From: "Laszlo Ersek" <lersek@redhat.com>
To: edk2-devel-groups-io <devel@edk2.groups.io>
Cc: edk2-rfc-groups-io <rfc@edk2.groups.io>,
qemu devel list <qemu-devel@nongnu.org>,
Igor Mammedov <imammedo@redhat.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Jiewen Yao <jiewen.yao@intel.com>,
Yingwen Chen <yingwen.chen@intel.com>,
Jun Nakajima <jun.nakajima@intel.com>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Joao Marcal Lemos Martins <joao.m.martins@oracle.com>,
Phillip Goerl <phillip.goerl@oracle.com>
Subject: Re: CPU hotplug using SMM with QEMU+OVMF
Date: Tue, 13 Aug 2019 18:18:23 +0200 [thread overview]
Message-ID: <55cc7921-2b91-5060-d5de-d7513067f76e@redhat.com> (raw)
In-Reply-To: <effa5e32-be1e-4703-4419-8866b7754e2d@redhat.com>
On 08/13/19 18:09, Laszlo Ersek wrote:
> On 08/13/19 16:16, Laszlo Ersek wrote:
>> (06) Host CPU: (SMM) Save 38000, Update 38000 -- fill simple SMM
>> rebase code.
>>
>> (07) Host CPU: (SMM) Send message to New CPU to Enable SMI.
>
> Aha, so this is the SMM-only register you mention in step (03). Is the
> register specified in the Intel SDM?
>
>
>> (08) New CPU: (Flash) Get message - Enable SMI.
>>
>> (09) Host CPU: (SMM) Send SMI to the new CPU only.
>>
>> (10) New CPU: (SMM) Response first SMI at 38000, and rebase SMBASE to
>> TSEG.
>
> What code does the new CPU execute after it completes step (10)? Does it
> halt?
>
>
>> (11) Host CPU: (SMM) Restore 38000.
>
> These steps (i.e., (06) through (11)) don't appear RAS-specific. The
> only platform-specific feature seems to be SMI masking register, which
> could be extracted into a new SmmCpuFeaturesLib API.
>
> Thus, would you please consider open sourcing firmware code for steps
> (06) through (11)?
>
>
> Alternatively -- and in particular because the stack for step (01)
> concerns me --, we could approach this from a high-level, functional
> perspective. The states that really matter are the relocated SMBASE for
> the new CPU, and the state of the full system, right at the end of step
> (11).
>
> When the SMM setup quiesces during normal firmware boot, OVMF could use
> existent (finalized) SMBASE infomation to *pre-program* some virtual
> QEMU hardware, with such state that would be expected, as "final" state,
> of any new hotplugged CPU. Afterwards, if / when the hotplug actually
> happens, QEMU could blanket-apply this state to the new CPU, and
> broadcast a hardware SMI to all CPUs except the new one.
>
> The hardware SMI should tell the firmware that the rest of the process
> -- step (12) below, and onward -- is being requested.
>
> If I understand right, this approach would produce an firmware & system
> state that's identical to what's expected right after step (11):
>
> - all SMBASEs relocated
> - all preexistent CPUs in SMM
> - new CPU halted / blocked from launch
> - DRAM at 0x30000 / 0x38000 contains OS-owned data
>
> Is my understanding correct that this is the expected state after step
> (11)?
Revisiting some of my notes from earlier, such as
<https://bugzilla.redhat.com/show_bug.cgi?id=1454803#c46> -- apologies,
private BZ... --, we discussed some of this stuff with Mike on the phone
in April.
And, it looked like generating a hardware SMI in QEMU, in association
with the hotplug action that was being requested through the QEMU
monitor, would be the right approach.
By now I have forgotten about that discussion -- hence "revisiting my
notes"--, but luckily, it seems consistent with what I've proposed
above, under "alternatively".
