/*
 * VMI specific paravirt-ops implementation
 *
 * Copyright (C) 2005, VMware, Inc.
 *
 * 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, GOOD TITLE or
 * NON INFRINGEMENT.  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., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 * Send feedback to zach@vmware.com
 *
 */

#include <linux/module.h>
#include <linux/cpu.h>
#include <linux/bootmem.h>
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/sched.h>
#include <asm/vmi.h>
#include <asm/io.h>
#include <asm/fixmap.h>
#include <asm/apicdef.h>
#include <asm/apic.h>
#include <asm/processor.h>
#include <asm/timer.h>
#include <asm/vmi_time.h>
#include <asm/kmap_types.h>

/* Convenient for calling VMI functions indirectly in the ROM */
typedef u32 __attribute__((regparm(1))) (VROMFUNC)(void);
typedef u64 __attribute__((regparm(2))) (VROMLONGFUNC)(int);

#define call_vrom_func(rom,func) \
   (((VROMFUNC *)(rom->func))())

#define call_vrom_long_func(rom,func,arg) \
   (((VROMLONGFUNC *)(rom->func)) (arg))

static struct vrom_header *vmi_rom;
static int disable_pge;
static int disable_pse;
static int disable_sep;
static int disable_tsc;
static int disable_mtrr;
static int disable_noidle;
static int disable_vmi_timer;

/* Cached VMI operations */
static struct {
        void (*cpuid)(void /* non-c */);
        void (*_set_ldt)(u32 selector);
        void (*set_tr)(u32 selector);
        void (*set_kernel_stack)(u32 selector, u32 esp0);
        void (*allocate_page)(u32, u32, u32, u32, u32);
        void (*release_page)(u32, u32);
        void (*set_pte)(pte_t, pte_t *, unsigned);
        void (*update_pte)(pte_t *, unsigned);
        void (*set_linear_mapping)(int, void *, u32, u32);
        void (*_flush_tlb)(int);
        void (*set_initial_ap_state)(int, int);
        void (*halt)(void);
        void (*set_lazy_mode)(int mode);
} vmi_ops;

/* Cached VMI operations */
struct vmi_timer_ops vmi_timer_ops;

/*
 * VMI patching routines.
 */
#define MNEM_CALL 0xe8
#define MNEM_JMP  0xe9
#define MNEM_RET  0xc3

#define IRQ_PATCH_INT_MASK 0
#define IRQ_PATCH_DISABLE  5

static inline void patch_offset(unsigned char *eip, unsigned char *dest)
{
        *(unsigned long *)(eip+1) = dest-eip-5;
}

static unsigned patch_internal(int call, unsigned len, void *insns)
{
        u64 reloc;
        struct vmi_relocation_info *const rel = (struct vmi_relocation_info *)&reloc;
        reloc = call_vrom_long_func(vmi_rom, get_reloc, call);
        switch(rel->type) {
                case VMI_RELOCATION_CALL_REL:
                        BUG_ON(len < 5);
                        *(char *)insns = MNEM_CALL;
                        patch_offset(insns, rel->eip);
                        return 5;

                case VMI_RELOCATION_JUMP_REL:
                        BUG_ON(len < 5);
                        *(char *)insns = MNEM_JMP;
                        patch_offset(insns, rel->eip);
                        return 5;

                case VMI_RELOCATION_NOP:
                        /* obliterate the whole thing */
                        return 0;

                case VMI_RELOCATION_NONE:
                        /* leave native code in place */
                        break;

                default:
                        BUG();
        }
        return len;
}

/*
 * Apply patch if appropriate, return length of new instruction
 * sequence.  The callee does nop padding for us.
 */
static unsigned vmi_patch(u8 type, u16 clobbers, void *insns, unsigned len)
{
        switch (type) {
                case PARAVIRT_PATCH(irq_disable):
                        return patch_internal(VMI_CALL_DisableInterrupts, len, insns);
                case PARAVIRT_PATCH(irq_enable):
                        return patch_internal(VMI_CALL_EnableInterrupts, len, insns);
                case PARAVIRT_PATCH(restore_fl):
                        return patch_internal(VMI_CALL_SetInterruptMask, len, insns);
                case PARAVIRT_PATCH(save_fl):
                        return patch_internal(VMI_CALL_GetInterruptMask, len, insns);
                case PARAVIRT_PATCH(iret):
                        return patch_internal(VMI_CALL_IRET, len, insns);
                case PARAVIRT_PATCH(irq_enable_sysexit):
                        return patch_internal(VMI_CALL_SYSEXIT, len, insns);
                default:
                        break;
        }
        return len;
}

