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-rw-r--r--arch/i386/xen/enlighten.c745
1 files changed, 745 insertions, 0 deletions
diff --git a/arch/i386/xen/enlighten.c b/arch/i386/xen/enlighten.c
new file mode 100644
index 00000000000..2d484f9320d
--- /dev/null
+++ b/arch/i386/xen/enlighten.c
@@ -0,0 +1,745 @@
+/*
+ * Core of Xen paravirt_ops implementation.
+ *
+ * This file contains the xen_paravirt_ops structure itself, and the
+ * implementations for:
+ * - privileged instructions
+ * - interrupt flags
+ * - segment operations
+ * - booting and setup
+ *
+ * Jeremy Fitzhardinge <jeremy@xensource.com>, XenSource Inc, 2007
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/smp.h>
+#include <linux/preempt.h>
+#include <linux/percpu.h>
+#include <linux/delay.h>
+#include <linux/start_kernel.h>
+#include <linux/sched.h>
+#include <linux/bootmem.h>
+#include <linux/module.h>
+
+#include <xen/interface/xen.h>
+#include <xen/interface/physdev.h>
+#include <xen/interface/vcpu.h>
+#include <xen/features.h>
+#include <xen/page.h>
+
+#include <asm/paravirt.h>
+#include <asm/page.h>
+#include <asm/xen/hypercall.h>
+#include <asm/xen/hypervisor.h>
+#include <asm/fixmap.h>
+#include <asm/processor.h>
+#include <asm/setup.h>
+#include <asm/desc.h>
+#include <asm/pgtable.h>
+
+#include "xen-ops.h"
+#include "multicalls.h"
+
+EXPORT_SYMBOL_GPL(hypercall_page);
+
+DEFINE_PER_CPU(enum paravirt_lazy_mode, xen_lazy_mode);
+
+DEFINE_PER_CPU(struct vcpu_info *, xen_vcpu);
+DEFINE_PER_CPU(struct vcpu_info, xen_vcpu_info);
+DEFINE_PER_CPU(unsigned long, xen_cr3);
+
+struct start_info *xen_start_info;
+EXPORT_SYMBOL_GPL(xen_start_info);
+
+static void xen_vcpu_setup(int cpu)
+{
+ per_cpu(xen_vcpu, cpu) = &HYPERVISOR_shared_info->vcpu_info[cpu];
+}
+
+static void __init xen_banner(void)
+{
+ printk(KERN_INFO "Booting paravirtualized kernel on %s\n",
+ paravirt_ops.name);
+ printk(KERN_INFO "Hypervisor signature: %s\n", xen_start_info->magic);
+}
+
+static void xen_cpuid(unsigned int *eax, unsigned int *ebx,
+ unsigned int *ecx, unsigned int *edx)
+{
+ unsigned maskedx = ~0;
+
+ /*
+ * Mask out inconvenient features, to try and disable as many
+ * unsupported kernel subsystems as possible.
+ */
+ if (*eax == 1)
+ maskedx = ~((1 << X86_FEATURE_APIC) | /* disable APIC */
+ (1 << X86_FEATURE_ACPI) | /* disable ACPI */
+ (1 << X86_FEATURE_ACC)); /* thermal monitoring */
+
+ asm(XEN_EMULATE_PREFIX "cpuid"
+ : "=a" (*eax),
+ "=b" (*ebx),
+ "=c" (*ecx),
+ "=d" (*edx)
+ : "0" (*eax), "2" (*ecx));
+ *edx &= maskedx;
+}
+
+static void xen_set_debugreg(int reg, unsigned long val)
+{
+ HYPERVISOR_set_debugreg(reg, val);
+}
+
+static unsigned long xen_get_debugreg(int reg)
+{
+ return HYPERVISOR_get_debugreg(reg);
+}
+
+static unsigned long xen_save_fl(void)
+{
+ struct vcpu_info *vcpu;
+ unsigned long flags;
+
+ preempt_disable();
+ vcpu = x86_read_percpu(xen_vcpu);
+ /* flag has opposite sense of mask */
+ flags = !vcpu->evtchn_upcall_mask;
+ preempt_enable();
+
+ /* convert to IF type flag
+ -0 -> 0x00000000
+ -1 -> 0xffffffff
+ */
+ return (-flags) & X86_EFLAGS_IF;
+}
+
+static void xen_restore_fl(unsigned long flags)
+{
+ struct vcpu_info *vcpu;
+
+ preempt_disable();
+
+ /* convert from IF type flag */
+ flags = !(flags & X86_EFLAGS_IF);
