From: "Michael D Kinney" <michael.d.kinney@intel.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
Laszlo Ersek <lersek@redhat.com>,
"rfc@edk2.groups.io" <rfc@edk2.groups.io>,
"Yao, Jiewen" <jiewen.yao@intel.com>,
"Kinney, Michael D" <michael.d.kinney@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 22:32:37 +0000 [thread overview]
Message-ID: <E92EE9817A31E24EB0585FDF735412F5B9DA218F@ORSMSX113.amr.corp.intel.com> (raw)
In-Reply-To: <7f2d2f1e-2dd8-6914-c55e-61067e06b142@redhat.com>
Paolo,
It is my understanding that real HW hot plug uses the SDM defined
methods. Meaning the initial SMI is to 3000:8000 and they rebase
to TSEG in the first SMI. They must have chipset specific methods
to protect 3000:8000 from DMA.
Can we add a chipset feature to prevent DMA to 64KB range from
0x30000-0x3FFFF and the UEFI Memory Map and ACPI content can be
updated so the Guest OS knows to not use that range for DMA?
Thanks,
Mike
> -----Original Message-----
> From: Paolo Bonzini [mailto:pbonzini@redhat.com]
> Sent: Thursday, August 22, 2019 3:18 PM
> To: Kinney, Michael D <michael.d.kinney@intel.com>;
> Laszlo Ersek <lersek@redhat.com>; rfc@edk2.groups.io;
> Yao, Jiewen <jiewen.yao@intel.com>
> Cc: Alex Williamson <alex.williamson@redhat.com>;
> 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
>
> On 22/08/19 22:06, Kinney, Michael D wrote:
> > The SMBASE register is internal and cannot be directly
> accessed by any
> > CPU. There is an SMBASE field that is member of the
> SMM Save State
> > area and can only be modified from SMM and requires the
> execution of
> > an RSM instruction from SMM for the SMBASE register to
> be updated from
> > the current SMBASE field value. The new SMBASE
> register value is only
> > used on the next SMI.
>
> Actually there is also an SMBASE MSR, even though in
> current silicon it's read-only and its use is
> theoretically limited to SMM-transfer monitors. If that
> MSR could be made accessible somehow outside SMM, that
> would be great.
>
> > Once all the CPUs have been initialized for SMM, the
> CPUs that are not
> > needed can be hot removed. As noted above, the SMBASE
> value does not
> > change on an INIT. So as long as the hot add operation
> does not do a
> > RESET, the SMBASE value must be preserved.
>
> IIRC, hot-remove + hot-add will unplugs/plugs a
> completely different CPU.
>
> > Another idea is to emulate this behavior. If the hot
> plug controller
> > provide registers (only accessible from SMM) to assign
> the SMBASE
> > address for every CPU. When a CPU is hot added, QEMU
> can set the
> > internal SMBASE register value from the hot plug
> controller register
> > value. If the SMM Monarch sends an INIT or an SMI from
> the Local APIC
> > to the hot added CPU, then the SMBASE register should
> not be modified
> > and the CPU starts execution within TSEG the first time
> it receives an SMI.
>
> Yes, this would work. But again---if the issue is real
> on current hardware too, I'd rather have a matching
> solution for virtual platforms.
>
> If the current hardware for example remembers INIT-
> preserved across hot-remove/hot-add, we could emulate
> that.
>
> I guess the fundamental question is: how do bare metal
> platforms avoid this issue, or plan to avoid this issue?
> Once we know that, we can use that information to find a
> way to implement it in KVM. Only if it is impossible
> we'll have a different strategy that is specific to our
> platform.
>
> Paolo
>
> > Jiewen and I can collect specific questions on this
> topic and continue
> > the discussion here. For example, I do not think there
> is any method
> > other than what I referenced above to program the
> SMBASE register, but
> > I can ask if there are any other methods.
next prev parent reply other threads:[~2019-08-22 22:32 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
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 [this message]
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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