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To: Ruiyu Ni <ruiyu.ni@intel.com>, edk2-devel@lists.01.org
Cc: Jiewen Yao <jiewen.yao@intel.com>, Eric Dong <eric.dong@intel.com>
References: <20181107085907.158392-1-ruiyu.ni@intel.com>
From: Laszlo Ersek <lersek@redhat.com>
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Date: Wed, 7 Nov 2018 15:46:28 +0100
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 (mx1.redhat.com [10.5.110.30]); Wed, 07 Nov 2018 14:46:31 +0000 (UTC)
Subject: Re: [PATCH v2] UefiCpuPkg/SmmCpu: Block access-out only when static paging is used
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On 11/07/18 09:59, Ruiyu Ni wrote:
> From: Jiewen Yao <jiewen.yao@intel.com>
> 
> When static paging is disabled, page table for below 4GB is created
> and page table for above 4GB is created dynamically in page fault
> handler.
> 
> Today's implementation only allow SMM access-out to below types of
> memory address no matter static paging is enabled or not:
> 1. Reserved, run time and ACPI NVS type
> 2. MMIO
> 
> But certain platform feature like RAS may need to access other types
> of memory from SMM. Today's code blocks these platforms.
> This patch simplifies the policy to only block when static paging
> is used so that the static paging can be disabled in these platforms
> to meet their SMM access-out need.
> 
> Setting PcdCpuSmmStaticPageTable to FALSE can disable the static
> paging.
> 
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Jiewen Yao <jiewen.yao@intel.com>
> Signed-off-by: Ruiyu Ni <ruiyu.ni@intel.com>
> Cc: Eric Dong <eric.dong@intel.com>
> Cc: Jiewen Yao <jiewen.yao@intel.com>
> Acked-by: Laszlo Ersek <lersek@redhat.com>
> ---
>  UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

Thanks, this has improved a lot!
Laszlo