| 1 | /** @file
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| 2 | Install a fake VGABIOS service handler (real mode Int10h) for the buggy
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| 3 | Windows 2008 R2 SP1 UEFI guest.
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| 4 |
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| 5 | The handler is never meant to be directly executed by a VCPU; it's there for
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| 6 | the internal real mode emulator of Windows 2008 R2 SP1.
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| 7 |
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| 8 | The code is based on Ralf Brown's Interrupt List:
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| 9 | <http://www.cs.cmu.edu/~ralf/files.html>
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| 10 | <http://www.ctyme.com/rbrown.htm>
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| 11 |
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| 12 | Copyright (C) 2020, Rebecca Cran <[email protected]>
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| 13 | Copyright (C) 2015, Nahanni Systems, Inc.
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| 14 | Copyright (C) 2014, Red Hat, Inc.
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| 15 | Copyright (c) 2013 - 2014, Intel Corporation. All rights reserved.<BR>
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| 16 |
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| 17 | SPDX-License-Identifier: BSD-2-Clause-Patent
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| 18 |
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| 19 | **/
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| 20 |
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| 21 | #include <IndustryStandard/LegacyVgaBios.h>
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| 22 | #include <Library/DebugLib.h>
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| 23 | #include <Library/PciLib.h>
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| 24 | #include <Library/PrintLib.h>
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| 25 |
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| 26 | #include "Gop.h"
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| 27 | #include "VbeShim.h"
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| 28 |
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| 29 | #pragma pack (1)
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| 30 | typedef struct {
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| 31 | UINT16 Offset;
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| 32 | UINT16 Segment;
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| 33 | } IVT_ENTRY;
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| 34 | #pragma pack ()
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| 35 |
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| 36 | //
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| 37 | // This string is displayed by Windows 2008 R2 SP1 in the Screen Resolution,
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| 38 | // Advanced Settings dialog. It should be short.
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| 39 | //
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| 40 | STATIC CONST CHAR8 mProductRevision[] = "2.0";
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| 41 |
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| 42 | #define NUM_VBE_MODES 3
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| 43 | STATIC CONST UINT16 vbeModeIds[] = {
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| 44 | 0x13f, // 640x480x32
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| 45 | 0x140, // 800x600x32
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| 46 | 0x141 // 1024x768x32
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| 47 | };
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| 48 |
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| 49 | // Modes can be toggled with bit-0
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| 50 | #define VBE_MODE_ENABLED 0x00BB
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| 51 | #define VBE_MODE_DISABLED 0x00BA
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| 52 |
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| 53 | STATIC VBE2_MODE_INFO vbeModes[] = {
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| 54 | { // 0x13f 640x480x32
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| 55 | // ModeAttr - BytesPerScanLine
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| 56 | VBE_MODE_DISABLED, 0x07, 0x00, 0x40, 0x40, 0xA000, 0x00, 0x0000, 640*4,
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| 57 | // Width, Height..., Vbe3
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| 58 | 640, 480, 16, 8, 1, 32, 1, 0x06, 0, 0, 1,
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| 59 | // Masks
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| 60 | 0x08, 0x10, 0x08, 0x08, 0x08, 0x00, 0x08, 0x18, 0x00,
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| 61 | // Framebuffer
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| 62 | 0xdeadbeef, 0x0000, 0x0000
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| 63 | },
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| 64 | { // 0x140 800x600x32
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| 65 | // ModeAttr - BytesPerScanLine
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| 66 | VBE_MODE_DISABLED, 0x07, 0x00, 0x40, 0x40, 0xA000, 0x00, 0x0000, 800*4,
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| 67 | // Width, Height..., Vbe3
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| 68 | 800, 600, 16, 8, 1, 32, 1, 0x06, 0, 0, 1,
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| 69 | // Masks
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| 70 | 0x08, 0x10, 0x08, 0x08, 0x08, 0x00, 0x08, 0x18, 0x00,
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| 71 | // Framebuffer
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| 72 | 0xdeadbeef, 0x0000, 0x0000
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| 73 | },
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| 74 | { // 0x141 1024x768x32
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| 75 | // ModeAttr - BytesPerScanLine
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| 76 | VBE_MODE_ENABLED, 0x07, 0x00, 0x40, 0x40, 0xA000, 0x00, 0x0000, 1024*4,
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| 77 | // Width, Height..., Vbe3
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| 78 | 1024, 768, 16, 8, 1, 32, 1, 0x06, 0, 0, 1,
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| 79 | // Masks
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| 80 | 0x08, 0x10, 0x08, 0x08, 0x08, 0x00, 0x08, 0x18, 0x00,
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| 81 | // Framebuffer
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| 82 | 0xdeadbeef, 0x0000, 0x0000
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| 83 | }
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| 84 | };
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| 85 |
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| 86 | /**
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| 87 | Install the VBE Info and VBE Mode Info structures, and the VBE service
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| 88 | handler routine in the C segment. Point the real-mode Int10h interrupt vector
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| 89 | to the handler. The only advertised mode is 1024x768x32.
