Commit d7e28ffe authored by Rusty Russell's avatar Rusty Russell Committed by Linus Torvalds
Browse files

lguest: the host code



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

[akpm@linux-foundation.org: update for futex-new-private-futexes]
[akpm@linux-foundation.org: build fix]
[jmorris@namei.org: lguest: use hrtimers]
[akpm@linux-foundation.org: x86_64 build fix]
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <ak@suse.de>
Cc: Eric Dumazet <dada1@cosmosbay.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 07ad157f
......@@ -27,6 +27,7 @@ static int tsc_enabled;
* an extra value to store the TSC freq
*/
unsigned int tsc_khz;
EXPORT_SYMBOL_GPL(tsc_khz);
int tsc_disable;
......@@ -58,10 +59,11 @@ __setup("notsc", tsc_setup);
*/
static int tsc_unstable;
static inline int check_tsc_unstable(void)
int check_tsc_unstable(void)
{
return tsc_unstable;
}
EXPORT_SYMBOL_GPL(check_tsc_unstable);
/* Accellerators for sched_clock()
* convert from cycles(64bits) => nanoseconds (64bits)
......
......@@ -44,7 +44,7 @@ unsigned long long sched_clock(void)
static int tsc_unstable;
static inline int check_tsc_unstable(void)
inline int check_tsc_unstable(void)
{
return tsc_unstable;
}
......
/* World's simplest hypervisor, to test paravirt_ops and show
* unbelievers that virtualization is the future. Plus, it's fun! */
#include <linux/module.h>
#include <linux/stringify.h>
#include <linux/stddef.h>
#include <linux/io.h>
#include <linux/mm.h>
#include <linux/vmalloc.h>
#include <linux/cpu.h>
#include <linux/freezer.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);
/* FIXME: Make dynamic. */
#define MAX_LGUEST_GUESTS 16
struct lguest lguests[MAX_LGUEST_GUESTS];
/* 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 __init int map_switcher(void)
{
int i, err;
struct page **pagep;
switcher_page = kmalloc(sizeof(switcher_page[0])*TOTAL_SWITCHER_PAGES,
GFP_KERNEL);
if (!switcher_page) {
err = -ENOMEM;
goto out;
}
for (i = 0; i < TOTAL_SWITCHER_PAGES; i++) {
unsigned long addr = get_zeroed_page(GFP_KERNEL);
if (!addr) {
err = -ENOMEM;
goto free_some_pages;
}
switcher_page[i] = virt_to_page(addr);
}
switcher_vma = __get_vm_area(TOTAL_SWITCHER_PAGES * PAGE_SIZE,
VM_ALLOC, SWITCHER_ADDR, VMALLOC_END);
if (!switcher_vma) {
err = -ENOMEM;
printk("lguest: could not map switcher pages high\n");
goto free_pages;
}
pagep = switcher_page;
err = map_vm_area(switcher_vma, PAGE_KERNEL, &pagep);
if (err) {
printk("lguest: map_vm_area failed: %i\n", err);
goto free_vma;
}
memcpy(switcher_vma->addr, start_switcher_text,
end_switcher_text - start_switcher_text);
/* Fix up IDT entries to point into copied text. */
for (i = 0; i < IDT_ENTRIES; i++)
default_idt_entries[i] += switcher_offset();
for_each_possible_cpu(i) {
struct lguest_pages *pages = lguest_pages(i);
struct lguest_ro_state *state = &pages->state;
/* These fields are static: rest done in copy_in_guest_info */
state->host_gdt_desc.size = GDT_SIZE-1;
state->host_gdt_desc.address = (long)get_cpu_gdt_table(i);
store_idt(&state->host_idt_desc);
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;
state->guest_tss.esp0 = (long)(&pages->regs + 1);
state->guest_tss.ss0 = LGUEST_DS;
/* No I/O for you! */
state->guest_tss.io_bitmap_base = sizeof(state->guest_tss);
setup_default_gdt_entries(state);
setup_default_idt_entries(state, default_idt_entries);
/* Setup LGUEST segments on all cpus */
get_cpu_gdt_table(i)[GDT_ENTRY_LGUEST_CS] = FULL_EXEC_SEGMENT;
