* [PATCH 5 of 7] lguest: the host code (lg.ko).
2007-02-09 15:09 ` [PATCH 4 of 7] lguest: Config and headers Rusty Russell
@ 2007-02-09 15:14 ` Rusty Russell
2007-02-09 15:17 ` [PATCH 6 of 7] lguest: Guest code Rusty Russell
2007-02-09 18:15 ` [PATCH 4 of 7] lguest: Config and headers James Morris
1 sibling, 1 reply; 12+ messages in thread
From: Rusty Russell @ 2007-02-09 15:14 UTC (permalink / raw)
To: lkml - Kernel Mailing List; +Cc: Andi Kleen, Andrew Morton, virtualization
[ This is patch 6b, with the following Andifications:
1) lguest_entry is now mark used: after the other changes, gcc
optimized it out.
2) Use header to define math_state_restore, not manual extern.
3) try_to_freeze() inside run loop.
4) cpu_hotplug locks on init and exit code as we frob PGE on all cpus.
5) Remove the log() macro which so amused lkml.
6) switch in IDT interpreting code instead of if chaining. ]
This is the host module (lg.ko) which supports lguest:
arch/i386/lguest/hypervisor.S:
The actual guest <-> host switching code. This is compiled into
a C array, which is mapped to 0xFFC01000 in host and guests.
arch/i386/lguest/core.c:
The core of the hypervisor, which calls into the assembler
code which does this actual switch. Also contains helper
routines.
arch/i386/lguest/hypercalls.c:
The entry point for the 19 hypercalls.
arch/i386/lguest/interrupts_and_traps.c:
Handling of interrupts and traps, except page faults.
arch/i386/lguest/io.c:
I/O from guest to host, and between guests.
arch/i386/lguest/lguest_user.c:
/dev/lguest interface for lguest program to launch/control guests.
arch/i386/lguest/page_tables.c:
Shadow Page table handling: generally we build up the shadow
page tables by converting from guest page tables when a fault occurs.
arch/i386/lguest/segments.c:
Segmentation (GDT) handling: we have to ensure they're trimmed
to avoid guest access to the switching code.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
===================================================================
--- /dev/null
+++ b/arch/i386/lguest/core.c
@@ -0,0 +1,432 @@
+/* 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/lguest.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"
+
+/* This is our hypervisor, compiled from hypervisor.S. */
+static char __initdata hypervisor_blob[] = {
+#include "hypervisor-blob.c"
+};
+
+#define MAX_LGUEST_GUESTS \
+ (((1 << HYPERVISOR_MAP_ORDER) - sizeof(hypervisor_blob)) \
+ / sizeof(struct lguest_state))
+
+static struct vm_struct *hypervisor_vma;
+static int cpu_had_pge;
+static struct {
+ unsigned long offset;
+ unsigned short segment;
+} lguest_entry __attribute_used__;
+struct page *hype_pages; /* Contiguous pages. */
+struct lguest lguests[MAX_LGUEST_GUESTS];
+DEFINE_MUTEX(lguest_lock);
+
+/* IDT entries are at start of hypervisor. */
+const unsigned long *__lguest_default_idt_entries(void)
+{
+ return (void *)HYPE_ADDR;
+}
+
+/* Next is switch_to_guest */
+static void *__lguest_switch_to_guest(void)
+{
+ return (void *)HYPE_ADDR + HYPE_DATA_SIZE;
+}
+
+/* Then we use everything else to hold guest state. */
+struct lguest_state *__lguest_states(void)
+{
+ return (void *)HYPE_ADDR + sizeof(hypervisor_blob);
+}
+
+static __init int map_hypervisor(void)
+{
+ unsigned int i;
+ int err;
+ struct page *pages[HYPERVISOR_PAGES], **pagep = pages;
+
+ hype_pages = alloc_pages(GFP_KERNEL|__GFP_ZERO, HYPERVISOR_MAP_ORDER);
+ if (!hype_pages)
+ return -ENOMEM;
+
+ hypervisor_vma = __get_vm_area(1 << HYPERVISOR_MAP_ORDER, VM_ALLOC,
+ HYPE_ADDR, VMALLOC_END);
+ if (!hypervisor_vma) {
+ err = -ENOMEM;
+ printk("lguest: could not map hypervisor pages high\n");
+ goto free_pages;
+ }
+
+ for (i = 0; i < HYPERVISOR_PAGES; i++)
+ pages[i] = hype_pages + i;
+
+ err = map_vm_area(hypervisor_vma, PAGE_KERNEL, &pagep);
+ if (err) {
+ printk("lguest: map_vm_area failed: %i\n", err);
+ goto free_vma;
+ }
+ memcpy(hypervisor_vma->addr, hypervisor_blob, sizeof(hypervisor_blob));
+
+ /* Setup LGUEST segments on all cpus */
+ for_each_possible_cpu(i) {
+ 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 hypervisor. */
+ lguest_entry.offset = (long)__lguest_switch_to_guest();
+ lguest_entry.segment = LGUEST_CS;
+
+ printk("lguest: mapped hypervisor at %p\n", hypervisor_vma->addr);
+ return 0;
+
+free_vma:
+ vunmap(hypervisor_vma->addr);
+free_pages:
+ __free_pages(hype_pages, HYPERVISOR_MAP_ORDER);
+ return err;
+}
+
+static __exit void unmap_hypervisor(void)
+{
+ vunmap(hypervisor_vma->addr);
+ __free_pages(hype_pages, HYPERVISOR_MAP_ORDER);
+}
+
+/* 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->state->regs.eip);
+
+ /* This only works for addresses in linear mapping... */
+ if (lg->state->regs.eip < lg->page_offset)
+ return 0;
+ lhread(lg, &insn, physaddr, 1);
+
+ /* Operand size prefix means it's actually for ax. */
+ if (insn == 0x66) {
+ shift = 16;
+ insnlen = 1;
+ lhread(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->state->regs.eax = 0xFFFFFFFF;
+ else
+ lg->state->regs.eax |= (0xFFFF << shift);
+ }
+ lg->state->regs.eip += insnlen;
+ return 1;
+}
+
+int find_free_guest(void)
+{
+ unsigned int i;
+ for (i = 0; i < MAX_LGUEST_GUESTS; i++)
+ if (!lguests[i].state)
+ return i;
+ return -1;
+}
+
+int lguest_address_ok(const struct lguest *lg, unsigned long addr)
+{
+ return addr / PAGE_SIZE < lg->pfn_limit;
+}
+
+/* Just like get_user, but don't let guest access lguest binary. */
+u32 lhread_u32(struct lguest *lg, u32 addr)
+{
+ u32 val = 0;
+
+ /* Don't let them access lguest_add */
+ if (!lguest_address_ok(lg, addr)
+ || get_user(val, (u32 __user *)addr) != 0)
+ kill_guest(lg, "bad read address %u", addr);
+ return val;
+}
+
+void lhwrite_u32(struct lguest *lg, u32 addr, u32 val)
+{
+ if (!lguest_address_ok(lg, addr)
+ || put_user(val, (u32 __user *)addr) != 0)
+ kill_guest(lg, "bad write address %u", addr);
+}
+
+void lhread(struct lguest *lg, void *b, u32 addr, unsigned bytes)
+{
+ if (addr + bytes < addr || !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 %u len %u", addr, bytes);
+ }
+}
+
+void lhwrite(struct lguest *lg, u32 addr, const void *b, unsigned bytes)
+{
+ if (addr + bytes < addr
+ || !lguest_address_ok(lg, addr+bytes)
+ || copy_to_user((void __user *)addr, b, bytes) != 0)
+ kill_guest(lg, "bad write address %u len %u", addr, bytes);
+}
+
+/* Saves exporting idt_table from kernel */
+static struct desc_struct *get_idt_table(void)
+{
+ struct Xgt_desc_struct idt;
+
+ asm("sidt %0":"=m" (idt));
+ return (void *)idt.address;
+}
+
+static int usermode(struct lguest_regs *regs)
+{
+ return (regs->cs & SEGMENT_RPL_MASK) == USER_RPL;
+}
+
+/* Trap page resets this when it reloads gs. */
+static int new_gfp_eip(struct lguest *lg, struct lguest_regs *regs)
+{
+ u32 eip;
+ get_user(eip, &lg->lguest_data->gs_gpf_eip);
+ if (eip == regs->eip)
+ return 0;
+ put_user(regs->eip, &lg->lguest_data->gs_gpf_eip);
+ return 1;
+}
+
+static void set_ts(unsigned int guest_ts)
+{
+ u32 cr0;
+ if (guest_ts) {
+ asm("movl %%cr0,%0":"=r" (cr0));
+ if (!(cr0 & 8))
+ asm("movl %0,%%cr0": :"r" (cr0|8));
+ }
+}
+
+static void run_guest_once(struct lguest *lg)
+{
+ unsigned int clobber;
+
+ /* Put eflags on stack, lcall does rest. */
+ asm volatile("pushf; lcall *lguest_entry"
+ : "=a"(clobber), "=d"(clobber)
+ : "0"(lg->state), "1"(get_idt_table())
+ : "memory");
+}
+
+int run_guest(struct lguest *lg, char *__user user)
+{
+ struct lguest_regs *regs = &lg->state->regs;
