Move lguest guest support to arch/x86.

Lguest has two sides: host support (to launch guests) and guest
support (replacement boot path and paravirt_ops).  This moves the
guest side to arch/x86/lguest where it's closer to related code.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <ak@suse.de>

3 files changed, 2 insertions, 1201 deletions

diff --git a/drivers/lguest/Makefile b/drivers/lguest/Makefile
index e5047471c334..2db98c233e54 100644
--- a/drivers/lguest/Makefile
+++ b/drivers/lguest/Makefile
@@ -1,5 +1,5 @@
-# Guest requires the paravirt_ops replacement and the bus driver.
-obj-$(CONFIG_LGUEST_GUEST) += lguest.o lguest_asm.o lguest_bus.o
+# Guest requires the bus driver.
+obj-$(CONFIG_LGUEST_GUEST) += lguest_bus.o
 
 # Host requires the other files, which can be a module.
 obj-$(CONFIG_LGUEST)	+= lg.o
diff --git a/drivers/lguest/lguest.c b/drivers/lguest/lguest.c
deleted file mode 100644
index 8e9e485a5cfa..000000000000
--- a/drivers/lguest/lguest.c
+++ /dev/null
@@ -1,1106 +0,0 @@
-/*P:010
- * A hypervisor allows multiple Operating Systems to run on a single machine.
- * To quote David Wheeler: "Any problem in computer science can be solved with
- * another layer of indirection."
- *
- * We keep things simple in two ways.  First, we start with a normal Linux
- * kernel and insert a module (lg.ko) which allows us to run other Linux
- * kernels the same way we'd run processes.  We call the first kernel the Host,
- * and the others the Guests.  The program which sets up and configures Guests
- * (such as the example in Documentation/lguest/lguest.c) is called the
- * Launcher.
- *
- * Secondly, we only run specially modified Guests, not normal kernels.  When
- * you set CONFIG_LGUEST to 'y' or 'm', this automatically sets
- * CONFIG_LGUEST_GUEST=y, which compiles this file into the kernel so it knows
- * how to be a Guest.  This means that you can use the same kernel you boot
- * normally (ie. as a Host) as a Guest.
- *
- * These Guests know that they cannot do privileged operations, such as disable
- * interrupts, and that they have to ask the Host to do such things explicitly.
- * This file consists of all the replacements for such low-level native
- * hardware operations: these special Guest versions call the Host.
- *
- * So how does the kernel know it's a Guest?  The Guest starts at a special
- * entry point marked with a magic string, which sets up a few things then
- * calls here.  We replace the native functions various "paravirt" structures
- * with our Guest versions, then boot like normal. :*/
-
-/*
- * Copyright (C) 2006, Rusty Russell <rusty@rustcorp.com.au> 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, 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.
- */
-#include <linux/kernel.h>
-#include <linux/start_kernel.h>
-#include <linux/string.h>
-#include <linux/console.h>
-#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>
-#include <asm/paravirt.h>
-#include <asm/param.h>
-#include <asm/page.h>
-#include <asm/pgtable.h>
-#include <asm/desc.h>
-#include <asm/setup.h>
-#include <asm/e820.h>
-#include <asm/mce.h>
-#include <asm/io.h>
-
-/*G:010 Welcome to the Guest!
- *
- * The Guest in our tale is a simple creature: identical to the Host but
- * behaving in simplified but equivalent ways.  In particular, the Guest is the
- * same kernel as the Host (or at least, built from the same source code). :*/
-
-/* Declarations for definitions in lguest_guest.S */
-extern char lguest_noirq_start[], lguest_noirq_end[];
-extern const char lgstart_cli[], lgend_cli[];
-extern const char lgstart_sti[], lgend_sti[];
-extern const char lgstart_popf[], lgend_popf[];
-extern const char lgstart_pushf[], lgend_pushf[];
-extern const char lgstart_iret[], lgend_iret[];
-extern void lguest_iret(void);
-
-struct lguest_data lguest_data = {
-	.hcall_status = { [0 ... LHCALL_RING_SIZE-1] = 0xFF },
-	.noirq_start = (u32)lguest_noirq_start,
-	.noirq_end = (u32)lguest_noirq_end,
-	.blocked_interrupts = { 1 }, /* Block timer interrupts */
-};
-static cycle_t clock_base;
-
-/*G:035 Notice the lazy_hcall() above, rather than hcall().  This is our first
- * real optimization trick!
- *
- * When lazy_mode is set, it means we're allowed to defer all hypercalls and do
- * them as a batch when lazy_mode is eventually turned off.  Because hypercalls
- * are reasonably expensive, batching them up makes sense.  For example, a
- * large mmap might update dozens of page table entries: that code calls
- * paravirt_enter_lazy_mmu(), does the dozen updates, then calls
- * lguest_leave_lazy_mode().
- *
- * So, when we're in lazy mode, we call async_hypercall() to store the call for
- * future processing.  When lazy mode is turned off we issue a hypercall to
- * flush the stored calls.
- */
-static void lguest_leave_lazy_mode(void)
-{
-	paravirt_leave_lazy(paravirt_get_lazy_mode());
-	hcall(LHCALL_FLUSH_ASYNC, 0, 0, 0);
-}
-
-static void lazy_hcall(unsigned long call,
-		       unsigned long arg1,
-		       unsigned long arg2,
-		       unsigned long arg3)
-{
-	if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE)
-		hcall(call, arg1, arg2, arg3);
-	else
-		async_hcall(call, arg1, arg2, arg3);
-}
-
-/* async_hcall() is pretty simple: I'm quite proud of it really.  We have a
- * ring buffer of stored hypercalls which the Host will run though next time we
- * do a normal hypercall.  Each entry in the ring has 4 slots for the hypercall
- * arguments, and a "hcall_status" word which is 0 if the call is ready to go,
- * and 255 once the Host has finished with it.
