-/*P:400 This contains run_guest() which actually calls into the Host<->Guest
+/*P:400
+ * This contains run_guest() which actually calls into the Host<->Guest
* Switcher and analyzes the return, such as determining if the Guest wants the
- * Host to do something. This file also contains useful helper routines, and a
- * couple of non-obvious setup and teardown pieces which were implemented after
- * days of debugging pain. :*/
+ * Host to do something. This file also contains useful helper routines.
+:*/
#include <linux/module.h>
#include <linux/stringify.h>
#include <linux/stddef.h>
/* This One Big lock protects all inter-guest data structures. */
DEFINE_MUTEX(lguest_lock);
-/*H:010 We need to set up the Switcher at a high virtual address. Remember the
+/*H:010
+ * We need to set up the Switcher at a high virtual address. Remember the
* Switcher is a few hundred bytes of assembler code which actually changes the
* CPU to run the Guest, and then changes back to the Host when a trap or
* interrupt happens.
* Host since it will be running as the switchover occurs.
*
* Trying to map memory at a particular address is an unusual thing to do, so
- * it's not a simple one-liner. */
+ * it's not a simple one-liner.
+ */
static __init int map_switcher(void)
{
int i, err;
* easy.
*/
- /* We allocate an array of "struct page"s. map_vm_area() wants the
- * pages in this form, rather than just an array of pointers. */
+ /*
+ * We allocate an array of struct page pointers. map_vm_area() wants
+ * this, rather than just an array of pages.
+ */
switcher_page = kmalloc(sizeof(switcher_page[0])*TOTAL_SWITCHER_PAGES,
GFP_KERNEL);
if (!switcher_page) {
goto out;
}
- /* Now we actually allocate the pages. The Guest will see these pages,
- * so we make sure they're zeroed. */
+ /*
+ * Now we actually allocate the pages. The Guest will see these pages,
+ * so we make sure they're zeroed.
+ */
for (i = 0; i < TOTAL_SWITCHER_PAGES; i++) {
- unsigned long addr = get_zeroed_page(GFP_KERNEL);
- if (!addr) {
+ switcher_page[i] = alloc_page(GFP_KERNEL|__GFP_ZERO);
+ if (!switcher_page[i]) {
err = -ENOMEM;
goto free_some_pages;
}
- switcher_page[i] = virt_to_page(addr);
}
- /* Now we reserve the "virtual memory area" we want: 0xFFC00000
+ /*
+ * First we check that the Switcher won't overlap the fixmap area at
+ * the top of memory. It's currently nowhere near, but it could have
+ * very strange effects if it ever happened.
+ */
+ if (SWITCHER_ADDR + (TOTAL_SWITCHER_PAGES+1)*PAGE_SIZE > FIXADDR_START){
+ err = -ENOMEM;
+ printk("lguest: mapping switcher would thwack fixmap\n");
+ goto free_pages;
+ }
+
+ /*
+ * Now we reserve the "virtual memory area" we want: 0xFFC00000
* (SWITCHER_ADDR). We might not get it in theory, but in practice
- * it's worked so far. */
+ * it's worked so far. The end address needs +1 because __get_vm_area
+ * allocates an extra guard page, so we need space for that.
+ */
switcher_vma = __get_vm_area(TOTAL_SWITCHER_PAGES * PAGE_SIZE,
- VM_ALLOC, SWITCHER_ADDR, VMALLOC_END);
+ VM_ALLOC, SWITCHER_ADDR, SWITCHER_ADDR
+ + (TOTAL_SWITCHER_PAGES+1) * PAGE_SIZE);
if (!switcher_vma) {
err = -ENOMEM;
printk("lguest: could not map switcher pages high\n");
goto free_pages;
}
- /* This code actually sets up the pages we've allocated to appear at
+ /*
+ * This code actually sets up the pages we've allocated to appear at
* SWITCHER_ADDR. map_vm_area() takes the vma we allocated above, the
* kind of pages we're mapping (kernel pages), and a pointer to our
* array of struct pages. It increments that pointer, but we don't
- * care. */
+ * care.
+ */
pagep = switcher_page;
- err = map_vm_area(switcher_vma, PAGE_KERNEL, &pagep);
+ err = map_vm_area(switcher_vma, PAGE_KERNEL_EXEC, &pagep);
if (err) {
printk("lguest: map_vm_area failed: %i\n", err);
goto free_vma;
}
- /* Now the Switcher is mapped at the right address, we can't fail!
- * Copy in the compiled-in Switcher code (from <arch>_switcher.S). */
+ /*
+ * Now the Switcher is mapped at the right address, we can't fail!
+ * Copy in the compiled-in Switcher code (from <arch>_switcher.S).
+ */
memcpy(switcher_vma->addr, start_switcher_text,
end_switcher_text - start_switcher_text);
}
/*:*/
-/* Cleaning up the mapping when the module is unloaded is almost...
