[edk2-devel] [RFC PATCH 0/5] support CPU hot-unplug
Laszlo Ersek
lersek at redhat.com
Mon Dec 21 14:44:35 UTC 2020
Hi Ankur,
On 12/08/20 06:34, Ankur Arora wrote:
> [ Resending to the correct edk2 alias this time. ]
>
> Hi,
>
> This series adds support for CPU hot-unplug with OVMF.
>
> Please see this in conjunction with the QEMU v2 series posted here:
> https://lore.kernel.org/qemu-devel/20201207140739.3829993-1-imammedo@redhat.com/
>
> In particular, would be glad for comments on Patch 4, specifically
> where we should be ejecting the CPU.
>
> Right now the ejection happens in UnplugCpus() (called from
> CpuHotplugMmi()):
> + QemuCpuhpWriteCpuSelector (mMmCpuIo, RemoveApicId);
> + QemuCpuhpWriteCpuStatus (mMmCpuIo, QEMU_CPUHP_STAT_EJECTED);
>
> That is way too early -- given that the actual unplug will happen
> in SmmCpuUpdate() and given that the BSPHandler() would have waited
> for the APs multiple times before then.
>
> Another possibility is that the actual ejection be deferred to the
> _EJ0 method after the return from the SMI. But, that seems like a
> hack. Additionally, Igor points out here that this approach has problems:
> https://lore.kernel.org/qemu-devel/20201204170939.1815522-1-imammedo@redhat.com/
I've filed:
https://bugzilla.tianocore.org/show_bug.cgi?id=3132
Can you please register an account in the TianoCore Bugzilla at
<https://bugzilla.tianocore.org/>, and assign the above ticket to yourself?
And then, the URL of the new BZ ticket should be included in every
commit message, like this:
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3132
just above your S-o-b.
No need to repost just because of this; I'll review the RFC series later.
Thanks,
Laszlo
>
> Please review.
>
> Thanks
> Ankur
>
> Ankur Arora (5):
> OvmfPkg/CpuHotplugSmm: move CPU Hotplug into PlugCpus()
> OvmfPkg/CpuHotplugSmm: handle fw_remove
> OvmfPkg/CpuHotplugSmm: add CpuStatus helper function
> OvmfPkg/CpuHotplugSmm: handle CPU hot-unplug
> OvmfPkg/SmmControl2Dxe: negotiate ICH9_LPC_SMI_F_CPU_HOT_UNPLUG
>
> OvmfPkg/CpuHotplugSmm/CpuHotplug.c | 293 ++++++++++++------
> OvmfPkg/CpuHotplugSmm/QemuCpuhp.c | 58 +++-
> OvmfPkg/CpuHotplugSmm/QemuCpuhp.h | 6 +
> .../Include/IndustryStandard/QemuCpuHotplug.h | 2 +
> OvmfPkg/SmmControl2Dxe/SmiFeatures.c | 21 +-
> 5 files changed, 280 insertions(+), 100 deletions(-)
>
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