- *
- * If we come around to a slot which hasn't been finished, then the table is
- * full and we just make the hypercall directly.  This has the nice side
- * effect of causing the Host to run all the stored calls in the ring buffer
- * which empties it for next time! */
-void async_hcall(unsigned long call,
-		 unsigned long arg1, unsigned long arg2, unsigned long arg3)
-{
-	/* Note: This code assumes we're uniprocessor. */
-	static unsigned int next_call;
-	unsigned long flags;
-
-	/* Disable interrupts if not already disabled: we don't want an
-	 * interrupt handler making a hypercall while we're already doing
-	 * one! */
-	local_irq_save(flags);
-	if (lguest_data.hcall_status[next_call] != 0xFF) {
-		/* Table full, so do normal hcall which will flush table. */
-		hcall(call, arg1, arg2, arg3);
-	} else {
-		lguest_data.hcalls[next_call].eax = call;
-		lguest_data.hcalls[next_call].edx = arg1;
-		lguest_data.hcalls[next_call].ebx = arg2;
-		lguest_data.hcalls[next_call].ecx = arg3;
-		/* Arguments must all be written before we mark it to go */
-		wmb();
-		lguest_data.hcall_status[next_call] = 0;
-		if (++next_call == LHCALL_RING_SIZE)
-			next_call = 0;
-	}
-	local_irq_restore(flags);
-}
-/*:*/
-
-/* Wrappers for the SEND_DMA and BIND_DMA hypercalls.  This is mainly because
- * Jeff Garzik complained that __pa() should never appear in drivers, and this
- * helps remove most of them.   But also, it wraps some ugliness. */
-void lguest_send_dma(unsigned long key, struct lguest_dma *dma)
-{
-	/* The hcall might not write this if something goes wrong */
-	dma->used_len = 0;
-	hcall(LHCALL_SEND_DMA, key, __pa(dma), 0);
-}
-
-int lguest_bind_dma(unsigned long key, struct lguest_dma *dmas,
-		    unsigned int num, u8 irq)
-{
-	/* This is the only hypercall which actually wants 5 arguments, and we
-	 * only support 4.  Fortunately the interrupt number is always less
-	 * than 256, so we can pack it with the number of dmas in the final
-	 * argument.  */
-	if (!hcall(LHCALL_BIND_DMA, key, __pa(dmas), (num << 8) | irq))
-		return -ENOMEM;
-	return 0;
-}
-
-/* Unbinding is the same hypercall as binding, but with 0 num & irq. */
-void lguest_unbind_dma(unsigned long key, struct lguest_dma *dmas)
-{
-	hcall(LHCALL_BIND_DMA, key, __pa(dmas), 0);
-}
-
-/* For guests, device memory can be used as normal memory, so we cast away the
- * __iomem to quieten sparse. */
-void *lguest_map(unsigned long phys_addr, unsigned long pages)
-{
-	return (__force void *)ioremap(phys_addr, PAGE_SIZE*pages);
-}
-
-void lguest_unmap(void *addr)
-{
-	iounmap((__force void __iomem *)addr);
-}
-
-/*G:033
- * Here are our first native-instruction replacements: four functions for
- * interrupt control.
- *
- * The simplest way of implementing these would be to have "turn interrupts
- * off" and "turn interrupts on" hypercalls.  Unfortunately, this is too slow:
- * these are by far the most commonly called functions of those we override.
- *
- * So instead we keep an "irq_enabled" field inside our "struct lguest_data",
- * which the Guest can update with a single instruction.  The Host knows to
- * check there when it wants to deliver an interrupt.
- */
-
-/* save_flags() is expected to return the processor state (ie. "eflags").  The
- * eflags word contains all kind of stuff, but in practice Linux only cares
- * about the interrupt flag.  Our "save_flags()" just returns that. */
-static unsigned long save_fl(void)
-{
-	return lguest_data.irq_enabled;
-}
-
-/* "restore_flags" just sets the flags back to the value given. */
-static void restore_fl(unsigned long flags)
-{
-	lguest_data.irq_enabled = flags;
-}
-
-/* Interrupts go off... */
-static void irq_disable(void)
-{
-	lguest_data.irq_enabled = 0;
-}
-
-/* Interrupts go on... */
-static void irq_enable(void)
-{
-	lguest_data.irq_enabled = X86_EFLAGS_IF;
-}
-/*:*/
-/*M:003 Note that we don't check for outstanding interrupts when we re-enable
- * them (or when we unmask an interrupt).  This seems to work for the moment,
- * since interrupts are rare and we'll just get the interrupt on the next timer
- * tick, but when we turn on CONFIG_NO_HZ, we should revisit this.  One way
- * would be to put the "irq_enabled" field in a page by itself, and have the
- * Host write-protect it when an interrupt comes in when irqs are disabled.
- * There will then be a page fault as soon as interrupts are re-enabled. :*/
-
-/*G:034
- * The Interrupt Descriptor Table (IDT).
- *
- * The IDT tells the processor what to do when an interrupt comes in.  Each
- * entry in the table is a 64-bit descriptor: this holds the privilege level,
- * address of the handler, and... well, who cares?  The Guest just asks the
- * Host to make the change anyway, because the Host controls the real IDT.
- */
-static void lguest_write_idt_entry(struct desc_struct *dt,
-				   int entrynum, u32 low, u32 high)
-{
-	/* Keep the local copy up to date. */
-	write_dt_entry(dt, entrynum, low, high);
-	/* Tell Host about this new entry. */
-	hcall(LHCALL_LOAD_IDT_ENTRY, entrynum, low, high);
-}
-
-/* Changing to a different IDT is very rare: we keep the IDT up-to-date every
- * time it is written, so we can simply loop through all entries and tell the
- * Host about them. */
-static void lguest_load_idt(const struct Xgt_desc_struct *desc)
-{
-	unsigned int i;
-	struct desc_struct *idt = (void *)desc->address;
-
-	for (i = 0; i < (desc->size+1)/8; i++)
-		hcall(LHCALL_LOAD_IDT_ENTRY, i, idt[i].a, idt[i].b);
-}
-
-/*
- * The Global Descriptor Table.
- *
- * The Intel architecture defines another table, called the Global Descriptor
- * Table (GDT).  You tell the CPU where it is (and its size) using the "lgdt"
- * instruction, and then several other instructions refer to entries in the
- * table.  There are three entries which the Switcher needs, so the Host simply
- * controls the entire thing and the Guest asks it to make changes using the
- * LOAD_GDT hypercall.
- *
- * This is the opposite of the IDT code where we have a LOAD_IDT_ENTRY
- * hypercall and use that repeatedly to load a new IDT.  I don't think it
- * really matters, but wouldn't it be nice if they were the same?
