Re: [PATCH Part2 RFC v4 01/40] KVM: SVM: Add support to handle AP reset MSR protocol
From: Joerg Roedel <hidden>
Date: 2021-07-15 07:40:07
Also in:
kvm, linux-crypto, linux-efi, linux-mm, lkml, platform-driver-x86
On Wed, Jul 14, 2021 at 08:17:29PM +0000, Sean Christopherson wrote:
On Wed, Jul 07, 2021, Brijesh Singh wrote:quoted
From: Tom Lendacky <thomas.lendacky@amd.com> Add support for AP Reset Hold being invoked using the GHCB MSR protocol, available in version 2 of the GHCB specification.Please provide a brief overview of the protocol, and why it's needed. I assume it's to allow AP wakeup without a shared GHCB?
Yes, this is needed for SEV-ES kexec support to park APs without the need for memory that will be owned by the new kernel when APs are woken up. You can have a look into my SEV-ES kexec/kdump patch-set for details: https://lore.kernel.org/lkml/20210705082443.14721-1-joro@8bytes.org/ (local) I also sent this patch separatly earlier this week to enable GHCB protocol version 2 support in KVM. Regards, Joerg