lguest: the host code

This is the code for the "lg.ko" module, which allows lguest guests to
be launched.

[akpm@linux-foundation.org: update for futex-new-private-futexes]
[akpm@linux-foundation.org: build fix]
[jmorris@namei.org: lguest: use hrtimers]
[akpm@linux-foundation.org: x86_64 build fix]
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <ak@suse.de>
Cc: Eric Dumazet <dada1@cosmosbay.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/i386/kernel/tsc.c

@@ -27,6 +27,7 @@ static int tsc_enabled;
  * an extra value to store the TSC freq
  */
 unsigned int tsc_khz;
+EXPORT_SYMBOL_GPL(tsc_khz);
 
 int tsc_disable;
 
@@ -58,10 +59,11 @@ __setup("notsc", tsc_setup);
  */
 static int tsc_unstable;
 
-static inline int check_tsc_unstable(void)
+int check_tsc_unstable(void)
 {
 	return tsc_unstable;
 }
+EXPORT_SYMBOL_GPL(check_tsc_unstable);
 
 /* Accellerators for sched_clock()
  * convert from cycles(64bits) => nanoseconds (64bits)

arch/x86_64/kernel/tsc.c

@@ -44,7 +44,7 @@ unsigned long long sched_clock(void)
 
 static int tsc_unstable;
 
-static inline int check_tsc_unstable(void)
+inline int check_tsc_unstable(void)
 {
 	return tsc_unstable;
 }

drivers/lguest/hypercalls.c

+/*  Actual hypercalls, which allow guests to actually do something.
+    Copyright (C) 2006 Rusty Russell IBM Corporation
+
+    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.  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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+*/
+#include <linux/uaccess.h>
+#include <linux/syscalls.h>
+#include <linux/mm.h>
+#include <asm/page.h>
+#include <asm/pgtable.h>
+#include <irq_vectors.h>
+#include "lg.h"
+
+static void do_hcall(struct lguest *lg, struct lguest_regs *regs)
+{
+	switch (regs->eax) {
+	case LHCALL_FLUSH_ASYNC:
+		break;
+	case LHCALL_LGUEST_INIT:
+		kill_guest(lg, "already have lguest_data");
+		break;
+	case LHCALL_CRASH: {
+		char msg[128];
+		lgread(lg, msg, regs->edx, sizeof(msg));
+		msg[sizeof(msg)-1] = '\0';
+		kill_guest(lg, "CRASH: %s", msg);
+		break;
+	}
+	case LHCALL_FLUSH_TLB:
+		if (regs->edx)
+			guest_pagetable_clear_all(lg);
+		else
+			guest_pagetable_flush_user(lg);
+		break;
+	case LHCALL_GET_WALLCLOCK: {
+		struct timespec ts;
+		ktime_get_real_ts(&ts);
+		regs->eax = ts.tv_sec;
+		break;
+	}
+	case LHCALL_BIND_DMA:
+		regs->eax = bind_dma(lg, regs->edx, regs->ebx,
+				     regs->ecx >> 8, regs->ecx & 0xFF);
+		break;
+	case LHCALL_SEND_DMA:
+		send_dma(lg, regs->edx, regs->ebx);
+		break;
+	case LHCALL_LOAD_GDT:
+		load_guest_gdt(lg, regs->edx, regs->ebx);
+		break;
+	case LHCALL_LOAD_IDT_ENTRY:
+		load_guest_idt_entry(lg, regs->edx, regs->ebx, regs->ecx);
+		break;
+	case LHCALL_NEW_PGTABLE:
+		guest_new_pagetable(lg, regs->edx);
+		break;
+	case LHCALL_SET_STACK:
+		guest_set_stack(lg, regs->edx, regs->ebx, regs->ecx);
+		break;
+	case LHCALL_SET_PTE:
+		guest_set_pte(lg, regs->edx, regs->ebx, mkgpte(regs->ecx));
+		break;
+	case LHCALL_SET_PMD:
+		guest_set_pmd(lg, regs->edx, regs->ebx);
+		break;
+	case LHCALL_LOAD_TLS:
+		guest_load_tls(lg, regs->edx);
+		break;
+	case LHCALL_SET_CLOCKEVENT:
+		guest_set_clockevent(lg, regs->edx);
+		break;
+	case LHCALL_TS:
+		lg->ts = regs->edx;
+		break;
+	case LHCALL_HALT:
+		lg->halted = 1;
+		break;
+	default:
+		kill_guest(lg, "Bad hypercall %li\n", regs->eax);
+	}
+}
+
+/* We always do queued calls before actual hypercall. */
+static void do_async_hcalls(struct lguest *lg)
+{
+	unsigned int i;
+	u8 st[LHCALL_RING_SIZE];
+
+	if (copy_from_user(&st, &lg->lguest_data->hcall_status, sizeof(st)))
+		return;
+
+	for (i = 0; i < ARRAY_SIZE(st); i++) {
+		struct lguest_regs regs;
+		unsigned int n = lg->next_hcall;
+
+		if (st[n] == 0xFF)
+			break;
+
+		if (++lg->next_hcall == LHCALL_RING_SIZE)
+			lg->next_hcall = 0;
+
+		if (get_user(regs.eax, &lg->lguest_data->hcalls[n].eax)
+		    || get_user(regs.edx, &lg->lguest_data->hcalls[n].edx)
+		    || get_user(regs.ecx, &lg->lguest_data->hcalls[n].ecx)
+		    || get_user(regs.ebx, &lg->lguest_data->hcalls[n].ebx)) {
+			kill_guest(lg, "Fetching async hypercalls");
+			break;
+		}
+
+		do_hcall(lg, &regs);
+		if (put_user(0xFF, &lg->lguest_data->hcall_status[n])) {
+			kill_guest(lg, "Writing result for async hypercall");
+			break;
+		}
+
+		if (lg->dma_is_pending)
+			break;
+	}
+}
+
+static void initialize(struct lguest *lg)
+{
+	u32 tsc_speed;
+
+	if (lg->regs->eax != LHCALL_LGUEST_INIT) {
+		kill_guest(lg, "hypercall %li before LGUEST_INIT",
+			   lg->regs->eax);
+		return;
+	}
+
+	/* We only tell the guest to use the TSC if it's reliable. */
+	if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC) && !check_tsc_unstable())
+		tsc_speed = tsc_khz;
+	else
+		tsc_speed = 0;
+
+	lg->lguest_data = (struct lguest_data __user *)lg->regs->edx;
+	/* We check here so we can simply copy_to_user/from_user */
+	if (!lguest_address_ok(lg, lg->regs->edx, sizeof(*lg->lguest_data))) {
+		kill_guest(lg, "bad guest page %p", lg->lguest_data);
+		return;
+	}
+	if (get_user(lg->noirq_start, &lg->lguest_data->noirq_start)
+	    || get_user(lg->noirq_end, &lg->lguest_data->noirq_end)
+	    /* We reserve the top pgd entry. */
+	    || put_user(4U*1024*1024, &lg->lguest_data->reserve_mem)
+	    || put_user(tsc_speed, &lg->lguest_data->tsc_khz)
+	    || put_user(lg->guestid, &lg->lguest_data->guestid))
+		kill_guest(lg, "bad guest page %p", lg->lguest_data);
+
+	/* This is the one case where the above accesses might have
+	 * been the first write to a Guest page.  This may have caused
+	 * a copy-on-write fault, but the Guest might be referring to
+	 * the old (read-only) page. */
+	guest_pagetable_clear_all(lg);
+}
+
+/* Even if we go out to userspace and come back, we don't want to do
+ * the hypercall again. */
+static void clear_hcall(struct lguest *lg)
+{
+	lg->regs->trapnum = 255;
+}
+
+void do_hypercalls(struct lguest *lg)
+{
+	if (unlikely(!lg->lguest_data)) {
+		if (lg->regs->trapnum == LGUEST_TRAP_ENTRY) {
+			initialize(lg);
+			clear_hcall(lg);
+		}
+		return;
+	}
+
+	do_async_hcalls(lg);
+	if (!lg->dma_is_pending && lg->regs->trapnum == LGUEST_TRAP_ENTRY) {
+		do_hcall(lg, lg->regs);
+		clear_hcall(lg);
+	}
+}