/* CPUID has non-C semantics, and paravirt-ops API doesn't match hardware ISA */
static void vmi_cpuid(unsigned int *eax, unsigned int *ebx,
                               unsigned int *ecx, unsigned int *edx)
{
        int override = 0;
        if (*eax == 1)
                override = 1;
        asm volatile ("call *%6"
                      : "=a" (*eax),
                        "=b" (*ebx),
                        "=c" (*ecx),
                        "=d" (*edx)
                      : "0" (*eax), "2" (*ecx), "r" (vmi_ops.cpuid));
        if (override) {
                if (disable_pse)
                        *edx &= ~X86_FEATURE_PSE;
                if (disable_pge)
                        *edx &= ~X86_FEATURE_PGE;
                if (disable_sep)
                        *edx &= ~X86_FEATURE_SEP;
                if (disable_tsc)
                        *edx &= ~X86_FEATURE_TSC;
                if (disable_mtrr)
                        *edx &= ~X86_FEATURE_MTRR;
        }
}

static inline void vmi_maybe_load_tls(struct desc_struct *gdt, int nr, struct desc_struct *new)
{
        if (gdt[nr].a != new->a || gdt[nr].b != new->b)
                write_gdt_entry(gdt, nr, new->a, new->b);
}

static void vmi_load_tls(struct thread_struct *t, unsigned int cpu)
{
        struct desc_struct *gdt = get_cpu_gdt_table(cpu);
        vmi_maybe_load_tls(gdt, GDT_ENTRY_TLS_MIN + 0, &t->tls_array[0]);
        vmi_maybe_load_tls(gdt, GDT_ENTRY_TLS_MIN + 1, &t->tls_array[1]);
        vmi_maybe_load_tls(gdt, GDT_ENTRY_TLS_MIN + 2, &t->tls_array[2]);
}

static void vmi_set_ldt(const void *addr, unsigned entries)
{
        unsigned cpu = smp_processor_id();
        u32 low, high;

        pack_descriptor(&low, &high, (unsigned long)addr,
                        entries * sizeof(struct desc_struct) - 1,
                        DESCTYPE_LDT, 0);
        write_gdt_entry(get_cpu_gdt_table(cpu), GDT_ENTRY_LDT, low, high);
        vmi_ops._set_ldt(entries ? GDT_ENTRY_LDT*sizeof(struct desc_struct) : 0);
}

static void vmi_set_tr(void)
{
        vmi_ops.set_tr(GDT_ENTRY_TSS*sizeof(struct desc_struct));
}

static void vmi_load_esp0(struct tss_struct *tss,
                                   struct thread_struct *thread)
{
        tss->x86_tss.esp0 = thread->esp0;

        /* This can only happen when SEP is enabled, no need to test "SEP"arately */
        if (unlikely(tss->x86_tss.ss1 != thread->sysenter_cs)) {
                tss->x86_tss.ss1 = thread->sysenter_cs;
                wrmsr(MSR_IA32_SYSENTER_CS, thread->sysenter_cs, 0);
        }
        vmi_ops.set_kernel_stack(__KERNEL_DS, tss->x86_tss.esp0);
}

static void vmi_flush_tlb_user(void)
{
        vmi_ops._flush_tlb(VMI_FLUSH_TLB);
}

static void vmi_flush_tlb_kernel(void)
{
        vmi_ops._flush_tlb(VMI_FLUSH_TLB | VMI_FLUSH_GLOBAL);
}

/* Stub to do nothing at all; used for delays and unimplemented calls */
static void vmi_nop(void)
{
}

#ifdef CONFIG_DEBUG_PAGE_TYPE

#ifdef CONFIG_X86_PAE
#define MAX_BOOT_PTS (2048+4+1)
#else
#define MAX_BOOT_PTS (1024+1)
#endif

/*
 * During boot, mem_map is not yet available in paging_init, so stash
 * all the boot page allocations here.
 */
static struct {
        u32 pfn;
        int type;
} boot_page_allocations[MAX_BOOT_PTS];
static int num_boot_page_allocations;
static int boot_allocations_applied;

void vmi_apply_boot_page_allocations(void)
{
        int i;
        BUG_ON(!mem_map);
        for (i = 0; i < num_boot_page_allocations; i++) {
                struct page *page = pfn_to_page(boot_page_allocations[i].pfn);
                page->type = boot_page_allocations[i].type;
                page->type = boot_page_allocations[i].type &
                                ~(VMI_PAGE_ZEROED | VMI_PAGE_CLONE);
        }
        boot_allocations_applied = 1;
}

static void record_page_type(u32 pfn, int type)
{
        BUG_ON(num_boot_page_allocations >= MAX_BOOT_PTS);
        boot_page_allocations[num_boot_page_allocations].pfn = pfn;
        boot_page_allocations[num_boot_page_allocations].type = type;
        num_boot_page_allocations++;
}

static void check_zeroed_page(u32 pfn, int type, struct page *page)
{
        u32 *ptr;
        int i;
        int limit = PAGE_SIZE / sizeof(int);

        if (page_address(page))
                ptr = (u32 *)page_address(page);
        else
                ptr = (u32 *)__va(pfn << PAGE_SHIFT);
        /*
         * When cloning the root in non-PAE mode, only the userspace
         * pdes need to be zeroed.
         */
        if (type & VMI_PAGE_CLONE)
                limit = USER_PTRS_PER_PGD;
        for (i = 0; i < limit; i++)
                BUG_ON(ptr[i]);
}

