Commit 07ad157f authored by Rusty Russell's avatar Rusty Russell Committed by Linus Torvalds
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lguest: the guest code



lguest is a simple hypervisor for Linux on Linux.  Unlike kvm it doesn't need
VT/SVM hardware.  Unlike Xen it's simply "modprobe and go".  Unlike both, it's
5000 lines and self-contained.

Performance is ok, but not great (-30% on kernel compile).  But given its
hackability, I expect this to improve, along with the paravirt_ops code which
it supplies a complete example for.  There's also a 64-bit version being
worked on and other craziness.

But most of all, lguest is awesome fun!  Too much of the kernel is a big ball
of hair.  lguest is simple enough to dive into and hack, plus has some warts
which scream "fork me!".

This patch:

This is the code and headers required to make an i386 kernel an lguest guest.
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <ak@suse.de>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 5992b6da
/*
* Lguest specific paravirt-ops implementation
*
* 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/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>
/* 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 */
};
struct lguest_device_desc *lguest_devices;
static __initdata const struct lguest_boot_info *boot = __va(0);
static enum paravirt_lazy_mode lazy_mode;
static void lguest_lazy_mode(enum paravirt_lazy_mode mode)
{
if (mode == PARAVIRT_LAZY_FLUSH) {
if (unlikely(lazy_mode != PARAVIRT_LAZY_NONE))
hcall(LHCALL_FLUSH_ASYNC, 0, 0, 0);
} else {
lazy_mode = mode;
if (mode == PARAVIRT_LAZY_NONE)
hcall(LHCALL_FLUSH_ASYNC, 0, 0, 0);
}
}
static void lazy_hcall(unsigned long call,
unsigned long arg1,
unsigned long arg2,
unsigned long arg3)
{
if (lazy_mode == PARAVIRT_LAZY_NONE)
hcall(call, arg1, arg2, arg3);
else
async_hcall(call, arg1, arg2, arg3);
}
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;
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;
/* Make sure host sees arguments before "valid" flag. */
wmb();
lguest_data.hcall_status[next_call] = 0;
if (++next_call == LHCALL_RING_SIZE)
next_call = 0;
}
local_irq_restore(flags);
}
void lguest_send_dma(unsigned long key, struct lguest_dma *dma)
{
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)
{
if (!hcall(LHCALL_BIND_DMA, key, __pa(dmas), (num << 8) | irq))
return -ENOMEM;
return 0;
}
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);
}
static unsigned long save_fl(void)
{
return lguest_data.irq_enabled;
}
static void restore_fl(unsigned long flags)
{
/* FIXME: Check if interrupt pending... */
lguest_data.irq_enabled = flags;
}
static void irq_disable(void)
{
lguest_data.irq_enabled = 0;
}
static void irq_enable(void)
{
/* FIXME: Check if interrupt pending... */
lguest_data.irq_enabled = X86_EFLAGS_IF;
}
static void lguest_write_idt_entry(struct desc_struct *dt,
int entrynum, u32 low, u32 high)
{
write_dt_entry(dt, entrynum, low, high);
hcall(LHCALL_LOAD_IDT_ENTRY, entrynum, low, high);
}
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);
}
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);
}
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);
}
static void lguest_load_tls(struct thread_struct *t, unsigned int cpu)
{
lazy_hcall(LHCALL_LOAD_TLS, __pa(&t->tls_array), cpu, 0);
}
static void lguest_set_ldt(const void *addr, unsigned entries)
{
}
static void lguest_load_tr_desc(void)
{
}
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;
/* Similarly: SSE, SSE2, FXSR, MMX, CMOV, CMPXCHG8B, FPU. */
*edx &= 0x07808101;
/* Host wants to know when we flush kernel pages: set PGE. */
*edx |= 0x00002000;
break;
case 0x80000000:
/* Futureproof this a little: if they ask how much extended
* processor information, limit it to known fields. */
if (*eax > 0x80000008)
*eax = 0x80000008;
break;
}
}
static unsigned long current_cr0, current_cr3;
static void lguest_write_cr0(unsigned long val)
{
lazy_hcall(LHCALL_TS, val & 8, 0, 0);
current_cr0 = val;
}
static unsigned long lguest_read_cr0(void)
{