drivers/lguest/interrupts_and_traps.c

+#include <linux/uaccess.h>
+#include "lg.h"
+
+static unsigned long idt_address(u32 lo, u32 hi)
+{
+	return (lo & 0x0000FFFF) | (hi & 0xFFFF0000);
+}
+
+static int idt_type(u32 lo, u32 hi)
+{
+	return (hi >> 8) & 0xF;
+}
+
+static int idt_present(u32 lo, u32 hi)
+{
+	return (hi & 0x8000);
+}
+
+static void push_guest_stack(struct lguest *lg, unsigned long *gstack, u32 val)
+{
+	*gstack -= 4;
+	lgwrite_u32(lg, *gstack, val);
+}
+
+static void set_guest_interrupt(struct lguest *lg, u32 lo, u32 hi, int has_err)
+{
+	unsigned long gstack;
+	u32 eflags, ss, irq_enable;
+
+	/* If they want a ring change, we use new stack and push old ss/esp */
+	if ((lg->regs->ss&0x3) != GUEST_PL) {
+		gstack = guest_pa(lg, lg->esp1);
+		ss = lg->ss1;
+		push_guest_stack(lg, &gstack, lg->regs->ss);
+		push_guest_stack(lg, &gstack, lg->regs->esp);
+	} else {
+		gstack = guest_pa(lg, lg->regs->esp);
+		ss = lg->regs->ss;
+	}
+
+	/* We use IF bit in eflags to indicate whether irqs were disabled
+	   (it's always 0, since irqs are enabled when guest is running). */
+	eflags = lg->regs->eflags;
+	if (get_user(irq_enable, &lg->lguest_data->irq_enabled))
+		irq_enable = 0;
+	eflags |= (irq_enable & X86_EFLAGS_IF);
+
+	push_guest_stack(lg, &gstack, eflags);
+	push_guest_stack(lg, &gstack, lg->regs->cs);
+	push_guest_stack(lg, &gstack, lg->regs->eip);
+
+	if (has_err)
+		push_guest_stack(lg, &gstack, lg->regs->errcode);
+
+	/* Change the real stack so switcher returns to trap handler */
+	lg->regs->ss = ss;
+	lg->regs->esp = gstack + lg->page_offset;
+	lg->regs->cs = (__KERNEL_CS|GUEST_PL);
+	lg->regs->eip = idt_address(lo, hi);
+
+	/* Disable interrupts for an interrupt gate. */
+	if (idt_type(lo, hi) == 0xE)
+		if (put_user(0, &lg->lguest_data->irq_enabled))
+			kill_guest(lg, "Disabling interrupts");
+}
+
+void maybe_do_interrupt(struct lguest *lg)
+{
+	unsigned int irq;
+	DECLARE_BITMAP(blk, LGUEST_IRQS);
+	struct desc_struct *idt;
+
+	if (!lg->lguest_data)
+		return;
+
+	/* Mask out any interrupts they have blocked. */
+	if (copy_from_user(&blk, lg->lguest_data->blocked_interrupts,
+			   sizeof(blk)))
+		return;
+
+	bitmap_andnot(blk, lg->irqs_pending, blk, LGUEST_IRQS);
+
+	irq = find_first_bit(blk, LGUEST_IRQS);
+	if (irq >= LGUEST_IRQS)
+		return;
+
+	if (lg->regs->eip >= lg->noirq_start && lg->regs->eip < lg->noirq_end)
+		return;
+
+	/* If they're halted, we re-enable interrupts. */
+	if (lg->halted) {
+		/* Re-enable interrupts. */
+		if (put_user(X86_EFLAGS_IF, &lg->lguest_data->irq_enabled))
+			kill_guest(lg, "Re-enabling interrupts");
+		lg->halted = 0;
+	} else {
+		/* Maybe they have interrupts disabled? */
+		u32 irq_enabled;
+		if (get_user(irq_enabled, &lg->lguest_data->irq_enabled))
+			irq_enabled = 0;
+		if (!irq_enabled)
+			return;
+	}
+
+	idt = &lg->idt[FIRST_EXTERNAL_VECTOR+irq];
+	if (idt_present(idt->a, idt->b)) {
+		clear_bit(irq, lg->irqs_pending);
+		set_guest_interrupt(lg, idt->a, idt->b, 0);
+	}
+}
+
+static int has_err(unsigned int trap)
+{
+	return (trap == 8 || (trap >= 10 && trap <= 14) || trap == 17);
+}
+
+int deliver_trap(struct lguest *lg, unsigned int num)
+{
+	u32 lo = lg->idt[num].a, hi = lg->idt[num].b;
+
+	if (!idt_present(lo, hi))
+		return 0;
+	set_guest_interrupt(lg, lo, hi, has_err(num));
+	return 1;
+}
+
+static int direct_trap(const struct lguest *lg,
+		       const struct desc_struct *trap,
+		       unsigned int num)
+{
+	/* Hardware interrupts don't go to guest (except syscall). */
+	if (num >= FIRST_EXTERNAL_VECTOR && num != SYSCALL_VECTOR)
+		return 0;
+
+	/* We intercept page fault (demand shadow paging & cr2 saving)
+	   protection fault (in/out emulation) and device not
+	   available (TS handling), and hypercall */
+	if (num == 14 || num == 13 || num == 7 || num == LGUEST_TRAP_ENTRY)
+		return 0;
+
+	/* Interrupt gates (0xE) or not present (0x0) can't go direct. */
+	return idt_type(trap->a, trap->b) == 0xF;
+}
+
+void pin_stack_pages(struct lguest *lg)
+{
+	unsigned int i;
+
+	for (i = 0; i < lg->stack_pages; i++)
+		pin_page(lg, lg->esp1 - i * PAGE_SIZE);
+}
+
+void guest_set_stack(struct lguest *lg, u32 seg, u32 esp, unsigned int pages)
+{
+	/* You cannot have a stack segment with priv level 0. */
+	if ((seg & 0x3) != GUEST_PL)
+		kill_guest(lg, "bad stack segment %i", seg);
+	if (pages > 2)
+		kill_guest(lg, "bad stack pages %u", pages);
+	lg->ss1 = seg;
+	lg->esp1 = esp;
+	lg->stack_pages = pages;
+	pin_stack_pages(lg);
+}
+
+/* Set up trap in IDT. */
+static void set_trap(struct lguest *lg, struct desc_struct *trap,
+		     unsigned int num, u32 lo, u32 hi)
+{
+	u8 type = idt_type(lo, hi);
+
+	if (!idt_present(lo, hi)) {
+		trap->a = trap->b = 0;
+		return;
+	}
+
+	if (type != 0xE && type != 0xF)
+		kill_guest(lg, "bad IDT type %i", type);
+
+	trap->a = ((__KERNEL_CS|GUEST_PL)<<16) | (lo&0x0000FFFF);
+	trap->b = (hi&0xFFFFEF00);
+}
+
+void load_guest_idt_entry(struct lguest *lg, unsigned int num, u32 lo, u32 hi)
+{
+	/* Guest never handles: NMI, doublefault, hypercall, spurious irq. */
+	if (num == 2 || num == 8 || num == 15 || num == LGUEST_TRAP_ENTRY)
+		return;
+
+	lg->changed |= CHANGED_IDT;
+	if (num < ARRAY_SIZE(lg->idt))
+		set_trap(lg, &lg->idt[num], num, lo, hi);
+	else if (num == SYSCALL_VECTOR)
+		set_trap(lg, &lg->syscall_idt, num, lo, hi);
+}
+
+static void default_idt_entry(struct desc_struct *idt,
+			      int trap,
+			      const unsigned long handler)
+{
+	u32 flags = 0x8e00;
+
+	/* They can't "int" into any of them except hypercall. */
+	if (trap == LGUEST_TRAP_ENTRY)
+		flags |= (GUEST_PL << 13);
+
+	idt->a = (LGUEST_CS<<16) | (handler&0x0000FFFF);
+	idt->b = (handler&0xFFFF0000) | flags;
+}
+
+void setup_default_idt_entries(struct lguest_ro_state *state,
+			       const unsigned long *def)
+{
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(state->guest_idt); i++)
+		default_idt_entry(&state->guest_idt[i], i, def[i]);
+}
+
+void copy_traps(const struct lguest *lg, struct desc_struct *idt,
+		const unsigned long *def)
+{
+	unsigned int i;
+
+	/* All hardware interrupts are same whatever the guest: only the
+	 * traps might be different. */
+	for (i = 0; i < FIRST_EXTERNAL_VECTOR; i++) {
+		if (direct_trap(lg, &lg->idt[i], i))
+			idt[i] = lg->idt[i];
+		else
+			default_idt_entry(&idt[i], i, def[i]);
+	}
+	i = SYSCALL_VECTOR;
+	if (direct_trap(lg, &lg->syscall_idt, i))
+		idt[i] = lg->syscall_idt;
+	else
+		default_idt_entry(&idt[i], i, def[i]);
+}
+
+void guest_set_clockevent(struct lguest *lg, unsigned long delta)
+{
+	ktime_t expires;
+
+	if (unlikely(delta == 0)) {
+		/* Clock event device is shutting down. */
+		hrtimer_cancel(&lg->hrt);
+		return;
+	}
+
+	expires = ktime_add_ns(ktime_get_real(), delta);
+	hrtimer_start(&lg->hrt, expires, HRTIMER_MODE_ABS);
+}
+
+static enum hrtimer_restart clockdev_fn(struct hrtimer *timer)
+{
+	struct lguest *lg = container_of(timer, struct lguest, hrt);
+
+	set_bit(0, lg->irqs_pending);
+	if (lg->halted)
+		wake_up_process(lg->tsk);
+	return HRTIMER_NORESTART;
+}
+
+void init_clockdev(struct lguest *lg)
+{
+	hrtimer_init(&lg->hrt, CLOCK_REALTIME, HRTIMER_MODE_ABS);
+	lg->hrt.function = clockdev_fn;
+}

