setup.c

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/*
 * Machine specific setup for xen
 *
 * Jeremy Fitzhardinge <[email protected]>, XenSource Inc, 2007
 */

#include <linux/module.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/pm.h>
#include <linux/memblock.h>
#include <linux/cpuidle.h>
#include <linux/cpufreq.h>

#include <asm/elf.h>
#include <asm/vdso.h>
#include <asm/e820.h>
#include <asm/setup.h>
#include <asm/acpi.h>
#include <asm/numa.h>
#include <asm/xen/hypervisor.h>
#include <asm/xen/hypercall.h>

#include <xen/xen.h>
#include <xen/page.h>
#include <xen/interface/callback.h>
#include <xen/interface/memory.h>
#include <xen/interface/physdev.h>
#include <xen/features.h>
#include "xen-ops.h"
#include "vdso.h"

/* These are code, but not functions.  Defined in entry.S */
extern const char xen_hypervisor_callback[];
extern const char xen_failsafe_callback[];
extern void xen_sysenter_target(void);
extern void xen_syscall_target(void);
extern void xen_syscall32_target(void);

/* Amount of extra memory space we add to the e820 ranges */
struct xen_memory_region xen_extra_mem[XEN_EXTRA_MEM_MAX_REGIONS] __initdata;

/* Number of pages released from the initial allocation. */
unsigned long xen_released_pages;

/* 
 * The maximum amount of extra memory compared to the base size.  The
 * main scaling factor is the size of struct page.  At extreme ratios
 * of base:extra, all the base memory can be filled with page
 * structures for the extra memory, leaving no space for anything
 * else.
 * 
 * 10x seems like a reasonable balance between scaling flexibility and
 * leaving a practically usable system.
 */
#define EXTRA_MEM_RATIO     (10)

static void __init xen_add_extra_mem(u64 start, u64 size)
{
    unsigned long pfn;
    int i;

    for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) {
        /* Add new region. */
        if (xen_extra_mem[i].size == 0) {
            xen_extra_mem[i].start = start;
            xen_extra_mem[i].size  = size;
            break;
        }
        /* Append to existing region. */
        if (xen_extra_mem[i].start + xen_extra_mem[i].size == start) {
            xen_extra_mem[i].size += size;
            break;
        }
    }
    if (i == XEN_EXTRA_MEM_MAX_REGIONS)
        printk(KERN_WARNING "Warning: not enough extra memory regions\n");

    memblock_reserve(start, size);

    xen_max_p2m_pfn = PFN_DOWN(start + size);
    for (pfn = PFN_DOWN(start); pfn < xen_max_p2m_pfn; pfn++) {
        unsigned long mfn = pfn_to_mfn(pfn);

        if (WARN(mfn == pfn, "Trying to over-write 1-1 mapping (pfn: %lx)\n", pfn))
            continue;
        WARN(mfn != INVALID_P2M_ENTRY, "Trying to remove %lx which has %lx mfn!\n",
            pfn, mfn);

        __set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
    }
}

static unsigned long __init xen_do_chunk(unsigned long start,
                     unsigned long end, bool release)
{
    struct xen_memory_reservation reservation = {
        .address_bits = 0,
        .extent_order = 0,
        .domid        = DOMID_SELF
    };
    unsigned long len = 0;
    unsigned long pfn;
    int ret;

    for (pfn = start; pfn < end; pfn++) {
        unsigned long frame;
        unsigned long mfn = pfn_to_mfn(pfn);

        if (release) {
            /* Make sure pfn exists to start with */
            if (mfn == INVALID_P2M_ENTRY || mfn_to_pfn(mfn) != pfn)
                continue;
            frame = mfn;
        } else {
            if (mfn != INVALID_P2M_ENTRY)
                continue;
            frame = pfn;
        }
        set_xen_guest_handle(reservation.extent_start, &frame);
        reservation.nr_extents = 1;

        ret = HYPERVISOR_memory_op(release ? XENMEM_decrease_reservation : XENMEM_populate_physmap,
                       &reservation);
        WARN(ret != 1, "Failed to %s pfn %lx err=%d\n",
             release ? "release" : "populate", pfn, ret);

        if (ret == 1) {
            if (!early_set_phys_to_machine(pfn, release ? INVALID_P2M_ENTRY : frame)) {
                if (release)
                    break;
                set_xen_guest_handle(reservation.extent_start, &frame);
                reservation.nr_extents = 1;
                ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation,
                               &reservation);
                break;
            }
            len++;
        } else
            break;
    }
    if (len)
        printk(KERN_INFO "%s %lx-%lx pfn range: %lu pages %s\n",
               release ? "Freeing" : "Populating",
               start, end, len,
               release ? "freed" : "added");

