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00e0	33 ff 33 33 33 ff 33 33 33 ff 33 33 33 ff 33 33 33 d0 33 33 33 42 00 00 00 00 00 00 00 00 00 00	3.333.333.333.333.333B..........
0100	00 00 33 33 33 d0 33 33 33 ff 33 33 33 ff 33 33 33 ff 33 33 33 ff 33 33 33 ff 33 33 33 ff 33 33	..333.333.333.333.333.333.333.33
0120	33 ff 33 33 33 ff 33 33 33 ff 33 33 33 ff 33 33 33 ff 33 33 33 d0 00 00 00 00 00 00 00 00 8c 8c	3.333.333.333.333.333...........
0140	8c ff 33 33 33 ff 33 33 33 ff 33 33 33 ff 33 33 33 ff 33 33 33 ff 3b 3b 3b ff d3 d3 d3 ff 3b 3b	..333.333.333.333.333.;;;.....;;
0160	3b ff 33 33 33 ff 33 33 33 ff 33 33 33 ff 33 33 33 ff 33 33 33 ff 8c 8c 8c ff 00 00 00 00 00 00	;.333.333.333.333.333...........
0180	00 00 33 33 33 ff 33 33 33 ff 33 33 33 ff 33 33 33 ff 33 33 33 ff 47 47 47 ff ff ff ff ff 47 47	..333.333.333.333.333.GGG.....GG
01a0	47 ff 33 33 33 ff 33 33 33 ff 33 33 33 ff 33 33 33 ff 33 33 33 ff 00 00 00 00 00 00 00 00 8c 8c	G.333.333.333.333.333...........
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01e0	f8 ff dc dc dc ff 56 56 56 ff 33 33 33 ff 33 33 33 ff 33 33 33 ff 8c 8c 8c ff 00 00 00 00 00 00	......VVV.333.333.333...........
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0260	47 ff 39 39 39 ff fd fd fd ff 87 87 87 ff 33 33 33 ff 33 33 33 ff 8c 8c 8c ff 00 00 00 00 00 00	G.999.........333.333...........
0280	00 00 33 33 33 ff 33 33 33 ff b0 b0 b0 ff f6 f6 f6 ff 33 33 33 ff 47 47 47 ff ff ff ff ff 47 47	..333.333.........333.GGG.....GG
02a0	47 ff 33 33 33 ff f6 f6 f6 ff af af af ff 33 33 33 ff 33 33 33 ff 00 00 00 00 00 00 00 00 8c 8c	G.333.........333.333...........
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02e0	47 ff 33 33 33 ff f5 f5 f5 ff b0 b0 b0 ff 33 33 33 ff 33 33 33 ff 8c 8c 8c ff 00 00 00 00 00 00	G.333.........333.333...........
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0320	47 ff 33 33 33 ff f5 f5 f5 ff b0 b0 b0 ff 33 33 33 ff 33 33 33 ff 00 00 00 00 00 00 00 00 8c 8c	G.333.........333.333...........
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0360	3b ff 33 33 33 ff ae ae ae ff 71 71 71 ff 33 33 33 ff 33 33 33 ff 8c 8c 8c ff 00 00 00 00 00 00	;.333.....qqq.333.333...........
0380	00 00 33 33 33 d0 33 33 33 ff 33 33 33 ff 33 33 33 ff 33 33 33 ff 33 33 33 ff 33 33 33 ff 33 33	..333.333.333.333.333.333.333.33
03a0	33 ff 33 33 33 ff 33 33 33 ff 33 33 33 ff 33 33 33 ff 33 33 33 d0 00 00 00 00 00 00 00 00 00 00	3.333.333.333.333.333...........
03c0	00 00 33 33 33 43 33 33 33 d0 33 33 33 ff 33 33 33 ff 33 33 33 ff 33 33 33 ff 33 33 33 ff 33 33	..333C333.333.333.333.333.333.33
03e0	33 ff 33 33 33 ff 33 33 33 ff 33 33 33 ff 33 33 33 d0 33 33 33 42 00 00 00 00 00 00 00 00 00 00	3.333.333.333.333.333B..........
0400	00 00 00 00 00 00 00 00 00 00 8c 8c 8c ff 00 00 00 00 8c 8c 8c ff 00 00 00 00 8c 8c 8c ff 00 00	................................
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0460	00 00 80 03 00 00 00 01 00 00 80 03 00 00 00 01 00 00 80 03 00 00 80 03 00 00 ea af 00 00	..............................