drivers/lguest/lg.h

+#ifndef _LGUEST_H
+#define _LGUEST_H
+
+#include <asm/desc.h>
+
+#define GDT_ENTRY_LGUEST_CS	10
+#define GDT_ENTRY_LGUEST_DS	11
+#define LGUEST_CS		(GDT_ENTRY_LGUEST_CS * 8)
+#define LGUEST_DS		(GDT_ENTRY_LGUEST_DS * 8)
+
+#ifndef __ASSEMBLY__
+#include <linux/types.h>
+#include <linux/init.h>
+#include <linux/stringify.h>
+#include <linux/binfmts.h>
+#include <linux/futex.h>
+#include <linux/lguest.h>
+#include <linux/lguest_launcher.h>
+#include <linux/wait.h>
+#include <linux/err.h>
+#include <asm/semaphore.h>
+#include "irq_vectors.h"
+
+#define GUEST_PL 1
+
+struct lguest_regs
+{
+	/* Manually saved part. */
+	unsigned long ebx, ecx, edx;
+	unsigned long esi, edi, ebp;
+	unsigned long gs;
+	unsigned long eax;
+	unsigned long fs, ds, es;
+	unsigned long trapnum, errcode;
+	/* Trap pushed part */
+	unsigned long eip;
+	unsigned long cs;
+	unsigned long eflags;
+	unsigned long esp;
+	unsigned long ss;
+};
+
+void free_pagetables(void);
+int init_pagetables(struct page **switcher_page, unsigned int pages);
+
+/* Full 4G segment descriptors, suitable for CS and DS. */
+#define FULL_EXEC_SEGMENT ((struct desc_struct){0x0000ffff, 0x00cf9b00})
+#define FULL_SEGMENT ((struct desc_struct){0x0000ffff, 0x00cf9300})
+
+struct lguest_dma_info
+{
+	struct list_head list;
+	union futex_key key;
+	unsigned long dmas;
+	u16 next_dma;
+	u16 num_dmas;
+	u16 guestid;
+	u8 interrupt; 	/* 0 when not registered */
+};
+
+/* We have separate types for the guest's ptes & pgds and the shadow ptes &
+ * pgds.  Since this host might use three-level pagetables and the guest and
+ * shadow pagetables don't, we can't use the normal pte_t/pgd_t. */
+typedef union {
+	struct { unsigned flags:12, pfn:20; };
+	struct { unsigned long val; } raw;
+} spgd_t;
+typedef union {
+	struct { unsigned flags:12, pfn:20; };
+	struct { unsigned long val; } raw;
+} spte_t;
+typedef union {
+	struct { unsigned flags:12, pfn:20; };
+	struct { unsigned long val; } raw;
+} gpgd_t;
+typedef union {
+	struct { unsigned flags:12, pfn:20; };
+	struct { unsigned long val; } raw;
+} gpte_t;
+#define mkgpte(_val) ((gpte_t){.raw.val = _val})
+#define mkgpgd(_val) ((gpgd_t){.raw.val = _val})
+
+struct pgdir
+{
+	unsigned long cr3;
+	spgd_t *pgdir;
+};
+
+/* This is a guest-specific page (mapped ro) into the guest. */
+struct lguest_ro_state
+{
+	/* Host information we need to restore when we switch back. */
+	u32 host_cr3;
+	struct Xgt_desc_struct host_idt_desc;
+	struct Xgt_desc_struct host_gdt_desc;
+	u32 host_sp;
+
+	/* Fields which are used when guest is running. */
+	struct Xgt_desc_struct guest_idt_desc;
+	struct Xgt_desc_struct guest_gdt_desc;
+	struct i386_hw_tss guest_tss;
+	struct desc_struct guest_idt[IDT_ENTRIES];
+	struct desc_struct guest_gdt[GDT_ENTRIES];
+};
+
+/* We have two pages shared with guests, per cpu.  */
+struct lguest_pages
+{
+	/* This is the stack page mapped rw in guest */
+	char spare[PAGE_SIZE - sizeof(struct lguest_regs)];
+	struct lguest_regs regs;
+
+	/* This is the host state & guest descriptor page, ro in guest */
+	struct lguest_ro_state state;
+} __attribute__((aligned(PAGE_SIZE)));
+
+#define CHANGED_IDT		1
+#define CHANGED_GDT		2
+#define CHANGED_GDT_TLS		4 /* Actually a subset of CHANGED_GDT */
+#define CHANGED_ALL	        3
+
+/* The private info the thread maintains about the guest. */
+struct lguest
+{
+	/* At end of a page shared mapped over lguest_pages in guest.  */
+	unsigned long regs_page;
+	struct lguest_regs *regs;
+	struct lguest_data __user *lguest_data;
+	struct task_struct *tsk;
+	struct mm_struct *mm; 	/* == tsk->mm, but that becomes NULL on exit */
+	u16 guestid;
+	u32 pfn_limit;
+	u32 page_offset;
+	u32 cr2;
+	int halted;
+	int ts;
+	u32 next_hcall;
+	u32 esp1;
+	u8 ss1;
+
+	/* Do we need to stop what we're doing and return to userspace? */
+	int break_out;
+	wait_queue_head_t break_wq;
+
+	/* Bitmap of what has changed: see CHANGED_* above. */
+	int changed;
+	struct lguest_pages *last_pages;
+
+	/* We keep a small number of these. */
+	u32 pgdidx;
+	struct pgdir pgdirs[4];
+
+	/* Cached wakeup: we hold a reference to this task. */
+	struct task_struct *wake;
+
+	unsigned long noirq_start, noirq_end;
+	int dma_is_pending;
+	unsigned long pending_dma; /* struct lguest_dma */
+	unsigned long pending_key; /* address they're sending to */
+
+	unsigned int stack_pages;
+	u32 tsc_khz;
+
+	struct lguest_dma_info dma[LGUEST_MAX_DMA];
+
+	/* Dead? */
+	const char *dead;
+
+	/* The GDT entries copied into lguest_ro_state when running. */
+	struct desc_struct gdt[GDT_ENTRIES];
+
+	/* The IDT entries: some copied into lguest_ro_state when running. */
+	struct desc_struct idt[FIRST_EXTERNAL_VECTOR+LGUEST_IRQS];
+	struct desc_struct syscall_idt;
+
+	/* Virtual clock device */
+	struct hrtimer hrt;
+
+	/* Pending virtual interrupts */
+	DECLARE_BITMAP(irqs_pending, LGUEST_IRQS);
+};
+
+extern struct lguest lguests[];
+extern struct mutex lguest_lock;
+
+/* core.c: */
+u32 lgread_u32(struct lguest *lg, unsigned long addr);
+void lgwrite_u32(struct lguest *lg, unsigned long addr, u32 val);
+void lgread(struct lguest *lg, void *buf, unsigned long addr, unsigned len);
+void lgwrite(struct lguest *lg, unsigned long, const void *buf, unsigned len);
+int find_free_guest(void);
+int lguest_address_ok(const struct lguest *lg,
+		      unsigned long addr, unsigned long len);
+int run_guest(struct lguest *lg, unsigned long __user *user);
+
+
+/* interrupts_and_traps.c: */
+void maybe_do_interrupt(struct lguest *lg);
+int deliver_trap(struct lguest *lg, unsigned int num);
+void load_guest_idt_entry(struct lguest *lg, unsigned int i, u32 low, u32 hi);
+void guest_set_stack(struct lguest *lg, u32 seg, u32 esp, unsigned int pages);
+void pin_stack_pages(struct lguest *lg);
+void setup_default_idt_entries(struct lguest_ro_state *state,
+			       const unsigned long *def);
+void copy_traps(const struct lguest *lg, struct desc_struct *idt,
+		const unsigned long *def);
+void guest_set_clockevent(struct lguest *lg, unsigned long delta);
+void init_clockdev(struct lguest *lg);
+
+/* segments.c: */
+void setup_default_gdt_entries(struct lguest_ro_state *state);
+void setup_guest_gdt(struct lguest *lg);
+void load_guest_gdt(struct lguest *lg, unsigned long table, u32 num);
+void guest_load_tls(struct lguest *lg, unsigned long tls_array);
+void copy_gdt(const struct lguest *lg, struct desc_struct *gdt);
+void copy_gdt_tls(const struct lguest *lg, struct desc_struct *gdt);
+
+/* page_tables.c: */
+int init_guest_pagetable(struct lguest *lg, unsigned long pgtable);
+void free_guest_pagetable(struct lguest *lg);
+void guest_new_pagetable(struct lguest *lg, unsigned long pgtable);
+void guest_set_pmd(struct lguest *lg, unsigned long cr3, u32 i);
+void guest_pagetable_clear_all(struct lguest *lg);
+void guest_pagetable_flush_user(struct lguest *lg);
+void guest_set_pte(struct lguest *lg, unsigned long cr3,
+		   unsigned long vaddr, gpte_t val);
+void map_switcher_in_guest(struct lguest *lg, struct lguest_pages *pages);
+int demand_page(struct lguest *info, unsigned long cr2, int errcode);
+void pin_page(struct lguest *lg, unsigned long vaddr);
+
+/* lguest_user.c: */
+int lguest_device_init(void);
+void lguest_device_remove(void);
+
+/* io.c: */
+void lguest_io_init(void);
+int bind_dma(struct lguest *lg,
+	     unsigned long key, unsigned long udma, u16 numdmas, u8 interrupt);
+void send_dma(struct lguest *info, unsigned long key, unsigned long udma);
+void release_all_dma(struct lguest *lg);
+unsigned long get_dma_buffer(struct lguest *lg, unsigned long key,
+			     unsigned long *interrupt);
+
+/* hypercalls.c: */
+void do_hypercalls(struct lguest *lg);
+
+#define kill_guest(lg, fmt...)					\
+do {								\
+	if (!(lg)->dead) {					\
+		(lg)->dead = kasprintf(GFP_ATOMIC, fmt);	\
+		if (!(lg)->dead)				\
+			(lg)->dead = ERR_PTR(-ENOMEM);		\
+	}							\
+} while(0)
+
+static inline unsigned long guest_pa(struct lguest *lg, unsigned long vaddr)
+{
+	return vaddr - lg->page_offset;
+}
+#endif	/* __ASSEMBLY__ */
+#endif	/* _LGUEST_H */

