Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 asm updates from Ingo Molnar:

 - Introduce the ORC unwinder, which can be enabled via
   CONFIG_ORC_UNWINDER=y.

   The ORC unwinder is a lightweight, Linux kernel specific debuginfo
   implementation, which aims to be DWARF done right for unwinding.
   Objtool is used to generate the ORC unwinder tables during build, so
   the data format is flexible and kernel internal: there's no
   dependency on debuginfo created by an external toolchain.

   The ORC unwinder is almost two orders of magnitude faster than the
   (out of tree) DWARF unwinder - which is important for perf call graph
   profiling. It is also significantly simpler and is coded defensively:
   there has not been a single ORC related kernel crash so far, even
   with early versions. (knock on wood!)

   But the main advantage is that enabling the ORC unwinder allows
   CONFIG_FRAME_POINTERS to be turned off - which speeds up the kernel
   measurably:

   With frame pointers disabled, GCC does not have to add frame pointer
   instrumentation code to every function in the kernel. The kernel's
   .text size decreases by about 3.2%, resulting in better cache
   utilization and fewer instructions executed, resulting in a broad
   kernel-wide speedup. Average speedup of system calls should be
   roughly in the 1-3% range - measurements by Mel Gorman [1] have shown
   a speedup of 5-10% for some function execution intense workloads.

   The main cost of the unwinder is that the unwinder data has to be
   stored in RAM: the memory cost is 2-4MB of RAM, depending on kernel
   config - which is a modest cost on modern x86 systems.

   Given how young the ORC unwinder code is it's not enabled by default
   - but given the performance advantages the plan is to eventually make
   it the default unwinder on x86.

   See Documentation/x86/orc-unwinder.txt for more details.

 - Remove lguest support: its intended role was that of a temporary
   proof of concept for virtualization, plus its removal will enable the
   reduction (removal) of the paravirt API as well, so Rusty agreed to
   its removal. (Juergen Gross)

 - Clean up and fix FSGS related functionality (Andy Lutomirski)

 - Clean up IO access APIs (Andy Shevchenko)

 - Enhance the symbol namespace (Jiri Slaby)

* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (47 commits)
  objtool: Handle GCC stack pointer adjustment bug
  x86/entry/64: Use ENTRY() instead of ALIGN+GLOBAL for stub32_clone()
  x86/fpu/math-emu: Add ENDPROC to functions
  x86/boot/64: Extract efi_pe_entry() from startup_64()
  x86/boot/32: Extract efi_pe_entry() from startup_32()
  x86/lguest: Remove lguest support
  x86/paravirt/xen: Remove xen_patch()
  objtool: Fix objtool fallthrough detection with function padding
  x86/xen/64: Fix the reported SS and CS in SYSCALL
  objtool: Track DRAP separately from callee-saved registers
  objtool: Fix validate_branch() return codes
  x86: Clarify/fix no-op barriers for text_poke_bp()
  x86/switch_to/64: Rewrite FS/GS switching yet again to fix AMD CPUs
  selftests/x86/fsgsbase: Test selectors 1, 2, and 3
  x86/fsgsbase/64: Report FSBASE and GSBASE correctly in core dumps
  x86/fsgsbase/64: Fully initialize FS and GS state in start_thread_common
  x86/asm: Fix UNWIND_HINT_REGS macro for older binutils
  x86/asm/32: Fix regs_get_register() on segment registers
  x86/xen/64: Rearrange the SYSCALL entries
  x86/asm/32: Remove a bunch of '& 0xffff' from pt_regs segment reads
  ...

