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- /** @file
- Install a fake VGABIOS service handler (real mode Int10h) for the buggy
- Windows 2008 R2 SP1 UEFI guest.
- The handler is never meant to be directly executed by a VCPU; it's there for
- the internal real mode emulator of Windows 2008 R2 SP1.
- The code is based on Ralf Brown's Interrupt List:
- <http://www.cs.cmu.edu/~ralf/files.html>
- <http://www.ctyme.com/rbrown.htm>
- Copyright (C) 2020, Rebecca Cran <rebecca@bsdio.com>
- Copyright (C) 2015, Nahanni Systems, Inc.
- Copyright (C) 2014, Red Hat, Inc.
- Copyright (c) 2013 - 2014, Intel Corporation. All rights reserved.<BR>
- SPDX-License-Identifier: BSD-2-Clause-Patent
- **/
- #include <IndustryStandard/LegacyVgaBios.h>
- #include <Library/DebugLib.h>
- #include <Library/PciLib.h>
- #include <Library/PrintLib.h>
- #include "Gop.h"
- #include "VbeShim.h"
- #pragma pack (1)
- typedef struct {
- UINT16 Offset;
- UINT16 Segment;
- } IVT_ENTRY;
- #pragma pack ()
- //
- // This string is displayed by Windows 2008 R2 SP1 in the Screen Resolution,
- // Advanced Settings dialog. It should be short.
- //
- STATIC CONST CHAR8 mProductRevision[] = "2.0";
- #define NUM_VBE_MODES 3
- STATIC CONST UINT16 vbeModeIds[] = {
- 0x13f, // 640x480x32
- 0x140, // 800x600x32
- 0x141 // 1024x768x32
- };
- // Modes can be toggled with bit-0
- #define VBE_MODE_ENABLED 0x00BB
- #define VBE_MODE_DISABLED 0x00BA
- STATIC VBE2_MODE_INFO vbeModes[] = {
- { // 0x13f 640x480x32
- // ModeAttr - BytesPerScanLine
- VBE_MODE_DISABLED, 0x07, 0x00, 0x40, 0x40, 0xA000, 0x00, 0x0000, 640*4,
- // Width, Height..., Vbe3
- 640, 480, 16, 8, 1, 32, 1, 0x06, 0, 0, 1,
- // Masks
- 0x08, 0x10, 0x08, 0x08, 0x08, 0x00, 0x08, 0x18, 0x00,
- // Framebuffer
- 0xdeadbeef, 0x0000, 0x0000
- },
- { // 0x140 800x600x32
- // ModeAttr - BytesPerScanLine
- VBE_MODE_DISABLED, 0x07, 0x00, 0x40, 0x40, 0xA000, 0x00, 0x0000, 800*4,
- // Width, Height..., Vbe3
- 800, 600, 16, 8, 1, 32, 1, 0x06, 0, 0, 1,
- // Masks
- 0x08, 0x10, 0x08, 0x08, 0x08, 0x00, 0x08, 0x18, 0x00,
- // Framebuffer
- 0xdeadbeef, 0x0000, 0x0000
- },
- { // 0x141 1024x768x32
- // ModeAttr - BytesPerScanLine
- VBE_MODE_ENABLED, 0x07, 0x00, 0x40, 0x40, 0xA000, 0x00, 0x0000, 1024*4,
- // Width, Height..., Vbe3
- 1024, 768, 16, 8, 1, 32, 1, 0x06, 0, 0, 1,
- // Masks
- 0x08, 0x10, 0x08, 0x08, 0x08, 0x00, 0x08, 0x18, 0x00,
- // Framebuffer
- 0xdeadbeef, 0x0000, 0x0000
- }
- };
- /**
- Install the VBE Info and VBE Mode Info structures, and the VBE service
- handler routine in the C segment. Point the real-mode Int10h interrupt vector
- to the handler. The only advertised mode is 1024x768x32.
- @param[in] CardName Name of the video card to be exposed in the
- Product Name field of the VBE Info structure.
- @param[in] FrameBufferBase Guest-physical base address of the video card's
- frame buffer.
- **/
- VOID
- InstallVbeShim (
- IN CONST CHAR16 *CardName,
- IN EFI_PHYSICAL_ADDRESS FrameBufferBase
- )
- {
- EFI_PHYSICAL_ADDRESS Segment0, SegmentC, SegmentF;
- UINTN Segment0Pages;
- IVT_ENTRY *Int0x10;
- EFI_STATUS Status;
- UINTN Pam1Address;
- UINT8 Pam1;
- UINTN SegmentCPages;
- VBE_INFO *VbeInfoFull;
- VBE_INFO_BASE *VbeInfo;
- UINT8 *Ptr;
- UINTN Printed;
- VBE_MODE_INFO *VbeModeInfo;
- UINTN i;
- Segment0 = 0x00000;
- SegmentC = 0xC0000;
- SegmentF = 0xF0000;
- //
- // Attempt to cover the real mode IVT with an allocation. This is a UEFI
- // driver, hence the arch protocols have been installed previously. Among
- // those, the CPU arch protocol has configured the IDT, so we can overwrite
- // the IVT used in real mode.
- //
- // The allocation request may fail, eg. if LegacyBiosDxe has already run.
- //
- Segment0Pages = 1;
- Int0x10 = (IVT_ENTRY *)(UINTN)Segment0 + 0x10;
- Status = gBS->AllocatePages (
- AllocateAddress,
- EfiBootServicesCode,
- Segment0Pages,
- &Segment0
- );
- if (EFI_ERROR (Status)) {
- EFI_PHYSICAL_ADDRESS Handler;
- //
- // Check if a video BIOS handler has been installed previously -- we
- // shouldn't override a real video BIOS with our shim, nor our own shim if
- // it's already present.