+ vcpu = x86_read_percpu(xen_vcpu);
+ vcpu->evtchn_upcall_mask = flags;
+
+ if (flags == 0) {
+ /* Unmask then check (avoid races). We're only protecting
+ against updates by this CPU, so there's no need for
+ anything stronger. */
+ barrier();
+
+ if (unlikely(vcpu->evtchn_upcall_pending))
+ force_evtchn_callback();
+ preempt_enable();
+ } else
+ preempt_enable_no_resched();
+}
+
+static void xen_irq_disable(void)
+{
+ struct vcpu_info *vcpu;
+ preempt_disable();
+ vcpu = x86_read_percpu(xen_vcpu);
+ vcpu->evtchn_upcall_mask = 1;
+ preempt_enable_no_resched();
+}
+
+static void xen_irq_enable(void)
+{
+ struct vcpu_info *vcpu;
+
+ preempt_disable();
+ vcpu = x86_read_percpu(xen_vcpu);
+ vcpu->evtchn_upcall_mask = 0;
+
+ /* Unmask then check (avoid races). We're only protecting
+ against updates by this CPU, so there's no need for
+ anything stronger. */
+ barrier();
+
+ if (unlikely(vcpu->evtchn_upcall_pending))
+ force_evtchn_callback();
+ preempt_enable();
+}
+
+static void xen_safe_halt(void)
+{
+ /* Blocking includes an implicit local_irq_enable(). */
+ if (HYPERVISOR_sched_op(SCHEDOP_block, 0) != 0)
+ BUG();
+}
+
+static void xen_halt(void)
+{
+ if (irqs_disabled())
+ HYPERVISOR_vcpu_op(VCPUOP_down, smp_processor_id(), NULL);
+ else
+ xen_safe_halt();
+}
+
+static void xen_set_lazy_mode(enum paravirt_lazy_mode mode)
+{
+ switch (mode) {
+ case PARAVIRT_LAZY_NONE:
+ BUG_ON(x86_read_percpu(xen_lazy_mode) == PARAVIRT_LAZY_NONE);
+ break;
+
+ case PARAVIRT_LAZY_MMU:
+ case PARAVIRT_LAZY_CPU:
+ BUG_ON(x86_read_percpu(xen_lazy_mode) != PARAVIRT_LAZY_NONE);
+ break;
+
+ case PARAVIRT_LAZY_FLUSH:
+ /* flush if necessary, but don't change state */
+ if (x86_read_percpu(xen_lazy_mode) != PARAVIRT_LAZY_NONE)
+ xen_mc_flush();
+ return;
+ }
+
+ xen_mc_flush();
+ x86_write_percpu(xen_lazy_mode, mode);
+}
+
+static unsigned long xen_store_tr(void)
+{
+ return 0;
+}
+
+static void xen_set_ldt(const void *addr, unsigned entries)
+{
+ unsigned long linear_addr = (unsigned long)addr;
+ struct mmuext_op *op;
+ struct multicall_space mcs = xen_mc_entry(sizeof(*op));
+
+ op = mcs.args;
+ op->cmd = MMUEXT_SET_LDT;
+ if (linear_addr) {
+ /* ldt my be vmalloced, use arbitrary_virt_to_machine */
+ xmaddr_t maddr;
+ maddr = arbitrary_virt_to_machine((unsigned long)addr);
+ linear_addr = (unsigned long)maddr.maddr;
+ }
+ op->arg1.linear_addr = linear_addr;
+ op->arg2.nr_ents = entries;
+
+ MULTI_mmuext_op(mcs.mc, op, 1, NULL, DOMID_SELF);
+
+ xen_mc_issue(PARAVIRT_LAZY_CPU);
+}
+
+static void xen_load_gdt(const struct Xgt_desc_struct *dtr)
+{
+ unsigned long *frames;
+ unsigned long va = dtr->address;
+ unsigned int size = dtr->size + 1;
+ unsigned pages = (size + PAGE_SIZE - 1) / PAGE_SIZE;
+ int f;
+ struct multicall_space mcs;
+
+ /* A GDT can be up to 64k in size, which corresponds to 8192
+ 8-byte entries, or 16 4k pages.. */
+
+ BUG_ON(size > 65536);
+ BUG_ON(va & ~PAGE_MASK);
+
+ mcs = xen_mc_entry(sizeof(*frames) * pages);
+ frames = mcs.args;
+
+ for (f = 0; va < dtr->address + size; va += PAGE_SIZE, f++) {
+ frames[f] = virt_to_mfn(va);
+ make_lowmem_page_readonly((void *)va);
+ }
+
+ MULTI_set_gdt(mcs.mc, frames, size / sizeof(struct desc_struct));
+
+ xen_mc_issue(PARAVIRT_LAZY_CPU);
+}
+
+static void load_TLS_descriptor(struct thread_struct *t,
