Merge branch 'omap-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

[deliverable/linux.git] / arch / x86 / xen / p2m.c

/*
 * Xen leaves the responsibility for maintaining p2m mappings to the
 * guests themselves, but it must also access and update the p2m array
 * during suspend/resume when all the pages are reallocated.
 *
 * The p2m table is logically a flat array, but we implement it as a
 * three-level tree to allow the address space to be sparse.
 *
 *                               Xen
 *                                |
 *     p2m_top              p2m_top_mfn
 *       /  \                   /   \
 * p2m_mid p2m_mid      p2m_mid_mfn p2m_mid_mfn
 *    / \      / \         /           /
 *  p2m p2m p2m p2m p2m p2m p2m ...
 *
 * The p2m_mid_mfn pages are mapped by p2m_top_mfn_p.
 *
 * The p2m_top and p2m_top_mfn levels are limited to 1 page, so the
 * maximum representable pseudo-physical address space is:
 *  P2M_TOP_PER_PAGE * P2M_MID_PER_PAGE * P2M_PER_PAGE pages
 *
 * P2M_PER_PAGE depends on the architecture, as a mfn is always
 * unsigned long (8 bytes on 64-bit, 4 bytes on 32), leading to
 * 512 and 1024 entries respectively. 
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/list.h>
#include <linux/hash.h>
#include <linux/sched.h>

#include <asm/cache.h>
#include <asm/setup.h>

#include <asm/xen/page.h>
#include <asm/xen/hypercall.h>
#include <asm/xen/hypervisor.h>

#include "xen-ops.h"

static void __init m2p_override_init(void);

unsigned long xen_max_p2m_pfn __read_mostly;

#define P2M_PER_PAGE            (PAGE_SIZE / sizeof(unsigned long))
#define P2M_MID_PER_PAGE        (PAGE_SIZE / sizeof(unsigned long *))
#define P2M_TOP_PER_PAGE        (PAGE_SIZE / sizeof(unsigned long **))

#define MAX_P2M_PFN             (P2M_TOP_PER_PAGE * P2M_MID_PER_PAGE * P2M_PER_PAGE)

/* Placeholders for holes in the address space */
static RESERVE_BRK_ARRAY(unsigned long, p2m_missing, P2M_PER_PAGE);
static RESERVE_BRK_ARRAY(unsigned long *, p2m_mid_missing, P2M_MID_PER_PAGE);
static RESERVE_BRK_ARRAY(unsigned long, p2m_mid_missing_mfn, P2M_MID_PER_PAGE);

static RESERVE_BRK_ARRAY(unsigned long **, p2m_top, P2M_TOP_PER_PAGE);
static RESERVE_BRK_ARRAY(unsigned long, p2m_top_mfn, P2M_TOP_PER_PAGE);
static RESERVE_BRK_ARRAY(unsigned long *, p2m_top_mfn_p, P2M_TOP_PER_PAGE);

RESERVE_BRK(p2m_mid, PAGE_SIZE * (MAX_DOMAIN_PAGES / (P2M_PER_PAGE * P2M_MID_PER_PAGE)));
RESERVE_BRK(p2m_mid_mfn, PAGE_SIZE * (MAX_DOMAIN_PAGES / (P2M_PER_PAGE * P2M_MID_PER_PAGE)));

static inline unsigned p2m_top_index(unsigned long pfn)
{
        BUG_ON(pfn >= MAX_P2M_PFN);
        return pfn / (P2M_MID_PER_PAGE * P2M_PER_PAGE);
}

static inline unsigned p2m_mid_index(unsigned long pfn)
{
        return (pfn / P2M_PER_PAGE) % P2M_MID_PER_PAGE;
}

static inline unsigned p2m_index(unsigned long pfn)
{
        return pfn % P2M_PER_PAGE;
}

static void p2m_top_init(unsigned long ***top)
{
        unsigned i;

        for (i = 0; i < P2M_TOP_PER_PAGE; i++)
                top[i] = p2m_mid_missing;
}

static void p2m_top_mfn_init(unsigned long *top)
{
        unsigned i;

        for (i = 0; i < P2M_TOP_PER_PAGE; i++)
                top[i] = virt_to_mfn(p2m_mid_missing_mfn);
}

static void p2m_top_mfn_p_init(unsigned long **top)
{
        unsigned i;

        for (i = 0; i < P2M_TOP_PER_PAGE; i++)
                top[i] = p2m_mid_missing_mfn;
}

static void p2m_mid_init(unsigned long **mid)
{
        unsigned i;

        for (i = 0; i < P2M_MID_PER_PAGE; i++)
                mid[i] = p2m_missing;
}

static void p2m_mid_mfn_init(unsigned long *mid)
{
        unsigned i;

        for (i = 0; i < P2M_MID_PER_PAGE; i++)
                mid[i] = virt_to_mfn(p2m_missing);
}

static void p2m_init(unsigned long *p2m)
{
        unsigned i;

        for (i = 0; i < P2M_MID_PER_PAGE; i++)
                p2m[i] = INVALID_P2M_ENTRY;
}