+
+ while (!lg->dead) {
+ unsigned int cr2 = 0; /* Damn gcc */
+
+ /* Hypercalls first: we might have been out to userspace */
+ if (do_async_hcalls(lg))
+ goto pending_dma;
+
+ if (regs->trapnum == LGUEST_TRAP_ENTRY) {
+ /* Only do hypercall once. */
+ regs->trapnum = 255;
+ if (hypercall(lg, regs))
+ goto pending_dma;
+ }
+
+ if (signal_pending(current))
+ return -EINTR;
+ maybe_do_interrupt(lg);
+
+ try_to_freeze();
+
+ if (lg->dead)
+ break;
+
+ if (lg->halted) {
+ set_current_state(TASK_INTERRUPTIBLE);
+ schedule_timeout(1);
+ continue;
+ }
+
+ /* Restore limits on TLS segments if in user mode. */
+ if (usermode(regs)) {
+ unsigned int i;
+ for (i = 0; i < ARRAY_SIZE(lg->tls_limits); i++)
+ lg->state->gdt_table[GDT_ENTRY_TLS_MIN+i].a
+ |= lg->tls_limits[i];
+ }
+
+ local_irq_disable();
+ map_trap_page(lg);
+
+ /* Host state to be restored after the guest returns. */
+ asm("sidt %0":"=m"(lg->state->host.idt));
+ lg->state->host.gdt = __get_cpu_var(cpu_gdt_descr);
+
+ /* Even if *we* don't want FPU trap, guest might... */
+ set_ts(lg->ts);
+
+ run_guest_once(lg);
+
+ /* Save cr2 now if we page-faulted. */
+ if (regs->trapnum == 14)
+ asm("movl %%cr2,%0" :"=r" (cr2));
+ else if (regs->trapnum == 7)
+ math_state_restore();
+ local_irq_enable();
+
+ switch (regs->trapnum) {
+ case 13: /* We've intercepted a GPF. */
+ if (regs->errcode == 0) {
+ if (emulate_insn(lg))
+ continue;
+
+ /* FIXME: If it's reloading %gs in a loop? */
+ if (usermode(regs) && new_gfp_eip(lg,regs))
+ continue;
+ }
+
+ if (reflect_trap(lg, &lg->gpf_trap, 1))
+ continue;
+ break;
+ case 14: /* We've intercepted a page fault. */
+ if (demand_page(lg, cr2, regs->errcode & 2))
+ continue;
+
+ /* If lguest_data is NULL, this won't hurt. */
+ put_user(cr2, &lg->lguest_data->cr2);
+ if (reflect_trap(lg, &lg->page_trap, 1))
+ continue;
+ kill_guest(lg, "unhandled page fault at %#x"
+ " (eip=%#x, errcode=%#x)",
+ cr2, regs->eip, regs->errcode);
+ 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;
+ if (reflect_trap(lg, &lg->fpu_trap, 0))
+ continue;
+ kill_guest(lg, "unhandled FPU fault at %#x",
+ regs->eip);
+ break;
+ case 32 ... 255: /* Real interrupt, fall thru */
+ cond_resched();
+ case LGUEST_TRAP_ENTRY: /* Handled at top of loop */
+ continue;
+ case 6: /* Invalid opcode before they installed handler */
+ check_bug_kill(lg);
+ }
+ kill_guest(lg,"unhandled trap %i at %#x (err=%i)",
+ regs->trapnum, regs->eip, regs->errcode);
+ }
+ return -ENOENT;
+
+pending_dma:
+ put_user(lg->pending_dma, (unsigned long *)user);
+ put_user(lg->pending_addr, (unsigned long *)user+1);
+ return sizeof(unsigned long)*2;
+}
+
+#define STRUCT_LGUEST_ELEM_SIZE(elem) sizeof(((struct lguest_state *)0)->elem)
+
+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())
+ return -EPERM;
+
+ err = map_hypervisor();
+ if (err)
+ return err;
+
+ err = init_pagetables(hype_pages);
+ if (err) {
+ unmap_hypervisor();
+ return err;
+ }
+ lguest_io_init();
+
+ err = lguest_device_init();
+ if (err) {
+ free_pagetables();
+ unmap_hypervisor();
+ 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, 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_hypervisor();
+ 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>");
===================================================================
--- /dev/null
+++ b/arch/i386/lguest/hypercalls.c
@@ -0,0 +1,189 @@
+/* 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 <linux/clocksource.h>
+#include <asm/lguest.h>
+#include <asm/page.h>
+#include <asm/pgtable.h>
+#include <irq_vectors.h>
+#include "lg.h"
+
+static void guest_set_stack(struct lguest *lg,
+ u32 seg, u32 esp, unsigned int pages)
+{
+ /* You cannot have a stack segment with priv level 0. */
+ if ((seg & 0x3) != GUEST_DPL)
+ kill_guest(lg, "bad stack segment %i", seg);
+ if (pages > 2)
+ kill_guest(lg, "bad stack pages %u", pages);
+ lg->state->tss.ss1 = seg;
+ lg->state->tss.esp1 = esp;
+ lg->stack_pages = pages;
+ pin_stack_pages(lg);
+}
+
+/* Return true if DMA to host userspace now pending. */
+static int 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];
+ lhread(lg, msg, regs->edx, sizeof(msg));
+ msg[sizeof(msg)-1] = '\0';
+ kill_guest(lg, "CRASH: %s", msg);
+ break;
+ }
+ case LHCALL_LOAD_GDT:
+ load_guest_gdt(lg, regs->edx, regs->ebx);
+ break;
+ case LHCALL_NEW_PGTABLE:
+ guest_new_pagetable(lg, regs->edx);
+ break;
+ case LHCALL_FLUSH_TLB:
+ if (regs->edx)
+ guest_pagetable_clear_all(lg);
+ else
+ guest_pagetable_flush_user(lg);
+ break;
+ case LHCALL_LOAD_IDT_ENTRY:
+ load_guest_idt_entry(lg, regs->edx, regs->ebx, regs->ecx);
+ break;
+ case LHCALL_SET_STACK:
+ guest_set_stack(lg, regs->edx, regs->ebx, regs->ecx);
+ break;
+ case LHCALL_TS:
+ lg->ts = regs->edx;
+ break;
+ case LHCALL_TIMER_READ: {
+ u32 now = jiffies;
+ mb();
+ regs->eax = now - lg->last_timer;
+ lg->last_timer = now;
+ break;
+ }
+ case LHCALL_TIMER_START:
+ lg->timer_on = 1;
+ if (regs->edx != HZ)
+ kill_guest(lg, "Bad clock speed %i", regs->edx);
+ lg->last_timer = jiffies;
+ break;
+ case LHCALL_HALT:
+ lg->halted = 1;
+ break;
+ case LHCALL_GET_WALLCLOCK: {
+ struct timeval tv;
+ do_gettimeofday(&tv);
+ regs->eax = tv.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:
+ return send_dma(lg, regs->edx, regs->ebx);
+ case LHCALL_SET_PTE:
+ guest_set_pte(lg, regs->edx, regs->ebx, regs->ecx);
+ break;
+ case LHCALL_SET_UNKNOWN_PTE:
+ guest_pagetable_clear_all(lg);
+ break;
+ case LHCALL_SET_PUD:
+ guest_set_pud(lg, regs->edx, regs->ebx);
+ break;
+ case LHCALL_LOAD_TLS:
+ guest_load_tls(lg, (struct desc_struct __user*)regs->edx);
+ break;
+ default:
+ kill_guest(lg, "Bad hypercall %i\n", regs->eax);
+ }
+ return 0;
+}
+
+/* We always do queued calls before actual hypercall. */
+int do_async_hcalls(struct lguest *lg)
+{
+ unsigned int i, pending;
+ u8 st[LHCALL_RING_SIZE];
+
+ if (!lg->lguest_data)
+ return 0;
+
+ copy_from_user(&st, &lg->lguest_data->hcall_status, sizeof(st));
+ 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;
+
+ 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);
+ pending = do_hcall(lg, ®s);
+ put_user(0xFF, &lg->lguest_data->hcall_status[n]);
+ if (pending)
+ return 1;
+ }
+
+ set_wakeup_process(lg, NULL);
+ return 0;
+}
+
+int hypercall(struct lguest *lg, struct lguest_regs *regs)
+{
+ int pending;
+
+ if (!lg->lguest_data) {
+ if (regs->eax != LHCALL_LGUEST_INIT) {
+ kill_guest(lg, "hypercall %i before LGUEST_INIT",
+ regs->eax);
+ return 0;
+ }
+
+ lg->lguest_data = (struct lguest_data __user *)regs->edx;
+ /* We check here so we can simply copy_to_user/from_user */
+ if (!lguest_address_ok(lg, (long)lg->lguest_data)
+ || !lguest_address_ok(lg, (long)(lg->lguest_data+1))){
+ kill_guest(lg, "bad guest page %p", lg->lguest_data);
+ return 0;
+ }
+ get_user(lg->noirq_start, &lg->lguest_data->noirq_start);
+ get_user(lg->noirq_end, &lg->lguest_data->noirq_end);
+ /* We reserve the top pgd entry. */
+ put_user(4U*1024*1024, &lg->lguest_data->reserve_mem);
+ put_user(lg->guestid, &lg->lguest_data->guestid);
+ put_user(clocksource_khz2mult(tsc_khz, 22),
+ &lg->lguest_data->clock_mult);
+ return 0;
+ }
+ pending = do_hcall(lg, regs);
+ set_wakeup_process(lg, NULL);
+ return pending;
+}
===================================================================
--- /dev/null
+++ b/arch/i386/lguest/hypervisor.S
@@ -0,0 +1,170 @@
+/* This code sits at 0xFFFF1000 to do the low-level guest<->host switch.