1 files changed, 0 insertions, 706 deletions

diff --git a/drivers/lguest/interrupts_and_traps.c b/drivers/lguest/interrupts_and_traps.c
deleted file mode 100644
index 67392b6ab845..000000000000
--- a/drivers/lguest/interrupts_and_traps.c
+++ /dev/null
@@ -1,706 +0,0 @@
-/*P:800
- * Interrupts (traps) are complicated enough to earn their own file.
- * There are three classes of interrupts:
- *
- * 1) Real hardware interrupts which occur while we're running the Guest,
- * 2) Interrupts for virtual devices attached to the Guest, and
- * 3) Traps and faults from the Guest.
- *
- * Real hardware interrupts must be delivered to the Host, not the Guest.
- * Virtual interrupts must be delivered to the Guest, but we make them look
- * just like real hardware would deliver them.  Traps from the Guest can be set
- * up to go directly back into the Guest, but sometimes the Host wants to see
- * them first, so we also have a way of "reflecting" them into the Guest as if
- * they had been delivered to it directly.
-:*/
-#include <linux/uaccess.h>
-#include <linux/interrupt.h>
-#include <linux/module.h>
-#include <linux/sched.h>
-#include "lg.h"
-
-/* Allow Guests to use a non-128 (ie. non-Linux) syscall trap. */
-static unsigned int syscall_vector = IA32_SYSCALL_VECTOR;
-module_param(syscall_vector, uint, 0444);
-
-/* The address of the interrupt handler is split into two bits: */
-static unsigned long idt_address(u32 lo, u32 hi)
-{
-	return (lo & 0x0000FFFF) | (hi & 0xFFFF0000);
-}
-
-/*
- * The "type" of the interrupt handler is a 4 bit field: we only support a
- * couple of types.
- */
-static int idt_type(u32 lo, u32 hi)
-{
-	return (hi >> 8) & 0xF;
-}
-
-/* An IDT entry can't be used unless the "present" bit is set. */
-static bool idt_present(u32 lo, u32 hi)
-{
-	return (hi & 0x8000);
-}
-
-/*
- * We need a helper to "push" a value onto the Guest's stack, since that's a
- * big part of what delivering an interrupt does.
- */
-static void push_guest_stack(struct lg_cpu *cpu, unsigned long *gstack, u32 val)
-{
-	/* Stack grows upwards: move stack then write value. */
-	*gstack -= 4;
-	lgwrite(cpu, *gstack, u32, val);
-}
-
-/*H:210
- * The push_guest_interrupt_stack() routine saves Guest state on the stack for
- * an interrupt or trap.  The mechanics of delivering traps and interrupts to
- * the Guest are the same, except some traps have an "error code" which gets
- * pushed onto the stack as well: the caller tells us if this is one.
- *
- * We set up the stack just like the CPU does for a real interrupt, so it's
- * identical for the Guest (and the standard "iret" instruction will undo
- * it).
- */
-static void push_guest_interrupt_stack(struct lg_cpu *cpu, bool has_err)
-{
-	unsigned long gstack, origstack;
-	u32 eflags, ss, irq_enable;
-	unsigned long virtstack;
-
-	/*
-	 * There are two cases for interrupts: one where the Guest is already
-	 * in the kernel, and a more complex one where the Guest is in
-	 * userspace.  We check the privilege level to find out.
-	 */
-	if ((cpu->regs->ss&0x3) != GUEST_PL) {
-		/*
-		 * The Guest told us their kernel stack with the SET_STACK
-		 * hypercall: both the virtual address and the segment.
-		 */
-		virtstack = cpu->esp1;
-		ss = cpu->ss1;
-
-		origstack = gstack = guest_pa(cpu, virtstack);
-		/*
-		 * We push the old stack segment and pointer onto the new