drivers/lguest/lguest.c

@@ -25,6 +25,8 @@
 #include <linux/screen_info.h>
 #include <linux/irq.h>
 #include <linux/interrupt.h>
+#include <linux/clocksource.h>
+#include <linux/clockchips.h>
 #include <linux/lguest.h>
 #include <linux/lguest_launcher.h>
 #include <linux/lguest_bus.h>
@@ -37,6 +39,7 @@
 #include <asm/e820.h>
 #include <asm/mce.h>
 #include <asm/io.h>
+//#include <asm/sched-clock.h>
 
 /* Declarations for definitions in lguest_guest.S */
 extern char lguest_noirq_start[], lguest_noirq_end[];
@@ -54,7 +57,6 @@ struct lguest_data lguest_data = {
 	.blocked_interrupts = { 1 }, /* Block timer interrupts */
 };
 struct lguest_device_desc *lguest_devices;
-static __initdata const struct lguest_boot_info *boot = __va(0);
 
 static enum paravirt_lazy_mode lazy_mode;
 static void lguest_lazy_mode(enum paravirt_lazy_mode mode)
@@ -210,7 +212,7 @@ static void lguest_cpuid(unsigned int *eax, unsigned int *ebx,
 	case 1:	/* Basic feature request. */
 		/* We only allow kernel to see SSE3, CMPXCHG16B and SSSE3 */
 		*ecx &= 0x00002201;
-		/* Similarly: SSE, SSE2, FXSR, MMX, CMOV, CMPXCHG8B, FPU. */
+		/* SSE, SSE2, FXSR, MMX, CMOV, CMPXCHG8B, FPU. */
 		*edx &= 0x07808101;
 		/* Host wants to know when we flush kernel pages: set PGE. */
 		*edx |= 0x00002000;
@@ -346,24 +348,104 @@ static unsigned long lguest_get_wallclock(void)
 	return hcall(LHCALL_GET_WALLCLOCK, 0, 0, 0);
 }
 