+ Layout is: default_idt_entries (1k), then switch_to_guest entry point. */
+#include <linux/linkage.h>
+#include <asm/asm-offsets.h>
+#include "lg.h"
+
+#define SAVE_REGS \
+ /* Save old guest/host state */ \
+ pushl %es; \
+ pushl %ds; \
+ pushl %fs; \
+ pushl %eax; \
+ pushl %gs; \
+ pushl %ebp; \
+ pushl %edi; \
+ pushl %esi; \
+ pushl %edx; \
+ pushl %ecx; \
+ pushl %ebx; \
+
+.text
+ENTRY(_start) /* ld complains unless _start is defined. */
+/* %eax contains ptr to target guest state, %edx contains host idt. */
+switch_to_guest:
+ pushl %ss
+ SAVE_REGS
+ /* Save old stack, switch to guest's stack. */
+ movl %esp, LGUEST_STATE_host_stackptr(%eax)
+ movl %eax, %esp
+ /* Guest registers will be at: %esp-$LGUEST_STATE_regs */
+ addl $LGUEST_STATE_regs, %esp
+ /* Switch to guest's GDT, IDT. */
+ lgdt LGUEST_STATE_gdt(%eax)
+ lidt LGUEST_STATE_idt(%eax)
+ /* Save page table top. */
+ movl %cr3, %ebx
+ movl %ebx, LGUEST_STATE_host_pgdir(%eax)
+ /* Set host's TSS to available (clear byte 5 bit 2). */
+ movl (LGUEST_STATE_host_gdt+2)(%eax), %ebx
+ andb $0xFD, (GDT_ENTRY_TSS*8 + 5)(%ebx)
+ /* Switch to guest page tables */
+ popl %ebx
+ movl %ebx, %cr3
+ /* Switch to guest's TSS. */
+ movl $(GDT_ENTRY_TSS*8), %ebx
+ ltr %bx
+ /* Restore guest regs */
+ popl %ebx
+ popl %ecx
+ popl %edx
+ popl %esi
+ popl %edi
+ popl %ebp
+ popl %gs
+ /* Now we've loaded gs, neuter the TLS entries down to 1 byte/page */
+ addl $(LGUEST_STATE_gdt_table+GDT_ENTRY_TLS_MIN*8), %eax
+ movw $0,(%eax)
+ movw $0,8(%eax)
+ movw $0,16(%eax)
+ popl %eax
+ popl %fs
+ popl %ds
+ popl %es
+ /* Skip error code and trap number */
+ addl $8, %esp
+ iret
+
+#define SWITCH_TO_HOST \
+ SAVE_REGS; \
+ /* Save old pgdir */ \
+ movl %cr3, %eax; \
+ pushl %eax; \
+ /* Load lguest ds segment for convenience. */ \
+ movl $(LGUEST_DS), %eax; \
+ movl %eax, %ds; \
+ /* Now figure out who we are */ \
+ movl %esp, %eax; \
+ subl $LGUEST_STATE_regs, %eax; \
+ /* Switch to host page tables (GDT, IDT and stack are in host \
+ mem, so need this first) */ \
+ movl LGUEST_STATE_host_pgdir(%eax), %ebx; \
+ movl %ebx, %cr3; \
+ /* Set guest's TSS to available (clear byte 5 bit 2). */ \
+ andb $0xFD, (LGUEST_STATE_gdt_table+GDT_ENTRY_TSS*8+5)(%eax);\
+ /* Switch to host's GDT & IDT. */ \
+ lgdt LGUEST_STATE_host_gdt(%eax); \
+ lidt LGUEST_STATE_host_idt(%eax); \
+ /* Switch to host's stack. */ \
+ movl LGUEST_STATE_host_stackptr(%eax), %esp; \
+ /* Switch to host's TSS */ \
+ movl $(GDT_ENTRY_TSS*8), %eax; \
+ ltr %ax; \
+ /* Restore host regs */ \
+ popl %ebx; \
+ popl %ecx; \
+ popl %edx; \
+ popl %esi; \
+ popl %edi; \
+ popl %ebp; \
+ popl %gs; \
+ popl %eax; \
+ popl %fs; \
+ popl %ds; \
+ popl %es; \
+ popl %ss
+
+/* Return to run_guest_once. */
+return_to_host:
+ SWITCH_TO_HOST
+ iret
+
+deliver_to_host:
+ SWITCH_TO_HOST
+decode_idt_and_jmp:
+ /* Decode IDT and jump to hosts' irq handler. When that does iret, it
+ * will return to run_guest_once. This is a feature. */
+ /* We told gcc we'd clobber edx and eax... */
+ movl LGUEST_STATE_trapnum(%eax), %eax
+ leal (%edx,%eax,8), %eax
+ movzwl (%eax),%edx
+ movl 4(%eax), %eax
+ xorw %ax, %ax
+ orl %eax, %edx
+ jmp *%edx
+
+deliver_to_host_with_errcode:
+ SWITCH_TO_HOST
+ pushl LGUEST_STATE_errcode(%eax)
+ jmp decode_idt_and_jmp
+
+/* Real hardware interrupts are delivered straight to the host. Others
+ cause us to return to run_guest_once so it can decide what to do. Note
+ that some of these are overridden by the guest to deliver directly, and
+ never enter here (see load_guest_idt_entry). */
+.macro IRQ_STUB N TARGET
+ .data; .long 1f; .text; 1:
+ /* Make an error number for most traps, which don't have one. */
+ .if (\N <> 2) && (\N <> 8) && (\N < 10 || \N > 14) && (\N <> 17)
+ pushl $0
+ .endif
+ pushl $\N
+ jmp \TARGET
+ ALIGN
+.endm
+
+.macro IRQ_STUBS FIRST LAST TARGET
+ irq=\FIRST
+ .rept \LAST-\FIRST+1
+ IRQ_STUB irq \TARGET
+ irq=irq+1
+ .endr
+.endm
+
+/* We intercept every interrupt, because we may need to switch back to
+ * host. Unfortunately we can't tell them apart except by entry
+ * point, so we need 256 entry points.
+ */
+irq_stubs:
+.data
+default_idt_entries:
+.text
+ IRQ_STUBS 0 1 return_to_host /* First two traps */
+ IRQ_STUB 2 deliver_to_host_with_errcode /* NMI */
+ IRQ_STUBS 3 31 return_to_host /* Rest of traps */
+ IRQ_STUBS 32 127 deliver_to_host /* Real interrupts */
+ IRQ_STUB 128 return_to_host /* System call (overridden) */
+ IRQ_STUBS 129 255 deliver_to_host /* Other real interrupts */
+
+/* Everything after this is used for the lguest_state structs. */
+ALIGN
===================================================================
--- /dev/null
+++ b/arch/i386/lguest/interrupts_and_traps.c
@@ -0,0 +1,230 @@
+#include <linux/uaccess.h>
+#include "lg.h"
+
+static void push_guest_stack(struct lguest *lg, u32 __user **gstack, u32 val)
+{
+ lhwrite_u32(lg, (u32)--(*gstack), val);
+}
+
+int reflect_trap(struct lguest *lg, const struct host_trap *trap, int has_err)
+{
+ u32 __user *gstack;
+ u32 eflags, ss, irq_enable;
+ struct lguest_regs *regs = &lg->state->regs;
+
+ if (!trap->addr)
+ return 0;
+
+ /* If they want a ring change, we use new stack and push old ss/esp */
+ if ((regs->ss&0x3) != GUEST_DPL) {
+ gstack = (u32 __user *)guest_pa(lg, lg->state->tss.esp1);
+ ss = lg->state->tss.ss1;
+ push_guest_stack(lg, &gstack, regs->ss);
+ push_guest_stack(lg, &gstack, regs->esp);
+ } else {
+ gstack = (u32 __user *)guest_pa(lg, regs->esp);
+ ss = regs->ss;
+ }
+
+ /* We use IF bit in eflags to indicate whether irqs were disabled
+ (it's always 0, since irqs are enabled when guest is running). */
+ eflags = regs->eflags;
+ get_user(irq_enable, &lg->lguest_data->irq_enabled);
+ eflags |= (irq_enable & 512);
+
+ push_guest_stack(lg, &gstack, eflags);
+ push_guest_stack(lg, &gstack, regs->cs);
+ push_guest_stack(lg, &gstack, regs->eip);
+
+ if (has_err)
+ push_guest_stack(lg, &gstack, regs->errcode);
+
+ /* Change the real stack so hypervisor returns to trap handler */
+ regs->ss = ss;
+ regs->esp = (u32)gstack + lg->page_offset;
+ regs->cs = (__KERNEL_CS|GUEST_DPL);
+ regs->eip = trap->addr;
+
+ /* GS will be neutered on way back to guest. */
+ put_user(0, &lg->lguest_data->gs_gpf_eip);
+
+ /* Disable interrupts for an interrupt gate. */
+ if (trap->disable_interrupts)
+ put_user(0, &lg->lguest_data->irq_enabled);
+ return 1;
+}
+
+void maybe_do_interrupt(struct lguest *lg)
+{
+ unsigned int irq;
+ DECLARE_BITMAP(irqs, LGUEST_IRQS);
+
+ if (!lg->lguest_data)
+ return;
+
+ /* If timer has changed, set timer interrupt. */
+ if (lg->timer_on && jiffies != lg->last_timer)
+ set_bit(0, lg->irqs_pending);
+
+ /* Mask out any interrupts they have blocked. */