-		 * stack: when the Guest does an "iret" back from the interrupt
-		 * handler the CPU will notice they're dropping privilege
-		 * levels and expect these here.
-		 */
-		push_guest_stack(cpu, &gstack, cpu->regs->ss);
-		push_guest_stack(cpu, &gstack, cpu->regs->esp);
-	} else {
-		/* We're staying on the same Guest (kernel) stack. */
-		virtstack = cpu->regs->esp;
-		ss = cpu->regs->ss;
-
-		origstack = gstack = guest_pa(cpu, virtstack);
-	}
-
-	/*
-	 * Remember that we never let the Guest actually disable interrupts, so
-	 * the "Interrupt Flag" bit is always set.  We copy that bit from the
-	 * Guest's "irq_enabled" field into the eflags word: we saw the Guest
-	 * copy it back in "lguest_iret".
-	 */
-	eflags = cpu->regs->eflags;
-	if (get_user(irq_enable, &cpu->lg->lguest_data->irq_enabled) == 0
-	    && !(irq_enable & X86_EFLAGS_IF))
-		eflags &= ~X86_EFLAGS_IF;
-
-	/*
-	 * An interrupt is expected to push three things on the stack: the old
-	 * "eflags" word, the old code segment, and the old instruction
-	 * pointer.
-	 */
-	push_guest_stack(cpu, &gstack, eflags);
-	push_guest_stack(cpu, &gstack, cpu->regs->cs);
-	push_guest_stack(cpu, &gstack, cpu->regs->eip);
-
-	/* For the six traps which supply an error code, we push that, too. */
-	if (has_err)
-		push_guest_stack(cpu, &gstack, cpu->regs->errcode);
-
-	/* Adjust the stack pointer and stack segment. */
-	cpu->regs->ss = ss;
-	cpu->regs->esp = virtstack + (gstack - origstack);
-}
-
-/*
- * This actually makes the Guest start executing the given interrupt/trap
- * handler.
- *
- * "lo" and "hi" are the two parts of the Interrupt Descriptor Table for this
- * interrupt or trap.  It's split into two parts for traditional reasons: gcc
- * on i386 used to be frightened by 64 bit numbers.
- */
-static void guest_run_interrupt(struct lg_cpu *cpu, u32 lo, u32 hi)
-{
-	/* If we're already in the kernel, we don't change stacks. */
-	if ((cpu->regs->ss&0x3) != GUEST_PL)
-		cpu->regs->ss = cpu->esp1;
-
-	/*
-	 * Set the code segment and the address to execute.
-	 */
-	cpu->regs->cs = (__KERNEL_CS|GUEST_PL);
-	cpu->regs->eip = idt_address(lo, hi);
-
-	/*
-	 * Trapping always clears these flags:
-	 * TF: Trap flag
-	 * VM: Virtual 8086 mode
-	 * RF: Resume
-	 * NT: Nested task.
-	 */
-	cpu->regs->eflags &=
-		~(X86_EFLAGS_TF|X86_EFLAGS_VM|X86_EFLAGS_RF|X86_EFLAGS_NT);
-
-	/*
-	 * There are two kinds of interrupt handlers: 0xE is an "interrupt
-	 * gate" which expects interrupts to be disabled on entry.
-	 */
-	if (idt_type(lo, hi) == 0xE)
-		if (put_user(0, &cpu->lg->lguest_data->irq_enabled))
-			kill_guest(cpu, "Disabling interrupts");
-}
-
-/* This restores the eflags word which was pushed on the stack by a trap */
-static void restore_eflags(struct lg_cpu *cpu)
-{
-	/* This is the physical address of the stack. */
-	unsigned long stack_pa = guest_pa(cpu, cpu->regs->esp);
-
-	/*
-	 * Stack looks like this:
-	 * Address	Contents
-	 * esp		EIP
-	 * esp + 4	CS
-	 * esp + 8	EFLAGS
-	 */
-	cpu->regs->eflags = lgread(cpu, stack_pa + 8, u32);
-	cpu->regs->eflags &=
-		~(X86_EFLAGS_TF|X86_EFLAGS_VM|X86_EFLAGS_RF|X86_EFLAGS_NT);
-}
-
-/*H:205
- * Virtual Interrupts.
- *
- * interrupt_pending() returns the first pending interrupt which isn't blocked
- * by the Guest.  It is called before every entry to the Guest, and just before