    return len;
}

static unsigned long __init xen_release_chunk(unsigned long start,
                          unsigned long end)
{
    return xen_do_chunk(start, end, true);
}

static unsigned long __init xen_populate_chunk(
    const struct e820entry *list, size_t map_size,
    unsigned long max_pfn, unsigned long *last_pfn,
    unsigned long credits_left)
{
    const struct e820entry *entry;
    unsigned int i;
    unsigned long done = 0;
    unsigned long dest_pfn;

    for (i = 0, entry = list; i < map_size; i++, entry++) {
        unsigned long s_pfn;
        unsigned long e_pfn;
        unsigned long pfns;
        long capacity;

        if (credits_left <= 0)
            break;

        if (entry->type != E820_RAM)
            continue;

        e_pfn = PFN_DOWN(entry->addr + entry->size);

        /* We only care about E820 after the xen_start_info->nr_pages */
        if (e_pfn <= max_pfn)
            continue;

        s_pfn = PFN_UP(entry->addr);
        /* If the E820 falls within the nr_pages, we want to start
         * at the nr_pages PFN.
         * If that would mean going past the E820 entry, skip it
         */
        if (s_pfn <= max_pfn) {
            capacity = e_pfn - max_pfn;
            dest_pfn = max_pfn;
        } else {
            capacity = e_pfn - s_pfn;
            dest_pfn = s_pfn;
        }

        if (credits_left < capacity)
            capacity = credits_left;

        pfns = xen_do_chunk(dest_pfn, dest_pfn + capacity, false);
        done += pfns;
        *last_pfn = (dest_pfn + pfns);
        if (pfns < capacity)
            break;
        credits_left -= pfns;
    }
    return done;
}

static void __init xen_set_identity_and_release_chunk(
    unsigned long start_pfn, unsigned long end_pfn, unsigned long nr_pages,
    unsigned long *released, unsigned long *identity)
{
    unsigned long pfn;

    /*
     * If the PFNs are currently mapped, the VA mapping also needs
     * to be updated to be 1:1.
     */
    for (pfn = start_pfn; pfn <= max_pfn_mapped && pfn < end_pfn; pfn++)
        (void)HYPERVISOR_update_va_mapping(
            (unsigned long)__va(pfn << PAGE_SHIFT),
            mfn_pte(pfn, PAGE_KERNEL_IO), 0);

    if (start_pfn < nr_pages)
        *released += xen_release_chunk(
            start_pfn, min(end_pfn, nr_pages));

    *identity += set_phys_range_identity(start_pfn, end_pfn);
}

static unsigned long __init xen_set_identity_and_release(
    const struct e820entry *list, size_t map_size, unsigned long nr_pages)
{
    phys_addr_t start = 0;
    unsigned long released = 0;
    unsigned long identity = 0;
    const struct e820entry *entry;
    int i;

    /*
     * Combine non-RAM regions and gaps until a RAM region (or the
     * end of the map) is reached, then set the 1:1 map and
     * release the pages (if available) in those non-RAM regions.
     *
     * The combined non-RAM regions are rounded to a whole number
     * of pages so any partial pages are accessible via the 1:1
     * mapping.  This is needed for some BIOSes that put (for
     * example) the DMI tables in a reserved region that begins on
     * a non-page boundary.
     */
    for (i = 0, entry = list; i < map_size; i++, entry++) {
        phys_addr_t end = entry->addr + entry->size;
        if (entry->type == E820_RAM || i == map_size - 1) {
            unsigned long start_pfn = PFN_DOWN(start);
            unsigned long end_pfn = PFN_UP(end);

            if (entry->type == E820_RAM)
                end_pfn = PFN_UP(entry->addr);

            if (start_pfn < end_pfn)
                xen_set_identity_and_release_chunk(
                    start_pfn, end_pfn, nr_pages,
                    &released, &identity);

            start = end;
        }
    }

    if (released)
        printk(KERN_INFO "Released %lu pages of unused memory\n", released);
    if (identity)
        printk(KERN_INFO "Set %ld page(s) to 1-1 mapping\n", identity);

    return released;
}

static unsigned long __init xen_get_max_pages(void)
{
    unsigned long max_pages = MAX_DOMAIN_PAGES;
    domid_t domid = DOMID_SELF;
    int ret;

    /*
     * For the initial domain we use the maximum reservation as
     * the maximum page.
     *
     * For guest domains the current maximum reservation reflects
     * the current maximum rather than the static maximum. In this
     * case the e820 map provided to us will cover the static
     * maximum region.
     */
    if (xen_initial_domain()) {
        ret = HYPERVISOR_memory_op(XENMEM_maximum_reservation, &domid);
        if (ret > 0)
            max_pages = ret;
    }

    return min(max_pages, MAX_DOMAIN_PAGES);
}

static void xen_align_and_add_e820_region(u64 start, u64 size, int type)
{
    u64 end = start + size;