+ copy_from_user(&irqs, lg->lguest_data->interrupts, sizeof(irqs));
+ bitmap_andnot(irqs, lg->irqs_pending, irqs, LGUEST_IRQS);
+
+ irq = find_first_bit(irqs, LGUEST_IRQS);
+ if (irq >= LGUEST_IRQS)
+ return;
+
+ /* If they're halted, we re-enable interrupts. */
+ if (lg->halted) {
+ /* Re-enable interrupts. */
+ put_user(512, &lg->lguest_data->irq_enabled);
+ lg->halted = 0;
+ } else {
+ /* Maybe they have interrupts disabled? */
+ u32 irq_enabled;
+ get_user(irq_enabled, &lg->lguest_data->irq_enabled);
+ if (!irq_enabled)
+ return;
+ }
+
+ if (lg->interrupt[irq].addr != 0) {
+ clear_bit(irq, lg->irqs_pending);
+ reflect_trap(lg, &lg->interrupt[irq], 0);
+ }
+}
+
+void check_bug_kill(struct lguest *lg)
+{
+#ifdef CONFIG_BUG
+ u32 eip = lg->state->regs.eip - PAGE_OFFSET;
+ u16 insn;
+
+ /* This only works for addresses in linear mapping... */
+ if (lg->state->regs.eip < PAGE_OFFSET)
+ return;
+ lhread(lg, &insn, eip, sizeof(insn));
+ if (insn == 0x0b0f) {
+#ifdef CONFIG_DEBUG_BUGVERBOSE
+ u16 l;
+ u32 f;
+ char file[128];
+ lhread(lg, &l, eip+sizeof(insn), sizeof(l));
+ lhread(lg, &f, eip+sizeof(insn)+sizeof(l), sizeof(f));
+ lhread(lg, file, f - PAGE_OFFSET, sizeof(file));
+ file[sizeof(file)-1] = 0;
+ kill_guest(lg, "BUG() at %#x %s:%u", eip, file, l);
+#else
+ kill_guest(lg, "BUG() at %#x", eip);
+#endif /* CONFIG_DEBUG_BUGVERBOSE */
+ }
+#endif /* CONFIG_BUG */
+}
+
+static void copy_trap(struct lguest *lg,
+ struct host_trap *trap,
+ const struct desc_struct *desc)
+{
+ u8 type = ((desc->b >> 8) & 0xF);
+
+ /* Not present? */
+ if (!(desc->b & 0x8000)) {
+ trap->addr = 0;
+ return;
+ }
+ if (type != 0xE && type != 0xF)
+ kill_guest(lg, "bad IDT type %i", type);
+ trap->disable_interrupts = (type == 0xE);
+ trap->addr = ((desc->a & 0x0000FFFF) | (desc->b & 0xFFFF0000));
+}
+
+/* FIXME: Put this in hypervisor.S and do something clever with relocs? */
+static u8 tramp[]
+= { 0x0f, 0xa8, 0x0f, 0xa9, /* push %gs; pop %gs */
+ 0x36, 0xc7, 0x05, 0x55, 0x55, 0x55, 0x55, 0x00, 0x00, 0x00, 0x00,
+ /* movl 0, %ss:lguest_data.gs_gpf_eip */
+ 0xe9, 0x55, 0x55, 0x55, 0x55 /* jmp dstaddr */
+};
+#define TRAMP_MOVL_TARGET_OFF 7
+#define TRAMP_JMP_TARGET_OFF 16
+
+static u32 setup_trampoline(struct lguest *lg, unsigned int i, u32 dstaddr)
+{
+ u32 addr, off;
+
+ off = sizeof(tramp)*i;
+ memcpy(lg->trap_page + off, tramp, sizeof(tramp));
+
+ /* 0 is to be placed in lguest_data.gs_gpf_eip. */
+ addr = (u32)&lg->lguest_data->gs_gpf_eip + lg->page_offset;
+ memcpy(lg->trap_page + off + TRAMP_MOVL_TARGET_OFF, &addr, 4);
+
+ /* Address is relative to where end of jmp will be. */
+ addr = dstaddr - ((-4*1024*1024) + off + sizeof(tramp));
+ memcpy(lg->trap_page + off + TRAMP_JMP_TARGET_OFF, &addr, 4);
+ return (-4*1024*1024) + off;
+}
+
+/* We bounce through the trap page, for two reasons: firstly, we need
+ the interrupt destination always mapped, to avoid double faults,
+ secondly we want to reload %gs to make it innocuous on entering kernel.
+ */
+static void setup_idt(struct lguest *lg,
+ unsigned int i,
+ const struct desc_struct *desc)
+{
+ u8 type = ((desc->b >> 8) & 0xF);
+ u32 taddr;
+
+ /* Not present? */
+ if (!(desc->b & 0x8000)) {
+ /* FIXME: When we need this, we'll know... */
+ if (lg->state->idt_table[i].a & 0x8000)
+ kill_guest(lg, "removing interrupts not supported");
+ return;
+ }
+
+ /* We could reflect and disable interrupts, but guest can do itself. */
+ if (type != 0xF)
+ kill_guest(lg, "bad direct IDT %i type %i", i, type);
+
+ taddr = setup_trampoline(lg, i, (desc->a&0xFFFF)|(desc->b&0xFFFF0000));
+
+ lg->state->idt_table[i].a = (((__KERNEL_CS|GUEST_DPL)<<16)
+ | (taddr & 0x0000FFFF));
+ lg->state->idt_table[i].b = (desc->b&0xEF00)|(taddr&0xFFFF0000);
+}
+
+void load_guest_idt_entry(struct lguest *lg, unsigned int i, u32 low, u32 high)
+{
+ struct desc_struct d = { low, high };
+
+ switch (i) {
+ /* Ignore NMI, doublefault, hypercall, spurious interrupt. */
+ case 2:
+ case 8:
+ case 15:
+ case LGUEST_TRAP_ENTRY:
+ /* FIXME: We should handle debug and int3 */
+ case 1:
+ case 3:
+ return;
+ /* We intercept page fault, general protection fault and fpu missing */
+ case 13:
+ copy_trap(lg, &lg->gpf_trap, &d);
+ return;
+ case 14:
+ copy_trap(lg, &lg->page_trap, &d);
+ return;
+ case 7:
+ copy_trap(lg, &lg->fpu_trap, &d);
+ return;
+ }
+
+ /* Other traps go straight to guest. */
+ if (i < FIRST_EXTERNAL_VECTOR || i == SYSCALL_VECTOR)
+ setup_idt(lg, i, &d);
+ /* A virtual interrupt */
+ else if (i < FIRST_EXTERNAL_VECTOR + LGUEST_IRQS)
+ copy_trap(lg, &lg->interrupt[i-FIRST_EXTERNAL_VECTOR], &d);
+}
+
===================================================================
--- /dev/null
+++ b/arch/i386/lguest/io.c
@@ -0,0 +1,413 @@
+/* Simple I/O model for guests, based on shared memory.
+ * 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/types.h>
+#include <linux/futex.h>
+#include <linux/jhash.h>
+#include <linux/mm.h>
+#include <linux/highmem.h>
+#include <linux/uaccess.h>
+#include "lg.h"
+
+static struct list_head dma_hash[64];
+
+/* FIXME: allow multi-page lengths. */
+static int check_dma_list(struct lguest *lg, const struct lguest_dma *dma)
+{
+ unsigned int i;
+
+ for (i = 0; i < LGUEST_MAX_DMA_SECTIONS; i++) {
+ if (!dma->len[i])
+ return 1;
+ if (!lguest_address_ok(lg, dma->addr[i]))
+ goto kill;
+ if (dma->len[i] > PAGE_SIZE)
+ goto kill;
+ /* We could do over a page, but is it worth it? */
+ if ((dma->addr[i] % PAGE_SIZE) + dma->len[i] > PAGE_SIZE)
+ goto kill;
+ }
+ return 1;
+
+kill:
+ kill_guest(lg, "bad DMA entry: %u@%#x", dma->len[i], dma->addr[i]);
+ return 0;
+}
+
+static unsigned int hash(const union futex_key *key)
+{
+ return jhash2((u32*)&key->both.word,
+ (sizeof(key->both.word)+sizeof(key->both.ptr))/4,
+ key->both.offset)
+ % ARRAY_SIZE(dma_hash);
+}
+
+/* Must hold read lock on dmainfo owner's current->mm->mmap_sem */
+static void unlink_dma(struct lguest_dma_info *dmainfo)
+{
+ BUG_ON(!mutex_is_locked(&lguest_lock));
+ dmainfo->interrupt = 0;
+ list_del(&dmainfo->list);
+ drop_futex_key_refs(&dmainfo->key);
+}
+
+static inline int key_eq(const union futex_key *a, const union futex_key *b)
+{
+ return (a->both.word == b->both.word
+ && a->both.ptr == b->both.ptr
+ && a->both.offset == b->both.offset);
+}
+
+static u32 unbind_dma(struct lguest *lg,
+ const union futex_key *key,
+ unsigned long dmas)
+{
+ int i, ret = 0;
+
+ for (i = 0; i < LGUEST_MAX_DMA; i++) {
+ if (key_eq(key, &lg->dma[i].key) && dmas == lg->dma[i].dmas) {
+ unlink_dma(&lg->dma[i]);
+ ret = 1;
+ break;
+ }
+ }
+ return ret;
+}
+
+u32 bind_dma(struct lguest *lg,
+ unsigned long addr, unsigned long dmas, u16 numdmas, u8 interrupt)
+{
+ unsigned int i;
+ u32 ret = 0;
+ union futex_key key;
+
