From: Laszlo Ersek <lersek@redhat.com>
To: Igor Mammedov <imammedo@redhat.com>
Cc: yingwen.chen@intel.com, Brijesh Singh <brijesh.singh@amd.com>,
devel@edk2.groups.io, phillip.goerl@oracle.com,
qemu-devel@nongnu.org, alex.williamson@redhat.com,
jiewen.yao@intel.com, jun.nakajima@intel.com,
michael.d.kinney@intel.com, pbonzini@redhat.com,
boris.ostrovsky@oracle.com, rfc@edk2.groups.io,
joao.m.martins@oracle.com
Subject: Re: [edk2-devel] [Qemu-devel] [PATCH 1/2] q35: implement 128K SMRAM at default SMBASE address
Date: Fri, 20 Sep 2019 11:28:22 +0200 [thread overview]
Message-ID: <a581abbc-ec03-c332-b225-6f7cd3cfadae@redhat.com> (raw)
In-Reply-To: <20190920102855.3fe2b689@redhat.com>
On 09/20/19 10:28, Igor Mammedov wrote:
> On Thu, 19 Sep 2019 19:02:07 +0200
> "Laszlo Ersek" <lersek@redhat.com> wrote:
>
>> Hi Igor,
>>
>> (+Brijesh)
>>
>> long-ish pondering ahead, with a question at the end.
> [...]
>
>> Finally: can you please remind me why we lock down 128KB (32 pages) at
>> 0x3_0000, and not just half of that? What do we need the range at
>> [0x4_0000..0x4_FFFF] for?
>
>
> If I recall correctly, CPU consumes 64K of save/restore area.
> The rest 64K are temporary RAM for using in SMI relocation handler,
> if it's possible to get away without it then we can drop it and
> lock only 64K required for CPU state. It won't help with SEV
> conflict though as it's in the first 64K.
OK. Let's go with 128KB for now. Shrinking the area is always easier
than growing it.
> On QEMU side, we can drop black-hole approach and allocate
> dedicated SMRAM region, which explicitly gets mapped into
> RAM address space and after SMI hanlder initialization, gets
> unmapped (locked). So that SMRAM would be accessible only
> from SMM context. That way RAM at 0x30000 could be used as
> normal when SMRAM is unmapped.
I prefer the black-hole approach, introduced in your current patch
series, if it can work. Way less opportunity for confusion.
I've started work on the counterpart OVMF patches; I'll report back.
Thanks
Laszlo
next prev parent reply other threads:[~2019-09-20 9:37 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-17 13:07 [Qemu-devel] [PATCH 0/2] q35: mch: allow to lock down 128K RAM at default SMBASE address Igor Mammedov
2019-09-17 13:07 ` [Qemu-devel] [PATCH 1/2] q35: implement 128K SMRAM " Igor Mammedov
2019-09-19 17:02 ` Laszlo Ersek
2019-09-20 8:28 ` [edk2-devel] " Igor Mammedov
2019-09-20 9:28 ` Laszlo Ersek [this message]
2019-09-23 18:35 ` Laszlo Ersek
2019-09-24 11:19 ` Igor Mammedov
2019-09-30 11:51 ` Laszlo Ersek
2019-09-30 12:36 ` Igor Mammedov
2019-09-30 14:22 ` Yao, Jiewen
2019-10-01 18:03 ` Laszlo Ersek
2019-10-04 11:31 ` Igor Mammedov
2019-10-07 9:44 ` Laszlo Ersek
2019-09-24 11:47 ` Paolo Bonzini
2019-09-17 13:07 ` [Qemu-devel] [PATCH 2/2] tests: q35: MCH: add default SMBASE SMRAM lock test Igor Mammedov
2019-09-17 15:23 ` [Qemu-devel] [edk2-devel] [PATCH 0/2] q35: mch: allow to lock down 128K RAM at default SMBASE address no-reply
2019-09-17 15:24 ` no-reply
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=a581abbc-ec03-c332-b225-6f7cd3cfadae@redhat.com \
--to=lersek@redhat.com \
--cc=alex.williamson@redhat.com \
--cc=boris.ostrovsky@oracle.com \
--cc=brijesh.singh@amd.com \
--cc=devel@edk2.groups.io \
--cc=imammedo@redhat.com \
--cc=jiewen.yao@intel.com \
--cc=joao.m.martins@oracle.com \
--cc=jun.nakajima@intel.com \
--cc=michael.d.kinney@intel.com \
--cc=pbonzini@redhat.com \
--cc=phillip.goerl@oracle.com \
--cc=qemu-devel@nongnu.org \
--cc=rfc@edk2.groups.io \
--cc=yingwen.chen@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.