    /* Align RAM regions to page boundaries. */
    if (type == E820_RAM) {
        start = PAGE_ALIGN(start);
        end &= ~((u64)PAGE_SIZE - 1);
    }

    e820_add_region(start, end - start, type);
}

char * __init xen_memory_setup(void)
{
    static struct e820entry map[E820MAX] __initdata;

    unsigned long max_pfn = xen_start_info->nr_pages;
    unsigned long long mem_end;
    int rc;
    struct xen_memory_map memmap;
    unsigned long max_pages;
    unsigned long last_pfn = 0;
    unsigned long extra_pages = 0;
    unsigned long populated;
    int i;
    int op;

    max_pfn = min(MAX_DOMAIN_PAGES, max_pfn);
    mem_end = PFN_PHYS(max_pfn);

    memmap.nr_entries = E820MAX;
    set_xen_guest_handle(memmap.buffer, map);

    op = xen_initial_domain() ?
        XENMEM_machine_memory_map :
        XENMEM_memory_map;
    rc = HYPERVISOR_memory_op(op, &memmap);
    if (rc == -ENOSYS) {
        BUG_ON(xen_initial_domain());
        memmap.nr_entries = 1;
        map[0].addr = 0ULL;
        map[0].size = mem_end;
        /* 8MB slack (to balance backend allocations). */
        map[0].size += 8ULL << 20;
        map[0].type = E820_RAM;
        rc = 0;
    }
    BUG_ON(rc);

    /* Make sure the Xen-supplied memory map is well-ordered. */
    sanitize_e820_map(map, memmap.nr_entries, &memmap.nr_entries);

    max_pages = xen_get_max_pages();
    if (max_pages > max_pfn)
        extra_pages += max_pages - max_pfn;

    /*
     * Set P2M for all non-RAM pages and E820 gaps to be identity
     * type PFNs.  Any RAM pages that would be made inaccesible by
     * this are first released.
     */
    xen_released_pages = xen_set_identity_and_release(
        map, memmap.nr_entries, max_pfn);

    /*
     * Populate back the non-RAM pages and E820 gaps that had been
     * released. */
    populated = xen_populate_chunk(map, memmap.nr_entries,
            max_pfn, &last_pfn, xen_released_pages);

    xen_released_pages -= populated;
    extra_pages += xen_released_pages;

    if (last_pfn > max_pfn) {
        max_pfn = min(MAX_DOMAIN_PAGES, last_pfn);
        mem_end = PFN_PHYS(max_pfn);
    }
    /*
     * Clamp the amount of extra memory to a EXTRA_MEM_RATIO
     * factor the base size.  On non-highmem systems, the base
     * size is the full initial memory allocation; on highmem it
     * is limited to the max size of lowmem, so that it doesn't
     * get completely filled.
     *
     * In principle there could be a problem in lowmem systems if
     * the initial memory is also very large with respect to
     * lowmem, but we won't try to deal with that here.
     */
    extra_pages = min(EXTRA_MEM_RATIO * min(max_pfn, PFN_DOWN(MAXMEM)),
              extra_pages);
    i = 0;
    while (i < memmap.nr_entries) {
        u64 addr = map[i].addr;
        u64 size = map[i].size;
        u32 type = map[i].type;

        if (type == E820_RAM) {
            if (addr < mem_end) {
                size = min(size, mem_end - addr);
            } else if (extra_pages) {
                size = min(size, (u64)extra_pages * PAGE_SIZE);
                extra_pages -= size / PAGE_SIZE;
                xen_add_extra_mem(addr, size);
            } else
                type = E820_UNUSABLE;
        }

        xen_align_and_add_e820_region(addr, size, type);

        map[i].addr += size;
        map[i].size -= size;
        if (map[i].size == 0)
            i++;
    }

    /*
     * In domU, the ISA region is normal, usable memory, but we
     * reserve ISA memory anyway because too many things poke
     * about in there.
     */
    e820_add_region(ISA_START_ADDRESS, ISA_END_ADDRESS - ISA_START_ADDRESS,
            E820_RESERVED);