+ if (interrupt >= LGUEST_IRQS)
+ return 0;
+
+ mutex_lock(&lguest_lock);
+ down_read(¤t->mm->mmap_sem);
+ if (get_futex_key((u32 __user *)addr, &key) != 0) {
+ kill_guest(lg, "bad dma address %#lx", addr);
+ goto unlock;
+ }
+ get_futex_key_refs(&key);
+
+ if (interrupt == 0)
+ ret = unbind_dma(lg, &key, dmas);
+ else {
+ for (i = 0; i < LGUEST_MAX_DMA; i++) {
+ if (lg->dma[i].interrupt == 0) {
+ lg->dma[i].dmas = dmas;
+ lg->dma[i].num_dmas = numdmas;
+ lg->dma[i].next_dma = 0;
+ lg->dma[i].key = key;
+ lg->dma[i].guestid = lg->guestid;
+ lg->dma[i].interrupt = interrupt;
+ list_add(&lg->dma[i].list,
+ &dma_hash[hash(&key)]);
+ ret = 1;
+ goto unlock;
+ }
+ }
+ }
+ drop_futex_key_refs(&key);
+unlock:
+ up_read(¤t->mm->mmap_sem);
+ mutex_unlock(&lguest_lock);
+ return ret;
+}
+
+/* lhread from another guest */
+static int lhread_other(struct lguest *lg,
+ void *buf, u32 addr, unsigned bytes)
+{
+ if (addr + bytes < addr
+ || !lguest_address_ok(lg, addr+bytes)
+ || access_process_vm(lg->tsk, addr, buf, bytes, 0) != bytes) {
+ memset(buf, 0, bytes);
+ kill_guest(lg, "bad address in registered DMA struct");
+ return 0;
+ }
+ return 1;
+}
+
+/* lhwrite to another guest */
+static int lhwrite_other(struct lguest *lg, u32 addr,
+ const void *buf, unsigned bytes)
+{
+ if (addr + bytes < addr
+ || !lguest_address_ok(lg, addr+bytes)
+ || (access_process_vm(lg->tsk, addr, (void *)buf, bytes, 1)
+ != bytes)) {
+ kill_guest(lg, "bad address writing to registered DMA");
+ return 0;
+ }
+ return 1;
+}
+
+static u32 copy_data(const struct lguest_dma *src,
+ const struct lguest_dma *dst,
+ struct page *pages[])
+{
+ unsigned int totlen, si, di, srcoff, dstoff;
+ void *maddr = NULL;
+
+ totlen = 0;
+ si = di = 0;
+ srcoff = dstoff = 0;
+ while (si < LGUEST_MAX_DMA_SECTIONS && src->len[si]
+ && di < LGUEST_MAX_DMA_SECTIONS && dst->len[di]) {
+ u32 len = min(src->len[si] - srcoff, dst->len[di] - dstoff);
+
+ if (!maddr)
+ maddr = kmap(pages[di]);
+
+ /* FIXME: This is not completely portable, since
+ archs do different things for copy_to_user_page. */
+ if (copy_from_user(maddr + (dst->addr[di] + dstoff)%PAGE_SIZE,
+ (void *__user)src->addr[si], len) != 0) {
+ totlen = 0;
+ break;
+ }
+
+ totlen += len;
+ srcoff += len;
+ dstoff += len;
+ if (srcoff == src->len[si]) {
+ si++;
+ srcoff = 0;
+ }
+ if (dstoff == dst->len[di]) {
+ kunmap(pages[di]);
+ maddr = NULL;
+ di++;
+ dstoff = 0;
+ }
+ }
+
+ if (maddr)
+ kunmap(pages[di]);
+
+ return totlen;
+}
+
+/* Src is us, ie. current. */
+static u32 do_dma(struct lguest *srclg, const struct lguest_dma *src,
+ struct lguest *dstlg, const struct lguest_dma *dst)
+{
+ int i;
+ u32 ret;
+ struct page *pages[LGUEST_MAX_DMA_SECTIONS];
+
+ if (!check_dma_list(dstlg, dst) || !check_dma_list(srclg, src))
+ return 0;
+
+ /* First get the destination pages */
+ for (i = 0; i < LGUEST_MAX_DMA_SECTIONS; i++) {
+ if (dst->len[i] == 0)
+ break;
+ if (get_user_pages(dstlg->tsk, dstlg->mm,
+ dst->addr[i], 1, 1, 1, pages+i, NULL)
+ != 1) {
+ ret = 0;
+ goto drop_pages;
+ }
+ }
+
+ /* Now copy until we run out of src or dst. */
+ ret = copy_data(src, dst, pages);
+
+drop_pages:
+ while (--i >= 0)
+ put_page(pages[i]);
+ return ret;
+}
+
+/* We cache one process to wakeup: helps for batching & wakes outside locks. */
+void set_wakeup_process(struct lguest *lg, struct task_struct *p)
+{
+ if (p == lg->wake)
+ return;
+
+ if (lg->wake) {
+ wake_up_process(lg->wake);
+ put_task_struct(lg->wake);
+ }
+ lg->wake = p;
+ if (lg->wake)
+ get_task_struct(lg->wake);
+}
+
+static int dma_transfer(struct lguest *srclg,
+ unsigned long udma,
+ struct lguest_dma_info *dst)
+{
+ struct lguest_dma dst_dma, src_dma;
+ struct lguest *dstlg;
+ u32 i, dma = 0;
+
+ dstlg = &lguests[dst->guestid];
+ /* Get our dma list. */
+ lhread(srclg, &src_dma, udma, sizeof(src_dma));
+
+ /* We can't deadlock against them dmaing to us, because this
+ * is all under the lguest_lock. */
+ down_read(&dstlg->mm->mmap_sem);
+
+ for (i = 0; i < dst->num_dmas; i++) {
+ dma = (dst->next_dma + i) % dst->num_dmas;
+ if (!lhread_other(dstlg, &dst_dma,
+ dst->dmas + dma * sizeof(struct lguest_dma),
+ sizeof(dst_dma))) {
+ goto fail;
+ }
+ if (!dst_dma.used_len)
+ break;
+ }
+ if (i != dst->num_dmas) {
+ unsigned long used_lenp;
+ unsigned int ret;
+
+ ret = do_dma(srclg, &src_dma, dstlg, &dst_dma);
+ /* Put used length in src. */
+ lhwrite_u32(srclg,
+ udma+offsetof(struct lguest_dma, used_len), ret);
+ if (ret == 0 && src_dma.len[0] != 0)
+ goto fail;
+
+ /* Make sure destination sees contents before length. */
+ mb();
+ used_lenp = dst->dmas
+ + dma * sizeof(struct lguest_dma)
+ + offsetof(struct lguest_dma, used_len);
+ lhwrite_other(dstlg, used_lenp, &ret, sizeof(ret));
+ dst->next_dma++;
+ }
+ up_read(&dstlg->mm->mmap_sem);
+
+ /* Do this last so dst doesn't simply sleep on lock. */
+ set_bit(dst->interrupt, dstlg->irqs_pending);
+ set_wakeup_process(srclg, dstlg->tsk);
+ return i == dst->num_dmas;
+
+fail:
+ up_read(&dstlg->mm->mmap_sem);
+ return 0;
+}
+
+int send_dma(struct lguest *lg, unsigned long addr, unsigned long udma)
+{
+ union futex_key key;
+ int pending = 0, empty = 0;
+
+again:
+ mutex_lock(&lguest_lock);
+ down_read(¤t->mm->mmap_sem);
+ if (get_futex_key((u32 __user *)addr, &key) != 0) {
+ kill_guest(lg, "bad sending DMA address");
+ goto unlock;
+ }
+ /* Shared mapping? Look for other guests... */
+ if (key.shared.offset & 1) {
+ struct lguest_dma_info *i, *n;
+ list_for_each_entry_safe(i, n, &dma_hash[hash(&key)], list) {
+ if (i->guestid == lg->guestid)
+ continue;
+ if (!key_eq(&key, &i->key))
+ continue;
+
+ empty += dma_transfer(lg, udma, i);
+ break;
+ }
+ if (empty == 1) {
+ /* Give any recipients one chance to restock. */
+ up_read(¤t->mm->mmap_sem);
+ mutex_unlock(&lguest_lock);
+ yield();
+ empty++;
+ goto again;
+ }
+ pending = 0;
+ } else {
+ /* Private mapping: tell our userspace. */
+ lg->dma_is_pending = 1;
+ lg->pending_dma = udma;
+ lg->pending_addr = addr;
+ pending = 1;
+ }
+unlock:
+ up_read(¤t->mm->mmap_sem);
+ mutex_unlock(&lguest_lock);
+ return pending;
+}
+
+void release_all_dma(struct lguest *lg)
+{
+ unsigned int i;
+
+ BUG_ON(!mutex_is_locked(&lguest_lock));
+
+ down_read(&lg->mm->mmap_sem);
+ for (i = 0; i < LGUEST_MAX_DMA; i++) {
+ if (lg->dma[i].interrupt)
+ unlink_dma(&lg->dma[i]);
+ }
+ up_read(&lg->mm->mmap_sem);
+}
+
+/* Userspace wants a dma buffer from this guest. */
+unsigned long get_dma_buffer(struct lguest *lg,
+ unsigned long addr, unsigned long *interrupt)
+{
+ unsigned long ret = 0;
+ union futex_key key;
+ struct lguest_dma_info *i;
+
+ mutex_lock(&lguest_lock);
+ down_read(¤t->mm->mmap_sem);
+ if (get_futex_key((u32 __user *)addr, &key) != 0) {