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| 90 |
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| 91 | @param[in] CardName Name of the video card to be exposed in the
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| 92 | Product Name field of the VBE Info structure.
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| 93 | @param[in] FrameBufferBase Guest-physical base address of the video card's
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| 94 | frame buffer.
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| 95 | **/
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| 96 | VOID
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| 97 | InstallVbeShim (
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| 98 | IN CONST CHAR16 *CardName,
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| 99 | IN EFI_PHYSICAL_ADDRESS FrameBufferBase
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| 100 | )
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| 101 | {
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| 102 | EFI_PHYSICAL_ADDRESS Segment0, SegmentC, SegmentF;
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| 103 | UINTN Segment0Pages;
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| 104 | IVT_ENTRY *Int0x10;
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| 105 | EFI_STATUS Status;
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| 106 | UINTN Pam1Address;
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| 107 | UINT8 Pam1;
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| 108 | UINTN SegmentCPages;
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| 109 | VBE_INFO *VbeInfoFull;
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| 110 | VBE_INFO_BASE *VbeInfo;
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| 111 | UINT8 *Ptr;
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| 112 | UINTN Printed;
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| 113 | VBE_MODE_INFO *VbeModeInfo;
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| 114 | UINTN i;
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| 115 |
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| 116 | Segment0 = 0x00000;
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| 117 | SegmentC = 0xC0000;
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| 118 | SegmentF = 0xF0000;
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| 119 |
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| 120 | //
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| 121 | // Attempt to cover the real mode IVT with an allocation. This is a UEFI
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| 122 | // driver, hence the arch protocols have been installed previously. Among
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| 123 | // those, the CPU arch protocol has configured the IDT, so we can overwrite
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| 124 | // the IVT used in real mode.
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| 125 | //
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| 126 | // The allocation request may fail, eg. if LegacyBiosDxe has already run.
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| 127 | //
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| 128 | Segment0Pages = 1;
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| 129 | Int0x10 = (IVT_ENTRY *)(UINTN)Segment0 + 0x10;
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| 130 | Status = gBS->AllocatePages (
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| 131 | AllocateAddress,
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| 132 | EfiBootServicesCode,
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| 133 | Segment0Pages,
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| 134 | &Segment0
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| 135 | );
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| 136 |
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| 137 | if (EFI_ERROR (Status)) {
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| 138 | EFI_PHYSICAL_ADDRESS Handler;
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| 139 |
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| 140 | //
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| 141 | // Check if a video BIOS handler has been installed previously -- we
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| 142 | // shouldn't override a real video BIOS with our shim, nor our own shim if
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| 143 | // it's already present.
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| 144 | //
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| 145 | Handler = (Int0x10->Segment << 4) + Int0x10->Offset;
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| 146 | if ((Handler >= SegmentC) && (Handler < SegmentF)) {
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| 147 | DEBUG ((
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| 148 | DEBUG_VERBOSE,
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| 149 | "%a: Video BIOS handler found at %04x:%04x\n",
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| 150 | __func__,
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| 151 | Int0x10->Segment,
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| 152 | Int0x10->Offset
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| 153 | ));
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| 154 | return;
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| 155 | }
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| 156 |
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| 157 | //
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| 158 | // Otherwise we'll overwrite the Int10h vector, even though we may not own
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| 159 | // the page at zero.
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| 160 | //
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| 161 | DEBUG ((
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| 162 | DEBUG_VERBOSE,
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| 163 | "%a: failed to allocate page at zero: %r\n",
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| 164 | __func__,
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| 165 | Status
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| 166 | ));
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| 167 | } else {
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| 168 | //
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| 169 | // We managed to allocate the page at zero. SVN r14218 guarantees that it
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| 170 | // is NUL-filled.
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| 171 | //
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| 172 | ASSERT (Int0x10->Segment == 0x0000);
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| 173 | ASSERT (Int0x10->Offset == 0x0000);
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| 174 | }
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| 175 |
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| 176 | //
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| 177 | // Put the shim in place first.
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| 178 | //
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| 179 | Pam1Address = PCI_LIB_ADDRESS (0, 0, 0, 0x5A);
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| 180 | //
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| 181 | // low nibble covers 0xC0000 to 0xC3FFF
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| 182 | // high nibble covers 0xC4000 to 0xC7FFF
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| 183 | // bit1 in each nibble is Write Enable
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| 184 | // bit0 in each nibble is Read Enable
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| 185 | //
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| 186 | Pam1 = PciRead8 (Pam1Address);
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| 187 | PciWrite8 (Pam1Address, Pam1 | (BIT1 | BIT0));
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| 188 |
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| 189 | //
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| 190 | // We never added memory space durig PEI or DXE for the C segment, so we
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| 191 | // don't need to (and can't) allocate from there. Also, guest operating
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| 192 | // systems will see a hole in the UEFI memory map there.
