| Message ID | 20190409110844.14746-7-anthony.perard@citrix.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Specific platform to run OVMF in Xen PVH and HVM guests | expand |
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" > >
On 09/04/2019 12:08, Anthony PERARD wrote: > 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 Where is the ABI described? Xen has no BIST, so this will always have the value 0. Stashing it in the stack pointer seems like a weird choice, and a recipe for subtle bugs. > + > + cli Interrupts are guaranteed to be off at this point. > + > + mov ebx, ADDR_OF(gdtr) > + lgdt [ebx] lgdt ADDR_OF(gdtr), presumably? This is 32bit code - there is no need for any indirection through registers for memory operands. > + > + 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 Is there any description of what OneTimeCallRet is, and why a simple jmp wont do? Irrespective of that, you're moving to a function whose name suggests it is in 16bit mode, while you are currently in 32bit flat mode. (SEC_DEFAULT_CR0 has PE set, and LINEAR_SEL is 32bit flat. This clearly isn't correct, but surely we want to skip all the 16bit setup, as well. ~Andrew
On Thu, Apr 11, 2019 at 01:52:27PM +0100, Andrew Cooper wrote: > On 09/04/2019 12:08, Anthony PERARD wrote: > > 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 > > Where is the ABI described? Xen has no BIST, so this will always have > the value 0. Stashing it in the stack pointer seems like a weird choice, > and a recipe for subtle bugs. I've just copied over what was done in the HVM case. I'll change that and ignore the value in `eax'. > > + > > + cli > > Interrupts are guaranteed to be off at this point. OK, I'll remove the instruction. > > + > > + mov ebx, ADDR_OF(gdtr) > > + lgdt [ebx] > > lgdt ADDR_OF(gdtr), presumably? > > This is 32bit code - there is no need for any indirection through > registers for memory operands. I'll change this, if it works. > > + > > + 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 > > Is there any description of what OneTimeCallRet is, and why a simple jmp > wont do? That's is used to return to where the `OneTimeCall' macro has been used. In this assembly, they don't use `call' and `ret', instead there is a set of two macros: %macro OneTimeCall 1 jmp %1 %1 %+ OneTimerCallReturn: %endmacro %macro OneTimeCallRet 1 jmp %1 %+ OneTimerCallReturn %endmacro > Irrespective of that, you're moving to a function whose name suggests it > is in 16bit mode, while you are currently in 32bit flat mode. > (SEC_DEFAULT_CR0 has PE set, and LINEAR_SEL is 32bit flat. This clearly > isn't correct, but surely we want to skip all the 16bit setup, as well. I think I need to change the comment. Main16 is just a label name for something that makes several "calls" and transition from 16bits to 32 or 64 before calling the next module in the firmware. That return simply jmp to the part of the main where we are supposed to be in 32bit flat mode. Thanks for the review,
On 15/04/2019 12:25, Anthony PERARD wrote: > On Thu, Apr 11, 2019 at 01:52:27PM +0100, Andrew Cooper wrote: >> On 09/04/2019 12:08, Anthony PERARD wrote: >>> 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 >> Where is the ABI described? Xen has no BIST, so this will always have >> the value 0. Stashing it in the stack pointer seems like a weird choice, >> and a recipe for subtle bugs. > I've just copied over what was done in the HVM case. I'll change that > and ignore the value in `eax'. The ASCII BP in %di is also bizarre without an explanation of where it is intended to be used. >>> + >>> + 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 >> Is there any description of what OneTimeCallRet is, and why a simple jmp >> wont do? > That's is used to return to where the `OneTimeCall' macro has been > used. In this assembly, they don't use `call' and `ret', instead there > is a set of two macros: > > %macro OneTimeCall 1 > jmp %1 > %1 %+ OneTimerCallReturn: > %endmacro > > %macro OneTimeCallRet 1 > jmp %1 %+ OneTimerCallReturn > %endmacro I found these, but the complete lack of any documentation makes them entirely opaque, especially as they are not actually call/ret instructions. Even if they are suppose to be used in matching pairs, OneTimeCall hasn't been used so far in the PVH code, so where is this going to actually go to? ~Andrew
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 @@ -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"
This one enter directly in 32bits 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(-)