Thanks,
Laszlo
next prev parent reply other threads:[~2019-08-13 16:18 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-13 14:16 CPU hotplug using SMM with QEMU+OVMF Laszlo Ersek
2019-08-13 16:09 ` Laszlo Ersek
2019-08-13 16:18 ` Laszlo Ersek [this message]
2019-08-14 13:20 ` Yao, Jiewen
2019-08-14 14:04 ` Paolo Bonzini
2019-08-15 9:55 ` Yao, Jiewen
2019-08-15 16:04 ` Paolo Bonzini
2019-08-15 15:00 ` [edk2-devel] " Laszlo Ersek
2019-08-15 16:16 ` Igor Mammedov
2019-08-15 16:21 ` Paolo Bonzini
2019-08-16 2:46 ` Yao, Jiewen
2019-08-16 7:20 ` Paolo Bonzini
2019-08-16 7:49 ` Yao, Jiewen
2019-08-16 20:15 ` Laszlo Ersek
2019-08-16 22:19 ` Alex Williamson
2019-08-17 0:20 ` Yao, Jiewen
2019-08-18 19:50 ` Paolo Bonzini
2019-08-18 23:00 ` Yao, Jiewen
2019-08-19 14:10 ` Paolo Bonzini
2019-08-21 12:07 ` Laszlo Ersek
2019-08-21 15:48 ` [edk2-rfc] " Michael D Kinney
2019-08-21 17:05 ` Paolo Bonzini
2019-08-21 17:25 ` Michael D Kinney
2019-08-21 17:39 ` Paolo Bonzini
2019-08-21 20:17 ` Michael D Kinney
2019-08-22 6:18 ` Paolo Bonzini
2019-08-22 18:29 ` Laszlo Ersek
2019-08-22 18:51 ` Paolo Bonzini
2019-08-23 14:53 ` Laszlo Ersek
2019-08-22 20:13 ` Michael D Kinney
2019-08-22 17:59 ` Laszlo Ersek
2019-08-22 18:43 ` Paolo Bonzini
2019-08-22 20:06 ` Michael D Kinney
2019-08-22 22:18 ` Paolo Bonzini
2019-08-22 22:32 ` Michael D Kinney
2019-08-22 23:11 ` Paolo Bonzini
2019-08-23 1:02 ` Michael D Kinney
2019-08-23 5:00 ` Yao, Jiewen
2019-08-23 15:25 ` Michael D Kinney
2019-08-24 1:48 ` Yao, Jiewen
2019-08-27 18:31 ` Igor Mammedov
2019-08-29 17:01 ` Laszlo Ersek
2019-08-30 14:48 ` Igor Mammedov
2019-08-30 18:46 ` Laszlo Ersek
2019-09-02 8:45 ` Igor Mammedov
2019-09-02 19:09 ` Laszlo Ersek
2019-09-03 14:53 ` [Qemu-devel] " Igor Mammedov
2019-09-03 17:20 ` Laszlo Ersek
2019-09-04 9:52 ` imammedo
2019-09-05 13:08 ` Laszlo Ersek
2019-09-05 15:45 ` Igor Mammedov
2019-09-05 15:49 ` [PATCH] q35: lpc: allow to lock down 128K RAM at default SMBASE address Igor Mammedov
2019-09-09 19:15 ` Laszlo Ersek
2019-09-09 19:20 ` Laszlo Ersek
2019-09-10 15:58 ` Igor Mammedov
2019-09-11 17:30 ` Laszlo Ersek
2019-09-17 13:11 ` [edk2-devel] " Igor Mammedov
2019-09-17 14:38 ` [staging/branch]: CdePkg - C Development Environment Package Minnow Ware
2019-08-26 15:30 ` [edk2-rfc] [edk2-devel] CPU hotplug using SMM with QEMU+OVMF Laszlo Ersek
2019-08-27 16:23 ` Igor Mammedov
2019-08-27 20:11 ` Laszlo Ersek
2019-08-28 12:01 ` Igor Mammedov
2019-08-29 16:25 ` Laszlo Ersek
2019-08-30 13:49 ` [Qemu-devel] " Igor Mammedov
2019-08-22 17:53 ` Laszlo Ersek
2019-08-16 20:00 ` Laszlo Ersek
2019-08-15 16:07 ` Igor Mammedov
2019-08-15 16:24 ` Paolo Bonzini
2019-08-16 7:42 ` Igor Mammedov
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