generated by cgit v1.2.3 (git 2.25.1) at 2026-01-07 05:03:25 +0000

/******************************************************************************
 * common/grant_table.c
 * 
 * Mechanism for granting foreign access to page frames, and receiving
 * page-ownership transfers.
 * 
 * Copyright (c) 2005 Christopher Clark
 * Copyright (c) 2004 K A Fraser
 * Copyright (c) 2005 Andrew Warfield
 * Modifications by Geoffrey Lefebvre are (c) Intel Research Cambridge
 * 
 * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <xen/lib.h>
#include <xen/sched.h>
#include <xen/shadow.h>
#include <xen/mm.h>
#include <xen/trace.h>
#include <xen/guest_access.h>
#include <acm/acm_hooks.h>

#define PIN_FAIL(_lbl, _rc, _f, _a...)          \
    do {                                        \
        DPRINTK( _f, ## _a );                   \
        rc = (_rc);                             \
        goto _lbl;                              \
    } while ( 0 )

static inline int
get_maptrack_handle(
    struct grant_table *t)
{
    unsigned int h;
    if ( unlikely((h = t->maptrack_head) == (t->maptrack_limit - 1)) )
        return -1;
    t->maptrack_head = t->maptrack[h].ref;
    t->map_count++;
    return h;
}

static inline void
put_maptrack_handle(
    struct grant_table *t, int handle)
{
    t->maptrack[handle].ref = t->maptrack_head;
    t->maptrack_head = handle;
    t->map_count--;
}

/*
 * Returns 0 if TLB flush / invalidate required by caller.
 * va will indicate the address to be invalidated.
 * 
 * addr is _either_ a host virtual address, or the address of the pte to
 * update, as indicated by the GNTMAP_contains_pte flag.
 */
static void
__gnttab_map_grant_ref(
    struct gnttab_map_grant_ref *op)
{
    struct domain *ld, *rd;
    struct vcpu   *led;
    int            handle;
    unsigned long  frame = 0;
    int            rc = GNTST_okay;
    struct active_grant_entry *act;

    /* Entry details from @rd's shared grant table. */
    grant_entry_t *sha;
    domid_t        sdom;
    u16            sflags;

    /*
     * We bound the number of times we retry CMPXCHG on memory locations that
     * we share with a guest OS. The reason is that the guest can modify that
     * location at a higher rate than we can read-modify-CMPXCHG, so the guest
     * could cause us to livelock. There are a few cases where it is valid for
     * the guest to race our updates (e.g., to change the GTF_readonly flag),
     * so we allow a few retries before failing.
     */
    int retries = 0;

    led = current;
    ld = led->domain;

    if ( unlikely(op->ref >= NR_GRANT_ENTRIES) ||
         unlikely((op->flags & (GNTMAP_device_map|GNTMAP_host_map)) == 0) )
    {
        DPRINTK("Bad ref (%d) or flags (%x).\n", op->ref, op->flags);
        op->status = GNTST_bad_gntref;
        return;
    }

    if ( acm_pre_grant_map_ref(op->dom) )
    {
        op->status = GNTST_permission_denied;
        return;
    }

    if ( unlikely((rd = find_domain_by_id(op->dom)) == NULL) )
    {
        if ( rd != NULL )
            put_domain(rd);
        DPRINTK("Could not find domain %d\n", op->dom);
        op->status = GNTST_bad_domain;
        return;
    }