/*
 * Build the parallel p2m_top_mfn and p2m_mid_mfn structures
 *
 * This is called both at boot time, and after resuming from suspend:
 * - At boot time we're called very early, and must use extend_brk()
 *   to allocate memory.
 *
 * - After resume we're called from within stop_machine, but the mfn
 *   tree should alreay be completely allocated.
 */
void xen_build_mfn_list_list(void)
{
        unsigned long pfn;

        /* Pre-initialize p2m_top_mfn to be completely missing */
        if (p2m_top_mfn == NULL) {
                p2m_mid_missing_mfn = extend_brk(PAGE_SIZE, PAGE_SIZE);
                p2m_mid_mfn_init(p2m_mid_missing_mfn);

                p2m_top_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE);
                p2m_top_mfn_p_init(p2m_top_mfn_p);

                p2m_top_mfn = extend_brk(PAGE_SIZE, PAGE_SIZE);
                p2m_top_mfn_init(p2m_top_mfn);
        } else {
                /* Reinitialise, mfn's all change after migration */
                p2m_mid_mfn_init(p2m_mid_missing_mfn);
        }

        for (pfn = 0; pfn < xen_max_p2m_pfn; pfn += P2M_PER_PAGE) {
                unsigned topidx = p2m_top_index(pfn);
                unsigned mididx = p2m_mid_index(pfn);
                unsigned long **mid;
                unsigned long *mid_mfn_p;

                mid = p2m_top[topidx];
                mid_mfn_p = p2m_top_mfn_p[topidx];

                /* Don't bother allocating any mfn mid levels if
                 * they're just missing, just update the stored mfn,
                 * since all could have changed over a migrate.
                 */
                if (mid == p2m_mid_missing) {
                        BUG_ON(mididx);
                        BUG_ON(mid_mfn_p != p2m_mid_missing_mfn);
                        p2m_top_mfn[topidx] = virt_to_mfn(p2m_mid_missing_mfn);
                        pfn += (P2M_MID_PER_PAGE - 1) * P2M_PER_PAGE;
                        continue;
                }

                if (mid_mfn_p == p2m_mid_missing_mfn) {
                        /*
                         * XXX boot-time only!  We should never find
                         * missing parts of the mfn tree after
                         * runtime.  extend_brk() will BUG if we call
                         * it too late.
                         */
                        mid_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE);
                        p2m_mid_mfn_init(mid_mfn_p);

                        p2m_top_mfn_p[topidx] = mid_mfn_p;
                }

                p2m_top_mfn[topidx] = virt_to_mfn(mid_mfn_p);
                mid_mfn_p[mididx] = virt_to_mfn(mid[mididx]);
        }
}

void xen_setup_mfn_list_list(void)
{
        BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info);

        HYPERVISOR_shared_info->arch.pfn_to_mfn_frame_list_list =
                virt_to_mfn(p2m_top_mfn);
        HYPERVISOR_shared_info->arch.max_pfn = xen_max_p2m_pfn;
}

/* Set up p2m_top to point to the domain-builder provided p2m pages */
void __init xen_build_dynamic_phys_to_machine(void)
{
        unsigned long *mfn_list = (unsigned long *)xen_start_info->mfn_list;
        unsigned long max_pfn = min(MAX_DOMAIN_PAGES, xen_start_info->nr_pages);
        unsigned long pfn;

        xen_max_p2m_pfn = max_pfn;

        p2m_missing = extend_brk(PAGE_SIZE, PAGE_SIZE);
        p2m_init(p2m_missing);

        p2m_mid_missing = extend_brk(PAGE_SIZE, PAGE_SIZE);
        p2m_mid_init(p2m_mid_missing);

        p2m_top = extend_brk(PAGE_SIZE, PAGE_SIZE);
        p2m_top_init(p2m_top);

        /*
         * The domain builder gives us a pre-constructed p2m array in
         * mfn_list for all the pages initially given to us, so we just
         * need to graft that into our tree structure.
         */
        for (pfn = 0; pfn < max_pfn; pfn += P2M_PER_PAGE) {
                unsigned topidx = p2m_top_index(pfn);
                unsigned mididx = p2m_mid_index(pfn);

                if (p2m_top[topidx] == p2m_mid_missing) {
                        unsigned long **mid = extend_brk(PAGE_SIZE, PAGE_SIZE);
                        p2m_mid_init(mid);