- * we go to sleep when the Guest has halted itself.
- */
-unsigned int interrupt_pending(struct lg_cpu *cpu, bool *more)
-{
-	unsigned int irq;
-	DECLARE_BITMAP(blk, LGUEST_IRQS);
-
-	/* If the Guest hasn't even initialized yet, we can do nothing. */
-	if (!cpu->lg->lguest_data)
-		return LGUEST_IRQS;
-
-	/*
-	 * Take our "irqs_pending" array and remove any interrupts the Guest
-	 * wants blocked: the result ends up in "blk".
-	 */
-	if (copy_from_user(&blk, cpu->lg->lguest_data->blocked_interrupts,
-			   sizeof(blk)))
-		return LGUEST_IRQS;
-	bitmap_andnot(blk, cpu->irqs_pending, blk, LGUEST_IRQS);
-
-	/* Find the first interrupt. */
-	irq = find_first_bit(blk, LGUEST_IRQS);
-	*more = find_next_bit(blk, LGUEST_IRQS, irq+1);
-
-	return irq;
-}
-
-/*
- * This actually diverts the Guest to running an interrupt handler, once an
- * interrupt has been identified by interrupt_pending().
- */
-void try_deliver_interrupt(struct lg_cpu *cpu, unsigned int irq, bool more)
-{
-	struct desc_struct *idt;
-
-	BUG_ON(irq >= LGUEST_IRQS);
-
-	/* If they're halted, interrupts restart them. */
-	if (cpu->halted) {
-		/* Re-enable interrupts. */
-		if (put_user(X86_EFLAGS_IF, &cpu->lg->lguest_data->irq_enabled))
-			kill_guest(cpu, "Re-enabling interrupts");
-		cpu->halted = 0;
-	} else {
-		/* Otherwise we check if they have interrupts disabled. */
-		u32 irq_enabled;
-		if (get_user(irq_enabled, &cpu->lg->lguest_data->irq_enabled))
-			irq_enabled = 0;
-		if (!irq_enabled) {
-			/* Make sure they know an IRQ is pending. */
-			put_user(X86_EFLAGS_IF,
-				 &cpu->lg->lguest_data->irq_pending);
-			return;
-		}
-	}
-
-	/*
-	 * Look at the IDT entry the Guest gave us for this interrupt.  The
-	 * first 32 (FIRST_EXTERNAL_VECTOR) entries are for traps, so we skip
-	 * over them.
-	 */
-	idt = &cpu->arch.idt[FIRST_EXTERNAL_VECTOR+irq];
-	/* If they don't have a handler (yet?), we just ignore it */
-	if (idt_present(idt->a, idt->b)) {
-		/* OK, mark it no longer pending and deliver it. */
-		clear_bit(irq, cpu->irqs_pending);
-
-		/*
-		 * They may be about to iret, where they asked us never to
-		 * deliver interrupts.  In this case, we can emulate that iret
-		 * then immediately deliver the interrupt.  This is basically
-		 * a noop: the iret would pop the interrupt frame and restore
-		 * eflags, and then we'd set it up again.  So just restore the
-		 * eflags word and jump straight to the handler in this case.
-		 *
-		 * Denys Vlasenko points out that this isn't quite right: if
-		 * the iret was returning to userspace, then that interrupt
-		 * would reset the stack pointer (which the Guest told us
-		 * about via LHCALL_SET_STACK).  But unless the Guest is being
-		 * *really* weird, that will be the same as the current stack
-		 * anyway.
-		 */
-		if (cpu->regs->eip == cpu->lg->noirq_iret) {
-			restore_eflags(cpu);
-		} else {
-			/*
-			 * set_guest_interrupt() takes a flag to say whether
-			 * this interrupt pushes an error code onto the stack
-			 * as well: virtual interrupts never do.
-			 */
-			push_guest_interrupt_stack(cpu, false);
-		}
-		/* Actually make Guest cpu jump to handler. */
-		guest_run_interrupt(cpu, idt->a, idt->b);
-	}
-
-	/*
-	 * Every time we deliver an interrupt, we update the timestamp in the
-	 * Guest's lguest_data struct.  It would be better for the Guest if we