/*
 * We stash the page type into struct page so we can verify the page
 * types are used properly.
 */
static void vmi_set_page_type(u32 pfn, int type)
{
        /* PAE can have multiple roots per page - don't track */
        if (PTRS_PER_PMD > 1 && (type & VMI_PAGE_PDP))
                return;

        if (boot_allocations_applied) {
                struct page *page = pfn_to_page(pfn);
                if (type != VMI_PAGE_NORMAL)
                        BUG_ON(page->type);
                else
                        BUG_ON(page->type == VMI_PAGE_NORMAL);
                page->type = type & ~(VMI_PAGE_ZEROED | VMI_PAGE_CLONE);
                if (type & VMI_PAGE_ZEROED)
                        check_zeroed_page(pfn, type, page);
        } else {
                record_page_type(pfn, type);
        }
}

static void vmi_check_page_type(u32 pfn, int type)
{
        /* PAE can have multiple roots per page - skip checks */
        if (PTRS_PER_PMD > 1 && (type & VMI_PAGE_PDP))
                return;

        type &= ~(VMI_PAGE_ZEROED | VMI_PAGE_CLONE);
        if (boot_allocations_applied) {
                struct page *page = pfn_to_page(pfn);
                BUG_ON((page->type ^ type) & VMI_PAGE_PAE);
                BUG_ON(type == VMI_PAGE_NORMAL && page->type);
                BUG_ON((type & page->type) == 0);
        }
}
#else
#define vmi_set_page_type(p,t) do { } while (0)
#define vmi_check_page_type(p,t) do { } while (0)
#endif

#ifdef CONFIG_HIGHPTE
static void *vmi_kmap_atomic_pte(struct page *page, enum km_type type)
{
        void *va = kmap_atomic(page, type);

        /*
         * Internally, the VMI ROM must map virtual addresses to physical
         * addresses for processing MMU updates.  By the time MMU updates
         * are issued, this information is typically already lost.
         * Fortunately, the VMI provides a cache of mapping slots for active
         * page tables.
         *
         * We use slot zero for the linear mapping of physical memory, and
         * in HIGHPTE kernels, slot 1 and 2 for KM_PTE0 and KM_PTE1.
         *
         *  args:                 SLOT                 VA    COUNT PFN
         */
        BUG_ON(type != KM_PTE0 && type != KM_PTE1);
        vmi_ops.set_linear_mapping((type - KM_PTE0)+1, va, 1, page_to_pfn(page));

        return va;
}
#endif

static void vmi_allocate_pt(u32 pfn)
{
        vmi_set_page_type(pfn, VMI_PAGE_L1);
        vmi_ops.allocate_page(pfn, VMI_PAGE_L1, 0, 0, 0);
}

static void vmi_allocate_pd(u32 pfn)
{
        /*
         * This call comes in very early, before mem_map is setup.
         * It is called only for swapper_pg_dir, which already has
         * data on it.
         */
        vmi_set_page_type(pfn, VMI_PAGE_L2);
        vmi_ops.allocate_page(pfn, VMI_PAGE_L2, 0, 0, 0);
}

static void vmi_allocate_pd_clone(u32 pfn, u32 clonepfn, u32 start, u32 count)
{
        vmi_set_page_type(pfn, VMI_PAGE_L2 | VMI_PAGE_CLONE);
        vmi_check_page_type(clonepfn, VMI_PAGE_L2);
        vmi_ops.allocate_page(pfn, VMI_PAGE_L2 | VMI_PAGE_CLONE, clonepfn, start, count);
}

static void vmi_release_pt(u32 pfn)
{
        vmi_ops.release_page(pfn, VMI_PAGE_L1);
        vmi_set_page_type(pfn, VMI_PAGE_NORMAL);
}

static void vmi_release_pd(u32 pfn)
{
        vmi_ops.release_page(pfn, VMI_PAGE_L2);
        vmi_set_page_type(pfn, VMI_PAGE_NORMAL);
}