return current_cr0;
}
static void lguest_clts(void)
{
lazy_hcall(LHCALL_TS, 0, 0, 0);
current_cr0 &= ~8U;
}
static unsigned long lguest_read_cr2(void)
{
return lguest_data.cr2;
}
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;
}
/* Used to enable/disable PGE, but we don't care. */
static unsigned long lguest_read_cr4(void)
{
return 0;
}
static void lguest_write_cr4(unsigned long val)
{
}
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);
}
/* We only support two-level pagetables at the moment. */
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);
}
/* FIXME: Eliminate all callers of this. */
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);
}
static void lguest_flush_tlb_single(unsigned long addr)
{
/* Simply set it to zero, and it will fault back in. */
lazy_hcall(LHCALL_SET_PTE, current_cr3, addr, 0);
}
static void lguest_flush_tlb_user(void)
{
lazy_hcall(LHCALL_FLUSH_TLB, 0, 0, 0);
}
static void lguest_flush_tlb_kernel(void)
{
lazy_hcall(LHCALL_FLUSH_TLB, 1, 0, 0);
}
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);
/* FIXME: If it's pending? */
}
static struct irq_chip lguest_irq_controller = {
.name = "lguest",
.mask = disable_lguest_irq,
.mask_ack = disable_lguest_irq,
.unmask = enable_lguest_irq,
};
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);
}
}
irq_ctx_init(smp_processor_id());
}
static unsigned long lguest_get_wallclock(void)
{
return hcall(LHCALL_GET_WALLCLOCK, 0, 0, 0);
}
static void lguest_time_irq(unsigned int irq, struct irq_desc *desc)
{
do_timer(hcall(LHCALL_TIMER_READ, 0, 0, 0));
update_process_times(user_mode_vm(get_irq_regs()));
}
static u64 sched_clock_base;
static void lguest_time_init(void)
{
set_irq_handler(0, lguest_time_irq);
hcall(LHCALL_TIMER_READ, 0, 0, 0);
sched_clock_base = jiffies_64;
enable_lguest_irq(0);
}
static unsigned long long lguest_sched_clock(void)
{
return (jiffies_64 - sched_clock_base) * (1000000000 / HZ);
}
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);
}
static void lguest_set_debugreg(int regno, unsigned long value)
{
/* FIXME: Implement */
}
static void lguest_wbinvd(void)
{
}
#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
static void lguest_safe_halt(void)
{
hcall(LHCALL_HALT, 0, 0, 0);
}
static void lguest_power_off(void)
{
hcall(LHCALL_CRASH, __pa("Power down"), 0, 0);
}
static int lguest_panic(struct notifier_block *nb, unsigned long l, void *p)
{
hcall(LHCALL_CRASH, __pa(p), 0, 0);
return NOTIFY_DONE;
}
static struct notifier_block paniced = {
.notifier_call = lguest_panic
};
static __init char *lguest_memory_setup(void)
{
/* We do this here because lockcheck barfs if before start_kernel */
atomic_notifier_chain_register(&panic_notifier_list, &paniced);
e820.nr_map = 0;
add_memory_region(0, PFN_PHYS(boot->max_pfn), E820_RAM);
return "LGUEST";
}
static const struct lguest_insns
{
const char *start, *end;
} lguest_insns[] = {
[PARAVIRT_PATCH(irq_disable)] = { lgstart_cli, lgend_cli },
[PARAVIRT_PATCH(irq_enable)] = { lgstart_sti, lgend_sti },
[PARAVIRT_PATCH(restore_fl)] = { lgstart_popf, lgend_popf },
[PARAVIRT_PATCH(save_fl)] = { lgstart_pushf, lgend_pushf },
};
static unsigned lguest_patch(u8 type, u16 clobber, void *insns, unsigned len)
{
unsigned int insn_len;
/* Don't touch it if we don't have a replacement */
if (type >= ARRAY_SIZE(lguest_insns) || !lguest_insns[type].start)
return paravirt_patch_default(type, clobber, insns, len);
insn_len = lguest_insns[type].end - lguest_insns[type].start;
/* Similarly if we can't fit replacement. */
if (len < insn_len)
return paravirt_patch_default(type, clobber, insns, len);
memcpy(insns, lguest_insns[type].start, insn_len);
return insn_len;
}
__init void lguest_init(void)
{
paravirt_ops.name = "lguest";
paravirt_ops.paravirt_enabled = 1;
paravirt_ops.kernel_rpl = 1;
paravirt_ops.save_fl = save_fl;
paravirt_ops.restore_fl = restore_fl;
paravirt_ops.irq_disable = irq_disable;
paravirt_ops.irq_enable = irq_enable;
paravirt_ops.load_gdt = lguest_load_gdt;
paravirt_ops.memory_setup = lguest_memory_setup;
paravirt_ops.cpuid = lguest_cpuid;
