Branch: refs/heads/master
Home: https://github.com/tianocore/edk2
Commit: dca5d26bc57ef4a554448e41d302e732bca03d8a
https://github.com/tianocore/edk2/commit/dca5d26bc57ef4a554448e41d302e732bca03d8a
Author: Tom Lendacky <thomas.lenda...@amd.com>
Date: 2025-05-02 (Fri, 02 May 2025)
Changed paths:
M UefiCpuPkg/Library/MpInitLib/AmdSev.c
M UefiCpuPkg/Library/MpInitLib/MpEqu.inc
M UefiCpuPkg/Library/MpInitLib/MpLib.h
M UefiCpuPkg/Library/MpInitLib/X64/AmdSev.c
M UefiCpuPkg/Library/MpInitLib/X64/AmdSev.nasm
M UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm
Log Message:
-----------
UefiCpuPkg/MpInitLib: Fix SNP AP creation when using known APIC IDs
A typical initial AP boot up will choose a CpuNumber based on the ApIndex
value that it gets back after a locked increment of the ApIndex value.
The ApIndex to APIC ID relationship is random, which is not an issue when
a broadcast INIT-SIPI is performed.
With SNP and a hypervisor that supports retrieval of the known APIC IDs,
the broadcast INIT-SIPI method is replaced by waking each individual vCPU.
In this situation, a specific VMSA is associated with a specific APIC ID.
However, random assignment of an ApIndex can break this association. This
isn't typically an issue, because the AP bring-up finishes with the AP
issuing a HLT instruction, which is intercepted by the hypervisor and the
AP won't run again until the next INIT-SIPI. However, when HLT isn't
intercepted by the hypervisor (Qemu '-overcommit cpu-pm=on' parameter),
then the HLT does not exit to the hypervisor. On the next INIT-SIPI, it
can happen that a VMRUN is executed with a different VMSA address than
was originally used, and if that VMSA is still in a VMRUN on another AP,
then the executing VMRUN will fail, crashing the guest.
To fix this issue, add a CPU exchange info field, SevSnpKnownInitApicId,
that indicates the APs are starting with an already known initial APIC ID
and set the initial APIC ID and APIC ID in the CPU_INFO_IN_HOB HOB.
During AP boot, the SevSnpKnownInitApicId field will result in the
CpuNumber being set to the index with a matching APIC ID (similar to AP
booting when the InitFlag != ApInitConfig).
Signed-off-by: Tom Lendacky <thomas.lenda...@amd.com>
To unsubscribe from these emails, change your notification settings at
https://github.com/tianocore/edk2/settings/notifications
_______________________________________________
edk2-commits mailing list
edk2-commits@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/edk2-commits