+ unsigned int cpu, unsigned int i)
+{
+ struct desc_struct *gdt = get_cpu_gdt_table(cpu);
+ xmaddr_t maddr = virt_to_machine(&gdt[GDT_ENTRY_TLS_MIN+i]);
+ struct multicall_space mc = __xen_mc_entry(0);
+
+ MULTI_update_descriptor(mc.mc, maddr.maddr, t->tls_array[i]);
+}
+
+static void xen_load_tls(struct thread_struct *t, unsigned int cpu)
+{
+ xen_mc_batch();
+
+ load_TLS_descriptor(t, cpu, 0);
+ load_TLS_descriptor(t, cpu, 1);
+ load_TLS_descriptor(t, cpu, 2);
+
+ xen_mc_issue(PARAVIRT_LAZY_CPU);
+}
+
+static void xen_write_ldt_entry(struct desc_struct *dt, int entrynum,
+ u32 low, u32 high)
+{
+ unsigned long lp = (unsigned long)&dt[entrynum];
+ xmaddr_t mach_lp = virt_to_machine(lp);
+ u64 entry = (u64)high << 32 | low;
+
+ xen_mc_flush();
+ if (HYPERVISOR_update_descriptor(mach_lp.maddr, entry))
+ BUG();
+}
+
+static int cvt_gate_to_trap(int vector, u32 low, u32 high,
+ struct trap_info *info)
+{
+ u8 type, dpl;
+
+ type = (high >> 8) & 0x1f;
+ dpl = (high >> 13) & 3;
+
+ if (type != 0xf && type != 0xe)
+ return 0;
+
+ info->vector = vector;
+ info->address = (high & 0xffff0000) | (low & 0x0000ffff);
+ info->cs = low >> 16;
+ info->flags = dpl;
+ /* interrupt gates clear IF */
+ if (type == 0xe)
+ info->flags |= 4;
+
+ return 1;
+}
+
+/* Locations of each CPU's IDT */
+static DEFINE_PER_CPU(struct Xgt_desc_struct, idt_desc);
+
+/* Set an IDT entry. If the entry is part of the current IDT, then
+ also update Xen. */
+static void xen_write_idt_entry(struct desc_struct *dt, int entrynum,
+ u32 low, u32 high)
+{
+
+ int cpu = smp_processor_id();
+ unsigned long p = (unsigned long)&dt[entrynum];
+ unsigned long start = per_cpu(idt_desc, cpu).address;
+ unsigned long end = start + per_cpu(idt_desc, cpu).size + 1;
+
+ xen_mc_flush();
+
+ write_dt_entry(dt, entrynum, low, high);
+
+ if (p >= start && (p + 8) <= end) {
+ struct trap_info info[2];
+
+ info[1].address = 0;
+
+ if (cvt_gate_to_trap(entrynum, low, high, &info[0]))
+ if (HYPERVISOR_set_trap_table(info))
+ BUG();
+ }
+}
+
+/* Load a new IDT into Xen. In principle this can be per-CPU, so we
+ hold a spinlock to protect the static traps[] array (static because
+ it avoids allocation, and saves stack space). */
+static void xen_load_idt(const struct Xgt_desc_struct *desc)
+{
+ static DEFINE_SPINLOCK(lock);
+ static struct trap_info traps[257];
+
+ int cpu = smp_processor_id();
+ unsigned in, out, count;
+
+ per_cpu(idt_desc, cpu) = *desc;
+
+ count = (desc->size+1) / 8;
+ BUG_ON(count > 256);
+
+ spin_lock(&lock);
+ for (in = out = 0; in < count; in++) {
+ const u32 *entry = (u32 *)(desc->address + in * 8);
+
+ if (cvt_gate_to_trap(in, entry[0], entry[1], &traps[out]))
+ out++;
+ }
+ traps[out].address = 0;
+
+ xen_mc_flush();
+ if (HYPERVISOR_set_trap_table(traps))
+ BUG();
+
+ spin_unlock(&lock);
+}
+
+/* Write a GDT descriptor entry. Ignore LDT descriptors, since
+ they're handled differently. */
+static void xen_write_gdt_entry(struct desc_struct *dt, int entry,
+ u32 low, u32 high)
+{
+ switch ((high >> 8) & 0xff) {
+ case DESCTYPE_LDT:
+ case DESCTYPE_TSS:
+ /* ignore */
+ break;
+
+ default: {
+ xmaddr_t maddr = virt_to_machine(&dt[entry]);
+ u64 desc = (u64)high << 32 | low;
+
+ xen_mc_flush();
+ if (HYPERVISOR_update_descriptor(maddr.maddr, desc))
+ BUG();
+ }
+
+ }
+}
+
+static void xen_load_esp0(struct tss_struct *tss,
+ struct thread_struct *thread)
+{
+ struct multicall_space mcs = xen_mc_entry(0);
+ MULTI_stack_switch(mcs.mc, __KERNEL_DS, thread->esp0);
+ xen_mc_issue(PARAVIRT_LAZY_CPU);
+}
+
+static void xen_set_iopl_mask(unsigned mask)
+{
+ struct physdev_set_iopl set_iopl;
+
+ /* Force the change at ring 0. */
+ set_iopl.iopl = (mask == 0) ? 1 : (mask >> 12) & 3;
+ HYPERVISOR_physdev_op(PHYSDEVOP_set_iopl, &set_iopl);
+}
+
+static void xen_io_delay(void)
+{
+}
+
+#ifdef CONFIG_X86_LOCAL_APIC
+static unsigned long xen_apic_read(unsigned long reg)
+{
+ return 0;
+}
+#endif
+
+static void xen_flush_tlb(void)
+{
+ struct mmuext_op op;
+
+ op.cmd = MMUEXT_TLB_FLUSH_LOCAL;
+ if (HYPERVISOR_mmuext_op(&op, 1, NULL, DOMID_SELF))
+ BUG();
+}
+
+static void xen_flush_tlb_single(unsigned long addr)
+{
+ struct mmuext_op op;
+
+ op.cmd = MMUEXT_INVLPG_LOCAL;
+ op.arg1.linear_addr = addr & PAGE_MASK;
+ if (HYPERVISOR_mmuext_op(&op, 1, NULL, DOMID_SELF))
+ BUG();
+}
+
+static unsigned long xen_read_cr2(void)
+{
+ return x86_read_percpu(xen_vcpu)->arch.cr2;
+}
+
+static void xen_write_cr4(unsigned long cr4)
+{
+ /* never allow TSC to be disabled */
+ native_write_cr4(cr4 & ~X86_CR4_TSD);
+}
+
+/*
+ * Page-directory addresses above 4GB do not fit into architectural %cr3.
+ * When accessing %cr3, or equivalent field in vcpu_guest_context, guests
+ * must use the following accessor macros to pack/unpack valid MFNs.
+ *
+ * Note that Xen is using the fact that the pagetable base is always
+ * page-aligned, and putting the 12 MSB of the address into the 12 LSB
+ * of cr3.
+ */
+#define xen_pfn_to_cr3(pfn) (((unsigned)(pfn) << 12) | ((unsigned)(pfn) >> 20))
+#define xen_cr3_to_pfn(cr3) (((unsigned)(cr3) >> 12) | ((unsigned)(cr3) << 20))
+
+static unsigned long xen_read_cr3(void)
+{
+ return x86_read_percpu(xen_cr3);
+}
+
+static void xen_write_cr3(unsigned long cr3)
+{
+ if (cr3 == x86_read_percpu(xen_cr3)) {
+ /* just a simple tlb flush */
+ xen_flush_tlb();
+ return;
+ }
+
+ x86_write_percpu(xen_cr3, cr3);
+
+
+ {
+ struct mmuext_op *op;
+ struct multicall_space mcs = xen_mc_entry(sizeof(*op));
+ unsigned long mfn = pfn_to_mfn(PFN_DOWN(cr3));
+
+ op = mcs.args;
+ op->cmd = MMUEXT_NEW_BASEPTR;
+ op->arg1.mfn = mfn;
+
+ MULTI_mmuext_op(mcs.mc, op, 1, NULL, DOMID_SELF);
+
+ xen_mc_issue(PARAVIRT_LAZY_CPU);
+ }
+}
+
+static void xen_alloc_pt(struct mm_struct *mm, u32 pfn)
+{
+ /* XXX pfn isn't necessarily a lowmem page */
+ make_lowmem_page_readonly(__va(PFN_PHYS(pfn)));
+}
+
+static void xen_alloc_pd(u32 pfn)
+{
+ make_lowmem_page_readonly(__va(PFN_PHYS(pfn)));
+}
+
+static void xen_release_pd(u32 pfn)
+{
+ make_lowmem_page_readwrite(__va(PFN_PHYS(pfn)));
+}
+
+static void xen_release_pt(u32 pfn)
+{
+ make_lowmem_page_readwrite(__va(PFN_PHYS(pfn)));
+}
+
+static void xen_alloc_pd_clone(u32 pfn, u32 clonepfn,
+ u32 start, u32 count)
+{
+ xen_alloc_pd(pfn);
+}
+
+static __init void xen_pagetable_setup_start(pgd_t *base)
+{
+ pgd_t *xen_pgd = (pgd_t *)xen_start_info->pt_base;
+
+ init_mm.pgd = base;
+ /*
+ * copy top-level of Xen-supplied pagetable into place. For
+ * !PAE we can use this as-is, but for PAE it is a stand-in
+ * while we copy the pmd pages.
+ */
+ memcpy(base, xen_pgd, PTRS_PER_PGD * sizeof(pgd_t));
+
+ if (PTRS_PER_PMD > 1) {
+ int i;
+ /*
+ * For PAE, need to allocate new pmds, rather than
+ * share Xen's, since Xen doesn't like pmd's being
+ * shared between address spaces.
+ */
+ for (i = 0; i < PTRS_PER_PGD; i++) {
+ if (pgd_val_ma(xen_pgd[i]) & _PAGE_PRESENT) {
+ pmd_t *pmd = (pmd_t *)alloc_bootmem_low_pages(PAGE_SIZE);
+
+ memcpy(pmd, (void *)pgd_page_vaddr(xen_pgd[i]),
+ PAGE_SIZE);
+
+ xen_alloc_pd(PFN_DOWN(__pa(pmd)));
+
+ set_pgd(&base[i], __pgd(1 + __pa(pmd)));
+ } else
+ pgd_clear(&base[i]);
+ }
+ }
+
+ /* make sure zero_page is mapped RO so we can use it in pagetables */
+ make_lowmem_page_readonly(empty_zero_page);
+ make_lowmem_page_readonly(base);
+ /*
+ * Switch to new pagetable. This is done before
+ * pagetable_init has done anything so that the new pages
+ * added to the table can be prepared properly for Xen.
+ */
+ xen_write_cr3(__pa(base));
+}
+
+static __init void xen_pagetable_setup_done(pgd_t *base)
+{
+ if (!xen_feature(XENFEAT_auto_translated_physmap)) {
+ /*
+ * Create a mapping for the shared info page.
+ * Should be set_fixmap(), but shared_info is a machine
+ * address with no corresponding pseudo-phys address.
+ */
+#if 0
+ set_pte_mfn(fix_to_virt(FIX_PARAVIRT_BOOTMAP),
+ PFN_DOWN(xen_start_info->shared_info),
+ PAGE_KERNEL);
+#endif
+
+ HYPERVISOR_shared_info =
+ (struct shared_info *)fix_to_virt(FIX_PARAVIRT_BOOTMAP);
+
+ } else
+ HYPERVISOR_shared_info =
+ (struct shared_info *)__va(xen_start_info->shared_info);
+
+#if 0
+ xen_pgd_pin(base);
+#endif
+
+ xen_vcpu_setup(smp_processor_id());
+}
+
+static const struct paravirt_ops xen_paravirt_ops __initdata = {
+ .paravirt_enabled = 1,
+ .shared_kernel_pmd = 0,
+
+ .name = "Xen",
+ .banner = xen_banner,
+
+ .patch = paravirt_patch_default,
+
+ .memory_setup = xen_memory_setup,
+ .arch_setup = xen_arch_setup,
+
+ .cpuid = xen_cpuid,
+
+ .set_debugreg = xen_set_debugreg,
+ .get_debugreg = xen_get_debugreg,
+
+ .clts = native_clts,
+
+ .read_cr0 = native_read_cr0,
+ .write_cr0 = native_write_cr0,
+
+ .read_cr2 = xen_read_cr2,
+ .write_cr2 = native_write_cr2,
+
+ .read_cr3 = xen_read_cr3,
+ .write_cr3 = xen_write_cr3,
+
+ .read_cr4 = native_read_cr4,
+ .read_cr4_safe = native_read_cr4_safe,
+ .write_cr4 = xen_write_cr4,
+
+ .save_fl = xen_save_fl,
+ .restore_fl = xen_restore_fl,
+ .irq_disable = xen_irq_disable,
+ .irq_enable = xen_irq_enable,
+ .safe_halt = xen_safe_halt,
+ .halt = xen_halt,
+ .wbinvd = native_wbinvd,
+
+ .read_msr = native_read_msr_safe,
+ .write_msr = native_write_msr_safe,
+ .read_tsc = native_read_tsc,
+ .read_pmc = native_read_pmc,
+
+ .iret = (void *)&hypercall_page[__HYPERVISOR_iret],
+ .irq_enable_sysexit = NULL, /* never called */
+
+ .load_tr_desc = paravirt_nop,
+ .set_ldt = xen_set_ldt,
+ .load_gdt = xen_load_gdt,
+ .load_idt = xen_load_idt,
+ .load_tls = xen_load_tls,
+
+ .store_gdt = native_store_gdt,
+ .store_idt = native_store_idt,
+ .store_tr = xen_store_tr,
+
+ .write_ldt_entry = xen_write_ldt_entry,
+ .write_gdt_entry = xen_write_gdt_entry,
+ .write_idt_entry = xen_write_idt_entry,
+ .load_esp0 = xen_load_esp0,
+
+ .set_iopl_mask = xen_set_iopl_mask,
+ .io_delay = xen_io_delay,
+
+#ifdef CONFIG_X86_LOCAL_APIC
+ .apic_write = paravirt_nop,
+ .apic_write_atomic = paravirt_nop,
+ .apic_read = xen_apic_read,
+ .setup_boot_clock = paravirt_nop,
+ .setup_secondary_clock = paravirt_nop,
+ .startup_ipi_hook = paravirt_nop,
+#endif
+
+ .flush_tlb_user = xen_flush_tlb,
+ .flush_tlb_kernel = xen_flush_tlb,
+ .flush_tlb_single = xen_flush_tlb_single,
+
+ .pte_update = paravirt_nop,
+ .pte_update_defer = paravirt_nop,
+
+ .pagetable_setup_start = xen_pagetable_setup_start,
+ .pagetable_setup_done = xen_pagetable_setup_done,
+
+ .alloc_pt = xen_alloc_pt,
+ .alloc_pd = xen_alloc_pd,
+ .alloc_pd_clone = xen_alloc_pd_clone,
+ .release_pd = xen_release_pd,
+ .release_pt = xen_release_pt,
+
+ .set_lazy_mode = xen_set_lazy_mode,
+};
+
+/* First C function to be called on Xen boot */
+asmlinkage void __init xen_start_kernel(void)
+{
+ pgd_t *pgd;
+
+ if (!xen_start_info)
+ return;
+
+ BUG_ON(memcmp(xen_start_info->magic, "xen-3.0", 7) != 0);
+
+ /* Install Xen paravirt ops */
+ paravirt_ops = xen_paravirt_ops;
+
+ xen_setup_features();
+
+ /* Get mfn list */
+ if (!xen_feature(XENFEAT_auto_translated_physmap))
+ phys_to_machine_mapping = (unsigned long *)xen_start_info->mfn_list;
+
+ pgd = (pgd_t *)xen_start_info->pt_base;
+
+ init_pg_tables_end = __pa(pgd) + xen_start_info->nr_pt_frames*PAGE_SIZE;
+
+ init_mm.pgd = pgd; /* use the Xen pagetables to start */
+
+ /* keep using Xen gdt for now; no urgent need to change it */
+
+ x86_write_percpu(xen_cr3, __pa(pgd));
+ xen_vcpu_setup(0);
+
+ paravirt_ops.kernel_rpl = 1;
+ if (xen_feature(XENFEAT_supervisor_mode_kernel))
+ paravirt_ops.kernel_rpl = 0;
+
+ /* set the limit of our address space */
+ reserve_top_address(-HYPERVISOR_VIRT_START + 2 * PAGE_SIZE);
+
+ /* set up basic CPUID stuff */
+ cpu_detect(&new_cpu_data);
+ new_cpu_data.hard_math = 1;
+ new_cpu_data.x86_capability[0] = cpuid_edx(1);
+
+ /* Poke various useful things into boot_params */
+ LOADER_TYPE = (9 << 4) | 0;
+ INITRD_START = xen_start_info->mod_start ? __pa(xen_start_info->mod_start) : 0;
+ INITRD_SIZE = xen_start_info->mod_len;
+
+ /* Start the world */
+ start_kernel();
+}