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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [edk2-devel] [PATCH v5 08/35] OvmfPkg/XenResetVector: Allow jumpstart from either hvmloader or PVH
Hi Anthony, On 08/13/19 13:30, Anthony PERARD wrote: > This patch allows the ResetVector to be run indenpendently from build > time addresses. > > The goal of the patch is to avoid having to create RAM just below 4G > when creating a Xen PVH guest while being compatible with the way > hvmloader currently load OVMF, just below 4G. > > Only the new PVH entry point will do the calculation. > > The ResetVector will figure out its current running address by creating > a temporary stack, make a call and calculate the difference between the > build time address and the address at run time. > > This patch copies and make the necessary modification to some other asm > files: > - copy of UefiCpuPkg/.../Flat32ToFlat64.asm: > Allow Transition32FlatTo64Flat to be run from anywhere in memory > - copy of UefiCpuPkg/../SearchForBfvBase.asm: > Add a extra parameter to indicate where to start the search for the > boot firmware volume. > > Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1689 > Signed-off-by: Anthony PERARD <anthony.perard@xxxxxxxxxx> > Acked-by: Laszlo Ersek <lersek@xxxxxxxxxx> > --- > > Notes: > v3: > - rebased, SPDX > - fix commit message > > .../XenResetVector/Ia16/Real16ToFlat32.asm | 3 + > .../XenResetVector/Ia32/Flat32ToFlat64.asm | 68 +++++++++++++++ > .../XenResetVector/Ia32/SearchForBfvBase.asm | 87 +++++++++++++++++++ > OvmfPkg/XenResetVector/Ia32/XenPVHMain.asm | 43 +++++++-- > 4 files changed, 194 insertions(+), 7 deletions(-) > create mode 100644 OvmfPkg/XenResetVector/Ia32/Flat32ToFlat64.asm > create mode 100644 OvmfPkg/XenResetVector/Ia32/SearchForBfvBase.asm > > diff --git a/OvmfPkg/XenResetVector/Ia16/Real16ToFlat32.asm > b/OvmfPkg/XenResetVector/Ia16/Real16ToFlat32.asm > index 5c329bfaea..36ea74f7fe 100644 > --- a/OvmfPkg/XenResetVector/Ia16/Real16ToFlat32.asm > +++ b/OvmfPkg/XenResetVector/Ia16/Real16ToFlat32.asm > @@ -54,6 +54,9 @@ jumpTo32BitAndLandHere: > mov gs, ax > mov ss, ax > > + ; parameter for Flat32SearchForBfvBase > + xor eax, eax ; Start searching from top of 4GB for BfvBase > + > OneTimeCallRet TransitionFromReal16To32BitFlat > > ALIGN 2 > diff --git a/OvmfPkg/XenResetVector/Ia32/Flat32ToFlat64.asm > b/OvmfPkg/XenResetVector/Ia32/Flat32ToFlat64.asm > new file mode 100644 > index 0000000000..661a8e7028 > --- /dev/null > +++ b/OvmfPkg/XenResetVector/Ia32/Flat32ToFlat64.asm > @@ -0,0 +1,68 @@ > +;------------------------------------------------------------------------------ > +; @file > +; Transition from 32 bit flat protected mode into 64 bit flat protected mode > +; > +; Copyright (c) 2008 - 2018, Intel Corporation. All rights reserved.