- */
-static void lguest_load_gdt(const struct Xgt_desc_struct *desc)
-{
-	BUG_ON((desc->size+1)/8 != GDT_ENTRIES);
-	hcall(LHCALL_LOAD_GDT, __pa(desc->address), GDT_ENTRIES, 0);
-}
-
-/* For a single GDT entry which changes, we do the lazy thing: alter our GDT,
- * then tell the Host to reload the entire thing.  This operation is so rare
- * that this naive implementation is reasonable. */
-static void lguest_write_gdt_entry(struct desc_struct *dt,
-				   int entrynum, u32 low, u32 high)
-{
-	write_dt_entry(dt, entrynum, low, high);
-	hcall(LHCALL_LOAD_GDT, __pa(dt), GDT_ENTRIES, 0);
-}
-
-/* OK, I lied.  There are three "thread local storage" GDT entries which change
- * on every context switch (these three entries are how glibc implements
- * __thread variables).  So we have a hypercall specifically for this case. */
-static void lguest_load_tls(struct thread_struct *t, unsigned int cpu)
-{
-	/* There's one problem which normal hardware doesn't have: the Host
-	 * can't handle us removing entries we're currently using.  So we clear
-	 * the GS register here: if it's needed it'll be reloaded anyway. */
-	loadsegment(gs, 0);
-	lazy_hcall(LHCALL_LOAD_TLS, __pa(&t->tls_array), cpu, 0);
-}
-
-/*G:038 That's enough excitement for now, back to ploughing through each of
- * the different pv_ops structures (we're about 1/3 of the way through).
- *
- * This is the Local Descriptor Table, another weird Intel thingy.  Linux only
- * uses this for some strange applications like Wine.  We don't do anything
- * here, so they'll get an informative and friendly Segmentation Fault. */
-static void lguest_set_ldt(const void *addr, unsigned entries)
-{
-}
-
-/* This loads a GDT entry into the "Task Register": that entry points to a
- * structure called the Task State Segment.  Some comments scattered though the
- * kernel code indicate that this used for task switching in ages past, along
- * with blood sacrifice and astrology.
- *
- * Now there's nothing interesting in here that we don't get told elsewhere.
- * But the native version uses the "ltr" instruction, which makes the Host
- * complain to the Guest about a Segmentation Fault and it'll oops.  So we
- * override the native version with a do-nothing version. */
-static void lguest_load_tr_desc(void)
-{
-}
-
-/* The "cpuid" instruction is a way of querying both the CPU identity
- * (manufacturer, model, etc) and its features.  It was introduced before the
- * Pentium in 1993 and keeps getting extended by both Intel and AMD.  As you
- * might imagine, after a decade and a half this treatment, it is now a giant
- * ball of hair.  Its entry in the current Intel manual runs to 28 pages.
- *
- * This instruction even it has its own Wikipedia entry.  The Wikipedia entry
- * has been translated into 4 languages.  I am not making this up!
- *
- * We could get funky here and identify ourselves as "GenuineLguest", but
- * instead we just use the real "cpuid" instruction.  Then I pretty much turned
- * off feature bits until the Guest booted.  (Don't say that: you'll damage
- * lguest sales!)  Shut up, inner voice!  (Hey, just pointing out that this is
- * hardly future proof.)  Noone's listening!  They don't like you anyway,
- * parenthetic weirdo!
- *
- * Replacing the cpuid so we can turn features off is great for the kernel, but
- * anyone (including userspace) can just use the raw "cpuid" instruction and
- * the Host won't even notice since it isn't privileged.  So we try not to get
- * too worked up about it. */
-static void lguest_cpuid(unsigned int *eax, unsigned int *ebx,
-			 unsigned int *ecx, unsigned int *edx)
-{
-	int function = *eax;
-
-	native_cpuid(eax, ebx, ecx, edx);
-	switch (function) {
-	case 1:	/* Basic feature request. */
-		/* We only allow kernel to see SSE3, CMPXCHG16B and SSSE3 */
-		*ecx &= 0x00002201;
-		/* SSE, SSE2, FXSR, MMX, CMOV, CMPXCHG8B, FPU. */
-		*edx &= 0x07808101;
-		/* The Host can do a nice optimization if it knows that the
-		 * kernel mappings (addresses above 0xC0000000 or whatever
-		 * PAGE_OFFSET is set to) haven't changed.  But Linux calls
-		 * flush_tlb_user() for both user and kernel mappings unless
-		 * the Page Global Enable (PGE) feature bit is set. */
-		*edx |= 0x00002000;
-		break;
-	case 0x80000000:
-		/* Futureproof this a little: if they ask how much extended
-		 * processor information there is, limit it to known fields. */
-		if (*eax > 0x80000008)
-			*eax = 0x80000008;
-		break;
-	}
-}
-
-/* Intel has four control registers, imaginatively named cr0, cr2, cr3 and cr4.
- * I assume there's a cr1, but it hasn't bothered us yet, so we'll not bother
- * it.  The Host needs to know when the Guest wants to change them, so we have
- * a whole series of functions like read_cr0() and write_cr0().
- *
- * We start with CR0.  CR0 allows you to turn on and off all kinds of basic
- * features, but Linux only really cares about one: the horrifically-named Task
- * Switched (TS) bit at bit 3 (ie. 8)
- *
- * What does the TS bit do?  Well, it causes the CPU to trap (interrupt 7) if
- * the floating point unit is used.  Which allows us to restore FPU state
- * lazily after a task switch, and Linux uses that gratefully, but wouldn't a
- * name like "FPUTRAP bit" be a little less cryptic?
