| 1 | /* $Id: vds.c 106061 2024-09-16 14:03:52Z vboxsync $ */
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| 2 | /** @file
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| 3 | * Utility routines for calling the Virtual DMA Services.
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| 4 | */
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| 5 |
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| 6 | /*
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| 7 | * Copyright (C) 2011-2024 Oracle and/or its affiliates.
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| 8 | *
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| 9 | * This file is part of VirtualBox base platform packages, as
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| 10 | * available from https://www.virtualbox.org.
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| 11 | *
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| 12 | * This program is free software; you can redistribute it and/or
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| 13 | * modify it under the terms of the GNU General Public License
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| 14 | * as published by the Free Software Foundation, in version 3 of the
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| 15 | * License.
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| 16 | *
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| 17 | * This program is distributed in the hope that it will be useful, but
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| 18 | * WITHOUT ANY WARRANTY; without even the implied warranty of
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| 19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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| 20 | * General Public License for more details.
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| 21 | *
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| 22 | * You should have received a copy of the GNU General Public License
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| 23 | * along with this program; if not, see <https://www.gnu.org/licenses>.
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| 24 | *
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| 25 | * SPDX-License-Identifier: GPL-3.0-only
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| 26 | */
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| 27 |
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| 28 |
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| 29 | #include <stdint.h>
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| 30 | #include "biosint.h"
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| 31 | #include "vds.h"
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| 32 |
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| 33 | typedef struct {
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| 34 | uint8_t major; /* VDS spec major version number. */
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| 35 | uint8_t minor; /* VDS spec minor version number. */
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| 36 | uint16_t flags; /* Capabilities/status flags. */
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| 37 | uint16_t prod_no; /* Product number. */
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| 38 | uint16_t prod_rev; /* Product revision number. */
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| 39 | uint32_t max_buf; /* Maximum buffer size supported. */
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| 40 | } vds_ver;
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| 41 |
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| 42 | int vds_is_present( void )
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| 43 | {
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| 44 | uint8_t __far *vds_flags;
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| 45 |
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| 46 | vds_flags = MK_FP( 0x40, VDS_FLAGS_OFS );
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| 47 | return( !!(*vds_flags & VDS_PRESENT) );
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| 48 | }
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| 49 |
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| 50 | int vds_lock_sg( vds_edds __far *edds );
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| 51 | #pragma aux vds_lock_sg = \
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| 52 | "mov ax, 8105h" \
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| 53 | "mov dx, 0" \
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| 54 | "int 4Bh" \
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| 55 | "jc error" \
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| 56 | "xor al, al" \
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| 57 | "error:" \
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| 58 | "cbw" \
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| 59 | parm [es di] value [ax] modify [dx];
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| 60 |
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| 61 | int vds_unlock_sg( vds_edds __far *edds );
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| 62 | #pragma aux vds_unlock_sg = \
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| 63 | "mov ax, 8106h" \
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| 64 | "mov dx, 0" \
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| 65 | "int 4Bh" \
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| 66 | "jc error" \
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| 67 | "xor al, al" \
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| 68 | "error:" \
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| 69 | "cbw" \
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| 70 | parm [es di] value [ax] modify [dx];
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| 71 |
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| 72 |
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| 73 | /*
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| 74 | * Convert a real mode 16:16 segmented address to a simple 32-bit
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| 75 | * linear address.
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| 76 | */
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| 77 | uint32_t vds_real_to_lin( void __far *ptr )
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| 78 | {
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| 79 | return( ((uint32_t)FP_SEG( ptr ) << 4) + FP_OFF( ptr ) );
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| 80 | }
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| 81 |
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| 82 | /*
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| 83 | * Build a VDS-style scatter/gather list, regardless of whether VDS is
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| 84 | * present or not. This routine either calls VDS to do the work or
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| 85 | * trivially creates the list if no remapping is needed.
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| 86 | */
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| 87 | int vds_build_sg_list( vds_edds __far *edds, void __far *buf, uint32_t len )
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| 88 | {
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| 89 | int rc;
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| 90 |
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| 91 | /* NB: The num_avail field in the EDDS must be set correctly! */
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| 92 | edds->region_size = len;
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| 93 | edds->offset = vds_real_to_lin( buf );
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| 94 | edds->seg_sel = 0; /* Indicates a linear address. */
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| 95 | if( vds_is_present() ) {
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| 96 | /* VDS is present, use it. */
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| 97 | rc = vds_lock_sg( edds );
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| 98 | } else {
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| 99 | /* No VDS, do it ourselves with one S/G entry. */
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| 100 | edds->num_used = 1;
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| 101 | edds->u.sg[0].phys_addr = edds->offset;
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| 102 | edds->u.sg[0].size = len;
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| 103 | rc = VDS_SUCCESS;
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| 104 | }
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| 105 | return( rc );
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| 106 | }
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| 107 |
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| 108 | /*
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| 109 | * Free a VDS-style scatter/gather list, regardless of whether VDS
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| 110 | * is present or not.
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| 111 | */
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| 112 | int vds_free_sg_list( vds_edds __far *edds )
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| 113 | {
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| 114 | int rc;
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| 115 |
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| 116 | if( vds_is_present() ) {
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| 117 | /* VDS is present, use it. */
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| 118 | rc = vds_unlock_sg( edds );
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| 119 | } else {
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| 120 | /* No VDS, not much to do. */
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| 121 | /* We could check here if the EDDS had in fact been built by us.
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| 122 | * But if VDS really went away, what can we do about it anyway?
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| 123 | */
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| 124 | rc = VDS_SUCCESS;
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| 125 | }
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| 126 | edds->num_used = 0;
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| 127 | return( rc );
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| 128 | }
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