-	 * did this more often, but it can actually be quite slow: doing it
-	 * here is a compromise which means at least it gets updated every
-	 * timer interrupt.
-	 */
-	write_timestamp(cpu);
-
-	/*
-	 * If there are no other interrupts we want to deliver, clear
-	 * the pending flag.
-	 */
-	if (!more)
-		put_user(0, &cpu->lg->lguest_data->irq_pending);
-}
-
-/* And this is the routine when we want to set an interrupt for the Guest. */
-void set_interrupt(struct lg_cpu *cpu, unsigned int irq)
-{
-	/*
-	 * Next time the Guest runs, the core code will see if it can deliver
-	 * this interrupt.
-	 */
-	set_bit(irq, cpu->irqs_pending);
-
-	/*
-	 * Make sure it sees it; it might be asleep (eg. halted), or running
-	 * the Guest right now, in which case kick_process() will knock it out.
-	 */
-	if (!wake_up_process(cpu->tsk))
-		kick_process(cpu->tsk);
-}
-/*:*/
-
-/*
- * Linux uses trap 128 for system calls.  Plan9 uses 64, and Ron Minnich sent
- * me a patch, so we support that too.  It'd be a big step for lguest if half
- * the Plan 9 user base were to start using it.
- *
- * Actually now I think of it, it's possible that Ron *is* half the Plan 9
- * userbase.  Oh well.
- */
-bool could_be_syscall(unsigned int num)
-{
-	/* Normal Linux IA32_SYSCALL_VECTOR or reserved vector? */
-	return num == IA32_SYSCALL_VECTOR || num == syscall_vector;
-}
-
-/* The syscall vector it wants must be unused by Host. */
-bool check_syscall_vector(struct lguest *lg)
-{
-	u32 vector;
-
-	if (get_user(vector, &lg->lguest_data->syscall_vec))
-		return false;
-
-	return could_be_syscall(vector);
-}
-
-int init_interrupts(void)
-{
-	/* If they want some strange system call vector, reserve it now */
-	if (syscall_vector != IA32_SYSCALL_VECTOR) {
-		if (test_bit(syscall_vector, used_vectors) ||
-		    vector_used_by_percpu_irq(syscall_vector)) {
-			printk(KERN_ERR "lg: couldn't reserve syscall %u\n",
-				 syscall_vector);
-			return -EBUSY;
-		}
-		set_bit(syscall_vector, used_vectors);
-	}
-
-	return 0;
-}
-
-void free_interrupts(void)
-{
-	if (syscall_vector != IA32_SYSCALL_VECTOR)
-		clear_bit(syscall_vector, used_vectors);
-}
-
-/*H:220
- * Now we've got the routines to deliver interrupts, delivering traps like
- * page fault is easy.  The only trick is that Intel decided that some traps
- * should have error codes:
- */
-static bool has_err(unsigned int trap)
-{
-	return (trap == 8 || (trap >= 10 && trap <= 14) || trap == 17);
-}
-
-/* deliver_trap() returns true if it could deliver the trap. */
-bool deliver_trap(struct lg_cpu *cpu, unsigned int num)
-{
-	/*
-	 * Trap numbers are always 8 bit, but we set an impossible trap number
-	 * for traps inside the Switcher, so check that here.
-	 */
-	if (num >= ARRAY_SIZE(cpu->arch.idt))
-		return false;
-
-	/*
-	 * Early on the Guest hasn't set the IDT entries (or maybe it put a
-	 * bogus one in): if we fail here, the Guest will be killed.
-	 */
-	if (!idt_present(cpu->arch.idt[num].a, cpu->arch.idt[num].b))
-		return false;
-	push_guest_interrupt_stack(cpu, has_err(num));
-	guest_run_interrupt(cpu, cpu->arch.idt[num].a,
-			    cpu->arch.idt[num].b);
-	return true;
-}
-
-/*H:250
- * Here's the hard part: returning to the Host every time a trap happens
- * and then calling deliver_trap() and re-entering the Guest is slow.
- * Particularly because Guest userspace system calls are traps (usually trap