- *
- * We store cr0 (and cr3) locally, because the Host never changes it.  The
- * Guest sometimes wants to read it and we'd prefer not to bother the Host
- * unnecessarily. */
-static unsigned long current_cr0, current_cr3;
-static void lguest_write_cr0(unsigned long val)
-{
-	/* 8 == TS bit. */
-	lazy_hcall(LHCALL_TS, val & 8, 0, 0);
-	current_cr0 = val;
-}
-
-static unsigned long lguest_read_cr0(void)
-{
-	return current_cr0;
-}
-
-/* Intel provided a special instruction to clear the TS bit for people too cool
- * to use write_cr0() to do it.  This "clts" instruction is faster, because all
- * the vowels have been optimized out. */
-static void lguest_clts(void)
-{
-	lazy_hcall(LHCALL_TS, 0, 0, 0);
-	current_cr0 &= ~8U;
-}
-
-/* CR2 is the virtual address of the last page fault, which the Guest only ever
- * reads.  The Host kindly writes this into our "struct lguest_data", so we
- * just read it out of there. */
-static unsigned long lguest_read_cr2(void)
-{
-	return lguest_data.cr2;
-}
-
-/* CR3 is the current toplevel pagetable page: the principle is the same as
- * cr0.  Keep a local copy, and tell the Host when it changes. */
-static void lguest_write_cr3(unsigned long cr3)
-{
-	lazy_hcall(LHCALL_NEW_PGTABLE, cr3, 0, 0);
-	current_cr3 = cr3;
-}
-
-static unsigned long lguest_read_cr3(void)
-{
-	return current_cr3;
-}
-
-/* CR4 is used to enable and disable PGE, but we don't care. */
-static unsigned long lguest_read_cr4(void)
-{
-	return 0;
-}
-
-static void lguest_write_cr4(unsigned long val)
-{
-}
-
-/*
- * Page Table Handling.
- *
- * Now would be a good time to take a rest and grab a coffee or similarly
- * relaxing stimulant.  The easy parts are behind us, and the trek gradually
- * winds uphill from here.
- *
- * Quick refresher: memory is divided into "pages" of 4096 bytes each.  The CPU
- * maps virtual addresses to physical addresses using "page tables".  We could
- * use one huge index of 1 million entries: each address is 4 bytes, so that's
- * 1024 pages just to hold the page tables.   But since most virtual addresses
- * are unused, we use a two level index which saves space.  The CR3 register
- * contains the physical address of the top level "page directory" page, which
- * contains physical addresses of up to 1024 second-level pages.  Each of these
- * second level pages contains up to 1024 physical addresses of actual pages,
- * or Page Table Entries (PTEs).
- *
- * Here's a diagram, where arrows indicate physical addresses:
- *
- * CR3 ---> +---------+
- *	    |  	   --------->+---------+
- *	    |	      |	     | PADDR1  |
- *	  Top-level   |	     | PADDR2  |
- *	  (PMD) page  |	     | 	       |
- *	    |	      |	   Lower-level |
- *	    |	      |	   (PTE) page  |
- *	    |	      |	     |	       |
- *	      ....    	     	 ....
- *
- * So to convert a virtual address to a physical address, we look up the top
- * level, which points us to the second level, which gives us the physical
- * address of that page.  If the top level entry was not present, or the second
- * level entry was not present, then the virtual address is invalid (we
- * say "the page was not mapped").
- *
- * Put another way, a 32-bit virtual address is divided up like so:
- *
- *  1 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
- * |<---- 10 bits ---->|<---- 10 bits ---->|<------ 12 bits ------>|
- *    Index into top     Index into second      Offset within page
- *  page directory page    pagetable page
- *
- * The kernel spends a lot of time changing both the top-level page directory
- * and lower-level pagetable pages.  The Guest doesn't know physical addresses,
- * so while it maintains these page tables exactly like normal, it also needs
- * to keep the Host informed whenever it makes a change: the Host will create
- * the real page tables based on the Guests'.
- */
-
-/* The Guest calls this to set a second-level entry (pte), ie. to map a page
- * into a process' address space.  We set the entry then tell the Host the
- * toplevel and address this corresponds to.  The Guest uses one pagetable per
- * process, so we need to tell the Host which one we're changing (mm->pgd). */
-static void lguest_set_pte_at(struct mm_struct *mm, unsigned long addr,
-			      pte_t *ptep, pte_t pteval)
-{
-	*ptep = pteval;
-	lazy_hcall(LHCALL_SET_PTE, __pa(mm->pgd), addr, pteval.pte_low);
-}
-
-/* The Guest calls this to set a top-level entry.  Again, we set the entry then
- * tell the Host which top-level page we changed, and the index of the entry we
- * changed. */
-static void lguest_set_pmd(pmd_t *pmdp, pmd_t pmdval)
-{
-	*pmdp = pmdval;
-	lazy_hcall(LHCALL_SET_PMD, __pa(pmdp)&PAGE_MASK,
-		   (__pa(pmdp)&(PAGE_SIZE-1))/4, 0);
-}
-
-/* There are a couple of legacy places where the kernel sets a PTE, but we
- * don't know the top level any more.  This is useless for us, since we don't
- * know which pagetable is changing or what address, so we just tell the Host
- * to forget all of them.  Fortunately, this is very rare.
- *
- * ... except in early boot when the kernel sets up the initial pagetables,
- * which makes booting astonishingly slow.  So we don't even tell the Host
- * anything changed until we've done the first page table switch.
- */
-static void lguest_set_pte(pte_t *ptep, pte_t pteval)
-{
-	*ptep = pteval;
-	/* Don't bother with hypercall before initial setup. */
-	if (current_cr3)
-		lazy_hcall(LHCALL_FLUSH_TLB, 1, 0, 0);
-}
-
-/* Unfortunately for Lguest, the pv_mmu_ops for page tables were based on
- * native page table operations.  On native hardware you can set a new page
- * table entry whenever you want, but if you want to remove one you have to do
- * a TLB flush (a TLB is a little cache of page table entries kept by the CPU).
- *
- * So the lguest_set_pte_at() and lguest_set_pmd() functions above are only
- * called when a valid entry is written, not when it's removed (ie. marked not
- * present).  Instead, this is where we come when the Guest wants to remove a
- * page table entry: we tell the Host to set that entry to 0 (ie. the present
- * bit is zero). */
-static void lguest_flush_tlb_single(unsigned long addr)
-{
-	/* Simply set it to zero: if it was not, it will fault back in. */
-	lazy_hcall(LHCALL_SET_PTE, current_cr3, addr, 0);
-}
-
-/* This is what happens after the Guest has removed a large number of entries.
- * This tells the Host that any of the page table entries for userspace might
- * have changed, ie. virtual addresses below PAGE_OFFSET. */
-static void lguest_flush_tlb_user(void)
-{
-	lazy_hcall(LHCALL_FLUSH_TLB, 0, 0, 0);
-}
-
-/* This is called when the kernel page tables have changed.  That's not very
- * common (unless the Guest is using highmem, which makes the Guest extremely
- * slow), so it's worth separating this from the user flushing above. */
-static void lguest_flush_tlb_kernel(void)
-{
-	lazy_hcall(LHCALL_FLUSH_TLB, 1, 0, 0);
-}
-
-/*
- * The Unadvanced Programmable Interrupt Controller.