get_cpu_gdt_table(i)[GDT_ENTRY_LGUEST_DS] = FULL_SEGMENT;
}
/* Initialize entry point into switcher. */
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);
return 0;
free_vma:
vunmap(switcher_vma->addr);
free_pages:
i = TOTAL_SWITCHER_PAGES;
free_some_pages:
for (--i; i >= 0; i--)
__free_pages(switcher_page[i], 0);
kfree(switcher_page);
out:
return err;
}
static void unmap_switcher(void)
{
unsigned int i;
vunmap(switcher_vma->addr);
for (i = 0; i < TOTAL_SWITCHER_PAGES; i++)
__free_pages(switcher_page[i], 0);
}
/* IN/OUT insns: enough to get us past boot-time probing. */
static int emulate_insn(struct lguest *lg)
{
u8 insn;
unsigned int insnlen = 0, in = 0, shift = 0;
unsigned long physaddr = guest_pa(lg, lg->regs->eip);
/* This only works for addresses in linear mapping... */
if (lg->regs->eip < lg->page_offset)
return 0;
lgread(lg, &insn, physaddr, 1);
/* Operand size prefix means it's actually for ax. */
if (insn == 0x66) {
shift = 16;
insnlen = 1;
lgread(lg, &insn, physaddr + insnlen, 1);
}
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:
return 0;
}
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);
}
lg->regs->eip += insnlen;
return 1;
}
int lguest_address_ok(const struct lguest *lg,
unsigned long addr, unsigned long len)
{
return (addr+len) / PAGE_SIZE < lg->pfn_limit && (addr+len >= addr);
}
/* Just like get_user, but don't let guest access lguest binary. */
u32 lgread_u32(struct lguest *lg, unsigned long addr)
{
u32 val = 0;
/* Don't let them access lguest binary */
if (!lguest_address_ok(lg, addr, sizeof(val))
|| get_user(val, (u32 __user *)addr) != 0)
kill_guest(lg, "bad read address %#lx", addr);
return val;
}
void lgwrite_u32(struct lguest *lg, unsigned long addr, u32 val)
{
if (!lguest_address_ok(lg, addr, sizeof(val))
|| put_user(val, (u32 __user *)addr) != 0)
kill_guest(lg, "bad write address %#lx", addr);
}
void lgread(struct lguest *lg, void *b, unsigned long addr, unsigned bytes)
{
if (!lguest_address_ok(lg, addr, bytes)
|| copy_from_user(b, (void __user *)addr, bytes) != 0) {
/* copy_from_user should do this, but as we rely on it... */
memset(b, 0, bytes);
kill_guest(lg, "bad read address %#lx len %u", addr, bytes);
}
}
void lgwrite(struct lguest *lg, unsigned long addr, const void *b,
unsigned bytes)
{
if (!lguest_address_ok(lg, addr, bytes)
|| copy_to_user((void __user *)addr, b, bytes) != 0)
kill_guest(lg, "bad write address %#lx len %u", addr, bytes);
}
static void set_ts(void)
{
u32 cr0;
cr0 = read_cr0();
if (!(cr0 & 8))
write_cr0(cr0|8);
}
static void copy_in_guest_info(struct lguest *lg, struct lguest_pages *pages)
{
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 are pretty cheap, so we do them unconditionally. */
pages->state.host_cr3 = __pa(current->mm->pgd);
map_switcher_in_guest(lg, pages);
pages->state.guest_tss.esp1 = lg->esp1;
pages->state.guest_tss.ss1 = lg->ss1;
/* Copy direct trap entries. */
if (lg->changed & CHANGED_IDT)
copy_traps(lg, pages->state.guest_idt, default_idt_entries);
/* Copy all GDT entries but the TSS. */
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);
lg->changed = 0;
}
static void run_guest_once(struct lguest *lg, struct lguest_pages *pages)
{
unsigned int clobber;
copy_in_guest_info(lg, pages);
/* Put eflags on stack, lcall does rest: suitable for iret return. */
asm volatile("pushf; lcall *lguest_entry"
: "=a"(clobber), "=b"(clobber)