- * 128).
- *
- * So we'd like to set up the IDT to tell the CPU to deliver traps directly
- * into the Guest.  This is possible, but the complexities cause the size of
- * this file to double!  However, 150 lines of code is worth writing for taking
- * system calls down from 1750ns to 270ns.  Plus, if lguest didn't do it, all
- * the other hypervisors would beat it up at lunchtime.
- *
- * This routine indicates if a particular trap number could be delivered
- * directly.
- *
- * Unfortunately, Linux 4.6 started using an interrupt gate instead of a
- * trap gate for syscalls, so this trick is ineffective.  See Mastery for
- * how we could do this anyway...
- */
-static bool direct_trap(unsigned int num)
-{
-	/*
-	 * Hardware interrupts don't go to the Guest at all (except system
-	 * call).
-	 */
-	if (num >= FIRST_EXTERNAL_VECTOR && !could_be_syscall(num))
-		return false;
-
-	/*
-	 * The Host needs to see page faults (for shadow paging and to save the
-	 * fault address), general protection faults (in/out emulation) and
-	 * device not available (TS handling) and of course, the hypercall trap.
-	 */
-	return num != 14 && num != 13 && num != 7 && num != LGUEST_TRAP_ENTRY;
-}
-/*:*/
-
-/*M:005
- * The Guest has the ability to turn its interrupt gates into trap gates,
- * if it is careful.  The Host will let trap gates can go directly to the
- * Guest, but the Guest needs the interrupts atomically disabled for an
- * interrupt gate.  The Host could provide a mechanism to register more
- * "no-interrupt" regions, and the Guest could point the trap gate at
- * instructions within that region, where it can safely disable interrupts.
- */
-
-/*M:006
- * The Guests do not use the sysenter (fast system call) instruction,
- * because it's hardcoded to enter privilege level 0 and so can't go direct.
- * It's about twice as fast as the older "int 0x80" system call, so it might
- * still be worthwhile to handle it in the Switcher and lcall down to the
- * Guest.  The sysenter semantics are hairy tho: search for that keyword in
- * entry.S
-:*/
-
-/*H:260
- * When we make traps go directly into the Guest, we need to make sure
- * the kernel stack is valid (ie. mapped in the page tables).  Otherwise, the
- * CPU trying to deliver the trap will fault while trying to push the interrupt
- * words on the stack: this is called a double fault, and it forces us to kill
- * the Guest.
- *
- * Which is deeply unfair, because (literally!) it wasn't the Guests' fault.
- */
-void pin_stack_pages(struct lg_cpu *cpu)
-{
-	unsigned int i;
-
-	/*
-	 * Depending on the CONFIG_4KSTACKS option, the Guest can have one or
-	 * two pages of stack space.
-	 */
-	for (i = 0; i < cpu->lg->stack_pages; i++)
-		/*
-		 * The stack grows *upwards*, so the address we're given is the
-		 * start of the page after the kernel stack.  Subtract one to
-		 * get back onto the first stack page, and keep subtracting to
-		 * get to the rest of the stack pages.
-		 */
-		pin_page(cpu, cpu->esp1 - 1 - i * PAGE_SIZE);
-}
-
-/*
- * Direct traps also mean that we need to know whenever the Guest wants to use
- * a different kernel stack, so we can change the guest TSS to use that
- * stack.  The TSS entries expect a virtual address, so unlike most addresses
- * the Guest gives us, the "esp" (stack pointer) value here is virtual, not