- *
- * This is an attempt to implement the simplest possible interrupt controller.
- * I spent some time looking though routines like set_irq_chip_and_handler,
- * set_irq_chip_and_handler_name, set_irq_chip_data and set_phasers_to_stun and
- * I *think* this is as simple as it gets.
- *
- * We can tell the Host what interrupts we want blocked ready for using the
- * lguest_data.interrupts bitmap, so disabling (aka "masking") them is as
- * simple as setting a bit.  We don't actually "ack" interrupts as such, we
- * just mask and unmask them.  I wonder if we should be cleverer?
- */
-static void disable_lguest_irq(unsigned int irq)
-{
-	set_bit(irq, lguest_data.blocked_interrupts);
-}
-
-static void enable_lguest_irq(unsigned int irq)
-{
-	clear_bit(irq, lguest_data.blocked_interrupts);
-}
-
-/* This structure describes the lguest IRQ controller. */
-static struct irq_chip lguest_irq_controller = {
-	.name		= "lguest",
-	.mask		= disable_lguest_irq,
-	.mask_ack	= disable_lguest_irq,
-	.unmask		= enable_lguest_irq,
-};
-
-/* This sets up the Interrupt Descriptor Table (IDT) entry for each hardware
- * interrupt (except 128, which is used for system calls), and then tells the
- * Linux infrastructure that each interrupt is controlled by our level-based
- * lguest interrupt controller. */
-static void __init lguest_init_IRQ(void)
-{
-	unsigned int i;
-
-	for (i = 0; i < LGUEST_IRQS; i++) {
-		int vector = FIRST_EXTERNAL_VECTOR + i;
-		if (vector != SYSCALL_VECTOR) {
-			set_intr_gate(vector, interrupt[i]);
-			set_irq_chip_and_handler(i, &lguest_irq_controller,
-						 handle_level_irq);
-		}
-	}
-	/* This call is required to set up for 4k stacks, where we have
-	 * separate stacks for hard and soft interrupts. */
-	irq_ctx_init(smp_processor_id());
-}
-
-/*
- * Time.
- *
- * It would be far better for everyone if the Guest had its own clock, but
- * until then the Host gives us the time on every interrupt.
- */
-static unsigned long lguest_get_wallclock(void)
-{
-	return lguest_data.time.tv_sec;
-}
-
-static cycle_t lguest_clock_read(void)
-{
-	unsigned long sec, nsec;
-
-	/* If the Host tells the TSC speed, we can trust that. */
-	if (lguest_data.tsc_khz)
-		return native_read_tsc();
-
-	/* If we can't use the TSC, we read the time value written by the Host.
-	 * Since it's in two parts (seconds and nanoseconds), we risk reading
-	 * it just as it's changing from 99 & 0.999999999 to 100 and 0, and
-	 * getting 99 and 0.  As Linux tends to come apart under the stress of
-	 * time travel, we must be careful: */
-	do {
-		/* First we read the seconds part. */
-		sec = lguest_data.time.tv_sec;
-		/* This read memory barrier tells the compiler and the CPU that
-		 * this can't be reordered: we have to complete the above
-		 * before going on. */
-		rmb();
-		/* Now we read the nanoseconds part. */
-		nsec = lguest_data.time.tv_nsec;
-		/* Make sure we've done that. */
-		rmb();
-		/* Now if the seconds part has changed, try again. */
-	} while (unlikely(lguest_data.time.tv_sec != sec));
-
-	/* Our non-TSC clock is in real nanoseconds. */
-	return sec*1000000000ULL + nsec;
-}
-
-/* This is what we tell the kernel is our clocksource.  */
-static struct clocksource lguest_clock = {
-	.name		= "lguest",
-	.rating		= 400,
-	.read		= lguest_clock_read,
-	.mask		= CLOCKSOURCE_MASK(64),
-	.mult		= 1 << 22,
-	.shift		= 22,
-	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
-};
-
-/* The "scheduler clock" is just our real clock, adjusted to start at zero */
-static unsigned long long lguest_sched_clock(void)
-{
-	return cyc2ns(&lguest_clock, lguest_clock_read() - clock_base);
-}
-
-/* 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();
-	case CLOCK_EVT_MODE_RESUME:
-		break;
-	}
-}
-
-/* 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)
-{
-	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);
-}
-
-/* At some point in the boot process, we get asked to set up our timing
- * infrastructure.  The kernel doesn't expect timer interrupts before this, but
- * we cleverly initialized the "blocked_interrupts" field of "struct
- * lguest_data" so that timer interrupts were blocked until now. */
-static void lguest_time_init(void)
-{
-	/* Set up the timer interrupt (0) to go to our simple timer routine */
-	set_irq_handler(0, lguest_time_irq);
-
-	/* Our clock structure look like arch/i386/kernel/tsc.c if we can use
-	 * the TSC, otherwise it's a dumb nanosecond-resolution clock.  Either
-	 * way, the "rating" is initialized so high that it's always chosen
-	 * over any other clocksource. */
-	if (lguest_data.tsc_khz)
-		lguest_clock.mult = clocksource_khz2mult(lguest_data.tsc_khz,
-							 lguest_clock.shift);
-	clock_base = lguest_clock_read();
-	clocksource_register(&lguest_clock);
-
-	/* Now we've set up our clock, we can use it as the scheduler clock */
-	pv_time_ops.sched_clock = lguest_sched_clock;
-
-	/* We can't set cpumask in the initializer: damn C limitations!  Set it
-	 * here and register our timer device. */
-	lguest_clockevent.cpumask = cpumask_of_cpu(0);
-	clockevents_register_device(&lguest_clockevent);
-
-	/* Finally, we unblock the timer interrupt. */
-	enable_lguest_irq(0);
-}
-
-/*
- * Miscellaneous bits and pieces.
- *
- * Here is an oddball collection of functions which the Guest needs for things
- * to work.  They're pretty simple.
- */
-
-/* The Guest needs to tell the host what stack it expects traps to use.  For
- * native hardware, this is part of the Task State Segment mentioned above in
- * lguest_load_tr_desc(), but to help hypervisors there's this special call.
