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OvmfPkg: introduce PcdQ35SmramAtDefaultSmbase

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For supporting VCPU hotplug with SMM enabled/required, QEMU offers the
(dynamically detectable) feature called "SMRAM at default SMBASE". When
the feature is enabled, the firmware can lock down the 128 KB range
starting at the default SMBASE; that is, the [0x3_0000, 0x4_FFFF]
interval. The goal is to shield the very first SMI handler of the
hotplugged VCPU from OS influence.

Multiple modules in OVMF will have to inter-operate for locking down this
range. Introduce a dynamic PCD that will reflect the feature (to be
negotiated by PlatformPei), for coordination between drivers.

Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1512
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
Message-Id: <20200129214412.2361-2-lersek@redhat.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
This commit is contained in:
Laszlo Ersek
2019-09-20 10:56:47 +02:00
committed by mergify[bot]
parent 422da35375
commit d74d56fcfa
4 changed files with 9 additions and 0 deletions
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OvmfPkg/OvmfPkgX64.dsc
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@@ -576,6 +576,7 @@
!if $(SMM_REQUIRE) == TRUE
gUefiOvmfPkgTokenSpaceGuid.PcdQ35TsegMbytes|8
gUefiOvmfPkgTokenSpaceGuid.PcdQ35SmramAtDefaultSmbase|FALSE
gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmSyncMode|0x01
gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmApSyncTimeout|100000
!endif