: "0"(pages), "1"(__pa(lg->pgdirs[lg->pgdidx].pgdir))
: "memory", "%edx", "%ecx", "%edi", "%esi");
}
int run_guest(struct lguest *lg, unsigned long __user *user)
{
while (!lg->dead) {
unsigned int cr2 = 0; /* Damn gcc */
/* Hypercalls first: we might have been out to userspace */
do_hypercalls(lg);
if (lg->dma_is_pending) {
if (put_user(lg->pending_dma, user) ||
put_user(lg->pending_key, user+1))
return -EFAULT;
return sizeof(unsigned long)*2;
}
if (signal_pending(current))
return -ERESTARTSYS;
/* If Waker set break_out, return to Launcher. */
if (lg->break_out)
return -EAGAIN;
maybe_do_interrupt(lg);
try_to_freeze();
if (lg->dead)
break;
if (lg->halted) {
set_current_state(TASK_INTERRUPTIBLE);
schedule();
continue;
}
local_irq_disable();
/* Even if *we* don't want FPU trap, guest might... */
if (lg->ts)
set_ts();
/* Don't let Guest do SYSENTER: we can't handle it. */
if (boot_cpu_has(X86_FEATURE_SEP))
wrmsr(MSR_IA32_SYSENTER_CS, 0, 0);
run_guest_once(lg, lguest_pages(raw_smp_processor_id()));
/* Save cr2 now if we page-faulted. */
if (lg->regs->trapnum == 14)
cr2 = read_cr2();
else if (lg->regs->trapnum == 7)
math_state_restore();
if (boot_cpu_has(X86_FEATURE_SEP))
wrmsr(MSR_IA32_SYSENTER_CS, __KERNEL_CS, 0);
local_irq_enable();
switch (lg->regs->trapnum) {
case 13: /* We've intercepted a GPF. */
if (lg->regs->errcode == 0) {
if (emulate_insn(lg))
continue;
}
break;
case 14: /* We've intercepted a page fault. */
if (demand_page(lg, cr2, lg->regs->errcode))
continue;
/* If lguest_data is NULL, this won't hurt. */
if (put_user(cr2, &lg->lguest_data->cr2))
kill_guest(lg, "Writing cr2");
break;
case 7: /* We've intercepted a Device Not Available fault. */
/* If they don't want to know, just absorb it. */
if (!lg->ts)
continue;
break;
case 32 ... 255: /* Real interrupt, fall thru */
cond_resched();
case LGUEST_TRAP_ENTRY: /* Handled at top of loop */
continue;
}
if (deliver_trap(lg, lg->regs->trapnum))
continue;
kill_guest(lg, "unhandled trap %li at %#lx (%#lx)",
lg->regs->trapnum, lg->regs->eip,
lg->regs->trapnum == 14 ? cr2 : lg->regs->errcode);
}
return -ENOENT;
}
int find_free_guest(void)
{
unsigned int i;
for (i = 0; i < MAX_LGUEST_GUESTS; i++)
if (!lguests[i].tsk)
return i;
return -1;
}
static void adjust_pge(void *on)
{
if (on)
write_cr4(read_cr4() | X86_CR4_PGE);
else
write_cr4(read_cr4() & ~X86_CR4_PGE);
}
static int __init init(void)
{
int err;
if (paravirt_enabled()) {
printk("lguest is afraid of %s\n", paravirt_ops.name);
return -EPERM;
}
err = map_switcher();
if (err)
return err;
err = init_pagetables(switcher_page, SHARED_SWITCHER_PAGES);
if (err) {
unmap_switcher();
return err;
}
lguest_io_init();
err = lguest_device_init();
if (err) {
free_pagetables();
unmap_switcher();
return err;
}
lock_cpu_hotplug();
if (cpu_has_pge) { /* We have a broader idea of "global". */
cpu_had_pge = 1;
on_each_cpu(adjust_pge, (void *)0, 0, 1);
clear_bit(X86_FEATURE_PGE, boot_cpu_data.x86_capability);
}
unlock_cpu_hotplug();
return 0;
}
static void __exit fini(void)
{
lguest_device_remove();
free_pagetables();
unmap_switcher();
lock_cpu_hotplug();
if (cpu_had_pge) {
set_bit(X86_FEATURE_PGE, boot_cpu_data.x86_capability);
on_each_cpu(adjust_pge, (void *)1, 0, 1);
}
unlock_cpu_hotplug();
}
module_init(init);
module_exit(fini);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Rusty Russell <rusty@rustcorp.com.au>");
/* Actual hypercalls, which allow guests to actually do something.
Copyright (C) 2006 Rusty Russell IBM Corporation
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <linux/uaccess.h>
#include <linux/syscalls.h>
#include <linux/mm.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <irq_vectors.h>
#include "lg.h"
static void do_hcall(struct lguest *lg, struct lguest_regs *regs)
{
switch (regs->eax) {
case LHCALL_FLUSH_ASYNC:
break;
case LHCALL_LGUEST_INIT:
kill_guest(lg, "already have lguest_data");
break;
case LHCALL_CRASH: {
char msg[128];
lgread(lg, msg, regs->edx, sizeof(msg));
msg[sizeof(msg)-1] = '\0';
kill_guest(lg, "CRASH: %s", msg);
break;
}
case LHCALL_FLUSH_TLB:
if (regs->edx)
guest_pagetable_clear_all(lg);
else
guest_pagetable_flush_user(lg);
break;
case LHCALL_GET_WALLCLOCK: {
struct timespec ts;
ktime_get_real_ts(&ts);
regs->eax = ts.tv_sec;
break;
}
case LHCALL_BIND_DMA:
regs->eax = bind_dma(lg, regs->edx, regs->ebx,
regs->ecx >> 8, regs->ecx & 0xFF);
break;
case LHCALL_SEND_DMA:
send_dma(lg, regs->edx, regs->ebx);
break;
case LHCALL_LOAD_GDT:
load_guest_gdt(lg, regs->edx, regs->ebx);
break;
case LHCALL_LOAD_IDT_ENTRY:
load_guest_idt_entry(lg, regs->edx, regs->ebx, regs->ecx);
break;
case LHCALL_NEW_PGTABLE:
guest_new_pagetable(lg, regs->edx);
break;
case LHCALL_SET_STACK:
guest_set_stack(lg, regs->edx, regs->ebx, regs->ecx);
break;
case LHCALL_SET_PTE:
guest_set_pte(lg, regs->edx, regs->ebx, mkgpte(regs->ecx));
break;
case LHCALL_SET_PMD:
guest_set_pmd(lg, regs->edx, regs->ebx);
break;
case LHCALL_LOAD_TLS:
guest_load_tls(lg, regs->edx);
break;
case LHCALL_SET_CLOCKEVENT:
guest_set_clockevent(lg, regs->edx);
break;
case LHCALL_TS:
lg->ts = regs->edx;
break;
case LHCALL_HALT:
lg->halted = 1;
break;
default:
kill_guest(lg, "Bad hypercall %li\n", regs->eax);
}
}
/* We always do queued calls before actual hypercall. */
static void do_async_hcalls(struct lguest *lg)
{
unsigned int i;
u8 st[LHCALL_RING_SIZE];
if (copy_from_user(&st, &lg->lguest_data->hcall_status, sizeof(st)))
return;
for (i = 0; i < ARRAY_SIZE(st); i++) {
struct lguest_regs regs;
unsigned int n = lg->next_hcall;
if (st[n] == 0xFF)
break;
if (++lg->next_hcall == LHCALL_RING_SIZE)
lg->next_hcall = 0;
if (get_user(regs.eax, &lg->lguest_data->hcalls[n].eax)
|| get_user(regs.edx, &lg->lguest_data->hcalls[n].edx)
|| get_user(regs.ecx, &lg->lguest_data->hcalls[n].ecx)
|| get_user(regs.ebx, &lg->lguest_data->hcalls[n].ebx)) {
kill_guest(lg, "Fetching async hypercalls");
break;
}
do_hcall(lg, &regs);
if (put_user(0xFF, &lg->lguest_data->hcall_status[n])) {