+ kill_guest(lg, "bad registered DMA buffer");
+ goto unlock;
+ }
+ list_for_each_entry(i, &dma_hash[hash(&key)], list) {
+ if (key_eq(&key, &i->key) && i->guestid == lg->guestid) {
+ unsigned int j;
+ for (j = 0; j < i->num_dmas; j++) {
+ struct lguest_dma dma;
+
+ ret = i->dmas + j * sizeof(struct lguest_dma);
+ lhread(lg, &dma, ret, sizeof(dma));
+ if (dma.used_len == 0)
+ break;
+ }
+ *interrupt = i->interrupt;
+ break;
+ }
+ }
+unlock:
+ up_read(¤t->mm->mmap_sem);
+ mutex_unlock(&lguest_lock);
+ return ret;
+}
+
+void lguest_io_init(void)
+{
+ unsigned int i;
+
+ for (i = 0; i < ARRAY_SIZE(dma_hash); i++)
+ INIT_LIST_HEAD(&dma_hash[i]);
+}
===================================================================
--- /dev/null
+++ b/arch/i386/lguest/lguest_user.c
@@ -0,0 +1,242 @@
+/* Userspace control of the guest, via /dev/lguest. */
+#include <linux/uaccess.h>
+#include <linux/miscdevice.h>
+#include <linux/fs.h>
+#include "lg.h"
+
+static struct lguest_state *setup_guest_state(unsigned int num, void *pgdir,
+ unsigned long start)
+{
+ struct lguest_state *guest = &__lguest_states()[num];
+ unsigned int i;
+ const long *def = __lguest_default_idt_entries();
+ struct lguest_regs *regs;
+
+ guest->gdt_table[GDT_ENTRY_KERNEL_CS] = FULL_EXEC_SEGMENT;
+ guest->gdt_table[GDT_ENTRY_KERNEL_DS] = FULL_SEGMENT;
+ guest->gdt.size = GDT_ENTRIES*8-1;
+ guest->gdt.address = (unsigned long)&guest->gdt_table;
+
+ /* Other guest's IDTs are initialized from default. */
+ guest->idt.size = 8 * IDT_ENTRIES;
+ guest->idt.address = (long)guest->idt_table;
+ for (i = 0; i < IDT_ENTRIES; i++) {
+ u32 flags = 0x8e00;
+
+ /* They can't "int" into any of them except hypercall. */
+ if (i == LGUEST_TRAP_ENTRY)
+ flags |= (GUEST_DPL << 13);
+
+ guest->idt_table[i].a = (LGUEST_CS<<16) | (def[i]&0x0000FFFF);
+ guest->idt_table[i].b = (def[i]&0xFFFF0000) | flags;
+ }
+
+ memset(&guest->tss, 0, sizeof(guest->tss));
+ guest->tss.ss0 = LGUEST_DS;
+ guest->tss.esp0 = (unsigned long)(guest+1);
+ guest->tss.io_bitmap_base = sizeof(guest->tss); /* No I/O for you! */
+
+ /* Write out stack in format lguest expects, so we can switch to it. */
+ regs = &guest->regs;
+ regs->cr3 = __pa(pgdir);
+ regs->eax = regs->ebx = regs->ecx = regs->edx = regs->esp = 0;
+ regs->edi = LGUEST_MAGIC_EDI;
+ regs->ebp = LGUEST_MAGIC_EBP;
+ regs->esi = LGUEST_MAGIC_ESI;
+ regs->gs = regs->fs = 0;
+ regs->ds = regs->es = __KERNEL_DS|GUEST_DPL;
+ regs->trapnum = regs->errcode = 0;
+ regs->eip = start;
+ regs->cs = __KERNEL_CS|GUEST_DPL;
+ regs->eflags = 0x202; /* Interrupts enabled. */
+ regs->ss = __KERNEL_DS|GUEST_DPL;
+
+ if (!fixup_gdt_table(guest->gdt_table, ARRAY_SIZE(guest->gdt_table),
+ &guest->regs, &guest->tss))
+ return NULL;
+
+ return guest;
+}
+
+/* + addr */
+static long user_get_dma(struct lguest *lg, const u32 __user *input)
+{
+ unsigned long addr, udma, irq;
+
+ if (get_user(addr, input) != 0)
+ return -EFAULT;
+ udma = get_dma_buffer(lg, addr, &irq);
+ if (!udma)
+ return -ENOENT;
+
+ /* We put irq number in udma->used_len. */
+ lhwrite_u32(lg, udma + offsetof(struct lguest_dma, used_len), irq);
+ return udma;
+}
+
+/* + irq */
+static int user_send_irq(struct lguest *lg, const u32 __user *input)
+{
+ u32 irq;
+
+ if (get_user(irq, input) != 0)
+ return -EFAULT;
+ if (irq >= LGUEST_IRQS)
+ return -EINVAL;
+ set_bit(irq, lg->irqs_pending);
+ return 0;
+}
+
+static ssize_t read(struct file *file, char __user *user, size_t size,loff_t*o)
+{
+ struct lguest *lg = file->private_data;
+
+ if (!lg)
+ return -EINVAL;
+
+ if (lg->dead) {
+ size_t len;
+
+ if (lg->dead == (void *)-1)
+ return -ENOMEM;
+
+ len = min(size, strlen(lg->dead)+1);
+ if (copy_to_user(user, lg->dead, len) != 0)
+ return -EFAULT;
+ return len;
+ }
+
+ if (lg->dma_is_pending)
+ lg->dma_is_pending = 0;
+
+ return run_guest(lg, user);
+}
+
+/* Take: pfnlimit, pgdir, start, pageoffset. */
+static int initialize(struct file *file, const u32 __user *input)
+{
+ struct lguest *lg;
+ int err, i;
+ u32 args[4];
+
+ if (file->private_data)
+ return -EBUSY;
+
+ if (copy_from_user(args, input, sizeof(args)) != 0)
+ return -EFAULT;
+
+ if (args[1] <= PAGE_SIZE)
+ return -EINVAL;
+
+ mutex_lock(&lguest_lock);
+ i = find_free_guest();
+ if (i < 0) {
+ err = -ENOSPC;
+ goto unlock;
+ }
+ lg = &lguests[i];
+ lg->guestid = i;
+ lg->pfn_limit = args[0];
+ lg->page_offset = args[3];
+
+ lg->trap_page = (u32 *)get_zeroed_page(GFP_KERNEL);
+ if (!lg->trap_page) {
+ err = -ENOMEM;
+ goto release_guest;
+ }
+
+ err = init_guest_pagetable(lg, args[1]);
+ if (err)
+ goto free_trap_page;
+
+ lg->state = setup_guest_state(i, lg->pgdirs[lg->pgdidx].pgdir,args[2]);
+ if (!lg->state) {
+ err = -ENOEXEC;
+ goto release_pgtable;
+ }
+ mutex_unlock(&lguest_lock);
+
+ lg->tsk = current;
+ lg->mm = get_task_mm(current);
+ file->private_data = lg;
+ return sizeof(args);
+
+release_pgtable:
+ free_guest_pagetable(lg);
+free_trap_page:
+ free_page((long)lg->trap_page);
+release_guest:
+ memset(lg, 0, sizeof(*lg));
+unlock:
+ mutex_unlock(&lguest_lock);
+ return err;
+}
+
+static ssize_t write(struct file *file, const char __user *input,
+ size_t size, loff_t *off)
+{
+ struct lguest *lg = file->private_data;
+ u32 req;
+
+ if (get_user(req, input) != 0)
+ return -EFAULT;
+ input += sizeof(req);
+
+ if (req != LHREQ_INITIALIZE && !lg)
+ return -EINVAL;
+ if (lg && lg->dead)
+ return -ENOENT;
+
+ switch (req) {
+ case LHREQ_INITIALIZE:
+ return initialize(file, (const u32 __user *)input);
+ case LHREQ_GETDMA:
+ return user_get_dma(lg, (const u32 __user *)input);
+ case LHREQ_IRQ:
+ return user_send_irq(lg, (const u32 __user *)input);
+ default:
+ return -EINVAL;
+ }
+}
+
+static int close(struct inode *inode, struct file *file)
+{
+ struct lguest *lg = file->private_data;
+
+ if (!lg)
+ return 0;
+
+ mutex_lock(&lguest_lock);
+ release_all_dma(lg);
+ free_page((long)lg->trap_page);
+ free_guest_pagetable(lg);
+ mmput(lg->mm);
+ if (lg->dead != (void *)1)
+ kfree(lg->dead);
+ memset(lg->state, 0, sizeof(*lg->state));
+ memset(lg, 0, sizeof(*lg));
+ mutex_unlock(&lguest_lock);
+ return 0;
+}
+
+static struct file_operations lguest_fops = {
+ .owner = THIS_MODULE,
+ .release = close,
+ .write = write,
+ .read = read,
+};
+static struct miscdevice lguest_dev = {
+ .minor = MISC_DYNAMIC_MINOR,
+ .name = "lguest",
+ .fops = &lguest_fops,
+};
+
+int __init lguest_device_init(void)
+{
+ return misc_register(&lguest_dev);
+}
+
+void __exit lguest_device_remove(void)
+{
+ misc_deregister(&lguest_dev);
+}
===================================================================
--- /dev/null
+++ b/arch/i386/lguest/page_tables.c
@@ -0,0 +1,374 @@
+/* Shadow page table operations.
+ * Copyright (C) Rusty Russell IBm Corporation 2006.