+static cycle_t lguest_clock_read(void)
+{
+	if (lguest_data.tsc_khz)
+		return native_read_tsc();
+	else
+		return jiffies;
+}
+
+/* This is what we tell the kernel is our clocksource.  */
+static struct clocksource lguest_clock = {
+	.name		= "lguest",
+	.rating		= 400,
+	.read		= lguest_clock_read,
+};
+
+/* We also need a "struct clock_event_device": Linux asks us to set it to go
+ * off some time in the future.  Actually, James Morris figured all this out, I
+ * just applied the patch. */
+static int lguest_clockevent_set_next_event(unsigned long delta,
+                                           struct clock_event_device *evt)
+{
+	if (delta < LG_CLOCK_MIN_DELTA) {
+		if (printk_ratelimit())
+			printk(KERN_DEBUG "%s: small delta %lu ns\n",
+			       __FUNCTION__, delta);
+		return -ETIME;
+	}
+	hcall(LHCALL_SET_CLOCKEVENT, delta, 0, 0);
+	return 0;
+}
+
+static void lguest_clockevent_set_mode(enum clock_event_mode mode,
+                                      struct clock_event_device *evt)
+{
+	switch (mode) {
+	case CLOCK_EVT_MODE_UNUSED:
+	case CLOCK_EVT_MODE_SHUTDOWN:
+		/* A 0 argument shuts the clock down. */
+		hcall(LHCALL_SET_CLOCKEVENT, 0, 0, 0);
+		break;
+	case CLOCK_EVT_MODE_ONESHOT:
+		/* This is what we expect. */
+		break;
+	case CLOCK_EVT_MODE_PERIODIC:
+		BUG();
+	}
+}
+
+/* This describes our primitive timer chip. */
+static struct clock_event_device lguest_clockevent = {
+	.name                   = "lguest",
+	.features               = CLOCK_EVT_FEAT_ONESHOT,
+	.set_next_event         = lguest_clockevent_set_next_event,
+	.set_mode               = lguest_clockevent_set_mode,
+	.rating                 = INT_MAX,
+	.mult                   = 1,
+	.shift                  = 0,
+	.min_delta_ns           = LG_CLOCK_MIN_DELTA,
+	.max_delta_ns           = LG_CLOCK_MAX_DELTA,
+};
+
+/* This is the Guest timer interrupt handler (hardware interrupt 0).  We just
+ * call the clockevent infrastructure and it does whatever needs doing. */
 static void lguest_time_irq(unsigned int irq, struct irq_desc *desc)
 {
-	do_timer(hcall(LHCALL_TIMER_READ, 0, 0, 0));
-	update_process_times(user_mode_vm(get_irq_regs()));
+	unsigned long flags;
+
+	/* Don't interrupt us while this is running. */
+	local_irq_save(flags);
+	lguest_clockevent.event_handler(&lguest_clockevent);
+	local_irq_restore(flags);
 }
 
-static u64 sched_clock_base;
 static void lguest_time_init(void)
 {
 	set_irq_handler(0, lguest_time_irq);
-	hcall(LHCALL_TIMER_READ, 0, 0, 0);
-	sched_clock_base = jiffies_64;
-	enable_lguest_irq(0);
-}
 
-static unsigned long long lguest_sched_clock(void)
-{
-	return (jiffies_64 - sched_clock_base) * (1000000000 / HZ);
+	/* We use the TSC if the Host tells us we can, otherwise a dumb
+	 * jiffies-based clock. */
+	if (lguest_data.tsc_khz) {
+		lguest_clock.shift = 22;
+		lguest_clock.mult = clocksource_khz2mult(lguest_data.tsc_khz,
+							 lguest_clock.shift);
+		lguest_clock.mask = CLOCKSOURCE_MASK(64);
+		lguest_clock.flags = CLOCK_SOURCE_IS_CONTINUOUS;
+	} else {
+		/* To understand this, start at kernel/time/jiffies.c... */
+		lguest_clock.shift = 8;
+		lguest_clock.mult = (((u64)NSEC_PER_SEC<<8)/ACTHZ) << 8;
+		lguest_clock.mask = CLOCKSOURCE_MASK(32);
+	}
+	clocksource_register(&lguest_clock);
+
+	/* We can't set cpumask in the initializer: damn C limitations! */
+	lguest_clockevent.cpumask = cpumask_of_cpu(0);
+	clockevents_register_device(&lguest_clockevent);
+
+	enable_lguest_irq(0);
 }
 
 static void lguest_load_esp0(struct tss_struct *tss,
@@ -418,8 +500,7 @@ static __init char *lguest_memory_setup(void)
 	/* We do this here because lockcheck barfs if before start_kernel */
 	atomic_notifier_chain_register(&panic_notifier_list, &paniced);
 
-	e820.nr_map = 0;
-	add_memory_region(0, PFN_PHYS(boot->max_pfn), E820_RAM);
+	add_memory_region(E820_MAP->addr, E820_MAP->size, E820_MAP->type);
 	return "LGUEST";
 }
 
@@ -450,8 +531,13 @@ static unsigned lguest_patch(u8 type, u16 clobber, void *insns, unsigned len)
 	return insn_len;
 }
 
-__init void lguest_init(void)
+__init void lguest_init(void *boot)
 {
+	/* Copy boot parameters first. */
+	memcpy(&boot_params, boot, PARAM_SIZE);
+	memcpy(boot_command_line, __va(boot_params.hdr.cmd_line_ptr),
+	       COMMAND_LINE_SIZE);
+
 	paravirt_ops.name = "lguest";
 	paravirt_ops.paravirt_enabled = 1;
 	paravirt_ops.kernel_rpl = 1;
@@ -498,10 +584,8 @@ __init void lguest_init(void)
 	paravirt_ops.time_init = lguest_time_init;
 	paravirt_ops.set_lazy_mode = lguest_lazy_mode;
 	paravirt_ops.wbinvd = lguest_wbinvd;
-	paravirt_ops.sched_clock = lguest_sched_clock;
 
 	hcall(LHCALL_LGUEST_INIT, __pa(&lguest_data), 0, 0);
-	strncpy(boot_command_line, boot->cmdline, COMMAND_LINE_SIZE);
 
 	/* We use top of mem for initial pagetables. */
 	init_pg_tables_end = __pa(pg0);
@@ -532,13 +616,6 @@ __init void lguest_init(void)
 
 	add_preferred_console("hvc", 0, NULL);
 
-	if (boot->initrd_size) {
-		/* We stash this at top of memory. */
-		INITRD_START = boot->max_pfn*PAGE_SIZE - boot->initrd_size;
-		INITRD_SIZE = boot->initrd_size;
-		LOADER_TYPE = 0xFF;
-	}
-
 	pm_power_off = lguest_power_off;
 	start_kernel();
 }

drivers/lguest/lguest_asm.S

@@ -10,7 +10,8 @@
  * This is where we begin: we have a magic signature which the launcher looks
  * for.  The plan is that the Linux boot protocol will be extended with a
  * "platform type" field which will guide us here from the normal entry point,
- * but for the moment this suffices.
+ * but for the moment this suffices.  We pass the virtual address of the boot
+ * info to lguest_init().
  *
  * We put it in .init.text will be discarded after boot.
  */
@@ -18,6 +19,8 @@
 .ascii "GenuineLguest"
 	/* Set up initial stack. */
  	movl $(init_thread_union+THREAD_SIZE),%esp
+	movl %esi, %eax
+	addl $__PAGE_OFFSET, %eax
 	jmp lguest_init
 