- *
- * We tell the Host the segment we want to use (__KERNEL_DS is the kernel data
- * segment), the privilege level (we're privilege level 1, the Host is 0 and
- * will not tolerate us trying to use that), the stack pointer, and the number
- * of pages in the stack. */
-static void lguest_load_esp0(struct tss_struct *tss,
-				     struct thread_struct *thread)
-{
-	lazy_hcall(LHCALL_SET_STACK, __KERNEL_DS|0x1, thread->esp0,
-		   THREAD_SIZE/PAGE_SIZE);
-}
-
-/* Let's just say, I wouldn't do debugging under a Guest. */
-static void lguest_set_debugreg(int regno, unsigned long value)
-{
-	/* FIXME: Implement */
-}
-
-/* There are times when the kernel wants to make sure that no memory writes are
- * caught in the cache (that they've all reached real hardware devices).  This
- * doesn't matter for the Guest which has virtual hardware.
- *
- * On the Pentium 4 and above, cpuid() indicates that the Cache Line Flush
- * (clflush) instruction is available and the kernel uses that.  Otherwise, it
- * uses the older "Write Back and Invalidate Cache" (wbinvd) instruction.
- * Unlike clflush, wbinvd can only be run at privilege level 0.  So we can
- * ignore clflush, but replace wbinvd.
- */
-static void lguest_wbinvd(void)
-{
-}
-
-/* If the Guest expects to have an Advanced Programmable Interrupt Controller,
- * we play dumb by ignoring writes and returning 0 for reads.  So it's no
- * longer Programmable nor Controlling anything, and I don't think 8 lines of
- * code qualifies for Advanced.  It will also never interrupt anything.  It
- * does, however, allow us to get through the Linux boot code. */
-#ifdef CONFIG_X86_LOCAL_APIC
-static void lguest_apic_write(unsigned long reg, unsigned long v)
-{
-}
-
-static unsigned long lguest_apic_read(unsigned long reg)
-{
-	return 0;
-}
-#endif
-
-/* STOP!  Until an interrupt comes in. */
-static void lguest_safe_halt(void)
-{
-	hcall(LHCALL_HALT, 0, 0, 0);
-}
-
-/* Perhaps CRASH isn't the best name for this hypercall, but we use it to get a
- * message out when we're crashing as well as elegant termination like powering
- * off.
- *
- * Note that the Host always prefers that the Guest speak in physical addresses
- * rather than virtual addresses, so we use __pa() here. */
-static void lguest_power_off(void)
-{
-	hcall(LHCALL_CRASH, __pa("Power down"), 0, 0);
-}
-
-/*
- * Panicing.
- *
- * Don't.  But if you did, this is what happens.
- */
-static int lguest_panic(struct notifier_block *nb, unsigned long l, void *p)
-{
-	hcall(LHCALL_CRASH, __pa(p), 0, 0);
-	/* The hcall won't return, but to keep gcc happy, we're "done". */
-	return NOTIFY_DONE;
-}
-
-static struct notifier_block paniced = {
-	.notifier_call = lguest_panic
-};
-
-/* Setting up memory is fairly easy. */
-static __init char *lguest_memory_setup(void)
-{
-	/* We do this here and not earlier because lockcheck barfs if we do it
-	 * before start_kernel() */
-	atomic_notifier_chain_register(&panic_notifier_list, &paniced);
-
-	/* The Linux bootloader header contains an "e820" memory map: the
-	 * Launcher populated the first entry with our memory limit. */
-	add_memory_region(boot_params.e820_map[0].addr,
-			  boot_params.e820_map[0].size,
-			  boot_params.e820_map[0].type);
-
-	/* This string is for the boot messages. */
-	return "LGUEST";
-}
-
-/*G:050
- * Patching (Powerfully Placating Performance Pedants)
- *
- * We have already seen that pv_ops structures let us replace simple
- * native instructions with calls to the appropriate back end all throughout
- * the kernel.  This allows the same kernel to run as a Guest and as a native
- * kernel, but it's slow because of all the indirect branches.
- *
- * Remember that David Wheeler quote about "Any problem in computer science can
- * be solved with another layer of indirection"?  The rest of that quote is
- * "... But that usually will create another problem."  This is the first of
- * those problems.
- *
- * Our current solution is to allow the paravirt back end to optionally patch
- * over the indirect calls to replace them with something more efficient.  We
- * patch the four most commonly called functions: disable interrupts, enable
- * interrupts, restore interrupts and save interrupts.  We usually have 10
- * bytes to patch into: the Guest versions of these operations are small enough
- * that we can fit comfortably.
- *
- * First we need assembly templates of each of the patchable Guest operations,
- * and these are in lguest_asm.S. */
-
-/*G:060 We construct a table from the assembler templates: */
-static const struct lguest_insns
-{
-	const char *start, *end;
-} lguest_insns[] = {
-	[PARAVIRT_PATCH(pv_irq_ops.irq_disable)] = { lgstart_cli, lgend_cli },
-	[PARAVIRT_PATCH(pv_irq_ops.irq_enable)] = { lgstart_sti, lgend_sti },
-	[PARAVIRT_PATCH(pv_irq_ops.restore_fl)] = { lgstart_popf, lgend_popf },
-	[PARAVIRT_PATCH(pv_irq_ops.save_fl)] = { lgstart_pushf, lgend_pushf },
-};
-
-/* Now our patch routine is fairly simple (based on the native one in
- * paravirt.c).  If we have a replacement, we copy it in and return how much of
- * the available space we used. */
-static unsigned lguest_patch(u8 type, u16 clobber, void *ibuf,
-			     unsigned long addr, unsigned len)
-{
-	unsigned int insn_len;
-
-	/* Don't do anything special if we don't have a replacement */
-	if (type >= ARRAY_SIZE(lguest_insns) || !lguest_insns[type].start)
-		return paravirt_patch_default(type, clobber, ibuf, addr, len);