/*
 * Helper macros for MMU update flags.  We can defer updates until a flush
 * or page invalidation only if the update is to the current address space
 * (otherwise, there is no flush).  We must check against init_mm, since
 * this could be a kernel update, which usually passes init_mm, although
 * sometimes this check can be skipped if we know the particular function
 * is only called on user mode PTEs.  We could change the kernel to pass
 * current->active_mm here, but in particular, I was unsure if changing
 * mm/highmem.c to do this would still be correct on other architectures.
 */
#define is_current_as(mm, mustbeuser) ((mm) == current->active_mm ||    \
                                       (!mustbeuser && (mm) == &init_mm))
#define vmi_flags_addr(mm, addr, level, user)                           \
        ((level) | (is_current_as(mm, user) ?                           \
                (VMI_PAGE_CURRENT_AS | ((addr) & VMI_PAGE_VA_MASK)) : 0))
#define vmi_flags_addr_defer(mm, addr, level, user)                     \
        ((level) | (is_current_as(mm, user) ?                           \
                (VMI_PAGE_DEFER | VMI_PAGE_CURRENT_AS | ((addr) & VMI_PAGE_VA_MASK)) : 0))

static void vmi_update_pte(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
{
        vmi_check_page_type(__pa(ptep) >> PAGE_SHIFT, VMI_PAGE_PTE);
        vmi_ops.update_pte(ptep, vmi_flags_addr(mm, addr, VMI_PAGE_PT, 0));
}

static void vmi_update_pte_defer(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
{
        vmi_check_page_type(__pa(ptep) >> PAGE_SHIFT, VMI_PAGE_PTE);
        vmi_ops.update_pte(ptep, vmi_flags_addr_defer(mm, addr, VMI_PAGE_PT, 0));
}

static void vmi_set_pte(pte_t *ptep, pte_t pte)
{
        /* XXX because of set_pmd_pte, this can be called on PT or PD layers */
        vmi_check_page_type(__pa(ptep) >> PAGE_SHIFT, VMI_PAGE_PTE | VMI_PAGE_PD);
        vmi_ops.set_pte(pte, ptep, VMI_PAGE_PT);
}

static void vmi_set_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep, pte_t pte)
{
        vmi_check_page_type(__pa(ptep) >> PAGE_SHIFT, VMI_PAGE_PTE);
        vmi_ops.set_pte(pte, ptep, vmi_flags_addr(mm, addr, VMI_PAGE_PT, 0));
}

static void vmi_set_pmd(pmd_t *pmdp, pmd_t pmdval)
{
#ifdef CONFIG_X86_PAE
        const pte_t pte = { pmdval.pmd, pmdval.pmd >> 32 };
        vmi_check_page_type(__pa(pmdp) >> PAGE_SHIFT, VMI_PAGE_PMD);
#else
        const pte_t pte = { pmdval.pud.pgd.pgd };
        vmi_check_page_type(__pa(pmdp) >> PAGE_SHIFT, VMI_PAGE_PGD);
#endif
        vmi_ops.set_pte(pte, (pte_t *)pmdp, VMI_PAGE_PD);
}

#ifdef CONFIG_X86_PAE

static void vmi_set_pte_atomic(pte_t *ptep, pte_t pteval)
{
        /*
         * XXX This is called from set_pmd_pte, but at both PT
         * and PD layers so the VMI_PAGE_PT flag is wrong.  But
         * it is only called for large page mapping changes,
         * the Xen backend, doesn't support large pages, and the
         * ESX backend doesn't depend on the flag.
         */
        set_64bit((unsigned long long *)ptep,pte_val(pteval));
        vmi_ops.update_pte(ptep, VMI_PAGE_PT);
}

static void vmi_set_pte_present(struct mm_struct *mm, unsigned long addr, pte_t *ptep, pte_t pte)
{
        vmi_check_page_type(__pa(ptep) >> PAGE_SHIFT, VMI_PAGE_PTE);
        vmi_ops.set_pte(pte, ptep, vmi_flags_addr_defer(mm, addr, VMI_PAGE_PT, 1));
}

static void vmi_set_pud(pud_t *pudp, pud_t pudval)
{
        /* Um, eww */
        const pte_t pte = { pudval.pgd.pgd, pudval.pgd.pgd >> 32 };
        vmi_check_page_type(__pa(pudp) >> PAGE_SHIFT, VMI_PAGE_PGD);
        vmi_ops.set_pte(pte, (pte_t *)pudp, VMI_PAGE_PDP);
}

static void vmi_pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
{
        const pte_t pte = { 0 };
        vmi_check_page_type(__pa(ptep) >> PAGE_SHIFT, VMI_PAGE_PTE);
        vmi_ops.set_pte(pte, ptep, vmi_flags_addr(mm, addr, VMI_PAGE_PT, 0));
}

static void vmi_pmd_clear(pmd_t *pmd)
{
        const pte_t pte = { 0 };
        vmi_check_page_type(__pa(pmd) >> PAGE_SHIFT, VMI_PAGE_PMD);
        vmi_ops.set_pte(pte, (pte_t *)pmd, VMI_PAGE_PD);
}
#endif