 /* The templates for inline patching. */

drivers/lguest/lguest_user.c

+/* Userspace control of the guest, via /dev/lguest. */
+#include <linux/uaccess.h>
+#include <linux/miscdevice.h>
+#include <linux/fs.h>
+#include "lg.h"
+
+static void setup_regs(struct lguest_regs *regs, unsigned long start)
+{
+	/* Write out stack in format lguest expects, so we can switch to it. */
+	regs->ds = regs->es = regs->ss = __KERNEL_DS|GUEST_PL;
+	regs->cs = __KERNEL_CS|GUEST_PL;
+	regs->eflags = 0x202; 	/* Interrupts enabled. */
+	regs->eip = start;
+	/* esi points to our boot information (physical address 0) */
+}
+
+/* + addr */
+static long user_get_dma(struct lguest *lg, const u32 __user *input)
+{
+	unsigned long key, udma, irq;
+
+	if (get_user(key, input) != 0)
+		return -EFAULT;
+	udma = get_dma_buffer(lg, key, &irq);
+	if (!udma)
+		return -ENOENT;
+
+	/* We put irq number in udma->used_len. */
+	lgwrite_u32(lg, udma + offsetof(struct lguest_dma, used_len), irq);
+	return udma;
+}
+
+/* To force the Guest to stop running and return to the Launcher, the
+ * Waker sets writes LHREQ_BREAK and the value "1" to /dev/lguest.  The
+ * Launcher then writes LHREQ_BREAK and "0" to release the Waker. */
+static int break_guest_out(struct lguest *lg, const u32 __user *input)
+{
+	unsigned long on;
+
+	/* Fetch whether they're turning break on or off.. */
+	if (get_user(on, input) != 0)
+		return -EFAULT;
+
+	if (on) {
+		lg->break_out = 1;
+		/* Pop it out (may be running on different CPU) */
+		wake_up_process(lg->tsk);
+		/* Wait for them to reset it */
+		return wait_event_interruptible(lg->break_wq, !lg->break_out);
+	} else {
+		lg->break_out = 0;
+		wake_up(&lg->break_wq);
+		return 0;
+	}
+}
+
+/* + irq */
+static int user_send_irq(struct lguest *lg, const u32 __user *input)
+{
+	u32 irq;
+
+	if (get_user(irq, input) != 0)
+		return -EFAULT;
+	if (irq >= LGUEST_IRQS)
+		return -EINVAL;
+	set_bit(irq, lg->irqs_pending);
+	return 0;
+}
+
+static ssize_t read(struct file *file, char __user *user, size_t size,loff_t*o)
+{
+	struct lguest *lg = file->private_data;
+
+	if (!lg)
+		return -EINVAL;
+
+	/* If you're not the task which owns the guest, go away. */
+	if (current != lg->tsk)
+		return -EPERM;
+
+	if (lg->dead) {
+		size_t len;
+
+		if (IS_ERR(lg->dead))
+			return PTR_ERR(lg->dead);
+
+		len = min(size, strlen(lg->dead)+1);
+		if (copy_to_user(user, lg->dead, len) != 0)
+			return -EFAULT;
+		return len;
+	}
+
+	if (lg->dma_is_pending)
+		lg->dma_is_pending = 0;
+
+	return run_guest(lg, (unsigned long __user *)user);
+}
+
+/* Take: pfnlimit, pgdir, start, pageoffset. */
+static int initialize(struct file *file, const u32 __user *input)
+{
+	struct lguest *lg;
+	int err, i;
+	u32 args[4];
+
+	/* We grab the Big Lguest lock, which protects the global array
+	 * "lguests" and multiple simultaneous initializations. */
+	mutex_lock(&lguest_lock);
+
+	if (file->private_data) {
+		err = -EBUSY;
+		goto unlock;
+	}
+
+	if (copy_from_user(args, input, sizeof(args)) != 0) {
+		err = -EFAULT;
+		goto unlock;
+	}
+
+	i = find_free_guest();
+	if (i < 0) {
+		err = -ENOSPC;
+		goto unlock;
+	}
+	lg = &lguests[i];
+	lg->guestid = i;
+	lg->pfn_limit = args[0];
+	lg->page_offset = args[3];
+	lg->regs_page = get_zeroed_page(GFP_KERNEL);
+	if (!lg->regs_page) {
+		err = -ENOMEM;
+		goto release_guest;
+	}
+	lg->regs = (void *)lg->regs_page + PAGE_SIZE - sizeof(*lg->regs);
+
+	err = init_guest_pagetable(lg, args[1]);
+	if (err)
+		goto free_regs;
+
+	setup_regs(lg->regs, args[2]);
+	setup_guest_gdt(lg);
+	init_clockdev(lg);
+	lg->tsk = current;
+	lg->mm = get_task_mm(lg->tsk);
+	init_waitqueue_head(&lg->break_wq);
+	lg->last_pages = NULL;
+	file->private_data = lg;
+
+	mutex_unlock(&lguest_lock);
+
+	return sizeof(args);
+
+free_regs:
+	free_page(lg->regs_page);
+release_guest:
+	memset(lg, 0, sizeof(*lg));
+unlock:
+	mutex_unlock(&lguest_lock);
+	return err;
+}
+
+static ssize_t write(struct file *file, const char __user *input,
+		     size_t size, loff_t *off)
+{
+	struct lguest *lg = file->private_data;
+	u32 req;
+
+	if (get_user(req, input) != 0)
+		return -EFAULT;
+	input += sizeof(req);
+
+	if (req != LHREQ_INITIALIZE && !lg)
+		return -EINVAL;
+	if (lg && lg->dead)
+		return -ENOENT;
+
+	/* If you're not the task which owns the Guest, you can only break */
+	if (lg && current != lg->tsk && req != LHREQ_BREAK)
+		return -EPERM;
+
+	switch (req) {
+	case LHREQ_INITIALIZE:
+		return initialize(file, (const u32 __user *)input);
+	case LHREQ_GETDMA:
+		return user_get_dma(lg, (const u32 __user *)input);
+	case LHREQ_IRQ:
+		return user_send_irq(lg, (const u32 __user *)input);
+	case LHREQ_BREAK:
+		return break_guest_out(lg, (const u32 __user *)input);
+	default:
+		return -EINVAL;
+	}
+}
+
+static int close(struct inode *inode, struct file *file)
+{
+	struct lguest *lg = file->private_data;
+
+	if (!lg)
+		return 0;
+
+	mutex_lock(&lguest_lock);
+	/* Cancels the hrtimer set via LHCALL_SET_CLOCKEVENT. */
+	hrtimer_cancel(&lg->hrt);
+	release_all_dma(lg);
+	free_guest_pagetable(lg);
+	mmput(lg->mm);
+	if (!IS_ERR(lg->dead))
+		kfree(lg->dead);
+	free_page(lg->regs_page);
+	memset(lg, 0, sizeof(*lg));
+	mutex_unlock(&lguest_lock);
+	return 0;
+}
+
+static struct file_operations lguest_fops = {
+	.owner	 = THIS_MODULE,
+	.release = close,
+	.write	 = write,
+	.read	 = read,
+};
+static struct miscdevice lguest_dev = {
+	.minor	= MISC_DYNAMIC_MINOR,
+	.name	= "lguest",
+	.fops	= &lguest_fops,
+};
+
+int __init lguest_device_init(void)
+{
+	return misc_register(&lguest_dev);
+}
+
+void __exit lguest_device_remove(void)
+{
+	misc_deregister(&lguest_dev);
+}

