From: "Laszlo Ersek" <lersek@redhat.com>
To: Igor Mammedov <imammedo@redhat.com>
Cc: devel@edk2.groups.io, ankur.a.arora@oracle.com,
boris.ostrovsky@oracle.com
Subject: Re: [edk2-devel] [RFC PATCH 0/5] support CPU hot-unplug
Date: Mon, 21 Dec 2020 20:57:19 +0100 [thread overview]
Message-ID: <55fac2cb-ea37-e920-d254-6a5e13adda52@redhat.com> (raw)
In-Reply-To: <20201221164639.24f83ba4@redhat.com>
On 12/21/20 16:46, Igor Mammedov wrote:
> On Mon, 21 Dec 2020 15:44:35 +0100
> "Laszlo Ersek" <lersek@redhat.com> wrote:
>
>> 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.
> BTW:
>
> meanwhile, QEMU part got merged so one doesn't need to hunt for it anymore.
> If something is broken there, we will have to fix it on top.
Thank you very much for the info!
Laszlo
next prev parent reply other threads:[~2020-12-21 19:57 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-08 5:34 [RFC PATCH 0/5] support CPU hot-unplug ankur.a.arora
2020-12-08 5:34 ` [RFC PATCH 1/5] OvmfPkg/CpuHotplugSmm: move CPU Hotplug into PlugCpus() Ankur Arora
2020-12-08 5:34 ` [RFC PATCH 2/5] OvmfPkg/CpuHotplugSmm: handle fw_remove Ankur Arora
2020-12-08 5:34 ` [RFC PATCH 3/5] OvmfPkg/CpuHotplugSmm: add CpuStatus helper function Ankur Arora
2020-12-08 5:34 ` [RFC PATCH 4/5] OvmfPkg/CpuHotplugSmm: handle CPU hot-unplug Ankur Arora
2020-12-08 5:34 ` [RFC PATCH 5/5] OvmfPkg/SmmControl2Dxe: negotiate ICH9_LPC_SMI_F_CPU_HOT_UNPLUG Ankur Arora
2020-12-10 9:21 ` [RFC PATCH 0/5] support CPU hot-unplug Laszlo Ersek
2020-12-10 20:08 ` Ankur Arora
2020-12-11 16:21 ` [edk2-devel] " Igor Mammedov
2020-12-21 14:44 ` Laszlo Ersek
2020-12-21 15:03 ` Laszlo Ersek
2020-12-21 15:46 ` Igor Mammedov
2020-12-21 19:57 ` Laszlo Ersek [this message]
2020-12-21 19:09 ` Ankur Arora
2020-12-21 19:58 ` Laszlo Ersek
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