Re: [PATCH v2 1/1] OvmfPkg/BaseMemEncryptSevLib: Enable protection for newly added page table

[Laszlo Ersek <lersek@redhat.com>]

On 01/11/18 20:51, Brijesh Singh wrote:
> Commit 2ac1730bf2a5 (MdeModulePkg/DxeIpl: Mark page table as read-only)
> sets the memory pages used for page table as read-only after paging is
> setup and sets CR0.WP to protect CPU modifying the read-only pages.
> The commit causes #PF when MemEncryptSevClearPageEncMask() or
> MemEncryptSevSetPageEncMask() tries to change the page-table attributes.
> 
> This patch takes the similar approach as Commit 147fd35c3e38
> (UefiCpuPkg/CpuDxe: Enable protection for newly added page table).
> When page table protection is enabled, we disable it temporarily before
> changing the page table attributes.
> 
> This patch makes use of the same approach as Commit 2ac1730bf2a5
> (MdeModulePkg/DxeIpl: Mark page table as read-only)) for allocating
> page table memory from reserved memory pool, which helps to reduce a
> potential "split" operation.
> 
> The patch duplicates code from commit 147fd35c3e38. The code duplication
> will be removed after we implement page table manipulation library. See
> bugzilla https://bugzilla.tianocore.org/show_bug.cgi?id=847.
> 
> Cc: Jian J Wang <jian.j.wang@intel.com>
> Cc: Jiewen Yao <jiewen.yao@intel.com>
> Cc: Jordan Justen <jordan.l.justen@intel.com>
> Cc: Laszlo Ersek <lersek@redhat.com>
> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
> ---
>  .../BaseMemEncryptSevLib/X64/VirtualMemory.c       | 378 ++++++++++++++++++++-
>  .../BaseMemEncryptSevLib/X64/VirtualMemory.h       |  28 ++
>  2 files changed, 399 insertions(+), 7 deletions(-)
> 

Sorry about the delay -- it was delivered to my mailbox late in the
evening on last Thursday, and on Friday I was out-of-office. Today there
has been some catching up with accumulated email...

Acked-by: Laszlo Ersek <lersek@redhat.com>

Pushed as commit b721aa749b86.

Thank you,
Laszlo