    /*
     * Reserve Xen bits:
     *  - mfn_list
     *  - xen_start_info
     * See comment above "struct start_info" in <xen/interface/xen.h>
     * We tried to make the the memblock_reserve more selective so
     * that it would be clear what region is reserved. Sadly we ran
     * in the problem wherein on a 64-bit hypervisor with a 32-bit
     * initial domain, the pt_base has the cr3 value which is not
     * neccessarily where the pagetable starts! As Jan put it: "
     * Actually, the adjustment turns out to be correct: The page
     * tables for a 32-on-64 dom0 get allocated in the order "first L1",
     * "first L2", "first L3", so the offset to the page table base is
     * indeed 2. When reading xen/include/public/xen.h's comment
     * very strictly, this is not a violation (since there nothing is said
     * that the first thing in the page table space is pointed to by
     * pt_base; I admit that this seems to be implied though, namely
     * do I think that it is implied that the page table space is the
     * range [pt_base, pt_base + nt_pt_frames), whereas that
     * range here indeed is [pt_base - 2, pt_base - 2 + nt_pt_frames),
     * which - without a priori knowledge - the kernel would have
     * difficulty to figure out)." - so lets just fall back to the
     * easy way and reserve the whole region.
     */
    memblock_reserve(__pa(xen_start_info->mfn_list),
             xen_start_info->pt_base - xen_start_info->mfn_list);

    sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &e820.nr_map);

    return "Xen";
}

/*
 * Set the bit indicating "nosegneg" library variants should be used.
 * We only need to bother in pure 32-bit mode; compat 32-bit processes
 * can have un-truncated segments, so wrapping around is allowed.
 */
static void __init fiddle_vdso(void)
{
#ifdef CONFIG_X86_32
    u32 *mask;
    mask = VDSO32_SYMBOL(&vdso32_int80_start, NOTE_MASK);
    *mask |= 1 << VDSO_NOTE_NONEGSEG_BIT;
    mask = VDSO32_SYMBOL(&vdso32_sysenter_start, NOTE_MASK);
    *mask |= 1 << VDSO_NOTE_NONEGSEG_BIT;
#endif
}

static int __cpuinit register_callback(unsigned type, const void *func)
{
    struct callback_register callback = {
        .type = type,
        .address = XEN_CALLBACK(__KERNEL_CS, func),
        .flags = CALLBACKF_mask_events,
    };

    return HYPERVISOR_callback_op(CALLBACKOP_register, &callback);
}

void __cpuinit xen_enable_sysenter(void)
{
    int ret;
    unsigned sysenter_feature;

#ifdef CONFIG_X86_32
    sysenter_feature = X86_FEATURE_SEP;
#else
    sysenter_feature = X86_FEATURE_SYSENTER32;
#endif

    if (!boot_cpu_has(sysenter_feature))
        return;

    ret = register_callback(CALLBACKTYPE_sysenter, xen_sysenter_target);
    if(ret != 0)
        setup_clear_cpu_cap(sysenter_feature);
}

void __cpuinit xen_enable_syscall(void)
{
#ifdef CONFIG_X86_64
    int ret;

    ret = register_callback(CALLBACKTYPE_syscall, xen_syscall_target);
    if (ret != 0) {
        printk(KERN_ERR "Failed to set syscall callback: %d\n", ret);
        /* Pretty fatal; 64-bit userspace has no other
           mechanism for syscalls. */
    }

    if (boot_cpu_has(X86_FEATURE_SYSCALL32)) {
        ret = register_callback(CALLBACKTYPE_syscall32,
                    xen_syscall32_target);
        if (ret != 0)
            setup_clear_cpu_cap(X86_FEATURE_SYSCALL32);
    }
#endif /* CONFIG_X86_64 */
}

void __init xen_arch_setup(void)
{
    xen_panic_handler_init();

    HYPERVISOR_vm_assist(VMASST_CMD_enable, VMASST_TYPE_4gb_segments);
    HYPERVISOR_vm_assist(VMASST_CMD_enable, VMASST_TYPE_writable_pagetables);

    if (!xen_feature(XENFEAT_auto_translated_physmap))
        HYPERVISOR_vm_assist(VMASST_CMD_enable,
                     VMASST_TYPE_pae_extended_cr3);

    if (register_callback(CALLBACKTYPE_event, xen_hypervisor_callback) ||
        register_callback(CALLBACKTYPE_failsafe, xen_failsafe_callback))
        BUG();

    xen_enable_sysenter();
    xen_enable_syscall();

#ifdef CONFIG_ACPI
    if (!(xen_start_info->flags & SIF_INITDOMAIN)) {
        printk(KERN_INFO "ACPI in unprivileged domain disabled\n");
        disable_acpi();
    }
#endif

    memcpy(boot_command_line, xen_start_info->cmd_line,
           MAX_GUEST_CMDLINE > COMMAND_LINE_SIZE ?
           COMMAND_LINE_SIZE : MAX_GUEST_CMDLINE);

    /* Set up idle, making sure it calls safe_halt() pvop */
#ifdef CONFIG_X86_32
    boot_cpu_data.hlt_works_ok = 1;
#endif
    disable_cpuidle();
    disable_cpufreq();
    WARN_ON(set_pm_idle_to_default());
    fiddle_vdso();
#ifdef CONFIG_NUMA
    numa_off = 1;
#endif
}