,0 +1,92 @@
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+Secure Encrypted Virtualization (SEV) is a feature found on AMD processors.
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+
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+SEV is an extension to the AMD-V architecture which supports running encrypted
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+virtual machine (VMs) under the control of KVM. Encrypted VMs have their pages
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+(code and data) secured such that only the guest itself has access to the
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+unencrypted version. Each encrypted VM is associated with a unique encryption
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+key; if its data is accessed to a different entity using a different key the
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+encrypted guests data will be incorrectly decrypted, leading to unintelligible
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+data.
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+
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+The key management of this feature is handled by separate processor known as
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+AMD secure processor (AMD-SP) which is present in AMD SOCs. Firmware running
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+inside the AMD-SP provide commands to support common VM lifecycle. This
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+includes commands for launching, snapshotting, migrating and debugging the
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+encrypted guest. Those SEV command can be issued via KVM_MEMORY_ENCRYPT_OP
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+ioctls.
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+
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+Launching
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+---------
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+Boot images (such as bios) must be encrypted before guest can be booted.
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+MEMORY_ENCRYPT_OP ioctl provides commands to encrypt the images :LAUNCH_START,
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+LAUNCH_UPDATE_DATA, LAUNCH_MEASURE and LAUNCH_FINISH. These four commands
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+together generate a fresh memory encryption key for the VM, encrypt the boot
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+images and provide a measurement than can be used as an attestation of the
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+successful launch.
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+
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+LAUNCH_START is called first to create a cryptographic launch context within
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+the firmware. To create this context, guest owner must provides guest policy,
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+its public Diffie-Hellman key (PDH) and session parameters. These inputs
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+should be treated as binary blob and must be passed as-is to the SEV firmware.
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+
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+The guest policy is passed as plaintext and hypervisor may able to read it
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+but should not modify it (any modification of the policy bits will result
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+in bad measurement). The guest policy is a 4-byte data structure containing
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+several flags that restricts what can be done on running SEV guest.
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+See KM Spec section 3 and 6.2 for more details.
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+
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+Guest owners provided DH certificate and session parameters will be used to
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+establish a cryptographic session with the guest owner to negotiate keys used
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+for the attestation.
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+
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+LAUNCH_UPDATE_DATA encrypts the memory region using the cryptographic context
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+created via LAUNCH_START command. If required, this command can be called
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+multiple times to encrypt different memory regions. The command also calculates
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+the measurement of the memory contents as it encrypts.
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+
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+LAUNCH_MEASURE command can be used to retrieve the measurement of encrypted
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+memory. This measurement is a signature of the memory contents that can be
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+sent to the guest owner as an attestation that the memory was encrypted
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+correctly by the firmware. The guest owner may wait to provide the guest
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+confidential information until it can verify the attestation measurement.
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+Since the guest owner knows the initial contents of the guest at boot, the
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+attestation measurement can be verified by comparing it to what the guest owner
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+expects.
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+
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+LAUNCH_FINISH command finalizes the guest launch and destroy's the cryptographic
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+context.
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+
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+See SEV KM API Spec [1] 'Launching a guest' usage flow (Appendix A) for the
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+complete flow chart.
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+
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+Debugging
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+-----------
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+Since memory contents of SEV guest is encrypted hence hypervisor access to the
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+guest memory will get a cipher text. If guest policy allows debugging, then
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+hypervisor can use DEBUG_DECRYPT and DEBUG_ENCRYPT commands access the guest
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+memory region for debug purposes.
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+
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+Snapshot/Restore
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+-----------------
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+TODO
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+
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+Live Migration
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+----------------
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+TODO
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+
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+References
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+-----------------
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+
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+AMD Memory Encryption whitepaper:
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+http://amd-dev.wpengine.netdna-cdn.com/wordpress/media/2013/12/AMD_Memory_Encryption_Whitepaper_v7-Public.pdf
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+
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+Secure Encrypted Virutualization Key Management:
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+[1] http://support.amd.com/TechDocs/55766_SEV-KM API_Specification.pdf
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+
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+KVM Forum slides:
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+http://www.linux-kvm.org/images/7/74/02x08A-Thomas_Lendacky-AMDs_Virtualizatoin_Memory_Encryption_Technology.pdf
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+
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+AMD64 Architecture Programmer's Manual:
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+ http://support.amd.com/TechDocs/24593.pdf
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+ SME is section 7.10
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+ SEV is section 15.34
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