+ * GPL v2 and any later version */
+#include <linux/mm.h>
+#include <linux/types.h>
+#include <linux/spinlock.h>
+#include <linux/random.h>
+#include <linux/percpu.h>
+#include <asm/tlbflush.h>
+#include "lg.h"
+
+#define PTES_PER_PAGE_SHIFT 10
+#define PTES_PER_PAGE (1 << PTES_PER_PAGE_SHIFT)
+#define HYPERVISOR_PGD_ENTRY (PTES_PER_PAGE - 1)
+
+static DEFINE_PER_CPU(u32 *, hypervisor_pte_pages) = { NULL };
+#define hypervisor_pte_page(cpu) per_cpu(hypervisor_pte_pages, cpu)
+
+static unsigned vaddr_to_pgd(unsigned long vaddr)
+{
+ return vaddr >> (PAGE_SHIFT + PTES_PER_PAGE_SHIFT);
+}
+
+/* These access the real versions. */
+static u32 *toplev(struct lguest *lg, u32 i, unsigned long vaddr)
+{
+ unsigned int index = vaddr_to_pgd(vaddr);
+
+ if (index >= HYPERVISOR_PGD_ENTRY) {
+ kill_guest(lg, "attempt to access hypervisor pages");
+ index = 0;
+ }
+ return &lg->pgdirs[i].pgdir[index];
+}
+
+static u32 *pteof(struct lguest *lg, u32 top, unsigned long vaddr)
+{
+ u32 *page = __va(top&PAGE_MASK);
+ BUG_ON(!(top & _PAGE_PRESENT));
+ return &page[(vaddr >> PAGE_SHIFT) % PTES_PER_PAGE];
+}
+
+/* These access the guest versions. */
+static u32 gtoplev(struct lguest *lg, unsigned long vaddr)
+{
+ unsigned int index = vaddr >> (PAGE_SHIFT + PTES_PER_PAGE_SHIFT);
+ return lg->pgdirs[lg->pgdidx].cr3 + index * sizeof(u32);
+}
+
+static u32 gpteof(struct lguest *lg, u32 gtop, unsigned long vaddr)
+{
+ u32 gpage = (gtop&PAGE_MASK);
+ BUG_ON(!(gtop & _PAGE_PRESENT));
+ return gpage + ((vaddr >> PAGE_SHIFT) % PTES_PER_PAGE) * sizeof(u32);
+}
+
+static void release_pte(u32 pte)
+{
+ if (pte & _PAGE_PRESENT)
+ put_page(pfn_to_page(pte >> PAGE_SHIFT));
+}
+
+/* Do a virtual -> physical mapping on a user page. */
+static unsigned long get_pfn(unsigned long virtpfn, int write)
+{
+ struct vm_area_struct *vma;
+ struct page *page;
+ unsigned long ret = -1UL;
+
+ down_read(¤t->mm->mmap_sem);
+ if (get_user_pages(current, current->mm, virtpfn << PAGE_SHIFT,
+ 1, write, 1, &page, &vma) == 1)
+ ret = page_to_pfn(page);
+ up_read(¤t->mm->mmap_sem);
+ return ret;
+}
+
+static u32 check_pgtable_entry(struct lguest *lg, u32 entry)
+{
+ if ((entry & (_PAGE_PWT|_PAGE_PSE))
+ || (entry >> PAGE_SHIFT) >= lg->pfn_limit)
+ kill_guest(lg, "bad page table entry");
+ return entry & ~_PAGE_GLOBAL;
+}
+
+static u32 get_pte(struct lguest *lg, u32 entry, int write)
+{
+ u32 pfn;
+
+ pfn = get_pfn(entry >> PAGE_SHIFT, write);
+ if (pfn == -1UL) {
+ kill_guest(lg, "failed to get page %u", entry>>PAGE_SHIFT);
+ return 0;
+ }
+ return ((pfn << PAGE_SHIFT) | (entry & (PAGE_SIZE-1)));
+}
+
+/* FIXME: We hold reference to pages, which prevents them from being
+ swapped. It'd be nice to have a callback when Linux wants to swap out. */
+
+/* We fault pages in, which allows us to update accessed/dirty bits.
+ * Return NULL or the pte page. */
+static int page_in(struct lguest *lg, u32 vaddr, unsigned flags)
+{
+ u32 gtop, gpte;
+ u32 *top, *pte, *ptepage;
+ u32 val;
+
+ gtop = gtoplev(lg, vaddr);
+ val = lhread_u32(lg, gtop);
+ if (!(val & _PAGE_PRESENT))
+ return 0;
+
+ top = toplev(lg, lg->pgdidx, vaddr);
+ if (!(*top & _PAGE_PRESENT)) {
+ /* Get a PTE page for them. */
+ ptepage = (void *)get_zeroed_page(GFP_KERNEL);
+ /* FIXME: Steal from self in this case? */
+ if (!ptepage) {
+ kill_guest(lg, "out of memory allocating pte page");
+ return 0;
+ }
+ val = check_pgtable_entry(lg, val);
+ *top = (__pa(ptepage) | (val & (PAGE_SIZE-1)));
+ } else
+ ptepage = __va(*top & PAGE_MASK);
+
+ gpte = gpteof(lg, val, vaddr);
+ val = lhread_u32(lg, gpte);
+
+ /* No page, or write to readonly page? */
+ if (!(val&_PAGE_PRESENT) || ((flags&_PAGE_DIRTY) && !(val&_PAGE_RW)))
+ return 0;
+
+ pte = pteof(lg, *top, vaddr);
+ val = check_pgtable_entry(lg, val) | flags;
+
+ /* We're done with the old pte. */
+ release_pte(*pte);
+
+ /* We don't make it writable if this isn't a write: later
+ * write will fault so we can set dirty bit in guest. */
+ if (val & _PAGE_DIRTY)
+ *pte = get_pte(lg, val, 1);
+ else
+ *pte = get_pte(lg, val & ~_PAGE_RW, 0);
+
+ /* Now we update dirty/accessed on guest. */
+ lhwrite_u32(lg, gpte, val);
+ return 1;
+}
+
+int demand_page(struct lguest *lg, u32 vaddr, int write)
+{
+ return page_in(lg, vaddr, (write ? _PAGE_DIRTY : 0)|_PAGE_ACCESSED);
+}
+
+void pin_stack_pages(struct lguest *lg)
+{
+ unsigned int i;
+ u32 stack = lg->state->tss.esp1;
+
+ for (i = 0; i < lg->stack_pages; i++)
+ if (!demand_page(lg, stack - i*PAGE_SIZE, 1))
+ kill_guest(lg, "bad stack page %i@%#x", i, stack);
+}
+
+static unsigned int find_pgdir(struct lguest *lg, u32 pgtable)
+{
+ unsigned int i;
+ for (i = 0; i < ARRAY_SIZE(lg->pgdirs); i++)
+ if (lg->pgdirs[i].cr3 == pgtable)
+ break;
+ return i;
+}
+
+static void release_pgd(struct lguest *lg, u32 *pgd)
+{
+ if (*pgd & _PAGE_PRESENT) {
+ unsigned int i;
+ u32 *ptepage = __va(*pgd & ~(PAGE_SIZE-1));
+ for (i = 0; i < PTES_PER_PAGE; i++)
+ release_pte(ptepage[i]);
+ free_page((long)ptepage);
+ *pgd = 0;
+ }
+}
+
+static void flush_user_mappings(struct lguest *lg, int idx)
+{
+ unsigned int i;
+ for (i = 0; i < vaddr_to_pgd(lg->page_offset); i++)
+ release_pgd(lg, lg->pgdirs[idx].pgdir + i);
+}
+
+void guest_pagetable_flush_user(struct lguest *lg)
+{
+ flush_user_mappings(lg, lg->pgdidx);
+}
+
+static unsigned int new_pgdir(struct lguest *lg, u32 cr3)
+{
+ unsigned int next;
+
+ next = (lg->pgdidx + random32()) % ARRAY_SIZE(lg->pgdirs);
+ if (!lg->pgdirs[next].pgdir) {
+ lg->pgdirs[next].pgdir = (u32 *)get_zeroed_page(GFP_KERNEL);
+ if (!lg->pgdirs[next].pgdir)
+ next = lg->pgdidx;
+ }
+ lg->pgdirs[next].cr3 = cr3;
+ /* Release all the non-kernel mappings. */
+ flush_user_mappings(lg, next);
+
+ return next;
+}
+
+void guest_new_pagetable(struct lguest *lg, u32 pgtable)
+{
+ int newpgdir;
+
+ newpgdir = find_pgdir(lg, pgtable);
+ if (newpgdir == ARRAY_SIZE(lg->pgdirs))
+ newpgdir = new_pgdir(lg, pgtable);
+ lg->pgdidx = newpgdir;
+ lg->state->regs.cr3 = __pa(lg->pgdirs[lg->pgdidx].pgdir);
+ pin_stack_pages(lg);
+}
+
+static void release_all_pagetables(struct lguest *lg)
+{
+ unsigned int i, j;
+
+ for (i = 0; i < ARRAY_SIZE(lg->pgdirs); i++)
+ if (lg->pgdirs[i].pgdir)
+ for (j = 0; j < HYPERVISOR_PGD_ENTRY; j++)
+ release_pgd(lg, lg->pgdirs[i].pgdir + j);
+}
+
+void guest_pagetable_clear_all(struct lguest *lg)
+{
+ release_all_pagetables(lg);
+ pin_stack_pages(lg);
+}
+
+static void do_set_pte(struct lguest *lg, int idx,
+ unsigned long vaddr, u32 val)
+{
+ u32 *top = toplev(lg, idx, vaddr);
+ if (*top & _PAGE_PRESENT) {
+ u32 *pte = pteof(lg, *top, vaddr);
+ release_pte(*pte);
+ if (val & (_PAGE_DIRTY | _PAGE_ACCESSED)) {
+ val = check_pgtable_entry(lg, val);
+ *pte = get_pte(lg, val, val & _PAGE_DIRTY);
+ } else
+ *pte = 0;
+ }
+}
+
+void guest_set_pte(struct lguest *lg,
+ unsigned long cr3, unsigned long vaddr, u32 val)
+{
+ /* Kernel mappings must be changed on all top levels. */
+ if (vaddr >= lg->page_offset) {
+ unsigned int i;
+ for (i = 0; i < ARRAY_SIZE(lg->pgdirs); i++)
+ if (lg->pgdirs[i].pgdir)
+ do_set_pte(lg, i, vaddr, val);
