On 07/18/19 08:58, Ni, Ray wrote:
> Commit c60d36b4d1ee1f69b7cca897d3621dfa951895c2
> * UefiCpuPkg/SmmCpu: Block access-out only when static paging is used
>
> updated page fault handler to treat SMM access-out as allowed
> address when static paging is not used.
>
> But that commit is not complete because the page table is still
> updated in SetUefiMemMapAttributes() for non-SMRAM memory. When SMM
> code accesses non-SMRAM memory, page fault is still generated.
>
> This patch skips to update page table for non-SMRAM memory and
> page table itself.
>
> Signed-off-by: Ray Ni <ray...@intel.com>
> Cc: Eric Dong <eric.d...@intel.com>
> Cc: Jiewen Yao <jiewen....@intel.com>
> Cc: Jian J Wang <jian.j.w...@intel.com>
> ---
> UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c | 21 +++++++++++++++------
> 1 file changed, 15 insertions(+), 6 deletions(-)
>
> diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c
> b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c
> index 2f7d777ee7..f75e75f55c 100644
> --- a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c
> +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c
> @@ -1103,6 +1103,9 @@ FindSmramInfo (
> *SmrrBase = (UINT32)CurrentSmramRange->CpuStart;
> *SmrrSize = (UINT32)CurrentSmramRange->PhysicalSize;
>
> + //
> + // Extend *SmrrBase/*SmrrSize to include adjacent SMRAM ranges
> + //
> do {
> Found = FALSE;
> for (Index = 0; Index < mSmmCpuSmramRangeCount; Index++) {
> @@ -1414,14 +1417,20 @@ PerformRemainingTasks (
> SetMemMapAttributes ();
>
> //
> - // For outside SMRAM, we only map SMM communication buffer or MMIO.
> + // Do not protect memory outside SMRAM when SMM static page table is not
> enabled.
> //
> - SetUefiMemMapAttributes ();
> + if (mCpuSmmStaticPageTable) {
>
> - //
> - // Set page table itself to be read-only
> - //
> - SetPageTableAttributes ();
> + //
> + // For outside SMRAM, we only map SMM communication buffer or MMIO.
> + //
> + SetUefiMemMapAttributes ();
> +
> + //
> + // Set page table itself to be read-only
> + //
> + SetPageTableAttributes ();
> + }
>
> //
> // Configure SMM Code Access Check feature if available.
>
This patch is a no-op for platforms with PcdCpuSmmStaticPageTable=TRUE
(which is both the UefiCpuPkg default and what OVMF uses), so, from my side:
Acked-by: Laszlo Ersek <ler...@redhat.com>
Thanks
Laszlo
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