-
-	insn_len = lguest_insns[type].end - lguest_insns[type].start;
-
-	/* Similarly if we can't fit replacement (shouldn't happen, but let's
-	 * be thorough). */
-	if (len < insn_len)
-		return paravirt_patch_default(type, clobber, ibuf, addr, len);
-
-	/* Copy in our instructions. */
-	memcpy(ibuf, lguest_insns[type].start, insn_len);
-	return insn_len;
-}
-
-/*G:030 Once we get to lguest_init(), we know we're a Guest.  The pv_ops
- * structures in the kernel provide points for (almost) every routine we have
- * to override to avoid privileged instructions. */
-__init void lguest_init(void *boot)
-{
-	/* Copy boot parameters first: the Launcher put the physical location
-	 * in %esi, and head.S converted that to a virtual address and handed
-	 * it to us.  We use "__memcpy" because "memcpy" sometimes tries to do
-	 * tricky things to go faster, and we're not ready for that. */
-	__memcpy(&boot_params, boot, PARAM_SIZE);
-	/* The boot parameters also tell us where the command-line is: save
-	 * that, too. */
-	__memcpy(boot_command_line, __va(boot_params.hdr.cmd_line_ptr),
-	       COMMAND_LINE_SIZE);
-
-	/* We're under lguest, paravirt is enabled, and we're running at
-	 * privilege level 1, not 0 as normal. */
-	pv_info.name = "lguest";
-	pv_info.paravirt_enabled = 1;
-	pv_info.kernel_rpl = 1;
-
-	/* We set up all the lguest overrides for sensitive operations.  These
-	 * are detailed with the operations themselves. */
-
-	/* interrupt-related operations */
-	pv_irq_ops.init_IRQ = lguest_init_IRQ;
-	pv_irq_ops.save_fl = save_fl;
-	pv_irq_ops.restore_fl = restore_fl;
-	pv_irq_ops.irq_disable = irq_disable;
-	pv_irq_ops.irq_enable = irq_enable;
-	pv_irq_ops.safe_halt = lguest_safe_halt;
-
-	/* init-time operations */
-	pv_init_ops.memory_setup = lguest_memory_setup;
-	pv_init_ops.patch = lguest_patch;
-
-	/* Intercepts of various cpu instructions */
-	pv_cpu_ops.load_gdt = lguest_load_gdt;
-	pv_cpu_ops.cpuid = lguest_cpuid;
-	pv_cpu_ops.load_idt = lguest_load_idt;
-	pv_cpu_ops.iret = lguest_iret;
-	pv_cpu_ops.load_esp0 = lguest_load_esp0;
-	pv_cpu_ops.load_tr_desc = lguest_load_tr_desc;
-	pv_cpu_ops.set_ldt = lguest_set_ldt;
-	pv_cpu_ops.load_tls = lguest_load_tls;
-	pv_cpu_ops.set_debugreg = lguest_set_debugreg;
-	pv_cpu_ops.clts = lguest_clts;
-	pv_cpu_ops.read_cr0 = lguest_read_cr0;
-	pv_cpu_ops.write_cr0 = lguest_write_cr0;
-	pv_cpu_ops.read_cr4 = lguest_read_cr4;
-	pv_cpu_ops.write_cr4 = lguest_write_cr4;
-	pv_cpu_ops.write_gdt_entry = lguest_write_gdt_entry;
-	pv_cpu_ops.write_idt_entry = lguest_write_idt_entry;
-	pv_cpu_ops.wbinvd = lguest_wbinvd;
-	pv_cpu_ops.lazy_mode.enter = paravirt_enter_lazy_cpu;
-	pv_cpu_ops.lazy_mode.leave = lguest_leave_lazy_mode;
-
-	/* pagetable management */
-	pv_mmu_ops.write_cr3 = lguest_write_cr3;
-	pv_mmu_ops.flush_tlb_user = lguest_flush_tlb_user;
-	pv_mmu_ops.flush_tlb_single = lguest_flush_tlb_single;
-	pv_mmu_ops.flush_tlb_kernel = lguest_flush_tlb_kernel;
-	pv_mmu_ops.set_pte = lguest_set_pte;
-	pv_mmu_ops.set_pte_at = lguest_set_pte_at;
-	pv_mmu_ops.set_pmd = lguest_set_pmd;
-	pv_mmu_ops.read_cr2 = lguest_read_cr2;
-	pv_mmu_ops.read_cr3 = lguest_read_cr3;
-	pv_mmu_ops.lazy_mode.enter = paravirt_enter_lazy_mmu;
-	pv_mmu_ops.lazy_mode.leave = lguest_leave_lazy_mode;
-
-#ifdef CONFIG_X86_LOCAL_APIC
-	/* apic read/write intercepts */
-	pv_apic_ops.apic_write = lguest_apic_write;
-	pv_apic_ops.apic_write_atomic = lguest_apic_write;
-	pv_apic_ops.apic_read = lguest_apic_read;
-#endif
-
-	/* time operations */
-	pv_time_ops.get_wallclock = lguest_get_wallclock;
-	pv_time_ops.time_init = lguest_time_init;
-
-	/* Now is a good time to look at the implementations of these functions
-	 * before returning to the rest of lguest_init(). */
-
-	/*G:070 Now we've seen all the paravirt_ops, we return to
-	 * lguest_init() where the rest of the fairly chaotic boot setup
-	 * occurs.
-	 *
-	 * The Host expects our first hypercall to tell it where our "struct
-	 * lguest_data" is, so we do that first. */
-	hcall(LHCALL_LGUEST_INIT, __pa(&lguest_data), 0, 0);
-
-	/* The native boot code sets up initial page tables immediately after
-	 * the kernel itself, and sets init_pg_tables_end so they're not
-	 * clobbered.  The Launcher places our initial pagetables somewhere at
-	 * the top of our physical memory, so we don't need extra space: set
-	 * init_pg_tables_end to the end of the kernel. */
-	init_pg_tables_end = __pa(pg0);
-
-	/* Load the %fs segment register (the per-cpu segment register) with
-	 * the normal data segment to get through booting. */
-	asm volatile ("mov %0, %%fs" : : "r" (__KERNEL_DS) : "memory");
-
-	/* Clear the part of the kernel data which is expected to be zero.
-	 * Normally it will be anyway, but if we're loading from a bzImage with
-	 * CONFIG_RELOCATALE=y, the relocations will be sitting here. */
-	memset(__bss_start, 0, __bss_stop - __bss_start);
-
-	/* The Host uses the top of the Guest's virtual address space for the
-	 * Host<->Guest Switcher, and it tells us how much it needs in
-	 * lguest_data.reserve_mem, set up on the LGUEST_INIT hypercall. */
-	reserve_top_address(lguest_data.reserve_mem);
-
-	/* If we don't initialize the lock dependency checker now, it crashes
-	 * paravirt_disable_iospace. */
-	lockdep_init();
-
-	/* The IDE code spends about 3 seconds probing for disks: if we reserve
-	 * all the I/O ports up front it can't get them and so doesn't probe.