                        p2m_top[topidx] = mid;
                }

                /*
                 * As long as the mfn_list has enough entries to completely
                 * fill a p2m page, pointing into the array is ok. But if
                 * not the entries beyond the last pfn will be undefined.
                 */
                if (unlikely(pfn + P2M_PER_PAGE > max_pfn)) {
                        unsigned long p2midx;

                        p2midx = max_pfn % P2M_PER_PAGE;
                        for ( ; p2midx < P2M_PER_PAGE; p2midx++)
                                mfn_list[pfn + p2midx] = INVALID_P2M_ENTRY;
                }
                p2m_top[topidx][mididx] = &mfn_list[pfn];
        }

        m2p_override_init();
}

unsigned long get_phys_to_machine(unsigned long pfn)
{
        unsigned topidx, mididx, idx;

        if (unlikely(pfn >= MAX_P2M_PFN))
                return INVALID_P2M_ENTRY;

        topidx = p2m_top_index(pfn);
        mididx = p2m_mid_index(pfn);
        idx = p2m_index(pfn);

        return p2m_top[topidx][mididx][idx];
}
EXPORT_SYMBOL_GPL(get_phys_to_machine);

static void *alloc_p2m_page(void)
{
        return (void *)__get_free_page(GFP_KERNEL | __GFP_REPEAT);
}

static void free_p2m_page(void *p)
{
        free_page((unsigned long)p);
}

/* 
 * Fully allocate the p2m structure for a given pfn.  We need to check
 * that both the top and mid levels are allocated, and make sure the
 * parallel mfn tree is kept in sync.  We may race with other cpus, so
 * the new pages are installed with cmpxchg; if we lose the race then
 * simply free the page we allocated and use the one that's there.
 */
static bool alloc_p2m(unsigned long pfn)
{
        unsigned topidx, mididx;
        unsigned long ***top_p, **mid;
        unsigned long *top_mfn_p, *mid_mfn;

        topidx = p2m_top_index(pfn);
        mididx = p2m_mid_index(pfn);

        top_p = &p2m_top[topidx];
        mid = *top_p;

        if (mid == p2m_mid_missing) {
                /* Mid level is missing, allocate a new one */
                mid = alloc_p2m_page();
                if (!mid)
                        return false;

                p2m_mid_init(mid);

                if (cmpxchg(top_p, p2m_mid_missing, mid) != p2m_mid_missing)
                        free_p2m_page(mid);
        }

        top_mfn_p = &p2m_top_mfn[topidx];
        mid_mfn = p2m_top_mfn_p[topidx];

        BUG_ON(virt_to_mfn(mid_mfn) != *top_mfn_p);

        if (mid_mfn == p2m_mid_missing_mfn) {
                /* Separately check the mid mfn level */
                unsigned long missing_mfn;
                unsigned long mid_mfn_mfn;

                mid_mfn = alloc_p2m_page();
                if (!mid_mfn)
                        return false;

                p2m_mid_mfn_init(mid_mfn);

                missing_mfn = virt_to_mfn(p2m_mid_missing_mfn);
                mid_mfn_mfn = virt_to_mfn(mid_mfn);
                if (cmpxchg(top_mfn_p, missing_mfn, mid_mfn_mfn) != missing_mfn)
                        free_p2m_page(mid_mfn);
                else
                        p2m_top_mfn_p[topidx] = mid_mfn;
        }

        if (p2m_top[topidx][mididx] == p2m_missing) {
                /* p2m leaf page is missing */
                unsigned long *p2m;

                p2m = alloc_p2m_page();
                if (!p2m)
                        return false;

                p2m_init(p2m);

                if (cmpxchg(&mid[mididx], p2m_missing, p2m) != p2m_missing)
                        free_p2m_page(p2m);
                else
                        mid_mfn[mididx] = virt_to_mfn(p2m);
        }

        return true;
}

/* Try to install p2m mapping; fail if intermediate bits missing */
bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn)
{
        unsigned topidx, mididx, idx;

        if (unlikely(pfn >= MAX_P2M_PFN)) {
                BUG_ON(mfn != INVALID_P2M_ENTRY);
                return true;
        }

        topidx = p2m_top_index(pfn);
        mididx = p2m_mid_index(pfn);
        idx = p2m_index(pfn);

        if (p2m_top[topidx][mididx] == p2m_missing)
                return mfn == INVALID_P2M_ENTRY;

        p2m_top[topidx][mididx][idx] = mfn;

        return true;
}

bool set_phys_to_machine(unsigned long pfn, unsigned long mfn)
{
        if (unlikely(xen_feature(XENFEAT_auto_translated_physmap))) {
                BUG_ON(pfn != mfn && mfn != INVALID_P2M_ENTRY);
                return true;
        }

        if (unlikely(!__set_phys_to_machine(pfn, mfn)))  {
                if (!alloc_p2m(pfn))
                        return false;

                if (!__set_phys_to_machine(pfn, mfn))
                        return false;
        }

        return true;
}

#define M2P_OVERRIDE_HASH_SHIFT 10
#define M2P_OVERRIDE_HASH       (1 << M2P_OVERRIDE_HASH_SHIFT)

static RESERVE_BRK_ARRAY(struct list_head, m2p_overrides, M2P_OVERRIDE_HASH);
static DEFINE_SPINLOCK(m2p_override_lock);

static void __init m2p_override_init(void)
{
        unsigned i;

        m2p_overrides = extend_brk(sizeof(*m2p_overrides) * M2P_OVERRIDE_HASH,
                                   sizeof(unsigned long));

        for (i = 0; i < M2P_OVERRIDE_HASH; i++)
                INIT_LIST_HEAD(&m2p_overrides[i]);
}

static unsigned long mfn_hash(unsigned long mfn)
{
        return hash_long(mfn, M2P_OVERRIDE_HASH_SHIFT);
}

/* Add an MFN override for a particular page */
int m2p_add_override(unsigned long mfn, struct page *page)
{
        unsigned long flags;
        unsigned long pfn;
        unsigned long address;
        unsigned level;
        pte_t *ptep = NULL;

        pfn = page_to_pfn(page);
        if (!PageHighMem(page)) {
                address = (unsigned long)__va(pfn << PAGE_SHIFT);
                ptep = lookup_address(address, &level);

                if (WARN(ptep == NULL || level != PG_LEVEL_4K,
                                        "m2p_add_override: pfn %lx not mapped", pfn))
                        return -EINVAL;
        }

        page->private = mfn;
        page->index = pfn_to_mfn(pfn);

        __set_phys_to_machine(pfn, FOREIGN_FRAME(mfn));
        if (!PageHighMem(page))
                /* Just zap old mapping for now */
                pte_clear(&init_mm, address, ptep);

        spin_lock_irqsave(&m2p_override_lock, flags);
        list_add(&page->lru,  &m2p_overrides[mfn_hash(mfn)]);
        spin_unlock_irqrestore(&m2p_override_lock, flags);

        return 0;
}

int m2p_remove_override(struct page *page)
{
        unsigned long flags;
        unsigned long mfn;
        unsigned long pfn;
        unsigned long address;
        unsigned level;
        pte_t *ptep = NULL;

        pfn = page_to_pfn(page);
        mfn = get_phys_to_machine(pfn);
        if (mfn == INVALID_P2M_ENTRY || !(mfn & FOREIGN_FRAME_BIT))
                return -EINVAL;

        if (!PageHighMem(page)) {
                address = (unsigned long)__va(pfn << PAGE_SHIFT);
                ptep = lookup_address(address, &level);

                if (WARN(ptep == NULL || level != PG_LEVEL_4K,
                                        "m2p_remove_override: pfn %lx not mapped", pfn))
                        return -EINVAL;
        }

        spin_lock_irqsave(&m2p_override_lock, flags);
        list_del(&page->lru);
        spin_unlock_irqrestore(&m2p_override_lock, flags);
        __set_phys_to_machine(pfn, page->index);

        if (!PageHighMem(page))
                set_pte_at(&init_mm, address, ptep,
                                pfn_pte(pfn, PAGE_KERNEL));
                /* No tlb flush necessary because the caller already
                 * left the pte unmapped. */

        return 0;
}

struct page *m2p_find_override(unsigned long mfn)
{
        unsigned long flags;
        struct list_head *bucket = &m2p_overrides[mfn_hash(mfn)];
        struct page *p, *ret;

        ret = NULL;

        spin_lock_irqsave(&m2p_override_lock, flags);

        list_for_each_entry(p, bucket, lru) {
                if (p->private == mfn) {
                        ret = p;
                        break;
                }
        }

        spin_unlock_irqrestore(&m2p_override_lock, flags);

        return ret;
}

unsigned long m2p_find_override_pfn(unsigned long mfn, unsigned long pfn)
{
        struct page *p = m2p_find_override(mfn);
        unsigned long ret = pfn;

        if (p)
                ret = page_to_pfn(p);

        return ret;
}
EXPORT_SYMBOL_GPL(m2p_find_override_pfn);