diff options
Diffstat (limited to 'roms/ipxe/src/interface/xen/xengrant.c')
| -rw-r--r-- | roms/ipxe/src/interface/xen/xengrant.c | 228 |
1 files changed, 228 insertions, 0 deletions
diff --git a/roms/ipxe/src/interface/xen/xengrant.c b/roms/ipxe/src/interface/xen/xengrant.c new file mode 100644 index 00000000..be12b23d --- /dev/null +++ b/roms/ipxe/src/interface/xen/xengrant.c @@ -0,0 +1,228 @@ +/* + * Copyright (C) 2014 Michael Brown <mbrown@fensystems.co.uk>. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation; either version 2 of the + * License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA + * 02110-1301, USA. + */ + +FILE_LICENCE ( GPL2_OR_LATER ); + +#include <stdint.h> +#include <strings.h> +#include <errno.h> +#include <assert.h> +#include <ipxe/io.h> +#include <ipxe/xen.h> +#include <ipxe/xengrant.h> + +/** @file + * + * Xen grant tables + * + */ + +/** Grant table version to try setting + * + * Using version 1 grant tables limits guests to using 16TB of + * grantable RAM, and prevents the use of subpage grants. Some + * versions of the Xen hypervisor refuse to allow the grant table + * version to be set after the first grant references have been + * created, so the loaded operating system may be stuck with whatever + * choice we make here. We therefore currently use version 2 grant + * tables, since they give the most flexibility to the loaded OS. + * + * Current versions (7.2.0) of the Windows PV drivers have no support + * for version 2 grant tables, and will merrily create version 1 + * entries in what the hypervisor believes to be a version 2 table. + * This causes some confusion. + * + * Avoid this problem by attempting to use version 1 tables, since + * otherwise we may render Windows unable to boot. + * + * Play nicely with other potential bootloaders by accepting either + * version 1 or version 2 grant tables (if we are unable to set our + * requested version). + */ +#define XENGRANT_TRY_VERSION 1 + +/** + * Initialise grant table + * + * @v xen Xen hypervisor + * @ret rc Return status code + */ +int xengrant_init ( struct xen_hypervisor *xen ) { + struct gnttab_query_size size; + struct gnttab_set_version set_version; + struct gnttab_get_version get_version; + struct grant_entry_v1 *v1; + union grant_entry_v2 *v2; + unsigned int version; + int xenrc; + int rc; + + /* Get grant table size */ + size.dom = DOMID_SELF; + if ( ( xenrc = xengrant_query_size ( xen, &size ) ) != 0 ) { + rc = -EXEN ( xenrc ); + DBGC ( xen, "XENGRANT could not get table size: %s\n", + strerror ( rc ) ); + return rc; + } + xen->grant.len = ( size.nr_frames * PAGE_SIZE ); + + /* Set grant table version, if applicable */ + set_version.version = XENGRANT_TRY_VERSION; + if ( ( xenrc = xengrant_set_version ( xen, &set_version ) ) != 0 ) { + rc = -EXEN ( xenrc ); + DBGC ( xen, "XENGRANT could not set version %d: %s\n", + XENGRANT_TRY_VERSION, strerror ( rc ) ); + /* Continue; use whatever version is current */ + } + + /* Get grant table version */ + get_version.dom = DOMID_SELF; + get_version.pad = 0; + if ( ( xenrc = xengrant_get_version ( xen, &get_version ) ) == 0 ) { + version = get_version.version; + switch ( version ) { + + case 0: + /* Version not yet specified: will be version 1 */ + version = 1; + break; + + case 1 : + /* Version 1 table: nothing special to do */ + break; + + case 2: + /* Version 2 table: configure shift appropriately */ + xen->grant.shift = ( fls ( sizeof ( *v2 ) / + sizeof ( *v1 ) ) - 1 ); + break; + + default: + /* Unsupported version */ + DBGC ( xen, "XENGRANT detected unsupported version " + "%d\n", version ); + return -ENOTSUP; + + } + } else { + rc = -EXEN ( xenrc ); + DBGC ( xen, "XENGRANT could not get version (assuming v1): " + "%s\n", strerror ( rc ) ); + version = 1; + } + + DBGC ( xen, "XENGRANT using v%d table with %d entries\n", + version, xengrant_entries ( xen ) ); + return 0; +} + +/** + * Allocate grant references + * + * @v xen Xen hypervisor + * @v refs Grant references to fill in + * @v count Number of references + * @ret rc Return status code + */ +int xengrant_alloc ( struct xen_hypervisor *xen, grant_ref_t *refs, + unsigned int count ) { + struct grant_entry_header *hdr; + unsigned int entries = xengrant_entries ( xen ); + unsigned int mask = ( entries - 1 ); + unsigned int check = 0; + unsigned int avail; + unsigned int ref; + + /* Fail unless we have enough references available */ + avail = ( entries - xen->grant.used - GNTTAB_NR_RESERVED_ENTRIES ); + if ( avail < count ) { + DBGC ( xen, "XENGRANT cannot allocate %d references (only %d " + "of %d available)\n", count, avail, entries ); + return -ENOBUFS; + } + DBGC ( xen, "XENGRANT allocating %d references (from %d of %d " + "available)\n", count, avail, entries ); + + /* Update number of references used */ + xen->grant.used += count; + + /* Find unused references */ + for ( ref = xen->grant.ref ; count ; ref = ( ( ref + 1 ) & mask ) ) { + + /* Sanity check */ + assert ( check++ < entries ); + + /* Skip reserved references */ + if ( ref < GNTTAB_NR_RESERVED_ENTRIES ) + continue; + + /* Skip in-use references */ + hdr = xengrant_header ( xen, ref ); + if ( readw ( &hdr->flags ) & GTF_type_mask ) + continue; + if ( readw ( &hdr->domid ) == DOMID_SELF ) + continue; + + /* Zero reference */ + xengrant_zero ( xen, hdr ); + + /* Mark reference as in-use. We leave the flags as + * empty (to avoid creating a valid grant table entry) + * and set the domid to DOMID_SELF. + */ + writew ( DOMID_SELF, &hdr->domid ); + DBGC2 ( xen, "XENGRANT allocated ref %d\n", ref ); + + /* Record reference */ + refs[--count] = ref; + } + + /* Update cursor */ + xen->grant.ref = ref; + + return 0; +} + +/** + * Free grant references + * + * @v xen Xen hypervisor + * @v refs Grant references + * @v count Number of references + */ +void xengrant_free ( struct xen_hypervisor *xen, grant_ref_t *refs, + unsigned int count ) { + struct grant_entry_header *hdr; + unsigned int ref; + unsigned int i; + + /* Free references */ + for ( i = 0 ; i < count ; i++ ) { + + /* Sanity check */ + ref = refs[i]; + assert ( ref < xengrant_entries ( xen ) ); + + /* Zero reference */ + hdr = xengrant_header ( xen, ref ); + xengrant_zero ( xen, hdr ); + DBGC2 ( xen, "XENGRANT freed ref %d\n", ref ); + } +} |