-	 * Other device drivers are similar (but less severe).  This cuts the
-	 * kernel boot time on my machine from 4.1 seconds to 0.45 seconds. */
-	paravirt_disable_iospace();
-
-	/* This is messy CPU setup stuff which the native boot code does before
-	 * start_kernel, so we have to do, too: */
-	cpu_detect(&new_cpu_data);
-	/* head.S usually sets up the first capability word, so do it here. */
-	new_cpu_data.x86_capability[0] = cpuid_edx(1);
-
-	/* Math is always hard! */
-	new_cpu_data.hard_math = 1;
-
-#ifdef CONFIG_X86_MCE
-	mce_disabled = 1;
-#endif
-#ifdef CONFIG_ACPI
-	acpi_disabled = 1;
-	acpi_ht = 0;
-#endif
-
-	/* We set the perferred console to "hvc".  This is the "hypervisor
-	 * virtual console" driver written by the PowerPC people, which we also
-	 * adapted for lguest's use. */
-	add_preferred_console("hvc", 0, NULL);
-
-	/* Last of all, we set the power management poweroff hook to point to
-	 * the Guest routine to power off. */
-	pm_power_off = lguest_power_off;
-
-	/* Now we're set up, call start_kernel() in init/main.c and we proceed
-	 * to boot as normal.  It never returns. */
-	start_kernel();
-}
-/*
- * This marks the end of stage II of our journey, The Guest.
- *
- * It is now time for us to explore the nooks and crannies of the three Guest
- * devices and complete our understanding of the Guest in "make Drivers".
- */
diff --git a/drivers/lguest/lguest_asm.S b/drivers/lguest/lguest_asm.S
deleted file mode 100644
index 1ddcd5cd20f6..000000000000
--- a/drivers/lguest/lguest_asm.S
+++ /dev/null
@@ -1,93 +0,0 @@
-#include <linux/linkage.h>
-#include <linux/lguest.h>
-#include <asm/asm-offsets.h>
-#include <asm/thread_info.h>
-#include <asm/processor-flags.h>
-
-/*G:020 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.  The normal boot code uses %esi for the
- * boot header, so we do too.  We convert it to a virtual address by adding
- * PAGE_OFFSET, and hand it to lguest_init() as its argument (ie. %eax).
- *
- * The .section line puts this code in .init.text so it will be discarded after
- * boot. */
-.section .init.text, "ax", @progbits
-.ascii "GenuineLguest"
-	/* Set up initial stack. */
- 	movl $(init_thread_union+THREAD_SIZE),%esp
-	movl %esi, %eax
-	addl $__PAGE_OFFSET, %eax
-	jmp lguest_init
-
-/*G:055 We create a macro which puts the assembler code between lgstart_ and
- * lgend_ markers.  These templates are put in the .text section: they can't be
- * discarded after boot as we may need to patch modules, too. */
-.text
-#define LGUEST_PATCH(name, insns...)			\
-	lgstart_##name:	insns; lgend_##name:;		\
-	.globl lgstart_##name; .globl lgend_##name
-
-LGUEST_PATCH(cli, movl $0, lguest_data+LGUEST_DATA_irq_enabled)
-LGUEST_PATCH(sti, movl $X86_EFLAGS_IF, lguest_data+LGUEST_DATA_irq_enabled)
-LGUEST_PATCH(popf, movl %eax, lguest_data+LGUEST_DATA_irq_enabled)
-LGUEST_PATCH(pushf, movl lguest_data+LGUEST_DATA_irq_enabled, %eax)
-/*:*/
-
-/* These demark the EIP range where host should never deliver interrupts. */
-.global lguest_noirq_start
-.global lguest_noirq_end
-
-/*M:004 When the Host reflects a trap or injects an interrupt into the Guest,
- * it sets the eflags interrupt bit on the stack based on
- * lguest_data.irq_enabled, so the Guest iret logic does the right thing when
- * restoring it.  However, when the Host sets the Guest up for direct traps,
- * such as system calls, the processor is the one to push eflags onto the
- * stack, and the interrupt bit will be 1 (in reality, interrupts are always
- * enabled in the Guest).
- *
- * This turns out to be harmless: the only trap which should happen under Linux
- * with interrupts disabled is Page Fault (due to our lazy mapping of vmalloc
- * regions), which has to be reflected through the Host anyway.  If another
- * trap *does* go off when interrupts are disabled, the Guest will panic, and
- * we'll never get to this iret! :*/
-
-/*G:045 There is one final paravirt_op that the Guest implements, and glancing
- * at it you can see why I left it to last.  It's *cool*!  It's in *assembler*!
- *
- * The "iret" instruction is used to return from an interrupt or trap.  The
- * stack looks like this:
- *   old address
- *   old code segment & privilege level
- *   old processor flags ("eflags")
- *
- * The "iret" instruction pops those values off the stack and restores them all
- * at once.  The only problem is that eflags includes the Interrupt Flag which
- * the Guest can't change: the CPU will simply ignore it when we do an "iret".
- * So we have to copy eflags from the stack to lguest_data.irq_enabled before
- * we do the "iret".
- *
- * There are two problems with this: firstly, we need to use a register to do
- * the copy and secondly, the whole thing needs to be atomic.  The first
- * problem is easy to solve: push %eax on the stack so we can use it, and then
- * restore it at the end just before the real "iret".
- *
- * The second is harder: copying eflags to lguest_data.irq_enabled will turn
- * interrupts on before we're finished, so we could be interrupted before we
- * return to userspace or wherever.  Our solution to this is to surround the
- * code with lguest_noirq_start: and lguest_noirq_end: labels.  We tell the
- * Host that it is *never* to interrupt us there, even if interrupts seem to be
- * enabled. */
-ENTRY(lguest_iret)
-	pushl	%eax
-	movl	12(%esp), %eax
-lguest_noirq_start:
-	/* Note the %ss: segment prefix here.  Normal data accesses use the
-	 * "ds" segment, but that will have already been restored for whatever
-	 * we're returning to (such as userspace): we can't trust it.  The %ss:
-	 * prefix makes sure we use the stack segment, which is still valid. */
-	movl	%eax,%ss:lguest_data+LGUEST_DATA_irq_enabled
-	popl	%eax
-	iret
-lguest_noirq_end: