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Move i386 part of core.c to x86/core.c. 

Separate i386 architecture specific from core.c and move it to
x86/core.c and add x86/lguest.h header file to match.

Signed-off-by: Jes Sorensen <jes@sgi.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Jes Sorensen 2007-10-22 11:03:28 +10:00 committed by Rusty Russell
parent 56adbe9ddc
commit 625efab1cd
9 changed files with 613 additions and 522 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/x86/lguest/boot.c
View File

@ -65,6 +65,7 @@
#include <asm/e820.h>
#include <asm/mce.h>
#include <asm/io.h>
#include <asm/i387.h>
/*G:010 Welcome to the Guest!
*

2
drivers/lguest/Makefile
View File

@ -6,7 +6,7 @@ obj-$(CONFIG_LGUEST) += lg.o
lg-y = core.o hypercalls.o page_tables.o interrupts_and_traps.o \
segments.o io.o lguest_user.o
lg-$(CONFIG_X86_32) += x86/switcher_32.o
lg-$(CONFIG_X86_32) += x86/switcher_32.o x86/core.o
Preparation Preparation!: PREFIX=P
Guest: PREFIX=G

459
drivers/lguest/core.c
View File

@ -11,54 +11,20 @@
#include <linux/vmalloc.h>
#include <linux/cpu.h>
#include <linux/freezer.h>
#include <linux/highmem.h>
#include <asm/paravirt.h>
#include <asm/desc.h>
#include <asm/pgtable.h>
#include <asm/uaccess.h>
#include <asm/poll.h>
#include <asm/highmem.h>
#include <asm/asm-offsets.h>
#include <asm/i387.h>
#include "lg.h"
/* Found in switcher.S */
extern char start_switcher_text[], end_switcher_text[], switch_to_guest[];
extern unsigned long default_idt_entries[];
/* Every guest maps the core switcher code. */
#define SHARED_SWITCHER_PAGES \
DIV_ROUND_UP(end_switcher_text - start_switcher_text, PAGE_SIZE)
/* Pages for switcher itself, then two pages per cpu */
#define TOTAL_SWITCHER_PAGES (SHARED_SWITCHER_PAGES + 2 * NR_CPUS)
/* We map at -4M for ease of mapping into the guest (one PTE page). */
#define SWITCHER_ADDR 0xFFC00000
static struct vm_struct *switcher_vma;
static struct page **switcher_page;
static int cpu_had_pge;
static struct {
unsigned long offset;
unsigned short segment;
} lguest_entry;
/* This One Big lock protects all inter-guest data structures. */
DEFINE_MUTEX(lguest_lock);
static DEFINE_PER_CPU(struct lguest *, last_guest);
/* Offset from where switcher.S was compiled to where we've copied it */
static unsigned long switcher_offset(void)
{
return SWITCHER_ADDR - (unsigned long)start_switcher_text;
}
/* This cpu's struct lguest_pages. */
static struct lguest_pages *lguest_pages(unsigned int cpu)
{
return &(((struct lguest_pages *)
(SWITCHER_ADDR + SHARED_SWITCHER_PAGES*PAGE_SIZE))[cpu]);
}
/*H:010 We need to set up the Switcher at a high virtual address. Remember the
* Switcher is a few hundred bytes of assembler code which actually changes the
@ -69,9 +35,7 @@ static struct lguest_pages *lguest_pages(unsigned int cpu)
* Host since it will be running as the switchover occurs.
*
* Trying to map memory at a particular address is an unusual thing to do, so
* it's not a simple one-liner. We also set up the per-cpu parts of the
* Switcher here.
*/
* it's not a simple one-liner. */
static __init int map_switcher(void)
{
int i, err;
@ -128,90 +92,11 @@ static __init int map_switcher(void)
goto free_vma;
}
/* Now the switcher is mapped at the right address, we can't fail!
* Copy in the compiled-in Switcher code (from switcher.S). */
/* Now the Switcher is mapped at the right address, we can't fail!
* Copy in the compiled-in Switcher code (from <arch>_switcher.S). */
memcpy(switcher_vma->addr, start_switcher_text,
end_switcher_text - start_switcher_text);
/* Most of the switcher.S doesn't care that it's been moved; on Intel,
* jumps are relative, and it doesn't access any references to external
* code or data.
*
* The only exception is the interrupt handlers in switcher.S: their
* addresses are placed in a table (default_idt_entries), so we need to
* update the table with the new addresses. switcher_offset() is a
* convenience function which returns the distance between the builtin
* switcher code and the high-mapped copy we just made. */
for (i = 0; i < IDT_ENTRIES; i++)
default_idt_entries[i] += switcher_offset();
/*
* Set up the Switcher's per-cpu areas.
*
* Each CPU gets two pages of its own within the high-mapped region
* (aka. "struct lguest_pages"). Much of this can be initialized now,
* but some depends on what Guest we are running (which is set up in
* copy_in_guest_info()).
*/
for_each_possible_cpu(i) {
/* lguest_pages() returns this CPU's two pages. */
struct lguest_pages *pages = lguest_pages(i);
/* This is a convenience pointer to make the code fit one
* statement to a line. */
struct lguest_ro_state *state = &pages->state;
/* The Global Descriptor Table: the Host has a different one
* for each CPU. We keep a descriptor for the GDT which says
* where it is and how big it is (the size is actually the last
* byte, not the size, hence the "-1"). */
state->host_gdt_desc.size = GDT_SIZE-1;
state->host_gdt_desc.address = (long)get_cpu_gdt_table(i);
/* All CPUs on the Host use the same Interrupt Descriptor
* Table, so we just use store_idt(), which gets this CPU's IDT
* descriptor. */
store_idt(&state->host_idt_desc);
/* The descriptors for the Guest's GDT and IDT can be filled
* out now, too. We copy the GDT & IDT into ->guest_gdt and
* ->guest_idt before actually running the Guest. */
state->guest_idt_desc.size = sizeof(state->guest_idt)-1;
state->guest_idt_desc.address = (long)&state->guest_idt;
state->guest_gdt_desc.size = sizeof(state->guest_gdt)-1;
state->guest_gdt_desc.address = (long)&state->guest_gdt;
/* We know where we want the stack to be when the Guest enters
* the switcher: in pages->regs. The stack grows upwards, so
* we start it at the end of that structure. */
state->guest_tss.esp0 = (long)(&pages->regs + 1);
/* And this is the GDT entry to use for the stack: we keep a
* couple of special LGUEST entries. */
state->guest_tss.ss0 = LGUEST_DS;
/* x86 can have a finegrained bitmap which indicates what I/O
* ports the process can use. We set it to the end of our
* structure, meaning "none". */
state->guest_tss.io_bitmap_base = sizeof(state->guest_tss);
/* Some GDT entries are the same across all Guests, so we can
* set them up now. */
setup_default_gdt_entries(state);
/* Most IDT entries are the same for all Guests, too.*/
setup_default_idt_entries(state, default_idt_entries);
/* The Host needs to be able to use the LGUEST segments on this
* CPU, too, so put them in the Host GDT. */
get_cpu_gdt_table(i)[GDT_ENTRY_LGUEST_CS] = FULL_EXEC_SEGMENT;
get_cpu_gdt_table(i)[GDT_ENTRY_LGUEST_DS] = FULL_SEGMENT;
}
/* In the Switcher, we want the %cs segment register to use the
* LGUEST_CS GDT entry: we've put that in the Host and Guest GDTs, so
* it will be undisturbed when we switch. To change %cs and jump we
* need this structure to feed to Intel's "lcall" instruction. */
lguest_entry.offset = (long)switch_to_guest + switcher_offset();
lguest_entry.segment = LGUEST_CS;
printk(KERN_INFO "lguest: mapped switcher at %p\n",
switcher_vma->addr);
/* And we succeeded... */
@ -243,80 +128,6 @@ static void unmap_switcher(void)
__free_pages(switcher_page[i], 0);
}
/*H:130 Our Guest is usually so well behaved; it never tries to do things it
* isn't allowed to. Unfortunately, Linux's paravirtual infrastructure isn't
* quite complete, because it doesn't contain replacements for the Intel I/O
* instructions. As a result, the Guest sometimes fumbles across one during
* the boot process as it probes for various things which are usually attached
* to a PC.
*
* When the Guest uses one of these instructions, we get trap #13 (General
* Protection Fault) and come here. We see if it's one of those troublesome
* instructions and skip over it. We return true if we did. */
static int emulate_insn(struct lguest *lg)
{
u8 insn;
unsigned int insnlen = 0, in = 0, shift = 0;
/* The eip contains the *virtual* address of the Guest's instruction:
* guest_pa just subtracts the Guest's page_offset. */
unsigned long physaddr = guest_pa(lg, lg->regs->eip);
/* The guest_pa() function only works for Guest kernel addresses, but
* that's all we're trying to do anyway. */
if (lg->regs->eip < lg->page_offset)
return 0;
/* Decoding x86 instructions is icky. */
lgread(lg, &insn, physaddr, 1);
/* 0x66 is an "operand prefix". It means it's using the upper 16 bits
of the eax register. */
if (insn == 0x66) {
shift = 16;
/* The instruction is 1 byte so far, read the next byte. */
insnlen = 1;
lgread(lg, &insn, physaddr + insnlen, 1);
}
/* We can ignore the lower bit for the moment and decode the 4 opcodes
* we need to emulate. */
switch (insn & 0xFE) {
case 0xE4: /* in <next byte>,%al */
insnlen += 2;
in = 1;
break;
case 0xEC: /* in (%dx),%al */
insnlen += 1;
in = 1;
break;
case 0xE6: /* out %al,<next byte> */
insnlen += 2;
break;
case 0xEE: /* out %al,(%dx) */
insnlen += 1;
break;
default:
/* OK, we don't know what this is, can't emulate. */
return 0;
}
/* If it was an "IN" instruction, they expect the result to be read
* into %eax, so we change %eax. We always return all-ones, which
* traditionally means "there's nothing there". */
if (in) {
/* Lower bit tells is whether it's a 16 or 32 bit access */
if (insn & 0x1)
lg->regs->eax = 0xFFFFFFFF;
else
lg->regs->eax |= (0xFFFF << shift);
}
/* Finally, we've "done" the instruction, so move past it. */
lg->regs->eip += insnlen;
/* Success! */
return 1;
}
/*:*/
/*L:305
* Dealing With Guest Memory.
*
@ -380,104 +191,6 @@ void lgwrite(struct lguest *lg, unsigned long addr, const void *b,
}
/* (end of memory access helper routines) :*/
static void set_ts(void)
{
u32 cr0;
cr0 = read_cr0();
if (!(cr0 & 8))
write_cr0(cr0|8);
}
/*S:010
* We are getting close to the Switcher.
*
* Remember that each CPU has two pages which are visible to the Guest when it
* runs on that CPU. This has to contain the state for that Guest: we copy the
* state in just before we run the Guest.
*
* Each Guest has "changed" flags which indicate what has changed in the Guest
* since it last ran. We saw this set in interrupts_and_traps.c and
* segments.c.
*/
static void copy_in_guest_info(struct lguest *lg, struct lguest_pages *pages)
{
/* Copying all this data can be quite expensive. We usually run the
* same Guest we ran last time (and that Guest hasn't run anywhere else
* meanwhile). If that's not the case, we pretend everything in the
* Guest has changed. */
if (__get_cpu_var(last_guest) != lg || lg->last_pages != pages) {
__get_cpu_var(last_guest) = lg;
lg->last_pages = pages;
lg->changed = CHANGED_ALL;
}
/* These copies are pretty cheap, so we do them unconditionally: */
/* Save the current Host top-level page directory. */
pages->state.host_cr3 = __pa(current->mm->pgd);
/* Set up the Guest's page tables to see this CPU's pages (and no
* other CPU's pages). */
map_switcher_in_guest(lg, pages);
/* Set up the two "TSS" members which tell the CPU what stack to use
* for traps which do directly into the Guest (ie. traps at privilege
* level 1). */
pages->state.guest_tss.esp1 = lg->esp1;
pages->state.guest_tss.ss1 = lg->ss1;
/* Copy direct-to-Guest trap entries. */
if (lg->changed & CHANGED_IDT)
copy_traps(lg, pages->state.guest_idt, default_idt_entries);
/* Copy all GDT entries which the Guest can change. */
if (lg->changed & CHANGED_GDT)
copy_gdt(lg, pages->state.guest_gdt);
/* If only the TLS entries have changed, copy them. */
else if (lg->changed & CHANGED_GDT_TLS)
copy_gdt_tls(lg, pages->state.guest_gdt);
/* Mark the Guest as unchanged for next time. */
lg->changed = 0;
}
/* Finally: the code to actually call into the Switcher to run the Guest. */
static void run_guest_once(struct lguest *lg, struct lguest_pages *pages)
{
/* This is a dummy value we need for GCC's sake. */
unsigned int clobber;
/* Copy the guest-specific information into this CPU's "struct
* lguest_pages". */
copy_in_guest_info(lg, pages);
/* Set the trap number to 256 (impossible value). If we fault while
* switching to the Guest (bad segment registers or bug), this will
* cause us to abort the Guest. */
lg->regs->trapnum = 256;
/* Now: we push the "eflags" register on the stack, then do an "lcall".
* This is how we change from using the kernel code segment to using
* the dedicated lguest code segment, as well as jumping into the
* Switcher.
*
* The lcall also pushes the old code segment (KERNEL_CS) onto the
* stack, then the address of this call. This stack layout happens to
* exactly match the stack of an interrupt... */
asm volatile("pushf; lcall *lguest_entry"
/* This is how we tell GCC that %eax ("a") and %ebx ("b")
* are changed by this routine. The "=" means output. */
: "=a"(clobber), "=b"(clobber)
/* %eax contains the pages pointer. ("0" refers to the
* 0-th argument above, ie "a"). %ebx contains the
* physical address of the Guest's top-level page
* directory. */
: "0"(pages), "1"(__pa(lg->pgdirs[lg->pgdidx].pgdir))
/* We tell gcc that all these registers could change,
* which means we don't have to save and restore them in
* the Switcher. */
: "memory", "%edx", "%ecx", "%edi", "%esi");
}
/*:*/
/*H:030 Let's jump straight to the the main loop which runs the Guest.
* Remember, this is called by the Launcher reading /dev/lguest, and we keep
* going around and around until something interesting happens. */
@ -485,11 +198,6 @@ int run_guest(struct lguest *lg, unsigned long __user *user)
{
/* We stop running once the Guest is dead. */
while (!lg->dead) {
/* We need to initialize this, otherwise gcc complains. It's
* not (yet) clever enough to see that it's initialized when we
* need it. */
unsigned int cr2 = 0; /* Damn gcc */
/* First we run any hypercalls the Guest wants done: either in
* the hypercall ring in "struct lguest_data", or directly by
* using int 31 (LGUEST_TRAP_ENTRY). */
@ -538,132 +246,20 @@ int run_guest(struct lguest *lg, unsigned long __user *user)
* the "Do Not Disturb" sign: */
local_irq_disable();
/* Remember the awfully-named TS bit? If the Guest has asked
* to set it we set it now, so we can trap and pass that trap
* to the Guest if it uses the FPU. */
if (lg->ts)
set_ts();
/* SYSENTER is an optimized way of doing system calls. We
* can't allow it because it always jumps to privilege level 0.
* A normal Guest won't try it because we don't advertise it in
* CPUID, but a malicious Guest (or malicious Guest userspace
* program) could, so we tell the CPU to disable it before
* running the Guest. */
if (boot_cpu_has(X86_FEATURE_SEP))
wrmsr(MSR_IA32_SYSENTER_CS, 0, 0);
/* Now we actually run the Guest. It will pop back out when
* something interesting happens, and we can examine its
* registers to see what it was doing. */
run_guest_once(lg, lguest_pages(raw_smp_processor_id()));
/* The "regs" pointer contains two extra entries which are not
* really registers: a trap number which says what interrupt or
* trap made the switcher code come back, and an error code
* which some traps set. */
/* If the Guest page faulted, then the cr2 register will tell
* us the bad virtual address. We have to grab this now,
* because once we re-enable interrupts an interrupt could
* fault and thus overwrite cr2, or we could even move off to a
* different CPU. */
if (lg->regs->trapnum == 14)
cr2 = read_cr2();
/* Similarly, if we took a trap because the Guest used the FPU,
* we have to restore the FPU it expects to see. */
else if (lg->regs->trapnum == 7)
math_state_restore();
/* Restore SYSENTER if it's supposed to be on. */
if (boot_cpu_has(X86_FEATURE_SEP))
wrmsr(MSR_IA32_SYSENTER_CS, __KERNEL_CS, 0);
/* Actually run the Guest until something happens. */
lguest_arch_run_guest(lg);
/* Now we're ready to be interrupted or moved to other CPUs */
local_irq_enable();
/* OK, so what happened? */
switch (lg->regs->trapnum) {
case 13: /* We've intercepted a GPF. */
/* Check if this was one of those annoying IN or OUT
* instructions which we need to emulate. If so, we
* just go back into the Guest after we've done it. */
if (lg->regs->errcode == 0) {
if (emulate_insn(lg))
continue;
}
break;
case 14: /* We've intercepted a page fault. */
/* The Guest accessed a virtual address that wasn't
* mapped. This happens a lot: we don't actually set
* up most of the page tables for the Guest at all when
* we start: as it runs it asks for more and more, and
* we set them up as required. In this case, we don't
* even tell the Guest that the fault happened.
*
* The errcode tells whether this was a read or a
* write, and whether kernel or userspace code. */
if (demand_page(lg, cr2, lg->regs->errcode))
continue;
/* OK, it's really not there (or not OK): the Guest
* needs to know. We write out the cr2 value so it
* knows where the fault occurred.
*
* Note that if the Guest were really messed up, this
* could happen before it's done the INITIALIZE
* hypercall, so lg->lguest_data will be NULL */
if (lg->lguest_data
&& put_user(cr2, &lg->lguest_data->cr2))
kill_guest(lg, "Writing cr2");
break;
case 7: /* We've intercepted a Device Not Available fault. */
/* If the Guest doesn't want to know, we already
* restored the Floating Point Unit, so we just
* continue without telling it. */
if (!lg->ts)
continue;
break;
case 32 ... 255:
/* These values mean a real interrupt occurred, in
* which case the Host handler has already been run.
* We just do a friendly check if another process
* should now be run, then fall through to loop
* around: */
cond_resched();
case LGUEST_TRAP_ENTRY: /* Handled at top of loop */
continue;
}
/* If we get here, it's a trap the Guest wants to know
* about. */
if (deliver_trap(lg, lg->regs->trapnum))
continue;
/* If the Guest doesn't have a handler (either it hasn't
* registered any yet, or it's one of the faults we don't let
* it handle), it dies with a cryptic error message. */
kill_guest(lg, "unhandled trap %li at %#lx (%#lx)",
lg->regs->trapnum, lg->regs->eip,
lg->regs->trapnum == 14 ? cr2 : lg->regs->errcode);
/* Now we deal with whatever happened to the Guest. */
lguest_arch_handle_trap(lg);
}
/* The Guest is dead => "No such file or directory" */
return -ENOENT;
}
/* Now we can look at each of the routines this calls, in increasing order of
* complexity: do_hypercalls(), emulate_insn(), maybe_do_interrupt(),
* deliver_trap() and demand_page(). After all those, we'll be ready to
* examine the Switcher, and our philosophical understanding of the Host/Guest
* duality will be complete. :*/
static void adjust_pge(void *on)
{
if (on)
write_cr4(read_cr4() | X86_CR4_PGE);
else
write_cr4(read_cr4() & ~X86_CR4_PGE);
}
/*H:000
* Welcome to the Host!
*
@ -705,31 +301,8 @@ static int __init init(void)
return err;
}
/* Finally, we need to turn off "Page Global Enable". PGE is an
* optimization where page table entries are specially marked to show
* they never change. The Host kernel marks all the kernel pages this
* way because it's always present, even when userspace is running.
*
* Lguest breaks this: unbeknownst to the rest of the Host kernel, we
* switch to the Guest kernel. If you don't disable this on all CPUs,
* you'll get really weird bugs that you'll chase for two days.
*
* I used to turn PGE off every time we switched to the Guest and back
* on when we return, but that slowed the Switcher down noticibly. */
/* We don't need the complexity of CPUs coming and going while we're
* doing this. */
lock_cpu_hotplug();
if (cpu_has_pge) { /* We have a broader idea of "global". */
/* Remember that this was originally set (for cleanup). */
cpu_had_pge = 1;
/* adjust_pge is a helper function which sets or unsets the PGE
* bit on its CPU, depending on the argument (0 == unset). */
on_each_cpu(adjust_pge, (void *)0, 0, 1);
/* Turn off the feature in the global feature set. */
clear_bit(X86_FEATURE_PGE, boot_cpu_data.x86_capability);
}
unlock_cpu_hotplug();
/* Finally we do some architecture-specific setup. */
lguest_arch_host_init();
/* All good! */
return 0;
@ -742,15 +315,9 @@ static void __exit fini(void)
free_pagetables();
unmap_switcher();
/* If we had PGE before we started, turn it back on now. */
lock_cpu_hotplug();
if (cpu_had_pge) {
set_bit(X86_FEATURE_PGE, boot_cpu_data.x86_capability);
/* adjust_pge's argument "1" means set PGE. */
on_each_cpu(adjust_pge, (void *)1, 0, 1);
}
unlock_cpu_hotplug();
lguest_arch_host_fini();
}
/*:*/
/* The Host side of lguest can be a module. This is a nice way for people to
* play with it. */

18
drivers/lguest/interrupts_and_traps.c
View File

@ -165,7 +165,7 @@ void maybe_do_interrupt(struct lguest *lg)
/* 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 = &lg->idt[FIRST_EXTERNAL_VECTOR+irq];
idt = &lg->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. */
@ -197,14 +197,14 @@ int deliver_trap(struct lguest *lg, 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(lg->idt))
if (num >= ARRAY_SIZE(lg->arch.idt))
return 0;
/* 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(lg->idt[num].a, lg->idt[num].b))
if (!idt_present(lg->arch.idt[num].a, lg->arch.idt[num].b))
return 0;
set_guest_interrupt(lg, lg->idt[num].a, lg->idt[num].b, has_err(num));
set_guest_interrupt(lg, lg->arch.idt[num].a, lg->arch.idt[num].b, has_err(num));
return 1;
}
@ -341,10 +341,10 @@ void load_guest_idt_entry(struct lguest *lg, unsigned int num, u32 lo, u32 hi)
lg->changed |= CHANGED_IDT;
/* Check that the Guest doesn't try to step outside the bounds. */
if (num >= ARRAY_SIZE(lg->idt))
if (num >= ARRAY_SIZE(lg->arch.idt))
kill_guest(lg, "Setting idt entry %u", num);
else
set_trap(lg, &lg->idt[num], num, lo, hi);
set_trap(lg, &lg->arch.idt[num], num, lo, hi);
}
/* The default entry for each interrupt points into the Switcher routines which
@ -387,7 +387,7 @@ void copy_traps(const struct lguest *lg, struct desc_struct *idt,
/* 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(lg->idt); i++) {
for (i = 0; i < ARRAY_SIZE(lg->arch.idt); i++) {
/* If no Guest can ever override this trap, leave it alone. */
if (!direct_trap(i))
continue;
@ -396,8 +396,8 @@ void copy_traps(const struct lguest *lg, struct desc_struct *idt,
* 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 (idt_type(lg->idt[i].a, lg->idt[i].b) == 0xF)
idt[i] = lg->idt[i];
if (idt_type(lg->arch.idt[i].a, lg->arch.idt[i].b) == 0xF)
idt[i] = lg->arch.idt[i];
else
/* Reset it to the default. */
default_idt_entry(&idt[i], i, def[i]);

63
drivers/lguest/lg.h
View File

@ -1,13 +1,6 @@
#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>
@ -18,34 +11,12 @@
#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;
};
#include <asm/lguest.h>
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;
@ -98,23 +69,6 @@ struct pgdir
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
{
@ -180,11 +134,7 @@ struct lguest
/* 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[IDT_ENTRIES];
struct lguest_arch arch;
/* Virtual clock device */
struct hrtimer hrt;
@ -239,6 +189,15 @@ 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);
/* <arch>/core.c: */
void lguest_arch_host_init(void);
void lguest_arch_host_fini(void);
void lguest_arch_run_guest(struct lguest *lg);
void lguest_arch_handle_trap(struct lguest *lg);
/* <arch>/switcher.S: */
extern char start_switcher_text[], end_switcher_text[], switch_to_guest[];
/* lguest_user.c: */
int lguest_device_init(void);
void lguest_device_remove(void);

26
drivers/lguest/segments.c
View File

@ -73,14 +73,14 @@ static void fixup_gdt_table(struct lguest *lg, unsigned start, unsigned end)
/* Segment descriptors contain a privilege level: the Guest is
* sometimes careless and leaves this as 0, even though it's
* running at privilege level 1. If so, we fix it here. */
if ((lg->gdt[i].b & 0x00006000) == 0)
lg->gdt[i].b |= (GUEST_PL << 13);
if ((lg->arch.gdt[i].b & 0x00006000) == 0)
lg->arch.gdt[i].b |= (GUEST_PL << 13);
/* Each descriptor has an "accessed" bit. If we don't set it
* now, the CPU will try to set it when the Guest first loads
* that entry into a segment register. But the GDT isn't
* writable by the Guest, so bad things can happen. */
lg->gdt[i].b |= 0x00000100;
lg->arch.gdt[i].b |= 0x00000100;
}
}
@ -106,12 +106,12 @@ void setup_default_gdt_entries(struct lguest_ro_state *state)
void setup_guest_gdt(struct lguest *lg)
{
/* Start with full 0-4G segments... */
lg->gdt[GDT_ENTRY_KERNEL_CS] = FULL_EXEC_SEGMENT;
lg->gdt[GDT_ENTRY_KERNEL_DS] = FULL_SEGMENT;
lg->arch.gdt[GDT_ENTRY_KERNEL_CS] = FULL_EXEC_SEGMENT;
lg->arch.gdt[GDT_ENTRY_KERNEL_DS] = FULL_SEGMENT;
/* ...except the Guest is allowed to use them, so set the privilege
* level appropriately in the flags. */
lg->gdt[GDT_ENTRY_KERNEL_CS].b |= (GUEST_PL << 13);
lg->gdt[GDT_ENTRY_KERNEL_DS].b |= (GUEST_PL << 13);
lg->arch.gdt[GDT_ENTRY_KERNEL_CS].b |= (GUEST_PL << 13);
lg->arch.gdt[GDT_ENTRY_KERNEL_DS].b |= (GUEST_PL << 13);
}
/* Like the IDT, we never simply use the GDT the Guest gives us. We set up the
@ -126,7 +126,7 @@ 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];
gdt[i] = lg->arch.gdt[i];
}
/* This is the full version */
@ -138,7 +138,7 @@ void copy_gdt(const struct lguest *lg, struct desc_struct *gdt)
* replaced. See ignored_gdt() above. */
for (i = 0; i < GDT_ENTRIES; i++)
if (!ignored_gdt(i))
gdt[i] = lg->gdt[i];
gdt[i] = lg->arch.gdt[i];
}
/* This is where the Guest asks us to load a new GDT (LHCALL_LOAD_GDT). */
@ -146,12 +146,12 @@ void load_guest_gdt(struct lguest *lg, unsigned long table, u32 num)
{
/* We assume the Guest has the same number of GDT entries as the
* Host, otherwise we'd have to dynamically allocate the Guest GDT. */
if (num > ARRAY_SIZE(lg->gdt))
if (num > ARRAY_SIZE(lg->arch.gdt))
kill_guest(lg, "too many gdt entries %i", num);
/* We read the whole thing in, then fix it up. */
lgread(lg, lg->gdt, table, num * sizeof(lg->gdt[0]));
fixup_gdt_table(lg, 0, ARRAY_SIZE(lg->gdt));
lgread(lg, lg->arch.gdt, table, num * sizeof(lg->arch.gdt[0]));
fixup_gdt_table(lg, 0, ARRAY_SIZE(lg->arch.gdt));
/* Mark that the GDT changed so the core knows it has to copy it again,
* even if the Guest is run on the same CPU. */
lg->changed |= CHANGED_GDT;
@ -159,7 +159,7 @@ void load_guest_gdt(struct lguest *lg, unsigned long table, u32 num)
void guest_load_tls(struct lguest *lg, unsigned long gtls)
{
struct desc_struct *tls = &lg->gdt[GDT_ENTRY_TLS_MIN];
struct desc_struct *tls = &lg->arch.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);

476
drivers/lguest/x86/core.c Normal file
View File

@ -0,0 +1,476 @@
/*
* Copyright (C) 2006, Rusty Russell <rusty@rustcorp.com.au> IBM Corporation.
* Copyright (C) 2007, Jes Sorensen <jes@sgi.com> SGI.
*
* 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/cpu.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/lguest.h>
#include <asm/uaccess.h>
#include <asm/i387.h>
#include "../lg.h"
static int cpu_had_pge;
static struct {
unsigned long offset;
unsigned short segment;
} lguest_entry;
/* Offset from where switcher.S was compiled to where we've copied it */
static unsigned long switcher_offset(void)
{
return SWITCHER_ADDR - (unsigned long)start_switcher_text;
}
/* This cpu's struct lguest_pages. */
static struct lguest_pages *lguest_pages(unsigned int cpu)
{
return &(((struct lguest_pages *)
(SWITCHER_ADDR + SHARED_SWITCHER_PAGES*PAGE_SIZE))[cpu]);
}
static DEFINE_PER_CPU(struct lguest *, last_guest);
/*S:010
* We are getting close to the Switcher.
*
* Remember that each CPU has two pages which are visible to the Guest when it
* runs on that CPU. This has to contain the state for that Guest: we copy the
* state in just before we run the Guest.
*
* Each Guest has "changed" flags which indicate what has changed in the Guest
* since it last ran. We saw this set in interrupts_and_traps.c and
* segments.c.
*/
static void copy_in_guest_info(struct lguest *lg, struct lguest_pages *pages)
{
/* Copying all this data can be quite expensive. We usually run the
* same Guest we ran last time (and that Guest hasn't run anywhere else
* meanwhile). If that's not the case, we pretend everything in the
* Guest has changed. */
if (__get_cpu_var(last_guest) != lg || lg->last_pages != pages) {
__get_cpu_var(last_guest) = lg;
lg->last_pages = pages;
lg->changed = CHANGED_ALL;
}
/* These copies are pretty cheap, so we do them unconditionally: */
/* Save the current Host top-level page directory. */
pages->state.host_cr3 = __pa(current->mm->pgd);
/* Set up the Guest's page tables to see this CPU's pages (and no
* other CPU's pages). */
map_switcher_in_guest(lg, pages);
/* Set up the two "TSS" members which tell the CPU what stack to use
* for traps which do directly into the Guest (ie. traps at privilege
* level 1). */
pages->state.guest_tss.esp1 = lg->esp1;
pages->state.guest_tss.ss1 = lg->ss1;
/* Copy direct-to-Guest trap entries. */
if (lg->changed & CHANGED_IDT)
copy_traps(lg, pages->state.guest_idt, default_idt_entries);
/* Copy all GDT entries which the Guest can change. */
if (lg->changed & CHANGED_GDT)
copy_gdt(lg, pages->state.guest_gdt);
/* If only the TLS entries have changed, copy them. */
else if (lg->changed & CHANGED_GDT_TLS)
copy_gdt_tls(lg, pages->state.guest_gdt);
/* Mark the Guest as unchanged for next time. */
lg->changed = 0;
}
/* Finally: the code to actually call into the Switcher to run the Guest. */
static void run_guest_once(struct lguest *lg, struct lguest_pages *pages)
{
/* This is a dummy value we need for GCC's sake. */
unsigned int clobber;
/* Copy the guest-specific information into this CPU's "struct
* lguest_pages". */
copy_in_guest_info(lg, pages);
/* Set the trap number to 256 (impossible value). If we fault while
* switching to the Guest (bad segment registers or bug), this will
* cause us to abort the Guest. */
lg->regs->trapnum = 256;
/* Now: we push the "eflags" register on the stack, then do an "lcall".
* This is how we change from using the kernel code segment to using
* the dedicated lguest code segment, as well as jumping into the
* Switcher.
*
* The lcall also pushes the old code segment (KERNEL_CS) onto the
* stack, then the address of this call. This stack layout happens to
* exactly match the stack of an interrupt... */
asm volatile("pushf; lcall *lguest_entry"
/* This is how we tell GCC that %eax ("a") and %ebx ("b")
* are changed by this routine. The "=" means output. */
: "=a"(clobber), "=b"(clobber)
/* %eax contains the pages pointer. ("0" refers to the
* 0-th argument above, ie "a"). %ebx contains the
* physical address of the Guest's top-level page
* directory. */
: "0"(pages), "1"(__pa(lg->pgdirs[lg->pgdidx].pgdir))
/* We tell gcc that all these registers could change,
* which means we don't have to save and restore them in
* the Switcher. */
: "memory", "%edx", "%ecx", "%edi", "%esi");
}
/*:*/
/*H:040 This is the i386-specific code to setup and run the Guest. Interrupts
* are disabled: we own the CPU. */
void lguest_arch_run_guest(struct lguest *lg)
{
/* Remember the awfully-named TS bit? If the Guest has asked
* to set it we set it now, so we can trap and pass that trap
* to the Guest if it uses the FPU. */
if (lg->ts)
lguest_set_ts();
/* SYSENTER is an optimized way of doing system calls. We
* can't allow it because it always jumps to privilege level 0.
* A normal Guest won't try it because we don't advertise it in
* CPUID, but a malicious Guest (or malicious Guest userspace
* program) could, so we tell the CPU to disable it before
* running the Guest. */
if (boot_cpu_has(X86_FEATURE_SEP))
wrmsr(MSR_IA32_SYSENTER_CS, 0, 0);
/* Now we actually run the Guest. It will pop back out when
* something interesting happens, and we can examine its
* registers to see what it was doing. */
run_guest_once(lg, lguest_pages(raw_smp_processor_id()));
/* The "regs" pointer contains two extra entries which are not
* really registers: a trap number which says what interrupt or
* trap made the switcher code come back, and an error code
* which some traps set. */
/* If the Guest page faulted, then the cr2 register will tell
* us the bad virtual address. We have to grab this now,
* because once we re-enable interrupts an interrupt could
* fault and thus overwrite cr2, or we could even move off to a
* different CPU. */
if (lg->regs->trapnum == 14)
lg->arch.last_pagefault = read_cr2();
/* Similarly, if we took a trap because the Guest used the FPU,
* we have to restore the FPU it expects to see. */
else if (lg->regs->trapnum == 7)
math_state_restore();
/* Restore SYSENTER if it's supposed to be on. */
if (boot_cpu_has(X86_FEATURE_SEP))
wrmsr(MSR_IA32_SYSENTER_CS, __KERNEL_CS, 0);
}
/*H:130 Our Guest is usually so well behaved; it never tries to do things it
* isn't allowed to. Unfortunately, Linux's paravirtual infrastructure isn't
* quite complete, because it doesn't contain replacements for the Intel I/O
* instructions. As a result, the Guest sometimes fumbles across one during
* the boot process as it probes for various things which are usually attached
* to a PC.
*
* When the Guest uses one of these instructions, we get trap #13 (General
* Protection Fault) and come here. We see if it's one of those troublesome
* instructions and skip over it. We return true if we did. */
static int emulate_insn(struct lguest *lg)
{
u8 insn;
unsigned int insnlen = 0, in = 0, shift = 0;
/* The eip contains the *virtual* address of the Guest's instruction:
* guest_pa just subtracts the Guest's page_offset. */
unsigned long physaddr = guest_pa(lg, lg->regs->eip);
/* The guest_pa() function only works for Guest kernel addresses, but
* that's all we're trying to do anyway. */
if (lg->regs->eip < lg->page_offset)
return 0;
/* Decoding x86 instructions is icky. */
lgread(lg, &insn, physaddr, 1);
/* 0x66 is an "operand prefix". It means it's using the upper 16 bits
of the eax register. */
if (insn == 0x66) {
shift = 16;
/* The instruction is 1 byte so far, read the next byte. */
insnlen = 1;
lgread(lg, &insn, physaddr + insnlen, 1);
}
/* We can ignore the lower bit for the moment and decode the 4 opcodes
* we need to emulate. */
switch (insn & 0xFE) {
case 0xE4: /* in <next byte>,%al */
insnlen += 2;
in = 1;
break;
case 0xEC: /* in (%dx),%al */
insnlen += 1;
in = 1;
break;
case 0xE6: /* out %al,<next byte> */
insnlen += 2;
break;
case 0xEE: /* out %al,(%dx) */
insnlen += 1;
break;
default:
/* OK, we don't know what this is, can't emulate. */
return 0;
}
/* If it was an "IN" instruction, they expect the result to be read
* into %eax, so we change %eax. We always return all-ones, which
* traditionally means "there's nothing there". */
if (in) {
/* Lower bit tells is whether it's a 16 or 32 bit access */
if (insn & 0x1)
lg->regs->eax = 0xFFFFFFFF;
else
lg->regs->eax |= (0xFFFF << shift);
}
/* Finally, we've "done" the instruction, so move past it. */
lg->regs->eip += insnlen;
/* Success! */
return 1;
}
/*H:050 Once we've re-enabled interrupts, we look at why the Guest exited. */
void lguest_arch_handle_trap(struct lguest *lg)
{
switch (lg->regs->trapnum) {
case 13: /* We've intercepted a GPF. */
/* Check if this was one of those annoying IN or OUT
* instructions which we need to emulate. If so, we
* just go back into the Guest after we've done it. */
if (lg->regs->errcode == 0) {
if (emulate_insn(lg))
return;
}
break;
case 14: /* We've intercepted a page fault. */
/* The Guest accessed a virtual address that wasn't
* mapped. This happens a lot: we don't actually set
* up most of the page tables for the Guest at all when
* we start: as it runs it asks for more and more, and
* we set them up as required. In this case, we don't
* even tell the Guest that the fault happened.
*
* The errcode tells whether this was a read or a
* write, and whether kernel or userspace code. */
if (demand_page(lg, lg->arch.last_pagefault, lg->regs->errcode))
return;
/* OK, it's really not there (or not OK): the Guest
* needs to know. We write out the cr2 value so it
* knows where the fault occurred.
*
* Note that if the Guest were really messed up, this
* could happen before it's done the INITIALIZE
* hypercall, so lg->lguest_data will be NULL */
if (lg->lguest_data &&
put_user(lg->arch.last_pagefault, &lg->lguest_data->cr2))
kill_guest(lg, "Writing cr2");
break;
case 7: /* We've intercepted a Device Not Available fault. */
/* If the Guest doesn't want to know, we already
* restored the Floating Point Unit, so we just
* continue without telling it. */
if (!lg->ts)
return;
break;
case 32 ... 255:
/* These values mean a real interrupt occurred, in
* which case the Host handler has already been run.
* We just do a friendly check if another process
* should now be run, then fall through to loop
* around: */
cond_resched();
case LGUEST_TRAP_ENTRY: /* Handled before re-entering Guest */
return;
}
/* We didn't handle the trap, so it needs to go to the Guest. */
if (!deliver_trap(lg, lg->regs->trapnum))
/* If the Guest doesn't have a handler (either it hasn't
* registered any yet, or it's one of the faults we don't let
* it handle), it dies with a cryptic error message. */
kill_guest(lg, "unhandled trap %li at %#lx (%#lx)",
lg->regs->trapnum, lg->regs->eip,
lg->regs->trapnum == 14 ? lg->arch.last_pagefault
: lg->regs->errcode);
}
/* Now we can look at each of the routines this calls, in increasing order of
* complexity: do_hypercalls(), emulate_insn(), maybe_do_interrupt(),
* deliver_trap() and demand_page(). After all those, we'll be ready to
* examine the Switcher, and our philosophical understanding of the Host/Guest
* duality will be complete. :*/
static void adjust_pge(void *on)
{
if (on)
write_cr4(read_cr4() | X86_CR4_PGE);
else
write_cr4(read_cr4() & ~X86_CR4_PGE);
}
/*H:020 Now the Switcher is mapped and every thing else is ready, we need to do
* some more i386-specific initialization. */
void __init lguest_arch_host_init(void)
{
int i;
/* Most of the i386/switcher.S doesn't care that it's been moved; on
* Intel, jumps are relative, and it doesn't access any references to
* external code or data.
*
* The only exception is the interrupt handlers in switcher.S: their
* addresses are placed in a table (default_idt_entries), so we need to
* update the table with the new addresses. switcher_offset() is a
* convenience function which returns the distance between the builtin
* switcher code and the high-mapped copy we just made. */
for (i = 0; i < IDT_ENTRIES; i++)
default_idt_entries[i] += switcher_offset();
/*
* Set up the Switcher's per-cpu areas.
*
* Each CPU gets two pages of its own within the high-mapped region
* (aka. "struct lguest_pages"). Much of this can be initialized now,
* but some depends on what Guest we are running (which is set up in
* copy_in_guest_info()).
*/
for_each_possible_cpu(i) {
/* lguest_pages() returns this CPU's two pages. */
struct lguest_pages *pages = lguest_pages(i);
/* This is a convenience pointer to make the code fit one
* statement to a line. */
struct lguest_ro_state *state = &pages->state;
/* The Global Descriptor Table: the Host has a different one
* for each CPU. We keep a descriptor for the GDT which says
* where it is and how big it is (the size is actually the last
* byte, not the size, hence the "-1"). */
state->host_gdt_desc.size = GDT_SIZE-1;
state->host_gdt_desc.address = (long)get_cpu_gdt_table(i);
/* All CPUs on the Host use the same Interrupt Descriptor
* Table, so we just use store_idt(), which gets this CPU's IDT
* descriptor. */
store_idt(&state->host_idt_desc);
/* The descriptors for the Guest's GDT and IDT can be filled
* out now, too. We copy the GDT & IDT into ->guest_gdt and
* ->guest_idt before actually running the Guest. */
state->guest_idt_desc.size = sizeof(state->guest_idt)-1;
state->guest_idt_desc.address = (long)&state->guest_idt;
state->guest_gdt_desc.size = sizeof(state->guest_gdt)-1;
state->guest_gdt_desc.address = (long)&state->guest_gdt;
/* We know where we want the stack to be when the Guest enters
* the switcher: in pages->regs. The stack grows upwards, so
* we start it at the end of that structure. */
state->guest_tss.esp0 = (long)(&pages->regs + 1);
/* And this is the GDT entry to use for the stack: we keep a
* couple of special LGUEST entries. */
state->guest_tss.ss0 = LGUEST_DS;
/* x86 can have a finegrained bitmap which indicates what I/O
* ports the process can use. We set it to the end of our
* structure, meaning "none". */
state->guest_tss.io_bitmap_base = sizeof(state->guest_tss);
/* Some GDT entries are the same across all Guests, so we can
* set them up now. */
setup_default_gdt_entries(state);
/* Most IDT entries are the same for all Guests, too.*/
setup_default_idt_entries(state, default_idt_entries);
/* The Host needs to be able to use the LGUEST segments on this
* CPU, too, so put them in the Host GDT. */
get_cpu_gdt_table(i)[GDT_ENTRY_LGUEST_CS] = FULL_EXEC_SEGMENT;
get_cpu_gdt_table(i)[GDT_ENTRY_LGUEST_DS] = FULL_SEGMENT;
}
/* In the Switcher, we want the %cs segment register to use the
* LGUEST_CS GDT entry: we've put that in the Host and Guest GDTs, so
* it will be undisturbed when we switch. To change %cs and jump we
* need this structure to feed to Intel's "lcall" instruction. */
lguest_entry.offset = (long)switch_to_guest + switcher_offset();
lguest_entry.segment = LGUEST_CS;
/* Finally, we need to turn off "Page Global Enable". PGE is an
* optimization where page table entries are specially marked to show
* they never change. The Host kernel marks all the kernel pages this
* way because it's always present, even when userspace is running.
*
* Lguest breaks this: unbeknownst to the rest of the Host kernel, we
* switch to the Guest kernel. If you don't disable this on all CPUs,
* you'll get really weird bugs that you'll chase for two days.
*
* I used to turn PGE off every time we switched to the Guest and back
* on when we return, but that slowed the Switcher down noticibly. */
/* We don't need the complexity of CPUs coming and going while we're
* doing this. */
lock_cpu_hotplug();
if (cpu_has_pge) { /* We have a broader idea of "global". */
/* Remember that this was originally set (for cleanup). */
cpu_had_pge = 1;
/* adjust_pge is a helper function which sets or unsets the PGE
* bit on its CPU, depending on the argument (0 == unset). */
on_each_cpu(adjust_pge, (void *)0, 0, 1);
/* Turn off the feature in the global feature set. */
clear_bit(X86_FEATURE_PGE, boot_cpu_data.x86_capability);
}
unlock_cpu_hotplug();
};
/*:*/
void __exit lguest_arch_host_fini(void)
{
/* If we had PGE before we started, turn it back on now. */
lock_cpu_hotplug();
if (cpu_had_pge) {
set_bit(X86_FEATURE_PGE, boot_cpu_data.x86_capability);
/* adjust_pge's argument "1" means set PGE. */
on_each_cpu(adjust_pge, (void *)1, 0, 1);
}
unlock_cpu_hotplug();
}

3
drivers/lguest/x86/switcher_32.S
View File

@ -48,7 +48,8 @@
#include <linux/linkage.h>
#include <asm/asm-offsets.h>
#include <asm/page.h>
#include "../lg.h"
#include <asm/segment.h>
#include <asm/lguest.h>
// We mark the start of the code to copy
// It's placed in .text tho it's never run here

87
include/asm-x86/lguest.h Normal file
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@ -0,0 +1,87 @@
#ifndef _X86_LGUEST_H
#define _X86_LGUEST_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 <asm/desc.h>
#define GUEST_PL 1
/* Every guest maps the core switcher code. */
#define SHARED_SWITCHER_PAGES \
DIV_ROUND_UP(end_switcher_text - start_switcher_text, PAGE_SIZE)
/* Pages for switcher itself, then two pages per cpu */
#define TOTAL_SWITCHER_PAGES (SHARED_SWITCHER_PAGES + 2 * NR_CPUS)
/* We map at -4M for ease of mapping into the guest (one PTE page). */
#define SWITCHER_ADDR 0xFFC00000
/* Found in switcher.S */
extern unsigned long default_idt_entries[];
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;
};
/* 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];
};
struct lguest_arch
{
/* 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[IDT_ENTRIES];
/* The address of the last guest-visible pagefault (ie. cr2). */
unsigned long last_pagefault;
};
static inline void lguest_set_ts(void)
{
u32 cr0;
cr0 = read_cr0();
if (!(cr0 & 8))
write_cr0(cr0|8);
}
/* 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})
#endif /* __ASSEMBLY__ */
#endif