From: Igor Mammedov <imammedo@redhat.com>
To: "Laszlo Ersek" <lersek@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 10:28:55 +0200 [thread overview]
Message-ID: <20190920102855.3fe2b689@redhat.com> (raw)
In-Reply-To: <561f4440-7c06-10d7-80ce-bbfa810fec59@redhat.com>
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.
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.
next prev parent reply other threads:[~2019-09-20 8:30 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 ` Igor Mammedov [this message]
2019-09-20 9:28 ` [edk2-devel] " Laszlo Ersek
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
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