/*
 * Machine specific setup for xen
 *
 * Jeremy Fitzhardinge <jeremy@xensource.com>, 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 <asm/elf.h>
#include <asm/vdso.h>
#include <asm/e820.h>
#include <asm/setup.h>
#include <asm/acpi.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++)
                __set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
}

static unsigned long __init xen_release_chunk(unsigned long start,
                                              unsigned long end)
{
        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 mfn = pfn_to_mfn(pfn);

                /* Make sure pfn exists to start with */
                if (mfn == INVALID_P2M_ENTRY || mfn_to_pfn(mfn) != pfn)
                        continue;

                set_xen_guest_handle(reservation.extent_start, &mfn);
                reservation.nr_extents = 1;

                ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation,
                                           &reservation);
                WARN(ret != 1, "Failed to release pfn %lx err=%d\n", pfn, ret);
                if (ret == 1) {
                        __set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
                        len++;
                }
        }
        printk(KERN_INFO "Freeing  %lx-%lx pfn range: %lu pages freed\n",
               start, end, len);

        return len;
}

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) {
                                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);
                        }
                        start = end;
                }
        }

        printk(KERN_INFO "Released %lu pages of unused memory\n", released);
        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);
}

/**
 * machine_specific_memory_setup - Hook for machine specific memory setup.
 **/
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 extra_pages = 0;
        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);
        extra_pages += xen_released_pages;

        /*
         * 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>
         */
        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();
        boot_option_idle_override = IDLE_HALT;
        WARN_ON(set_pm_idle_to_default());
        fiddle_vdso();
}