- * physical.
- *
- * In Linux each process has its own kernel stack, so this happens a lot: we
- * change stacks on each context switch.
- */
-void guest_set_stack(struct lg_cpu *cpu, u32 seg, u32 esp, unsigned int pages)
-{
-	/*
-	 * You're not allowed a stack segment with privilege level 0: bad Guest!
-	 */
-	if ((seg & 0x3) != GUEST_PL)
-		kill_guest(cpu, "bad stack segment %i", seg);
-	/* We only expect one or two stack pages. */
-	if (pages > 2)
-		kill_guest(cpu, "bad stack pages %u", pages);
-	/* Save where the stack is, and how many pages */
-	cpu->ss1 = seg;
-	cpu->esp1 = esp;
-	cpu->lg->stack_pages = pages;
-	/* Make sure the new stack pages are mapped */
-	pin_stack_pages(cpu);
-}
-
-/*
- * All this reference to mapping stacks leads us neatly into the other complex
- * part of the Host: page table handling.
- */
-
-/*H:235
- * This is the routine which actually checks the Guest's IDT entry and
- * transfers it into the entry in "struct lguest":
- */
-static void set_trap(struct lg_cpu *cpu, struct desc_struct *trap,
-		     unsigned int num, u32 lo, u32 hi)
-{
-	u8 type = idt_type(lo, hi);
-
-	/* We zero-out a not-present entry */
-	if (!idt_present(lo, hi)) {
-		trap->a = trap->b = 0;
-		return;
-	}
-
-	/* We only support interrupt and trap gates. */
-	if (type != 0xE && type != 0xF)
-		kill_guest(cpu, "bad IDT type %i", type);
-
-	/*
-	 * We only copy the handler address, present bit, privilege level and
-	 * type.  The privilege level controls where the trap can be triggered
-	 * manually with an "int" instruction.  This is usually GUEST_PL,
-	 * except for system calls which userspace can use.
-	 */
-	trap->a = ((__KERNEL_CS|GUEST_PL)<<16) | (lo&0x0000FFFF);
-	trap->b = (hi&0xFFFFEF00);
-}
-
-/*H:230
- * While we're here, dealing with delivering traps and interrupts to the
- * Guest, we might as well complete the picture: how the Guest tells us where
- * it wants them to go.  This would be simple, except making traps fast
- * requires some tricks.
- *
- * We saw the Guest setting Interrupt Descriptor Table (IDT) entries with the
- * LHCALL_LOAD_IDT_ENTRY hypercall before: that comes here.
- */
-void load_guest_idt_entry(struct lg_cpu *cpu, unsigned int num, u32 lo, u32 hi)
-{
-	/*
-	 * Guest never handles: NMI, doublefault, spurious interrupt or
-	 * hypercall.  We ignore when it tries to set them.
-	 */
-	if (num == 2 || num == 8 || num == 15 || num == LGUEST_TRAP_ENTRY)
-		return;
-
-	/*
-	 * Mark the IDT as changed: next time the Guest runs we'll know we have
-	 * to copy this again.
-	 */
-	cpu->changed |= CHANGED_IDT;
-
-	/* Check that the Guest doesn't try to step outside the bounds. */
-	if (num >= ARRAY_SIZE(cpu->arch.idt))
-		kill_guest(cpu, "Setting idt entry %u", num);
-	else
-		set_trap(cpu, &cpu->arch.idt[num], num, lo, hi);
-}
-
-/*
- * The default entry for each interrupt points into the Switcher routines which
- * simply return to the Host.  The run_guest() loop will then call
- * deliver_trap() to bounce it back into the Guest.
- */
-static void default_idt_entry(struct desc_struct *idt,
-			      int trap,
-			      const unsigned long handler,
-			      const struct desc_struct *base)
-{
-	/* A present interrupt gate. */
-	u32 flags = 0x8e00;
-
-	/*
-	 * Set the privilege level on the entry for the hypercall: this allows