drivers/lguest/segments.c

+#include "lg.h"
+
+static int desc_ok(const struct desc_struct *gdt)
+{
+	/* MBZ=0, P=1, DT=1  */
+	return ((gdt->b & 0x00209000) == 0x00009000);
+}
+
+static int segment_present(const struct desc_struct *gdt)
+{
+	return gdt->b & 0x8000;
+}
+
+static int ignored_gdt(unsigned int num)
+{
+	return (num == GDT_ENTRY_TSS
+		|| num == GDT_ENTRY_LGUEST_CS
+		|| num == GDT_ENTRY_LGUEST_DS
+		|| num == GDT_ENTRY_DOUBLEFAULT_TSS);
+}
+
+/* We don't allow removal of CS, DS or SS; it doesn't make sense. */
+static void check_segment_use(struct lguest *lg, unsigned int desc)
+{
+	if (lg->regs->gs / 8 == desc)
+		lg->regs->gs = 0;
+	if (lg->regs->fs / 8 == desc)
+		lg->regs->fs = 0;
+	if (lg->regs->es / 8 == desc)
+		lg->regs->es = 0;
+	if (lg->regs->ds / 8 == desc
+	    || lg->regs->cs / 8 == desc
+	    || lg->regs->ss / 8 == desc)
+		kill_guest(lg, "Removed live GDT entry %u", desc);
+}
+
+static void fixup_gdt_table(struct lguest *lg, unsigned start, unsigned end)
+{
+	unsigned int i;
+
+	for (i = start; i < end; i++) {
+		/* We never copy these ones to real gdt */
+		if (ignored_gdt(i))
+			continue;
+
+		/* We could fault in switch_to_guest if they are using
+		 * a removed segment. */
+		if (!segment_present(&lg->gdt[i])) {
+			check_segment_use(lg, i);
+			continue;
+		}
+
+		if (!desc_ok(&lg->gdt[i]))
+			kill_guest(lg, "Bad GDT descriptor %i", i);
+
+		/* DPL 0 presumably means "for use by guest". */
+		if ((lg->gdt[i].b & 0x00006000) == 0)
+			lg->gdt[i].b |= (GUEST_PL << 13);
+
+		/* Set accessed bit, since gdt isn't writable. */
+		lg->gdt[i].b |= 0x00000100;
+	}
+}
+
+void setup_default_gdt_entries(struct lguest_ro_state *state)
+{
+	struct desc_struct *gdt = state->guest_gdt;
+	unsigned long tss = (unsigned long)&state->guest_tss;
+
+	/* Hypervisor segments. */
+	gdt[GDT_ENTRY_LGUEST_CS] = FULL_EXEC_SEGMENT;
+	gdt[GDT_ENTRY_LGUEST_DS] = FULL_SEGMENT;
+
+	/* This is the one which we *cannot* copy from guest, since tss
+	   is depended on this lguest_ro_state, ie. this cpu. */
+	gdt[GDT_ENTRY_TSS].a = 0x00000067 | (tss << 16);
+	gdt[GDT_ENTRY_TSS].b = 0x00008900 | (tss & 0xFF000000)
+		| ((tss >> 16) & 0x000000FF);
+}
+
+void setup_guest_gdt(struct lguest *lg)
+{
+	lg->gdt[GDT_ENTRY_KERNEL_CS] = FULL_EXEC_SEGMENT;
+	lg->gdt[GDT_ENTRY_KERNEL_DS] = FULL_SEGMENT;
+	lg->gdt[GDT_ENTRY_KERNEL_CS].b |= (GUEST_PL << 13);
+	lg->gdt[GDT_ENTRY_KERNEL_DS].b |= (GUEST_PL << 13);
+}
+
+/* This is a fast version for the common case where only the three TLS entries
+ * have changed. */
+void copy_gdt_tls(const struct lguest *lg, struct desc_struct *gdt)
+{
+	unsigned int i;
+
+	for (i = GDT_ENTRY_TLS_MIN; i <= GDT_ENTRY_TLS_MAX; i++)
+		gdt[i] = lg->gdt[i];
+}
+
+void copy_gdt(const struct lguest *lg, struct desc_struct *gdt)
+{
+	unsigned int i;
+
+	for (i = 0; i < GDT_ENTRIES; i++)
+		if (!ignored_gdt(i))
+			gdt[i] = lg->gdt[i];
+}
+
+void load_guest_gdt(struct lguest *lg, unsigned long table, u32 num)
+{
+	if (num > ARRAY_SIZE(lg->gdt))
+		kill_guest(lg, "too many gdt entries %i", num);
+
+	lgread(lg, lg->gdt, table, num * sizeof(lg->gdt[0]));
+	fixup_gdt_table(lg, 0, ARRAY_SIZE(lg->gdt));
+	lg->changed |= CHANGED_GDT;
+}
+
+void guest_load_tls(struct lguest *lg, unsigned long gtls)
+{
+	struct desc_struct *tls = &lg->gdt[GDT_ENTRY_TLS_MIN];
+
+	lgread(lg, tls, gtls, sizeof(*tls)*GDT_ENTRY_TLS_ENTRIES);
+	fixup_gdt_table(lg, GDT_ENTRY_TLS_MIN, GDT_ENTRY_TLS_MAX+1);
+	lg->changed |= CHANGED_GDT_TLS;
+}

drivers/lguest/switcher.S

+/* This code sits at 0xFFC00000 to do the low-level guest<->host switch.
+
+   There is are two pages above us for this CPU (struct lguest_pages).
+   The second page (struct lguest_ro_state) becomes read-only after the
+   context switch.  The first page (the stack for traps) remains writable,
+   but while we're in here, the guest cannot be running.
+*/
+#include <linux/linkage.h>
+#include <asm/asm-offsets.h>
+#include "lg.h"
+
+.text
+ENTRY(start_switcher_text)
+
+/* %eax points to lguest pages for this CPU.  %ebx contains cr3 value.
+   All normal registers can be clobbered! */
+ENTRY(switch_to_guest)
+	/* Save host segments on host stack. */
+	pushl	%es
+	pushl	%ds
+	pushl	%gs
+	pushl	%fs
+	/* With CONFIG_FRAME_POINTER, gcc doesn't let us clobber this! */
+	pushl	%ebp
+	/* Save host stack. */
+	movl	%esp, LGUEST_PAGES_host_sp(%eax)
+	/* Switch to guest stack: if we get NMI we expect to be there. */
+	movl	%eax, %edx
+	addl	$LGUEST_PAGES_regs, %edx
+	movl	%edx, %esp
+	/* Switch to guest's GDT, IDT. */
+	lgdt	LGUEST_PAGES_guest_gdt_desc(%eax)
+	lidt	LGUEST_PAGES_guest_idt_desc(%eax)
+	/* Switch to guest's TSS while GDT still writable. */
+	movl	$(GDT_ENTRY_TSS*8), %edx
+	ltr	%dx
+	/* Set host's TSS GDT entry to available (clear byte 5 bit 2). */
+	movl	(LGUEST_PAGES_host_gdt_desc+2)(%eax), %edx
+	andb	$0xFD, (GDT_ENTRY_TSS*8 + 5)(%edx)
+	/* Switch to guest page tables:	lguest_pages->state now read-only. */
+	movl	%ebx, %cr3
+	/* Restore guest regs */
+	popl	%ebx
+	popl	%ecx
+	popl	%edx
+	popl	%esi
+	popl	%edi
+	popl	%ebp
+	popl	%gs
+	popl	%eax
+	popl	%fs
+	popl	%ds
+	popl	%es
+	/* Skip error code and trap number */
+	addl	$8, %esp
+	iret
+
+#define SWITCH_TO_HOST							\
+	/* Save guest state */						\
+	pushl	%es;							\
+	pushl	%ds;							\
+	pushl	%fs;							\
+	pushl	%eax;							\
+	pushl	%gs;							\
+	pushl	%ebp;							\
+	pushl	%edi;							\
+	pushl	%esi;							\
+	pushl	%edx;							\
+	pushl	%ecx;							\
+	pushl	%ebx;							\
+	/* Load lguest ds segment for convenience. */			\
+	movl	$(LGUEST_DS), %eax;					\
+	movl	%eax, %ds;						\
+	/* Figure out where we are, based on stack (at top of regs). */	\
+	movl	%esp, %eax;						\
+	subl	$LGUEST_PAGES_regs, %eax;				\
+	/* Put trap number in %ebx before we switch cr3 and lose it. */ \
+	movl	LGUEST_PAGES_regs_trapnum(%eax), %ebx;			\
+	/* Switch to host page tables (host GDT, IDT and stack are in host   \
+	   mem, so need this first) */					\
+	movl	LGUEST_PAGES_host_cr3(%eax), %edx;			\
+	movl	%edx, %cr3;						\
+	/* Set guest's TSS to available (clear byte 5 bit 2). */	\
+	andb	$0xFD, (LGUEST_PAGES_guest_gdt+GDT_ENTRY_TSS*8+5)(%eax); \
+	/* Switch to host's GDT & IDT. */				\
+	lgdt	LGUEST_PAGES_host_gdt_desc(%eax);			\
+	lidt	LGUEST_PAGES_host_idt_desc(%eax);			\
+	/* Switch to host's stack. */					\
+	movl	LGUEST_PAGES_host_sp(%eax), %esp;			\
+	/* Switch to host's TSS */					\
+	movl	$(GDT_ENTRY_TSS*8), %edx;				\
+	ltr	%dx;							\
+	popl	%ebp;							\
+	popl	%fs;							\
+	popl	%gs;							\
+	popl	%ds;							\
+	popl	%es
+
+/* Return to run_guest_once. */
+return_to_host:
+	SWITCH_TO_HOST
+	iret
+
+deliver_to_host:
+	SWITCH_TO_HOST
+	/* Decode IDT and jump to hosts' irq handler.  When that does iret, it
+	 * will return to run_guest_once.  This is a feature. */
+	movl	(LGUEST_PAGES_host_idt_desc+2)(%eax), %edx
+	leal	(%edx,%ebx,8), %eax
+	movzwl	(%eax),%edx
+	movl	4(%eax), %eax
+	xorw	%ax, %ax
+	orl	%eax, %edx
+	jmp	*%edx
+
+/* Real hardware interrupts are delivered straight to the host.  Others
+   cause us to return to run_guest_once so it can decide what to do.  Note
+   that some of these are overridden by the guest to deliver directly, and
+   never enter here (see load_guest_idt_entry). */
+.macro IRQ_STUB N TARGET
+	.data; .long 1f; .text; 1:
+ /* Make an error number for most traps, which don't have one. */
+ .if (\N <> 8) && (\N < 10 || \N > 14) && (\N <> 17)
+	pushl	$0
+ .endif
+	pushl	$\N
+	jmp	\TARGET
+	ALIGN
+.endm
+
+.macro IRQ_STUBS FIRST LAST TARGET
+ irq=\FIRST
+ .rept \LAST-\FIRST+1
+	IRQ_STUB irq \TARGET
+  irq=irq+1
+ .endr
+.endm
+
+/* We intercept every interrupt, because we may need to switch back to
+ * host.  Unfortunately we can't tell them apart except by entry
+ * point, so we need 256 entry points.
+ */
+.data
+.global default_idt_entries
+default_idt_entries:
+.text
+	IRQ_STUBS 0 1 return_to_host		/* First two traps */
+	IRQ_STUB 2 handle_nmi			/* NMI */
+	IRQ_STUBS 3 31 return_to_host		/* Rest of traps */
+	IRQ_STUBS 32 127 deliver_to_host	/* Real interrupts */
+	IRQ_STUB 128 return_to_host		/* System call (overridden) */
+	IRQ_STUBS 129 255 deliver_to_host	/* Other real interrupts */
+
+/* We ignore NMI and return. */
+handle_nmi:
+	addl	$8, %esp
+	iret
+
+ENTRY(end_switcher_text)