#ifdef CONFIG_SMP
static void __devinit
vmi_startup_ipi_hook(int phys_apicid, unsigned long start_eip,
                     unsigned long start_esp)
{
        struct vmi_ap_state ap;

        /* Default everything to zero.  This is fine for most GPRs. */
        memset(&ap, 0, sizeof(struct vmi_ap_state));

        ap.gdtr_limit = GDT_SIZE - 1;
        ap.gdtr_base = (unsigned long) get_cpu_gdt_table(phys_apicid);

        ap.idtr_limit = IDT_ENTRIES * 8 - 1;
        ap.idtr_base = (unsigned long) idt_table;

        ap.ldtr = 0;

        ap.cs = __KERNEL_CS;
        ap.eip = (unsigned long) start_eip;
        ap.ss = __KERNEL_DS;
        ap.esp = (unsigned long) start_esp;

        ap.ds = __USER_DS;
        ap.es = __USER_DS;
        ap.fs = __KERNEL_PERCPU;
        ap.gs = 0;

        ap.eflags = 0;

#ifdef CONFIG_X86_PAE
        /* efer should match BSP efer. */
        if (cpu_has_nx) {
                unsigned l, h;
                rdmsr(MSR_EFER, l, h);
                ap.efer = (unsigned long long) h << 32 | l;
        }
#endif

        ap.cr3 = __pa(swapper_pg_dir);
        /* Protected mode, paging, AM, WP, NE, MP. */
        ap.cr0 = 0x80050023;
        ap.cr4 = mmu_cr4_features;
        vmi_ops.set_initial_ap_state((u32)&ap, phys_apicid);
}
#endif

static void vmi_set_lazy_mode(enum paravirt_lazy_mode mode)
{
        static DEFINE_PER_CPU(enum paravirt_lazy_mode, lazy_mode);

        if (!vmi_ops.set_lazy_mode)
                return;

        /* Modes should never nest or overlap */
        BUG_ON(__get_cpu_var(lazy_mode) && !(mode == PARAVIRT_LAZY_NONE ||
                                             mode == PARAVIRT_LAZY_FLUSH));

        if (mode == PARAVIRT_LAZY_FLUSH) {
                vmi_ops.set_lazy_mode(0);
                vmi_ops.set_lazy_mode(__get_cpu_var(lazy_mode));
        } else {
                vmi_ops.set_lazy_mode(mode);
                __get_cpu_var(lazy_mode) = mode;
        }
}

static inline int __init check_vmi_rom(struct vrom_header *rom)
{
        struct pci_header *pci;
        struct pnp_header *pnp;
        const char *manufacturer = "UNKNOWN";
        const char *product = "UNKNOWN";
        const char *license = "unspecified";

        if (rom->rom_signature != 0xaa55)
                return 0;
        if (rom->vrom_signature != VMI_SIGNATURE)
                return 0;
        if (rom->api_version_maj != VMI_API_REV_MAJOR ||
            rom->api_version_min+1 < VMI_API_REV_MINOR+1) {
                printk(KERN_WARNING "VMI: Found mismatched rom version %d.%d\n",
                                rom->api_version_maj,
                                rom->api_version_min);
                return 0;
        }

        /*
         * Relying on the VMI_SIGNATURE field is not 100% safe, so check
         * the PCI header and device type to make sure this is really a
         * VMI device.
         */
        if (!rom->pci_header_offs) {
                printk(KERN_WARNING "VMI: ROM does not contain PCI header.\n");
                return 0;
        }

        pci = (struct pci_header *)((char *)rom+rom->pci_header_offs);
        if (pci->vendorID != PCI_VENDOR_ID_VMWARE ||
            pci->deviceID != PCI_DEVICE_ID_VMWARE_VMI) {
                /* Allow it to run... anyways, but warn */
                printk(KERN_WARNING "VMI: ROM from unknown manufacturer\n");
        }

        if (rom->pnp_header_offs) {
                pnp = (struct pnp_header *)((char *)rom+rom->pnp_header_offs);
                if (pnp->manufacturer_offset)
                        manufacturer = (const char *)rom+pnp->manufacturer_offset;
                if (pnp->product_offset)
                        product = (const char *)rom+pnp->product_offset;
        }

        if (rom->license_offs)
                license = (char *)rom+rom->license_offs;

        printk(KERN_INFO "VMI: Found %s %s, API version %d.%d, ROM version %d.%d\n",
                manufacturer, product,
                rom->api_version_maj, rom->api_version_min,
                pci->rom_version_maj, pci->rom_version_min);

        /* Don't allow BSD/MIT here for now because we don't want to end up
           with any binary only shim layers */
        if (strcmp(license, "GPL") && strcmp(license, "GPL v2")) {
                printk(KERN_WARNING "VMI: Non GPL license `%s' found for ROM. Not used.\n",
                        license);
                return 0;
        }

        return 1;
}

/*
 * Probe for the VMI option ROM
 */
static inline int __init probe_vmi_rom(void)
{
        unsigned long base;

        /* VMI ROM is in option ROM area, check signature */
        for (base = 0xC0000; base < 0xE0000; base += 2048) {
                struct vrom_header *romstart;
                romstart = (struct vrom_header *)isa_bus_to_virt(base);
                if (check_vmi_rom(romstart)) {
                        vmi_rom = romstart;
                        return 1;
                }
        }
        return 0;
}

/*
 * VMI setup common to all processors
 */
void vmi_bringup(void)
{
        /* We must establish the lowmem mapping for MMU ops to work */
        if (vmi_ops.set_linear_mapping)
                vmi_ops.set_linear_mapping(0, (void *)__PAGE_OFFSET, max_low_pfn, 0);
}

/*
 * Return a pointer to a VMI function or NULL if unimplemented
 */
static void *vmi_get_function(int vmicall)
{
        u64 reloc;
        const struct vmi_relocation_info *rel = (struct vmi_relocation_info *)&reloc;
        reloc = call_vrom_long_func(vmi_rom, get_reloc, vmicall);
        BUG_ON(rel->type == VMI_RELOCATION_JUMP_REL);
        if (rel->type == VMI_RELOCATION_CALL_REL)
                return (void *)rel->eip;
        else
                return NULL;
}

/*
 * Helper macro for making the VMI paravirt-ops fill code readable.
 * For unimplemented operations, fall back to default, unless nop
 * is returned by the ROM.
 */
#define para_fill(opname, vmicall)                              \
do {                                                            \
        reloc = call_vrom_long_func(vmi_rom, get_reloc,         \
                                    VMI_CALL_##vmicall);        \
        if (rel->type == VMI_RELOCATION_CALL_REL)               \
                paravirt_ops.opname = (void *)rel->eip;         \
        else if (rel->type == VMI_RELOCATION_NOP)               \
                paravirt_ops.opname = (void *)vmi_nop;          \
        else if (rel->type != VMI_RELOCATION_NONE)              \
                printk(KERN_WARNING "VMI: Unknown relocation "  \
                                    "type %d for " #vmicall"\n",\
                                        rel->type);             \
} while (0)

/*
 * Helper macro for making the VMI paravirt-ops fill code readable.
 * For cached operations which do not match the VMI ROM ABI and must
 * go through a tranlation stub.  Ignore NOPs, since it is not clear
 * a NOP * VMI function corresponds to a NOP paravirt-op when the
 * functions are not in 1-1 correspondence.
 */
#define para_wrap(opname, wrapper, cache, vmicall)              \
do {                                                            \
        reloc = call_vrom_long_func(vmi_rom, get_reloc,         \
                                    VMI_CALL_##vmicall);        \
        BUG_ON(rel->type == VMI_RELOCATION_JUMP_REL);           \
        if (rel->type == VMI_RELOCATION_CALL_REL) {             \
                paravirt_ops.opname = wrapper;                  \
                vmi_ops.cache = (void *)rel->eip;               \
        }                                                       \
} while (0)

/*
 * Activate the VMI interface and switch into paravirtualized mode
 */
static inline int __init activate_vmi(void)
{
        short kernel_cs;
        u64 reloc;
        const struct vmi_relocation_info *rel = (struct vmi_relocation_info *)&reloc;

        if (call_vrom_func(vmi_rom, vmi_init) != 0) {
                printk(KERN_ERR "VMI ROM failed to initialize!");
                return 0;
        }
        savesegment(cs, kernel_cs);

        paravirt_ops.paravirt_enabled = 1;
        paravirt_ops.kernel_rpl = kernel_cs & SEGMENT_RPL_MASK;

        paravirt_ops.patch = vmi_patch;
        paravirt_ops.name = "vmi";

        /*
         * Many of these operations are ABI compatible with VMI.
         * This means we can fill in the paravirt-ops with direct
         * pointers into the VMI ROM.  If the calling convention for
         * these operations changes, this code needs to be updated.
         *
         * Exceptions
         *  CPUID paravirt-op uses pointers, not the native ISA
         *  halt has no VMI equivalent; all VMI halts are "safe"
         *  no MSR support yet - just trap and emulate.  VMI uses the
         *    same ABI as the native ISA, but Linux wants exceptions
         *    from bogus MSR read / write handled
         *  rdpmc is not yet used in Linux
         */