-	 * the Guest to use the "int" instruction to trigger it.
-	 */
-	if (trap == LGUEST_TRAP_ENTRY)
-		flags |= (GUEST_PL << 13);
-	else if (base)
-		/*
-		 * Copy privilege level from what Guest asked for.  This allows
-		 * debug (int 3) traps from Guest userspace, for example.
-		 */
-		flags |= (base->b & 0x6000);
-
-	/* Now pack it into the IDT entry in its weird format. */
-	idt->a = (LGUEST_CS<<16) | (handler&0x0000FFFF);
-	idt->b = (handler&0xFFFF0000) | flags;
-}
-
-/* When the Guest first starts, we put default entries into the IDT. */
-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], NULL);
-}
-
-/*H:240
- * We don't use the IDT entries in the "struct lguest" directly, instead
- * we copy them into the IDT which we've set up for Guests on this CPU, just
- * before we run the Guest.  This routine does that copy.
- */
-void copy_traps(const struct lg_cpu *cpu, struct desc_struct *idt,
-		const unsigned long *def)
-{
-	unsigned int i;
-
-	/*
-	 * We can simply copy the direct traps, otherwise we use the default
-	 * ones in the Switcher: they will return to the Host.
-	 */
-	for (i = 0; i < ARRAY_SIZE(cpu->arch.idt); i++) {
-		const struct desc_struct *gidt = &cpu->arch.idt[i];
-
-		/* If no Guest can ever override this trap, leave it alone. */
-		if (!direct_trap(i))
-			continue;
-
-		/*
-		 * Only trap gates (type 15) can go direct to the Guest.
-		 * Interrupt gates (type 14) disable interrupts as they are
-		 * entered, which we never let the Guest do.  Not present
-		 * entries (type 0x0) also can't go direct, of course.
-		 *
-		 * If it can't go direct, we still need to copy the priv. level:
-		 * they might want to give userspace access to a software
-		 * interrupt.
-		 */
-		if (idt_type(gidt->a, gidt->b) == 0xF)
-			idt[i] = *gidt;
-		else
-			default_idt_entry(&idt[i], i, def[i], gidt);
-	}
-}
-
-/*H:200
- * The Guest Clock.
- *
- * There are two sources of virtual interrupts.  We saw one in lguest_user.c:
- * the Launcher sending interrupts for virtual devices.  The other is the Guest
- * timer interrupt.
- *
- * The Guest uses the LHCALL_SET_CLOCKEVENT hypercall to tell us how long to
- * the next timer interrupt (in nanoseconds).  We use the high-resolution timer
- * infrastructure to set a callback at that time.
- *
- * 0 means "turn off the clock".
- */
-void guest_set_clockevent(struct lg_cpu *cpu, unsigned long delta)
-{
-	ktime_t expires;
-
-	if (unlikely(delta == 0)) {
-		/* Clock event device is shutting down. */
-		hrtimer_cancel(&cpu->hrt);
-		return;
-	}
-
-	/*
-	 * We use wallclock time here, so the Guest might not be running for
-	 * all the time between now and the timer interrupt it asked for.  This
-	 * is almost always the right thing to do.
-	 */
-	expires = ktime_add_ns(ktime_get_real(), delta);
-	hrtimer_start(&cpu->hrt, expires, HRTIMER_MODE_ABS);
-}
-
-/* This is the function called when the Guest's timer expires. */
-static enum hrtimer_restart clockdev_fn(struct hrtimer *timer)
-{
-	struct lg_cpu *cpu = container_of(timer, struct lg_cpu, hrt);
-
-	/* Remember the first interrupt is the timer interrupt. */
-	set_interrupt(cpu, 0);
-	return HRTIMER_NORESTART;
-}
-
-/* This sets up the timer for this Guest. */
-void init_clockdev(struct lg_cpu *cpu)
-{
-	hrtimer_init(&cpu->hrt, CLOCK_REALTIME, HRTIMER_MODE_ABS);
-	cpu->hrt.function = clockdev_fn;
-}