/*

 * pv/mm.c

 *

 * Memory managment code for PV guests

 *

 * Copyright (c) 2002-2005 K A Fraser

 * Copyright (c) 2004 Christian Limpach

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms and conditions of the GNU General Public

 * License, version 2, as published by the Free Software Foundation.

 *

 * 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, see <http://www.gnu.org/licenses/>.

 */

#include <xen/guest_access.h>

#include <asm/current.h>

#include <asm/p2m.h>

#include "mm.h"

/* Override macros from asm/page.h to make them work with mfn_t */

#undef mfn_to_page

#define mfn_to_page(mfn) __mfn_to_page(mfn_x(mfn))

#undef page_to_mfn

#define page_to_mfn(pg) _mfn(__page_to_mfn(pg))

/*

 * Get a mapping of a PV guest's l1e for this linear address.  The return

 * pointer should be unmapped using unmap_domain_page().

 */

l1_pgentry_t *map_guest_l1e(unsigned long linear, mfn_t *gl1mfn)

{

    l2_pgentry_t l2e;

    ASSERT(!paging_mode_translate(current->domain));

    ASSERT(!paging_mode_external(current->domain));

    if ( unlikely(!__addr_ok(linear)) )

        return NULL;

    /* Find this l1e and its enclosing l1mfn in the linear map. */

    if ( __copy_from_user(&l2e,

                          &__linear_l2_table[l2_linear_offset(linear)],

                          sizeof(l2_pgentry_t)) )

        return NULL;

    /* Check flags that it will be safe to read the l1e. */

    if ( (l2e_get_flags(l2e) & (_PAGE_PRESENT | _PAGE_PSE)) != _PAGE_PRESENT )

        return NULL;

    *gl1mfn = l2e_get_mfn(l2e);

    return (l1_pgentry_t *)map_domain_page(*gl1mfn) + l1_table_offset(linear);

}

/*

 * Read the guest's l1e that maps this address, from the kernel-mode

 * page tables.

 */

static l1_pgentry_t guest_get_eff_kern_l1e(unsigned long linear)

{

    struct vcpu *curr = current;

    const bool user_mode = !(curr->arch.flags & TF_kernel_mode);

    l1_pgentry_t l1e;

    if ( user_mode )

        toggle_guest_mode(curr);

    l1e = guest_get_eff_l1e(linear);

    if ( user_mode )

        toggle_guest_mode(curr);

    return l1e;

}

/*

 * Map a guest's LDT page (covering the byte at @offset from start of the LDT)

 * into Xen's virtual range.  Returns true if the mapping changed, false

 * otherwise.

 */

bool pv_map_ldt_shadow_page(unsigned int offset)

{

    struct vcpu *curr = current;

    struct domain *currd = curr->domain;

    struct page_info *page;

    l1_pgentry_t gl1e, *pl1e;

    unsigned long linear = curr->arch.pv_vcpu.ldt_base + offset;

    BUG_ON(unlikely(in_irq()));

    /*

     * Hardware limit checking should guarantee this property.  NB. This is

     * safe as updates to the LDT can only be made by MMUEXT_SET_LDT to the

     * current vcpu, and vcpu_reset() will block until this vcpu has been

     * descheduled before continuing.

     */

    ASSERT((offset >> 3) <= curr->arch.pv_vcpu.ldt_ents);

    if ( is_pv_32bit_domain(currd) )

        linear = (uint32_t)linear;

    gl1e = guest_get_eff_kern_l1e(linear);

    if ( unlikely(!(l1e_get_flags(gl1e) & _PAGE_PRESENT)) )

        return false;

    page = get_page_from_gfn(currd, l1e_get_pfn(gl1e), NULL, P2M_ALLOC);

    if ( unlikely(!page) )

        return false;

    if ( unlikely(!get_page_type(page, PGT_seg_desc_page)) )

    {

        put_page(page);

        return false;

    }

    pl1e = &pv_ldt_ptes(curr)[offset >> PAGE_SHIFT];

    l1e_add_flags(gl1e, _PAGE_RW);

    spin_lock(&curr->arch.pv_vcpu.shadow_ldt_lock);

    l1e_write(pl1e, gl1e);

    curr->arch.pv_vcpu.shadow_ldt_mapcnt++;

    spin_unlock(&curr->arch.pv_vcpu.shadow_ldt_lock);

    return true;

}

/*

 * Local variables:

 * mode: C

 * c-file-style: "BSD"

 * c-basic-offset: 4

 * tab-width: 4

 * indent-tabs-mode: nil

 * End:

 */