Re: [edk2-devel] [PATCH v2 06/31] OvmfPkg/XenResetVector: Add new entry point for Xen PVH

["Laszlo Ersek" <lersek@redhat.com>]

On 04/09/19 13:08, Anthony PERARD wrote:
> This one enter directly in 32bits

(1) I probably mentioned this elsewhere, but it bears repeating (it
applies to all patches): please don't start the body of the commit
message mid-sentence or mid-paragraph. The body should be self-contained.

> Information on the expected state of the machine when this entry point
> is used can be found at:
> https://xenbits.xenproject.org/docs/unstable/misc/pvh.html
> 
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
> ---
>  {UefiCpuPkg/ResetVector/Vtf0 => OvmfPkg/XenResetVector}/Ia16/ResetVectorVtf0.asm | 18 +++++++-
>  OvmfPkg/XenResetVector/Ia32/XenPVHMain.asm                                       | 47 ++++++++++++++++++++
>  OvmfPkg/XenResetVector/XenResetVector.nasmb                                      |  1 +
>  3 files changed, 65 insertions(+), 1 deletion(-)
> 
> diff --git a/UefiCpuPkg/ResetVector/Vtf0/Ia16/ResetVectorVtf0.asm b/OvmfPkg/XenResetVector/Ia16/ResetVectorVtf0.asm
> similarity index 76%
> copy from UefiCpuPkg/ResetVector/Vtf0/Ia16/ResetVectorVtf0.asm
> copy to OvmfPkg/XenResetVector/Ia16/ResetVectorVtf0.asm
> index 142d9f3212..46eec66859 100644
> --- a/UefiCpuPkg/ResetVector/Vtf0/Ia16/ResetVectorVtf0.asm
> +++ b/OvmfPkg/XenResetVector/Ia16/ResetVectorVtf0.asm
> @@ -3,6 +3,8 @@
>  ; First code executed by processor after resetting.
>  ;
>  ; Copyright (c) 2008 - 2014, Intel Corporation. All rights reserved.<BR>
> +; Copyright (c) 2019, Citrix Systems, Inc.
> +;
>  ; This program and the accompanying materials
>  ; are licensed and made available under the terms and conditions of the BSD License
>  ; which accompanies this distribution.  The full text of the license may be found at

(2) Probably also mentioned elsewhere, but all the new files should come
with SPDX license IDs, if possible. (Once you rebase, such omissions
will become apparent anyway, because the copy-origin files now carry
SPDX IDs, but the copies you created earlier don't, and that will
present itself as a difference with --find-copies-harder.)

With the above two formalities fixed:

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

Thanks
Laszlo

> @@ -27,9 +29,23 @@ ALIGN   16
>  ; located just below 0x100000000 (4GB) in the firmware device.
>  ;
>  %ifdef ALIGN_TOP_TO_4K_FOR_PAGING
> -    TIMES (0x1000 - ($ - EndOfPageTables) - 0x20) DB 0
> +    TIMES (0x1000 - ($ - EndOfPageTables) - (fourGigabytes - xenPVHEntryPoint)) DB 0
>  %endif
>  
> +BITS    32
> +xenPVHEntryPoint:
> +;
> +; Entry point to use when running as a Xen PVH guest. (0xffffffd0)
> +;
> +; Description of the expected state of the machine when this entry point is
> +; used can be found at:
> +; https://xenbits.xenproject.org/docs/unstable/misc/pvh.html
> +;
> +    jmp     xenPVHMain
> +
> +BITS    16
> +ALIGN   16
> +
>  applicationProcessorEntryPoint:
>  ;
>  ; Application Processors entry point
> diff --git a/OvmfPkg/XenResetVector/Ia32/XenPVHMain.asm b/OvmfPkg/XenResetVector/Ia32/XenPVHMain.asm
> new file mode 100644
> index 0000000000..c4802bf4d1
> --- /dev/null
> +++ b/OvmfPkg/XenResetVector/Ia32/XenPVHMain.asm
> @@ -0,0 +1,47 @@
> +;------------------------------------------------------------------------------
> +; @file
> +; An entry point use by Xen when a guest is started in PVH mode.
> +;
> +; Copyright (c) 2019, Citrix Systems, Inc.
> +;
> +; This program and the accompanying materials are licensed and made available
> +; under the terms and conditions of the BSD License which accompanies this
> +; distribution.  The full text of the license may be found at
> +; http://opensource.org/licenses/bsd-license.php
> +;
> +; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT
> +; WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
> +;
> +;------------------------------------------------------------------------------
> +
> +BITS    32
> +
> +xenPVHMain:
> +    mov     di, 'BP'
> +
> +    ; ESP -  Initial value of the EAX register (BIST: Built-in Self Test)
> +    mov     esp, eax
> +
> +    cli
> +
> +    mov     ebx, ADDR_OF(gdtr)
> +    lgdt    [ebx]
> +
> +    mov     eax, SEC_DEFAULT_CR0
> +    mov     cr0, eax
> +
> +    jmp     LINEAR_CODE_SEL:ADDR_OF(.jmpToNewCodeSeg)
> +.jmpToNewCodeSeg:
> +
> +    mov     eax, SEC_DEFAULT_CR4
> +    mov     cr4, eax
> +
> +    mov     ax, LINEAR_SEL
> +    mov     ds, ax
> +    mov     es, ax
> +    mov     fs, ax
> +    mov     gs, ax
> +    mov     ss, ax
> +
> +    ; return to the Main16
> +    OneTimeCallRet TransitionFromReal16To32BitFlat
> diff --git a/OvmfPkg/XenResetVector/XenResetVector.nasmb b/OvmfPkg/XenResetVector/XenResetVector.nasmb
> index 49f2bab001..d5a791c139 100644
> --- a/OvmfPkg/XenResetVector/XenResetVector.nasmb
> +++ b/OvmfPkg/XenResetVector/XenResetVector.nasmb
> @@ -70,6 +70,7 @@
>  %include "Ia16/Init16.asm"
>  
>  %include "Main.asm"
> +%include "Ia32/XenPVHMain.asm"
>  
>  %include "Ia16/ResetVectorVtf0.asm"
>  
>