From: "Laszlo Ersek" <lersek@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
"Kinney, Michael D" <michael.d.kinney@intel.com>,
"rfc@edk2.groups.io" <rfc@edk2.groups.io>,
"Yao, Jiewen" <jiewen.yao@intel.com>
Cc: Alex Williamson <alex.williamson@redhat.com>,
"devel@edk2.groups.io" <devel@edk2.groups.io>,
qemu devel list <qemu-devel@nongnu.org>,
Igor Mammedov <imammedo@redhat.com>,
"Chen, Yingwen" <yingwen.chen@intel.com>,
"Nakajima, Jun" <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: [edk2-rfc] [edk2-devel] CPU hotplug using SMM with QEMU+OVMF
Date: Thu, 22 Aug 2019 19:59:23 +0200 [thread overview]
Message-ID: <b3907432-b149-3f96-6d93-f443f215e0f8@redhat.com> (raw)
In-Reply-To: <a76014e2-2f0a-afce-6d15-1c45c5c1e467@redhat.com>
On 08/21/19 19:05, Paolo Bonzini wrote:
> On 21/08/19 17:48, Kinney, Michael D wrote:
>> Perhaps there is a way to avoid the 3000:8000 startup
>> vector.
>>
>> If a CPU is added after a cold reset, it is already in a
>> different state because one of the active CPUs needs to
>> release it by interacting with the hot plug controller.
>>
>> Can the SMRR for CPUs in that state be pre-programmed to
>> match the SMRR in the rest of the active CPUs?
>>
>> For OVMF we expect all the active CPUs to use the same
>> SMRR value, so a check can be made to verify that all
>> the active CPUs have the same SMRR value. If they do,
>> then any CPU released through the hot plug controller
>> can have its SMRR pre-programmed and the initial SMI
>> will start within TSEG.
>>
>> We just need to decide what to do in the unexpected
>> case where all the active CPUs do not have the same
>> SMRR value.
>>
>> This should also reduce the total number of steps.
>
> The problem is not the SMRR but the SMBASE. If the SMBASE area is
> outside TSEG, it is vulnerable to DMA attacks independent of the SMRR.
> SMBASE is also different for all CPUs, so it cannot be preprogrammed.
The firmware and QEMU could agree on a formula, which would compute the
CPU-specific SMBASE from a value pre-programmed by the firmware, and the
initial APIC ID of the hot-added CPU.
Yes, it would duplicate code -- the calculation -- between QEMU and
edk2. While that's not optimal, it wouldn't be a first.
Thanks
Laszlo
next prev parent reply other threads:[~2019-08-22 18:00 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
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 [this message]
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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