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| 193 | //
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| 194 | SegmentCPages = 4;
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| 195 |
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| 196 | ASSERT (sizeof mVbeShim <= EFI_PAGES_TO_SIZE (SegmentCPages));
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| 197 | CopyMem ((VOID *)(UINTN)SegmentC, mVbeShim, sizeof mVbeShim);
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| 198 |
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| 199 | //
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| 200 | // Fill in the VBE INFO structure.
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| 201 | //
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| 202 | VbeInfoFull = (VBE_INFO *)(UINTN)SegmentC;
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| 203 | VbeInfo = &VbeInfoFull->Base;
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| 204 | Ptr = VbeInfoFull->Buffer;
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| 205 |
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| 206 | CopyMem (VbeInfo->Signature, "VESA", 4);
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| 207 | VbeInfo->VesaVersion = 0x0200;
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| 208 |
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| 209 | VbeInfo->OemNameAddress = (UINT32)SegmentC << 12 | (UINT16)((UINTN)Ptr-SegmentC);
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| 210 | CopyMem (Ptr, "FBSD", 5);
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| 211 | Ptr += 5;
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| 212 |
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| 213 | VbeInfo->Capabilities = BIT1 | BIT0; // DAC can be switched into 8-bit mode
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| 214 |
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| 215 | VbeInfo->ModeListAddress = (UINT32)SegmentC << 12 | (UINT16)((UINTN)Ptr-SegmentC);
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| 216 | for (i = 0; i < NUM_VBE_MODES; i++) {
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| 217 | *(UINT16 *)Ptr = vbeModeIds[i]; // mode number
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| 218 | Ptr += 2;
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| 219 | }
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| 220 |
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| 221 | *(UINT16 *)Ptr = 0xFFFF; // mode list terminator
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| 222 | Ptr += 2;
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| 223 |
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| 224 | VbeInfo->VideoMem64K = (UINT16)((1024 * 768 * 4 + 65535) / 65536);
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| 225 | VbeInfo->OemSoftwareVersion = 0x0200;
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| 226 |
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| 227 | VbeInfo->VendorNameAddress = (UINT32)SegmentC << 12 | (UINT16)((UINTN)Ptr-SegmentC);
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| 228 | CopyMem (Ptr, "FBSD", 5);
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| 229 | Ptr += 5;
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| 230 |
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| 231 | VbeInfo->ProductNameAddress = (UINT32)SegmentC << 12 | (UINT16)((UINTN)Ptr-SegmentC);
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| 232 | Printed = AsciiSPrint (
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| 233 | (CHAR8 *)Ptr,
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| 234 | sizeof VbeInfoFull->Buffer - (Ptr - VbeInfoFull->Buffer),
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| 235 | "%s",
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| 236 | CardName
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| 237 | );
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| 238 | Ptr += Printed + 1;
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| 239 |
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| 240 | VbeInfo->ProductRevAddress = (UINT32)SegmentC << 12 | (UINT16)((UINTN)Ptr-SegmentC);
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| 241 | CopyMem (Ptr, mProductRevision, sizeof mProductRevision);
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| 242 | Ptr += sizeof mProductRevision;
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| 243 |
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| 244 | ASSERT (sizeof VbeInfoFull->Buffer >= Ptr - VbeInfoFull->Buffer);
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| 245 | ZeroMem (Ptr, sizeof VbeInfoFull->Buffer - (Ptr - VbeInfoFull->Buffer));
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| 246 |
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| 247 | //
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| 248 | // Fill in the VBE MODE INFO structure list
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| 249 | //
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| 250 | VbeModeInfo = (VBE_MODE_INFO *)(VbeInfoFull + 1);
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| 251 | Ptr = (UINT8 *)VbeModeInfo;
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| 252 | for (i = 0; i < NUM_VBE_MODES; i++) {
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| 253 | vbeModes[i].LfbAddress = (UINT32)FrameBufferBase;
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| 254 | CopyMem (Ptr, &vbeModes[i], 0x32);
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| 255 | Ptr += 0x32;
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| 256 | }
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| 257 |
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| 258 | ZeroMem (Ptr, 56); // Clear remaining bytes
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| 259 |
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| 260 | //
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| 261 | // Clear Write Enable (bit1), keep Read Enable (bit0) set
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| 262 | //
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| 263 | PciWrite8 (Pam1Address, (Pam1 & ~BIT1) | BIT0);
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| 264 |
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| 265 | //
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| 266 | // Second, point the Int10h vector at the shim.
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| 267 | //
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| 268 | Int0x10->Segment = (UINT16)((UINT32)SegmentC >> 4);
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| 269 | Int0x10->Offset = (UINT16)((UINTN)(VbeModeInfo + 1) - SegmentC);
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| 270 |
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| 271 | DEBUG ((
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| 272 | DEBUG_INFO,
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| 273 | "%a: VBE shim installed to %x:%x\n",
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| 274 | __func__,
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| 275 | Int0x10->Segment,
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| 276 | Int0x10->Offset
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| 277 | ));
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| 278 | }
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