        /* CPUID is special, so very special it gets wrapped like a present */
        para_wrap(cpuid, vmi_cpuid, cpuid, CPUID);

        para_fill(clts, CLTS);
        para_fill(get_debugreg, GetDR);
        para_fill(set_debugreg, SetDR);
        para_fill(read_cr0, GetCR0);
        para_fill(read_cr2, GetCR2);
        para_fill(read_cr3, GetCR3);
        para_fill(read_cr4, GetCR4);
        para_fill(write_cr0, SetCR0);
        para_fill(write_cr2, SetCR2);
        para_fill(write_cr3, SetCR3);
        para_fill(write_cr4, SetCR4);
        para_fill(save_fl, GetInterruptMask);
        para_fill(restore_fl, SetInterruptMask);
        para_fill(irq_disable, DisableInterrupts);
        para_fill(irq_enable, EnableInterrupts);

        para_fill(wbinvd, WBINVD);
        para_fill(read_tsc, RDTSC);

        /* The following we emulate with trap and emulate for now */
        /* paravirt_ops.read_msr = vmi_rdmsr */
        /* paravirt_ops.write_msr = vmi_wrmsr */
        /* paravirt_ops.rdpmc = vmi_rdpmc */

        /* TR interface doesn't pass TR value, wrap */
        para_wrap(load_tr_desc, vmi_set_tr, set_tr, SetTR);

        /* LDT is special, too */
        para_wrap(set_ldt, vmi_set_ldt, _set_ldt, SetLDT);

        para_fill(load_gdt, SetGDT);
        para_fill(load_idt, SetIDT);
        para_fill(store_gdt, GetGDT);
        para_fill(store_idt, GetIDT);
        para_fill(store_tr, GetTR);
        paravirt_ops.load_tls = vmi_load_tls;
        para_fill(write_ldt_entry, WriteLDTEntry);
        para_fill(write_gdt_entry, WriteGDTEntry);
        para_fill(write_idt_entry, WriteIDTEntry);
        para_wrap(load_esp0, vmi_load_esp0, set_kernel_stack, UpdateKernelStack);
        para_fill(set_iopl_mask, SetIOPLMask);
        para_fill(io_delay, IODelay);
        para_wrap(set_lazy_mode, vmi_set_lazy_mode, set_lazy_mode, SetLazyMode);

        /* user and kernel flush are just handled with different flags to FlushTLB */
        para_wrap(flush_tlb_user, vmi_flush_tlb_user, _flush_tlb, FlushTLB);
        para_wrap(flush_tlb_kernel, vmi_flush_tlb_kernel, _flush_tlb, FlushTLB);
        para_fill(flush_tlb_single, InvalPage);

        /*
         * Until a standard flag format can be agreed on, we need to
         * implement these as wrappers in Linux.  Get the VMI ROM
         * function pointers for the two backend calls.
         */
#ifdef CONFIG_X86_PAE
        vmi_ops.set_pte = vmi_get_function(VMI_CALL_SetPxELong);
        vmi_ops.update_pte = vmi_get_function(VMI_CALL_UpdatePxELong);
#else
        vmi_ops.set_pte = vmi_get_function(VMI_CALL_SetPxE);
        vmi_ops.update_pte = vmi_get_function(VMI_CALL_UpdatePxE);
#endif

        if (vmi_ops.set_pte) {
                paravirt_ops.set_pte = vmi_set_pte;
                paravirt_ops.set_pte_at = vmi_set_pte_at;
                paravirt_ops.set_pmd = vmi_set_pmd;
#ifdef CONFIG_X86_PAE
                paravirt_ops.set_pte_atomic = vmi_set_pte_atomic;
                paravirt_ops.set_pte_present = vmi_set_pte_present;
                paravirt_ops.set_pud = vmi_set_pud;
                paravirt_ops.pte_clear = vmi_pte_clear;
                paravirt_ops.pmd_clear = vmi_pmd_clear;
#endif
        }

        if (vmi_ops.update_pte) {
                paravirt_ops.pte_update = vmi_update_pte;
                paravirt_ops.pte_update_defer = vmi_update_pte_defer;
        }

        vmi_ops.allocate_page = vmi_get_function(VMI_CALL_AllocatePage);
        if (vmi_ops.allocate_page) {
                paravirt_ops.alloc_pt = vmi_allocate_pt;
                paravirt_ops.alloc_pd = vmi_allocate_pd;
                paravirt_ops.alloc_pd_clone = vmi_allocate_pd_clone;
        }

        vmi_ops.release_page = vmi_get_function(VMI_CALL_ReleasePage);
        if (vmi_ops.release_page) {
                paravirt_ops.release_pt = vmi_release_pt;
                paravirt_ops.release_pd = vmi_release_pd;
        }

        /* Set linear is needed in all cases */
        vmi_ops.set_linear_mapping = vmi_get_function(VMI_CALL_SetLinearMapping);
#ifdef CONFIG_HIGHPTE
        if (vmi_ops.set_linear_mapping)
                paravirt_ops.kmap_atomic_pte = vmi_kmap_atomic_pte;
#endif

        /*
         * These MUST always be patched.  Don't support indirect jumps
         * through these operations, as the VMI interface may use either
         * a jump or a call to get to these operations, depending on
         * the backend.  They are performance critical anyway, so requiring
         * a patch is not a big problem.
         */
        paravirt_ops.irq_enable_sysexit = (void *)0xfeedbab0;
        paravirt_ops.iret = (void *)0xbadbab0;

#ifdef CONFIG_SMP
        para_wrap(startup_ipi_hook, vmi_startup_ipi_hook, set_initial_ap_state, SetInitialAPState);
#endif

#ifdef CONFIG_X86_LOCAL_APIC
        para_fill(apic_read, APICRead);
        para_fill(apic_write, APICWrite);
        para_fill(apic_write_atomic, APICWrite);
#endif

        /*
         * Check for VMI timer functionality by probing for a cycle frequency method
         */
        reloc = call_vrom_long_func(vmi_rom, get_reloc, VMI_CALL_GetCycleFrequency);
        if (!disable_vmi_timer && rel->type != VMI_RELOCATION_NONE) {
                vmi_timer_ops.get_cycle_frequency = (void *)rel->eip;
                vmi_timer_ops.get_cycle_counter =
                        vmi_get_function(VMI_CALL_GetCycleCounter);
                vmi_timer_ops.get_wallclock =
                        vmi_get_function(VMI_CALL_GetWallclockTime);
                vmi_timer_ops.wallclock_updated =
                        vmi_get_function(VMI_CALL_WallclockUpdated);
                vmi_timer_ops.set_alarm = vmi_get_function(VMI_CALL_SetAlarm);
                vmi_timer_ops.cancel_alarm =
                         vmi_get_function(VMI_CALL_CancelAlarm);
                paravirt_ops.time_init = vmi_time_init;
                paravirt_ops.get_wallclock = vmi_get_wallclock;
                paravirt_ops.set_wallclock = vmi_set_wallclock;
#ifdef CONFIG_X86_LOCAL_APIC
                paravirt_ops.setup_boot_clock = vmi_time_bsp_init;
                paravirt_ops.setup_secondary_clock = vmi_time_ap_init;
#endif
                paravirt_ops.get_scheduled_cycles = vmi_get_sched_cycles;
                paravirt_ops.get_cpu_khz = vmi_cpu_khz;

                /* We have true wallclock functions; disable CMOS clock sync */
                no_sync_cmos_clock = 1;
        } else {
                disable_noidle = 1;
                disable_vmi_timer = 1;
        }

        para_fill(safe_halt, Halt);

        /*
         * Alternative instruction rewriting doesn't happen soon enough
         * to convert VMI_IRET to a call instead of a jump; so we have
         * to do this before IRQs get reenabled.  Fortunately, it is
         * idempotent.
         */
        apply_paravirt(__parainstructions, __parainstructions_end);

        vmi_bringup();

        return 1;
}

#undef para_fill

void __init vmi_init(void)
{
        unsigned long flags;

        if (!vmi_rom)
                probe_vmi_rom();
        else
                check_vmi_rom(vmi_rom);

        /* In case probing for or validating the ROM failed, basil */
        if (!vmi_rom)
                return;

        reserve_top_address(-vmi_rom->virtual_top);

        local_irq_save(flags);
        activate_vmi();

#ifdef CONFIG_X86_IO_APIC
        /* This is virtual hardware; timer routing is wired correctly */
        no_timer_check = 1;
#endif
        local_irq_restore(flags & X86_EFLAGS_IF);
}

static int __init parse_vmi(char *arg)
{
        if (!arg)
                return -EINVAL;

        if (!strcmp(arg, "disable_pge")) {
                clear_bit(X86_FEATURE_PGE, boot_cpu_data.x86_capability);
                disable_pge = 1;
        } else if (!strcmp(arg, "disable_pse")) {
                clear_bit(X86_FEATURE_PSE, boot_cpu_data.x86_capability);
                disable_pse = 1;
        } else if (!strcmp(arg, "disable_sep")) {
                clear_bit(X86_FEATURE_SEP, boot_cpu_data.x86_capability);
                disable_sep = 1;
        } else if (!strcmp(arg, "disable_tsc")) {
                clear_bit(X86_FEATURE_TSC, boot_cpu_data.x86_capability);
                disable_tsc = 1;
        } else if (!strcmp(arg, "disable_mtrr")) {
                clear_bit(X86_FEATURE_MTRR, boot_cpu_data.x86_capability);
                disable_mtrr = 1;
        } else if (!strcmp(arg, "disable_timer")) {
                disable_vmi_timer = 1;
                disable_noidle = 1;
        } else if (!strcmp(arg, "disable_noidle"))
                disable_noidle = 1;
        return 0;
}

early_param("vmi", parse_vmi);