include/asm-i386/tsc.h

@@ -63,6 +63,7 @@ extern void tsc_init(void);
 extern void mark_tsc_unstable(char *reason);
 extern int unsynchronized_tsc(void);
 extern void init_tsc_clocksource(void);
+int check_tsc_unstable(void);
 
 /*
  * Boot-time check whether the TSCs are synchronized across

include/linux/lguest.h

@@ -3,11 +3,6 @@
 #ifndef _ASM_LGUEST_H
 #define _ASM_LGUEST_H
 
-/* These are randomly chosen numbers which indicate we're an lguest at boot */
-#define LGUEST_MAGIC_EBP 0x4C687970
-#define LGUEST_MAGIC_EDI 0x652D4D65
-#define LGUEST_MAGIC_ESI 0xFFFFFFFF
-
 #ifndef __ASSEMBLY__
 #include <asm/irq.h>
 
@@ -20,7 +15,7 @@
 #define LHCALL_LOAD_IDT_ENTRY	6
 #define LHCALL_SET_STACK	7
 #define LHCALL_TS		8
-#define LHCALL_TIMER_READ	9
+#define LHCALL_SET_CLOCKEVENT	9
 #define LHCALL_HALT		10
 #define LHCALL_GET_WALLCLOCK	11
 #define LHCALL_BIND_DMA		12
@@ -29,6 +24,9 @@
 #define LHCALL_SET_PMD		15
 #define LHCALL_LOAD_TLS		16
 
+#define LG_CLOCK_MIN_DELTA	100UL
+#define LG_CLOCK_MAX_DELTA	ULONG_MAX
+
 #define LGUEST_TRAP_ENTRY 0x1F
 
 static inline unsigned long
@@ -75,6 +73,8 @@ struct lguest_data
 	unsigned long reserve_mem;
 	/* ID of this guest (used by network driver to set ethernet address) */
 	u16 guestid;
+	/* KHz for the TSC clock. */
+	u32 tsc_khz;
 
 /* Fields initialized by the guest at boot: */
 	/* Instruction range to suppress interrupts even if enabled */

include/linux/lguest_launcher.h

+#ifndef _ASM_LGUEST_USER
+#define _ASM_LGUEST_USER
+/* Everything the "lguest" userspace program needs to know. */
+/* They can register up to 32 arrays of lguest_dma. */
+#define LGUEST_MAX_DMA		32
+/* At most we can dma 16 lguest_dma in one op. */
+#define LGUEST_MAX_DMA_SECTIONS	16
+
+/* How many devices?  Assume each one wants up to two dma arrays per device. */
+#define LGUEST_MAX_DEVICES (LGUEST_MAX_DMA/2)
+
+struct lguest_dma
+{
+	/* 0 if free to be used, filled by hypervisor. */
+ 	u32 used_len;
+	unsigned long addr[LGUEST_MAX_DMA_SECTIONS];
+	u16 len[LGUEST_MAX_DMA_SECTIONS];
+};
+
+struct lguest_block_page
+{
+	/* 0 is a read, 1 is a write. */
+	int type;
+	u32 sector; 	/* Offset in device = sector * 512. */
+	u32 bytes;	/* Length expected to be read/written in bytes */
+	/* 0 = pending, 1 = done, 2 = done, error */
+	int result;
+	u32 num_sectors; /* Disk length = num_sectors * 512 */
+};
+
+/* There is a shared page of these. */
+struct lguest_net
+{
+	/* Simply the mac address (with multicast bit meaning promisc). */
+	unsigned char mac[6];
+};
+
+/* Where the Host expects the Guest to SEND_DMA console output to. */
+#define LGUEST_CONSOLE_DMA_KEY 0
+
+/* We have a page of these descriptors in the lguest_device page. */
+struct lguest_device_desc {
+	u16 type;
+#define LGUEST_DEVICE_T_CONSOLE	1
+#define LGUEST_DEVICE_T_NET	2
+#define LGUEST_DEVICE_T_BLOCK	3
+
+	u16 features;
+#define LGUEST_NET_F_NOCSUM		0x4000 /* Don't bother checksumming */
+#define LGUEST_DEVICE_F_RANDOMNESS	0x8000 /* IRQ is fairly random */
+
+	u16 status;
+/* 256 and above are device specific. */
+#define LGUEST_DEVICE_S_ACKNOWLEDGE	1 /* We have seen device. */
+#define LGUEST_DEVICE_S_DRIVER		2 /* We have found a driver */
+#define LGUEST_DEVICE_S_DRIVER_OK	4 /* Driver says OK! */
+#define LGUEST_DEVICE_S_REMOVED		8 /* Device has gone away. */
+#define LGUEST_DEVICE_S_REMOVED_ACK	16 /* Driver has been told. */
+#define LGUEST_DEVICE_S_FAILED		128 /* Something actually failed */
+
+	u16 num_pages;
+	u32 pfn;
+};
+
+/* Write command first word is a request. */
+enum lguest_req
+{
+	LHREQ_INITIALIZE, /* + pfnlimit, pgdir, start, pageoffset */
+	LHREQ_GETDMA, /* + addr (returns &lguest_dma, irq in ->used_len) */
+	LHREQ_IRQ, /* + irq */
+	LHREQ_BREAK, /* + on/off flag (on blocks until someone does off) */
+};
+#endif /* _ASM_LGUEST_USER */

kernel/fork.c

@@ -127,7 +127,6 @@ void __put_task_struct(struct task_struct *tsk)
 	if (!profile_handoff_task(tsk))
 		free_task(tsk);
 }
-EXPORT_SYMBOL_GPL(__put_task_struct);
 
 void __init fork_init(unsigned long mempages)
 {