- //
- Handler = (Int0x10->Segment << 4) + Int0x10->Offset;
- if ((Handler >= SegmentC) && (Handler < SegmentF)) {
- DEBUG ((
- DEBUG_VERBOSE,
- "%a: Video BIOS handler found at %04x:%04x\n",
- __FUNCTION__,
- Int0x10->Segment,
- Int0x10->Offset
- ));
- return;
- }
- //
- // Otherwise we'll overwrite the Int10h vector, even though we may not own
- // the page at zero.
- //
- DEBUG ((
- DEBUG_VERBOSE,
- "%a: failed to allocate page at zero: %r\n",
- __FUNCTION__,
- Status
- ));
- } else {
- //
- // We managed to allocate the page at zero. SVN r14218 guarantees that it
- // is NUL-filled.
- //
- ASSERT (Int0x10->Segment == 0x0000);
- ASSERT (Int0x10->Offset == 0x0000);
- }
- //
- // Put the shim in place first.
- //
- Pam1Address = PCI_LIB_ADDRESS (0, 0, 0, 0x5A);
- //
- // low nibble covers 0xC0000 to 0xC3FFF
- // high nibble covers 0xC4000 to 0xC7FFF
- // bit1 in each nibble is Write Enable
- // bit0 in each nibble is Read Enable
- //
- Pam1 = PciRead8 (Pam1Address);
- PciWrite8 (Pam1Address, Pam1 | (BIT1 | BIT0));
- //
- // We never added memory space durig PEI or DXE for the C segment, so we
- // don't need to (and can't) allocate from there. Also, guest operating
- // systems will see a hole in the UEFI memory map there.
- //
- SegmentCPages = 4;
- ASSERT (sizeof mVbeShim <= EFI_PAGES_TO_SIZE (SegmentCPages));
- CopyMem ((VOID *)(UINTN)SegmentC, mVbeShim, sizeof mVbeShim);
- //
- // Fill in the VBE INFO structure.
- //
- VbeInfoFull = (VBE_INFO *)(UINTN)SegmentC;
- VbeInfo = &VbeInfoFull->Base;
- Ptr = VbeInfoFull->Buffer;
- CopyMem (VbeInfo->Signature, "VESA", 4);
- VbeInfo->VesaVersion = 0x0200;
- VbeInfo->OemNameAddress = (UINT32)SegmentC << 12 | (UINT16)((UINTN)Ptr-SegmentC);
- CopyMem (Ptr, "FBSD", 5);
- Ptr += 5;
- VbeInfo->Capabilities = BIT1 | BIT0; // DAC can be switched into 8-bit mode
- VbeInfo->ModeListAddress = (UINT32)SegmentC << 12 | (UINT16)((UINTN)Ptr-SegmentC);
- for (i = 0; i < NUM_VBE_MODES; i++) {
- *(UINT16 *)Ptr = vbeModeIds[i]; // mode number
- Ptr += 2;
- }
- *(UINT16 *)Ptr = 0xFFFF; // mode list terminator
- Ptr += 2;
- VbeInfo->VideoMem64K = (UINT16)((1024 * 768 * 4 + 65535) / 65536);
- VbeInfo->OemSoftwareVersion = 0x0200;
- VbeInfo->VendorNameAddress = (UINT32)SegmentC << 12 | (UINT16)((UINTN)Ptr-SegmentC);
- CopyMem (Ptr, "FBSD", 5);
- Ptr += 5;
- VbeInfo->ProductNameAddress = (UINT32)SegmentC << 12 | (UINT16)((UINTN)Ptr-SegmentC);
- Printed = AsciiSPrint (
- (CHAR8 *)Ptr,
- sizeof VbeInfoFull->Buffer - (Ptr - VbeInfoFull->Buffer),
- "%s",
- CardName
- );
- Ptr += Printed + 1;
- VbeInfo->ProductRevAddress = (UINT32)SegmentC << 12 | (UINT16)((UINTN)Ptr-SegmentC);
- CopyMem (Ptr, mProductRevision, sizeof mProductRevision);
- Ptr += sizeof mProductRevision;
- ASSERT (sizeof VbeInfoFull->Buffer >= Ptr - VbeInfoFull->Buffer);
- ZeroMem (Ptr, sizeof VbeInfoFull->Buffer - (Ptr - VbeInfoFull->Buffer));
- //
- // Fill in the VBE MODE INFO structure list
- //
- VbeModeInfo = (VBE_MODE_INFO *)(VbeInfoFull + 1);
- Ptr = (UINT8 *)VbeModeInfo;
- for (i = 0; i < NUM_VBE_MODES; i++) {
- vbeModes[i].LfbAddress = (UINT32)FrameBufferBase;
- CopyMem (Ptr, &vbeModes[i], 0x32);
- Ptr += 0x32;
- }
- ZeroMem (Ptr, 56); // Clear remaining bytes
- //
- // Clear Write Enable (bit1), keep Read Enable (bit0) set
- //
- PciWrite8 (Pam1Address, (Pam1 & ~BIT1) | BIT0);
- //
- // Second, point the Int10h vector at the shim.
- //
- Int0x10->Segment = (UINT16)((UINT32)SegmentC >> 4);
- Int0x10->Offset = (UINT16)((UINTN)(VbeModeInfo + 1) - SegmentC);
- DEBUG ((
- DEBUG_INFO,
- "%a: VBE shim installed to %x:%x\n",
- __FUNCTION__,
- Int0x10->Segment,
- Int0x10->Offset
- ));
- }
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