    /* Get a maptrack handle. */
    if ( unlikely((handle = get_maptrack_handle(ld->grant_table)) == -1) )
    {
        int                   i;
        struct grant_mapping *new_mt;
        struct grant_table   *lgt = ld->grant_table;

        if ( (lgt->maptrack_limit << 1) > MAPTRACK_MAX_ENTRIES )
        {
            put_domain(rd);
            DPRINTK("Maptrack table is at maximum size.\n");
            op->status = GNTST_no_device_space;
            return;
        }

        /* Grow the maptrack table. */
        new_mt = alloc_xenheap_pages(lgt->maptrack_order + 1);
        if ( new_mt == NULL )
        {
            put_domain(rd);
            DPRINTK("No more map handles available.\n");
            op->status = GNTST_no_device_space;
            return;
        }

        memcpy(new_mt, lgt->maptrack, PAGE_SIZE << lgt->maptrack_order);
        for ( i = lgt->maptrack_limit; i < (lgt->maptrack_limit << 1); i++ )
            new_mt[i].ref = i+1;

        free_xenheap_pages(lgt->maptrack, lgt->maptrack_order);
        lgt->maptrack          = new_mt;
        lgt->maptrack_order   += 1;
        lgt->maptrack_limit  <<= 1;

        DPRINTK("Doubled maptrack size\n");
        handle = get_maptrack_handle(ld->grant_table);
    }

    act = &rd->grant_table->active[op->ref];
    sha = &rd->grant_table->shared[op->ref];

    spin_lock(&rd->grant_table->lock);

    if ( !act->pin ||
         (!(op->flags & GNTMAP_readonly) &&
          !(act->pin & (GNTPIN_hstw_mask|GNTPIN_devw_mask))) )
    {
        sflags = sha->flags;
        sdom   = sha->domid;

        /*
         * This loop attempts to set the access (reading/writing) flags
         * in the grant table entry.  It tries a cmpxchg on the field
         * up to five times, and then fails under the assumption that 
         * the guest is misbehaving.
         */
        for ( ; ; )
        {
            u32 scombo, prev_scombo, new_scombo;

            if ( unlikely((sflags & GTF_type_mask) != GTF_permit_access) ||
                 unlikely(sdom != led->domain->domain_id) )
                PIN_FAIL(unlock_out, GNTST_general_error,
                         "Bad flags (%x) or dom (%d). (NB. expected dom %d)\n",
                         sflags, sdom, led->domain->domain_id);

            /* Merge two 16-bit values into a 32-bit combined update. */
            /* NB. Endianness! */
            scombo = ((u32)sdom << 16) | (u32)sflags;

            new_scombo = scombo | GTF_reading;
            if ( !(op->flags & GNTMAP_readonly) )
            {
                new_scombo |= GTF_writing;
                if ( unlikely(sflags & GTF_readonly) )
                    PIN_FAIL(unlock_out, GNTST_general_error,
                             "Attempt to write-pin a r/o grant entry.\n");
            }

            prev_scombo = cmpxchg((u32 *)&sha->flags, scombo, new_scombo);

            /* Did the combined update work (did we see what we expected?). */
            if ( likely(prev_scombo == scombo) )
                break;

            if ( retries++ == 4 )
                PIN_FAIL(unlock_out, GNTST_general_error,
                         "Shared grant entry is unstable.\n");

            /* Didn't see what we expected. Split out the seen flags & dom. */
            /* NB. Endianness! */
            sflags = (u16)prev_scombo;
            sdom   = (u16)(prev_scombo >> 16);
        }

        if ( !act->pin )
        {
            act->domid = sdom;
            act->frame = gmfn_to_mfn(rd, sha->frame);
        }
    }
    else if ( (act->pin & 0x80808080U) != 0 )
        PIN_FAIL(unlock_out, ENOSPC,
                 "Risk of counter overflow %08x\n", act->pin);

    if ( op->flags & GNTMAP_device_map )