paravirt_ops.write_cr3 = lguest_write_cr3;
paravirt_ops.flush_tlb_user = lguest_flush_tlb_user;
paravirt_ops.flush_tlb_single = lguest_flush_tlb_single;
paravirt_ops.flush_tlb_kernel = lguest_flush_tlb_kernel;
paravirt_ops.set_pte = lguest_set_pte;
paravirt_ops.set_pte_at = lguest_set_pte_at;
paravirt_ops.set_pmd = lguest_set_pmd;
#ifdef CONFIG_X86_LOCAL_APIC
paravirt_ops.apic_write = lguest_apic_write;
paravirt_ops.apic_write_atomic = lguest_apic_write;
paravirt_ops.apic_read = lguest_apic_read;
#endif
paravirt_ops.load_idt = lguest_load_idt;
paravirt_ops.iret = lguest_iret;
paravirt_ops.load_esp0 = lguest_load_esp0;
paravirt_ops.load_tr_desc = lguest_load_tr_desc;
paravirt_ops.set_ldt = lguest_set_ldt;
paravirt_ops.load_tls = lguest_load_tls;
paravirt_ops.set_debugreg = lguest_set_debugreg;
paravirt_ops.clts = lguest_clts;
paravirt_ops.read_cr0 = lguest_read_cr0;
paravirt_ops.write_cr0 = lguest_write_cr0;
paravirt_ops.init_IRQ = lguest_init_IRQ;
paravirt_ops.read_cr2 = lguest_read_cr2;
paravirt_ops.read_cr3 = lguest_read_cr3;
paravirt_ops.read_cr4 = lguest_read_cr4;
paravirt_ops.write_cr4 = lguest_write_cr4;
paravirt_ops.write_gdt_entry = lguest_write_gdt_entry;
paravirt_ops.write_idt_entry = lguest_write_idt_entry;
paravirt_ops.patch = lguest_patch;
paravirt_ops.safe_halt = lguest_safe_halt;
paravirt_ops.get_wallclock = lguest_get_wallclock;
paravirt_ops.time_init = lguest_time_init;
paravirt_ops.set_lazy_mode = lguest_lazy_mode;
paravirt_ops.wbinvd = lguest_wbinvd;
paravirt_ops.sched_clock = lguest_sched_clock;
hcall(LHCALL_LGUEST_INIT, __pa(&lguest_data), 0, 0);
strncpy(boot_command_line, boot->cmdline, COMMAND_LINE_SIZE);
/* We use top of mem for initial pagetables. */
init_pg_tables_end = __pa(pg0);
asm volatile ("mov %0, %%fs" : : "r" (__KERNEL_DS) : "memory");
reserve_top_address(lguest_data.reserve_mem);
lockdep_init();
paravirt_disable_iospace();
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
add_preferred_console("hvc", 0, NULL);
if (boot->initrd_size) {
/* We stash this at top of memory. */
INITRD_START = boot->max_pfn*PAGE_SIZE - boot->initrd_size;
INITRD_SIZE = boot->initrd_size;
LOADER_TYPE = 0xFF;
}
pm_power_off = lguest_power_off;
start_kernel();
}
#include <linux/linkage.h>
#include <linux/lguest.h>
#include <asm/asm-offsets.h>
#include <asm/thread_info.h>
/* FIXME: Once asm/processor-flags.h goes in, include that */
#define X86_EFLAGS_IF 0x00000200
/*
* 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.
*
* We put it in .init.text will be discarded after boot.
*/
.section .init.text, "ax", @progbits
.ascii "GenuineLguest"
/* Set up initial stack. */
movl $(init_thread_union+THREAD_SIZE),%esp
jmp lguest_init
/* The templates for inline patching. */
#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)
.text
/* These demark the EIP range where host should never deliver interrupts. */
.global lguest_noirq_start
.global lguest_noirq_end
/*
* We move eflags word to lguest_data.irq_enabled to restore interrupt state.
* For page faults, gpfs and virtual interrupts, the hypervisor has saved
* eflags manually, otherwise it was delivered directly and so eflags reflects
* the real machine IF state, ie. interrupts on. Since the kernel always dies
* if it takes such a trap with interrupts disabled anyway, turning interrupts
* back on unconditionally here is OK.
*/
ENTRY(lguest_iret)
pushl %eax
movl 12(%esp), %eax
lguest_noirq_start:
movl %eax,%ss:lguest_data+LGUEST_DATA_irq_enabled
popl %eax
iret
lguest_noirq_end:
#include <linux/init.h>
#include <linux/bootmem.h>
#include <linux/lguest_bus.h>
#include <asm/io.h>
static ssize_t type_show(struct device *_dev,
struct device_attribute *attr, char *buf)
{
struct lguest_device *dev = container_of(_dev,struct lguest_device,dev);
return sprintf(buf, "%hu", lguest_devices[dev->index].type);
}
static ssize_t features_show(struct device *_dev,
struct device_attribute *attr, char *buf)
{
struct lguest_device *dev = container_of(_dev,struct lguest_device,dev);
return sprintf(buf, "%hx", lguest_devices[dev->index].features);
}