70 lines
3.0 KiB
Diff
70 lines
3.0 KiB
Diff
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From 2da2e7ebea456360cc41881ff2e4a81a03b6d10c Mon Sep 17 00:00:00 2001
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From: Brijesh Singh <brijesh.singh@amd.com>
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Date: Thu, 7 May 2020 22:26:17 +0000
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Subject: [PATCH] doc: update AMD SEV to include Live migration flow
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cherry-picked from https://github.com/AMDESE/qemu/commit/0e2b3d80e3.
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Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
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Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
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Signed-off-by: hanliyang <hanliyang@hygon.cn>
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---
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docs/system/i386/amd-memory-encryption.rst | 40 +++++++++++++++++++++-
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1 file changed, 39 insertions(+), 1 deletion(-)
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diff --git a/docs/system/i386/amd-memory-encryption.rst b/docs/system/i386/amd-memory-encryption.rst
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index e9bc142bc1..b7e3f46ff6 100644
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--- a/docs/system/i386/amd-memory-encryption.rst
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+++ b/docs/system/i386/amd-memory-encryption.rst
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@@ -177,7 +177,45 @@ TODO
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Live Migration
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---------------
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-TODO
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+AMD SEV encrypts the memory of VMs and because a different key is used
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+in each VM, the hypervisor will be unable to simply copy the
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+ciphertext from one VM to another to migrate the VM. Instead the AMD SEV Key
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+Management API provides sets of function which the hypervisor can use
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+to package a guest page for migration, while maintaining the confidentiality
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+provided by AMD SEV.
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+
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+SEV guest VMs have the concept of private and shared memory. The private
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+memory is encrypted with the guest-specific key, while shared memory may
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+be encrypted with the hypervisor key. The migration APIs provided by the
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+SEV API spec should be used for migrating the private pages. The
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+KVM_GET_PAGE_ENC_BITMAP ioctl can be used to get the guest page encryption
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+bitmap. The bitmap can be used to check if the given guest page is
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+private or shared.
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+
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+Before initiating the migration, we need to know the targets machine's public
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+Diffie-Hellman key (PDH) and certificate chain. It can be retrieved
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+with the 'query-sev-capabilities' QMP command or using the sev-tool. The
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+migrate-set-parameter can be used to pass the target machine's PDH and
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+certificate chain.
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+
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+During the migration flow, the SEND_START is called on the source hypervisor
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+to create an outgoing encryption context. The SEV guest policy dictates whether
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+the certificate passed through the migrate-sev-set-info command will be
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+validated. SEND_UPDATE_DATA is called to encrypt the guest private pages.
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+After migration is completed, SEND_FINISH is called to destroy the encryption
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+context and make the VM non-runnable to protect it against cloning.
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+
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+On the target machine, RECEIVE_START is called first to create an
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+incoming encryption context. The RECEIVE_UPDATE_DATA is called to copy
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+the received encrypted page into guest memory. After migration has
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+completed, RECEIVE_FINISH is called to make the VM runnable.
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+
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+For more information about the migration see SEV API Appendix A
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+Usage flow (Live migration section).
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+
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+NOTE:
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+To protect against the memory clone SEV APIs are designed to make the VM
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+unrunnable in case of the migration failure.
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References
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----------
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--
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2.41.0.windows.1
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