<BR> > +; Copyright (c) 2019, Citrix Systems, Inc. > +; > +; SPDX-License-Identifier: BSD-2-Clause-Patent > +; > +;------------------------------------------------------------------------------ > + > +BITS 32 > + > +; > +; Modified: EAX, EBX, ECX, EDX, ESP > +; > +Transition32FlatTo64Flat: > + > + OneTimeCall SetCr3ForPageTables64 > + > + mov eax, cr4 > + bts eax, 5 ; enable PAE > + mov cr4, eax > + > + mov ecx, 0xc0000080 > + rdmsr > + bts eax, 8 ; set LME > + wrmsr > + > + mov eax, cr0 > + bts eax, 31 ; set PG > + mov cr0, eax ; enable paging > + > + ; > + ; backup ESP > + ; > + mov ebx, esp > + > + ; > + ; recalculate delta > + ; > + mov esp, PVH_SPACE(16) > + call .delta > +.delta: > + pop edx > + sub edx, ADDR_OF(.delta) > + > + ; > + ; push return addr and seg to the stack, then return far > + ; > + push dword LINEAR_CODE64_SEL > + mov eax, ADDR_OF(jumpTo64BitAndLandHere) > + add eax, edx ; add delta > + push eax > + retf > + > +BITS 64 > +jumpTo64BitAndLandHere: > + > + ; > + ; restore ESP > + ; > + mov esp, ebx > + > + debugShowPostCode POSTCODE_64BIT_MODE > + > + OneTimeCallRet Transition32FlatTo64Flat > + > diff --git a/OvmfPkg/XenResetVector/Ia32/SearchForBfvBase.asm > b/OvmfPkg/XenResetVector/Ia32/SearchForBfvBase.asm > new file mode 100644 > index 0000000000..190389c46f > --- /dev/null > +++ b/OvmfPkg/XenResetVector/Ia32/SearchForBfvBase.asm > @@ -0,0 +1,87 @@ > +;------------------------------------------------------------------------------ > +; @file > +; Search for the Boot Firmware Volume (BFV) base address > +; > +; Copyright (c) 2008 - 2009, Intel Corporation. All rights reserved.<BR> > +; Copyright (c) 2019, Citrix Systems, Inc. > +; > +; SPDX-License-Identifier: BSD-2-Clause-Patent > +; > +;------------------------------------------------------------------------------ > + > +;#define EFI_FIRMWARE_FILE_SYSTEM2_GUID \ > +; { 0x8c8ce578, 0x8a3d, 0x4f1c, { 0x99, 0x35, 0x89, 0x61, 0x85, 0xc3, 0x2d, > 0xd3 } } > +%define FFS_GUID_DWORD0 0x8c8ce578 > +%define FFS_GUID_DWORD1 0x4f1c8a3d > +%define FFS_GUID_DWORD2 0x61893599 > +%define FFS_GUID_DWORD3 0xd32dc385 > + > +BITS 32 > + > +; > +; Modified: EAX, EBX, ECX > +; Preserved: EDI, ESP > +; > +; @param[in] EAX Start search from here > +; @param[out] EBP Address of Boot Firmware Volume (BFV) > +; > +Flat32SearchForBfvBase: > + > + mov ecx, eax > +searchingForBfvHeaderLoop: > + ; > + ; We check for a firmware volume at every 4KB address in the 16MB > + ; just below where we started, ECX. > + ; > + sub eax, 0x1000 > + mov ebx, ecx > + sub ebx, eax > + cmp ebx, 0x01000000 > + ; if ECX-EAX > 16MB; jump notfound > + ja searchedForBfvHeaderButNotFound > + > + ; > + ; Check FFS GUID > + ; > + cmp dword [eax + 0x10], FFS_GUID_DWORD0 > + jne searchingForBfvHeaderLoop > + cmp dword [eax + 0x14], FFS_GUID_DWORD1 > + jne searchingForBfvHeaderLoop > + cmp dword [eax + 0x18], FFS_GUID_DWORD2 > + jne searchingForBfvHeaderLoop > + cmp dword [eax + 0x1c], FFS_GUID_DWORD3 > + jne searchingForBfvHeaderLoop > + > + ; > + ; Check FV Length > + ; > + cmp dword [eax + 0x24], 0 > + jne searchingForBfvHeaderLoop > + mov ebx, eax > + add ebx, dword [eax + 0x20] > + cmp ebx, ecx > + jnz searchingForBfvHeaderLoop > + > + jmp searchedForBfvHeaderAndItWasFound > + > +searchedForBfvHeaderButNotFound: > + ; > + ; Hang if the SEC entry point was not found > + ; > + debugShowPostCode POSTCODE_BFV_NOT_FOUND > + > + ; > + ; 0xbfbfbfbf in the EAX & EBP registers helps signal what failed > + ; for debugging purposes. > + ; > + mov eax, 0xBFBFBFBF > + mov ebp, eax > + jmp $ > + > +searchedForBfvHeaderAndItWasFound: > + mov ebp, eax > + > + debugShowPostCode POSTCODE_BFV_FOUND > + > + OneTimeCallRet Flat32SearchForBfvBase > + > diff --git a/OvmfPkg/XenResetVector/Ia32/XenPVHMain.asm > b/OvmfPkg/XenResetVector/Ia32/XenPVHMain.asm > index f42df3dba2..2df0f12e18 100644 > --- a/OvmfPkg/XenResetVector/Ia32/XenPVHMain.asm > +++ b/OvmfPkg/XenResetVector/Ia32/XenPVHMain.asm > @@ -16,25 +16,42 @@ xenPVHMain: > ; > mov di, 'BP' > > - ; > - ; ESP will be used as initial value of the EAX register > - ; in Main.asm > - ; > - xor esp, esp > - > ; > ; Store "Start of day" struct pointer for later use > ; > mov dword[PVH_SPACE (0)], ebx > mov dword[PVH_SPACE (4)], 'XPVH' > > + ; > + ; calculate delta between build-addr and run position > + ; > + mov esp, PVH_SPACE(16) ; create a temporary stack > + call .delta > +.delta: > + pop edx ; get addr of .delta > + sub edx, ADDR_OF(.delta) ; calculate delta > + > + ; > + ; Find address of GDT and gdtr and fix the later > + ; > mov ebx, ADDR_OF(gdtr) > + add ebx, edx ; add delta gdtr > + mov eax, ADDR_OF(GDT_BASE) > + add eax, edx ; add delta to GDT_BASE > + mov dword[ebx + 2], eax ; fix GDT_BASE addr in gdtr > lgdt [ebx] > > mov eax, SEC_DEFAULT_CR0 > mov cr0, eax > > - jmp LINEAR_CODE_SEL:ADDR_OF(.jmpToNewCodeSeg) > + ; > + ; push return addr to the stack, then return far > + ; > + push dword LINEAR_CODE_SEL ; segment to select > + mov eax, ADDR_OF(.jmpToNewCodeSeg) ; return addr > + add eax, edx ; add delta to return addr > + push eax > + retf > .jmpToNewCodeSeg: > > mov eax, SEC_DEFAULT_CR4 > @@ -47,6 +64,18 @@ xenPVHMain: > mov gs, ax > mov ss, ax > > + ; > + ; ESP will be used as initial value of the EAX register > + ; in Main.asm > + ; > + xor esp, esp > + > + ; > + ; parameter for Flat32SearchForBfvBase > + ; > + mov eax, ADDR_OF(fourGigabytes) I've just noticed that the line above triggers the following NASM warning: Ia32/XenPVHMain.asm:76: warning: dword data exceeds bounds The warning does not stop the build. The macro comes from "UefiCpuPkg/ResetVector/Vtf0/CommonMacros.inc": %define ADDR_OF(x) (0x100000000 - fourGigabytes + x) So I believe we effectively store 0 to EAX. If that's the intent (I think it *could* be), please submit a cleanup in the next development cycle -- we could store a 0 explicitly and add a comment, just to shut up the warning. If, on the other hand, this is a bug, please submit a fix soon (for the upcoming release). Thanks Laszlo > + add eax, edx ; add delta > + > ; > ; Jump to the main routine of the pre-SEC code > ; skiping the 16-bit part of the routine and > _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/mailman/listinfo/xen-devel
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