+ } else {
+ int pgdir = find_pgdir(lg, cr3);
+ if (pgdir != ARRAY_SIZE(lg->pgdirs))
+ do_set_pte(lg, pgdir, vaddr, val);
+ }
+}
+
+void guest_set_pud(struct lguest *lg, unsigned long cr3, u32 idx)
+{
+ int pgdir;
+
+ if (idx >= HYPERVISOR_PGD_ENTRY)
+ return;
+
+ pgdir = find_pgdir(lg, cr3);
+ if (pgdir < ARRAY_SIZE(lg->pgdirs))
+ release_pgd(lg, lg->pgdirs[pgdir].pgdir + idx);
+}
+
+int init_guest_pagetable(struct lguest *lg, u32 pgtable)
+{
+ /* We assume this in flush_user_mappings, so check now */
+ if (vaddr_to_pgd(lg->page_offset) >= HYPERVISOR_PGD_ENTRY)
+ return -EINVAL;
+ lg->pgdidx = 0;
+ lg->pgdirs[lg->pgdidx].cr3 = pgtable;
+ lg->pgdirs[lg->pgdidx].pgdir = (u32*)get_zeroed_page(GFP_KERNEL);
+ if (!lg->pgdirs[lg->pgdidx].pgdir)
+ return -ENOMEM;
+ return 0;
+}
+
+void free_guest_pagetable(struct lguest *lg)
+{
+ unsigned int i;
+
+ release_all_pagetables(lg);
+ for (i = 0; i < ARRAY_SIZE(lg->pgdirs); i++)
+ free_page((long)lg->pgdirs[i].pgdir);
+}
+
+/* Caller must be preempt-safe */
+void map_trap_page(struct lguest *lg)
+{
+ int cpu = smp_processor_id();
+
+ hypervisor_pte_page(cpu)[0] = (__pa(lg->trap_page)|_PAGE_PRESENT);
+
+ /* Since hypervisor less that 4MB, we simply mug top pte page. */
+ lg->pgdirs[lg->pgdidx].pgdir[HYPERVISOR_PGD_ENTRY] =
+ (__pa(hypervisor_pte_page(cpu))| _PAGE_KERNEL);
+}
+
+static void free_hypervisor_pte_pages(void)
+{
+ int i;
+
+ for_each_possible_cpu(i)
+ free_page((long)hypervisor_pte_page(i));
+}
+
+static __init int alloc_hypervisor_pte_pages(void)
+{
+ int i;
+
+ for_each_possible_cpu(i) {
+ hypervisor_pte_page(i) = (u32 *)get_zeroed_page(GFP_KERNEL);
+ if (!hypervisor_pte_page(i)) {
+ free_hypervisor_pte_pages();
+ return -ENOMEM;
+ }
+ }
+ return 0;
+}
+
+static __init void populate_hypervisor_pte_page(int cpu)
+{
+ int i;
+ u32 *pte = hypervisor_pte_page(cpu);
+
+ for (i = 0; i < HYPERVISOR_PAGES; i++) {
+ /* First entry set dynamically in map_trap_page */
+ pte[i+1] = ((page_to_pfn(&hype_pages[i]) << PAGE_SHIFT)
+ | _PAGE_KERNEL_EXEC);
+ }
+}
+
+__init int init_pagetables(struct page hype_pages[])
+{
+ int ret;
+ unsigned int i;
+
+ ret = alloc_hypervisor_pte_pages();
+ if (ret)
+ return ret;
+
+ for_each_possible_cpu(i)
+ populate_hypervisor_pte_page(i);
+ return 0;
+}
+
+__exit void free_pagetables(void)
+{
+ free_hypervisor_pte_pages();
+}
===================================================================
--- /dev/null
+++ b/arch/i386/lguest/segments.c
@@ -0,0 +1,171 @@
+#include "lg.h"
+
+/* Dealing with GDT entries is such a horror, I convert to sanity and back */
+struct decoded_gdt_entry
+{
+ u32 base, limit;
+ union {
+ struct {
+ unsigned type:4;
+ unsigned dtype:1;
+ unsigned dpl:2;
+ unsigned present:1;
+ unsigned unused:4;
+ unsigned avl:1;
+ unsigned mbz:1;
+ unsigned def:1;
+ unsigned page_granularity:1;
+ };
+ u16 raw_attributes;
+ };
+};
+
+static struct decoded_gdt_entry decode_gdt_entry(const struct desc_struct *en)
+{
+ struct decoded_gdt_entry de;
+ de.base = ((en->a >> 16) | ((en->b & 0xff) << 16)
+ | (en->b & 0xFF000000));
+ de.limit = ((en->a & 0xFFFF) | (en->b & 0xF0000));
+ de.raw_attributes = (en->b >> 8);
+ return de;
+}
+
+static struct desc_struct encode_gdt_entry(const struct decoded_gdt_entry *de)
+{
+ struct desc_struct en;
+ en.a = ((de->limit & 0xFFFF) | (de->base << 16));
+ en.b = (((de->base >> 16) & 0xFF)
+ | ((((u32)de->raw_attributes) & 0xF0FF) << 8)
+ | (de->limit & 0xF0000)
+ | (de->base & 0xFF000000));
+ return en;
+}
+
+static int check_desc(const struct decoded_gdt_entry *dec)
+{
+ return (dec->mbz == 0 && dec->dtype == 1 && (dec->type & 4) == 0);
+}
+
+static void check_segment(const struct desc_struct *gdt, u32 *segreg)
+{
+ if (*segreg > 255 || !(gdt[*segreg >> 3].b & 0x8000))
+ *segreg = 0;
+}
+
+/* Ensure our manually-loaded segment regs don't fault in switch_to_guest. */
+static void check_live_segments(const struct desc_struct *gdt,
+ struct lguest_regs *regs)
+{
+ check_segment(gdt, ®s->es);
+ check_segment(gdt, ®s->ds);
+ check_segment(gdt, ®s->fs);
+ check_segment(gdt, ®s->gs);
+}
+
+int fixup_gdt_table(struct desc_struct *gdt, unsigned int num,
+ struct lguest_regs *regs, struct x86_tss *tss)
+{
+ unsigned int i;
+ struct decoded_gdt_entry dec;
+
+ for (i = 0; i < num; i++) {
+ unsigned long base, length;
+
+ /* We override these ones, so we don't care what they give. */
+ if (i == GDT_ENTRY_TSS
+ || i == GDT_ENTRY_LGUEST_CS
+ || i == GDT_ENTRY_LGUEST_DS
+ || i == GDT_ENTRY_DOUBLEFAULT_TSS)
+ continue;
+
+ dec = decode_gdt_entry(&gdt[i]);
+ if (!dec.present)
+ continue;
+
+ if (!check_desc(&dec))
+ return 0;
+
+ base = dec.base;
+ length = dec.limit + 1;
+ if (dec.page_granularity) {
+ base *= PAGE_SIZE;
+ length *= PAGE_SIZE;
+ }
+
+ /* Unacceptable base? */
+ if (base >= HYPE_ADDR)
+ return 0;
+
+ /* Wrap around or segment overlaps hypervisor mem? */
+ if (!length
+ || base + length < base
+ || base + length > HYPE_ADDR) {
+ /* Trim to edge of hypervisor. */
+ length = HYPE_ADDR - base;
+ if (dec.page_granularity)
+ dec.limit = (length / PAGE_SIZE) - 1;
+ else
+ dec.limit = length - 1;
+ }
+ if (dec.dpl == 0)
+ dec.dpl = GUEST_DPL;
+ gdt[i] = encode_gdt_entry(&dec);
+ }
+ check_live_segments(gdt, regs);
+
+ /* Now put in hypervisor data and code segments. */
+ gdt[GDT_ENTRY_LGUEST_CS] = FULL_EXEC_SEGMENT;
+ gdt[GDT_ENTRY_LGUEST_DS] = FULL_SEGMENT;
+
+ /* Finally, TSS entry */
+ dec.base = (unsigned long)tss;
+ dec.limit = sizeof(*tss)-1;
+ dec.type = 0x9;
+ dec.dtype = 0;
+ dec.def = 0;
+ dec.present = 1;
+ dec.mbz = 0;
+ dec.page_granularity = 0;
+ gdt[GDT_ENTRY_TSS] = encode_gdt_entry(&dec);
+
+ return 1;
+}
+
+void load_guest_gdt(struct lguest *lg, u32 table, u32 num)
+{
+ if (num > GDT_ENTRIES)
+ kill_guest(lg, "too many gdt entries %i", num);
+
+ lhread(lg, lg->state->gdt_table, table,
+ num * sizeof(lg->state->gdt_table[0]));
+ if (!fixup_gdt_table(lg->state->gdt_table, num,
+ &lg->state->regs, &lg->state->tss))
+ kill_guest(lg, "bad gdt table");
+}
+
+/* We don't care about limit here, since we only let them use these in
+ * usermode (where lack of USER bit in pagetable protects hypervisor mem).
+ * However, we want to ensure it doesn't fault when loaded, since *we* are
+ * the ones who will load it in switch_to_guest.
+ */
+void guest_load_tls(struct lguest *lg, const struct desc_struct __user *gtls)
+{
+ unsigned int i;
+ struct desc_struct *tls = &lg->state->gdt_table[GDT_ENTRY_TLS_MIN];
+
+ lhread(lg, tls, (u32)gtls, sizeof(*tls)*GDT_ENTRY_TLS_ENTRIES);
+ for (i = 0; i < ARRAY_SIZE(lg->tls_limits); i++) {
+ struct decoded_gdt_entry dec = decode_gdt_entry(&tls[i]);
+
+ if (!dec.present)
+ continue;
+
+ /* We truncate to one byte/page (depending on G bit) to neuter
+ it, so ensure it's more than 1 page below trap page. */
+ tls[i].a &= 0xFFFF0000;
+ lg->tls_limits[i] = dec.limit;
+ if (!check_desc(&dec) || dec.base > HYPE_ADDR - PAGE_SIZE)
+ kill_guest(lg, "bad TLS descriptor %i", i);
+ }
+ check_live_segments(lg->state->gdt_table, &lg->state->regs);
+}
^ permalink raw reply [flat|nested] 12+ messages in thread