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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v2 08/31] OvmfPkg/XenResetVector: Allow to jumpstart from either hvmloader or PVH
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 been 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 been runnned 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.
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
---
OvmfPkg/XenResetVector/Ia16/Real16ToFlat32.asm
| 3 ++
{UefiCpuPkg/ResetVector/Vtf0 =>
OvmfPkg/XenResetVector}/Ia32/Flat32ToFlat64.asm | 25 ++++++++++++++--
{UefiCpuPkg/ResetVector/Vtf0 =>
OvmfPkg/XenResetVector}/Ia32/SearchForBfvBase.asm | 19 +++++++++----
OvmfPkg/XenResetVector/Ia32/XenPVHMain.asm
| 30 ++++++++++++++++++--
4 files changed, 66 insertions(+), 11 deletions(-)
diff --git a/OvmfPkg/XenResetVector/Ia16/Real16ToFlat32.asm
b/OvmfPkg/XenResetVector/Ia16/Real16ToFlat32.asm
index e22e92c8a6..eebced6ced 100644
--- a/OvmfPkg/XenResetVector/Ia16/Real16ToFlat32.asm
+++ b/OvmfPkg/XenResetVector/Ia16/Real16ToFlat32.asm
@@ -61,6 +61,9 @@ 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/UefiCpuPkg/ResetVector/Vtf0/Ia32/Flat32ToFlat64.asm
b/OvmfPkg/XenResetVector/Ia32/Flat32ToFlat64.asm
similarity index 69%
copy from UefiCpuPkg/ResetVector/Vtf0/Ia32/Flat32ToFlat64.asm
copy to OvmfPkg/XenResetVector/Ia32/Flat32ToFlat64.asm
index 5b6b375330..ca03ea43e0 100644
--- a/UefiCpuPkg/ResetVector/Vtf0/Ia32/Flat32ToFlat64.asm
+++ b/OvmfPkg/XenResetVector/Ia32/Flat32ToFlat64.asm
@@ -3,6 +3,8 @@
; 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.
+;
; 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
@@ -16,7 +18,7 @@
BITS 32
;
-; Modified: EAX
+; Modified: EAX, EBX, ECX, EDX, ESP
;
Transition32FlatTo64Flat:
@@ -35,10 +37,29 @@ Transition32FlatTo64Flat:
bts eax, 31 ; set PG
mov cr0, eax ; enable paging
- jmp LINEAR_CODE64_SEL:ADDR_OF(jumpTo64BitAndLandHere)
+ ; 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/UefiCpuPkg/ResetVector/Vtf0/Ia32/SearchForBfvBase.asm
b/OvmfPkg/XenResetVector/Ia32/SearchForBfvBase.asm
similarity index 83%
copy from UefiCpuPkg/ResetVector/Vtf0/Ia32/SearchForBfvBase.asm
copy to OvmfPkg/XenResetVector/Ia32/SearchForBfvBase.asm
index d0c2d8c39c..0519e05601 100644
--- a/UefiCpuPkg/ResetVector/Vtf0/Ia32/SearchForBfvBase.asm
+++ b/OvmfPkg/XenResetVector/Ia32/SearchForBfvBase.asm
@@ -3,6 +3,8 @@
; 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.
+;
; 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
@@ -23,22 +25,26 @@
BITS 32
;
-; Modified: EAX, EBX
+; Modified: EAX, EBX, ECX
; Preserved: EDI, ESP
;
+; @param[in] EAX Start search from here
; @param[out] EBP Address of Boot Firmware Volume (BFV)
;
Flat32SearchForBfvBase:
- xor eax, eax
+ mov ecx, eax
searchingForBfvHeaderLoop:
;
- ; We check for a firmware volume at every 4KB address in the top 16MB
- ; just below 4GB. (Addresses at 0xffHHH000 where H is any hex digit.)
+ ; We check for a firmware volume at every 4KB address in the 16MB
+ ; just below where we started, ECX.
;
sub eax, 0x1000
- cmp eax, 0xff000000
- jb searchedForBfvHeaderButNotFound
+ mov ebx, ecx
+ sub ebx, eax
+ cmp ebx, 0x01000000
+ ; if ECX-EAX > 16MB; jump notfound
+ ja searchedForBfvHeaderButNotFound
;
; Check FFS GUID
@@ -59,6 +65,7 @@ searchingForBfvHeaderLoop:
jne searchingForBfvHeaderLoop
mov ebx, eax
add ebx, dword [eax + 0x20]
+ cmp ebx, ecx
jnz searchingForBfvHeaderLoop
jmp searchedForBfvHeaderAndItWasFound
diff --git a/OvmfPkg/XenResetVector/Ia32/XenPVHMain.asm
b/OvmfPkg/XenResetVector/Ia32/XenPVHMain.asm
index 4e55b0ac1f..612b2e9c44 100644
--- a/OvmfPkg/XenResetVector/Ia32/XenPVHMain.asm
+++ b/OvmfPkg/XenResetVector/Ia32/XenPVHMain.asm
@@ -19,22 +19,39 @@ BITS 32
xenPVHMain:
mov di, 'BP'
- ; ESP - Initial value of the EAX register (BIST: Built-in Self Test)
- mov esp, eax
+ ; EBP - Initial value of the EAX register (BIST: Built-in Self Test)
+ mov ebp, eax
;; 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
+
cli
+ ;; 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
@@ -47,5 +64,12 @@ xenPVHMain:
mov gs, ax
mov ss, ax
+ ; ESP - Initial value of the EAX register (BIST: Built-in Self Test)
+ mov esp, ebp
+
+ ; parameter for Flat32SearchForBfvBase
+ mov eax, ADDR_OF(fourGigabytes)
+ add eax, edx ; add delta
+
; return to the Main16
OneTimeCallRet TransitionFromReal16To32BitFlat
--
Anthony PERARD
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