- * too easy. */
+/* Cleaning up the mapping when the module is unloaded is almost... too easy. */
static void unmap_switcher(void)
{
unsigned int i;
/* Now we just need to free the pages we copied the switcher into */
for (i = 0; i < TOTAL_SWITCHER_PAGES; i++)
__free_pages(switcher_page[i], 0);
+ kfree(switcher_page);
}
/*H:032
* But we can't trust the Guest: it might be trying to access the Launcher
* code. We have to check that the range is below the pfn_limit the Launcher
* gave us. We have to make sure that addr + len doesn't give us a false
- * positive by overflowing, too. */
-int lguest_address_ok(const struct lguest *lg,
- unsigned long addr, unsigned long len)
+ * positive by overflowing, too.
+ */
+bool lguest_address_ok(const struct lguest *lg,
+ unsigned long addr, unsigned long len)
{
return (addr+len) / PAGE_SIZE < lg->pfn_limit && (addr+len >= addr);
}
-/* This routine copies memory from the Guest. Here we can see how useful the
+/*
+ * This routine copies memory from the Guest. Here we can see how useful the
* kill_lguest() routine we met in the Launcher can be: we return a random
- * value (all zeroes) instead of needing to return an error. */
-void __lgread(struct lguest *lg, void *b, unsigned long addr, unsigned bytes)
+ * value (all zeroes) instead of needing to return an error.
+ */
+void __lgread(struct lg_cpu *cpu, void *b, unsigned long addr, unsigned bytes)
{
- if (!lguest_address_ok(lg, addr, bytes)
- || copy_from_user(b, lg->mem_base + addr, bytes) != 0) {
+ if (!lguest_address_ok(cpu->lg, addr, bytes)
+ || copy_from_user(b, cpu->lg->mem_base + 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);
+ kill_guest(cpu, "bad read address %#lx len %u", addr, bytes);
}
}
-/* This is the write (copy into guest) version. */
-void __lgwrite(struct lguest *lg, unsigned long addr, const void *b,
+/* This is the write (copy into Guest) version. */
+void __lgwrite(struct lg_cpu *cpu, unsigned long addr, const void *b,
unsigned bytes)
{
- if (!lguest_address_ok(lg, addr, bytes)
- || copy_to_user(lg->mem_base + addr, b, bytes) != 0)
- kill_guest(lg, "bad write address %#lx len %u", addr, bytes);
+ if (!lguest_address_ok(cpu->lg, addr, bytes)
+ || copy_to_user(cpu->lg->mem_base + addr, b, bytes) != 0)
+ kill_guest(cpu, "bad write address %#lx len %u", addr, bytes);
}
/*:*/
-/*H:030 Let's jump straight to the the main loop which runs the Guest.
+/*H:030
+ * Let's jump straight to the the main loop which runs the Guest.
* Remember, this is called by the Launcher reading /dev/lguest, and we keep
- * going around and around until something interesting happens. */
+ * going around and around until something interesting happens.
+ */
int run_guest(struct lg_cpu *cpu, unsigned long __user *user)
{
- struct lguest *lg = cpu->lg;
-
/* We stop running once the Guest is dead. */
- while (!lg->dead) {
+ while (!cpu->lg->dead) {
+ unsigned int irq;
+ bool more;
+
/* First we run any hypercalls the Guest wants done. */
- if (lg->hcall)
- do_hypercalls(lg);
-
- /* It's possible the Guest did a NOTIFY hypercall to the
- * Launcher, in which case we return from the read() now. */
- if (lg->pending_notify) {
- if (put_user(lg->pending_notify, user))
- return -EFAULT;
- return sizeof(lg->pending_notify);
+ if (cpu->hcall)
+ do_hypercalls(cpu);
+
+ /*
+ * It's possible the Guest did a NOTIFY hypercall to the
+ * Launcher.
+ */
+ if (cpu->pending_notify) {
+ /*
+ * Does it just needs to write to a registered
+ * eventfd (ie. the appropriate virtqueue thread)?
+ */
+ if (!send_notify_to_eventfd(cpu)) {
+ /* OK, we tell the main Laucher. */
+ if (put_user(cpu->pending_notify, user))
+ return -EFAULT;
+ return sizeof(cpu->pending_notify);
+ }
}
/* Check for signals */
if (signal_pending(current))
return -ERESTARTSYS;
- /* If Waker set break_out, return to Launcher. */
- if (lg->break_out)
- return -EAGAIN;
-
- /* Check if there are any interrupts which can be delivered
- * now: if so, this sets up the hander to be executed when we
- * next run the Guest. */
- maybe_do_interrupt(lg);
-
- /* All long-lived kernel loops need to check with this horrible
+ /*
+ * Check if there are any interrupts which can be delivered now:
+ * if so, this sets up the hander to be executed when we next
+ * run the Guest.
+ */
+ irq = interrupt_pending(cpu, &more);
+ if (irq < LGUEST_IRQS)
+ try_deliver_interrupt(cpu, irq, more);
+
+ /*
+ * All long-lived kernel loops need to check with this horrible
* thing called the freezer. If the Host is trying to suspend,
- * it stops us. */
+ * it stops us.
+ */
try_to_freeze();
- /* Just make absolutely sure the Guest is still alive. One of
- * those hypercalls could have been fatal, for example. */
- if (lg->dead)
+ /*
+ * Just make absolutely sure the Guest is still alive. One of
+ * those hypercalls could have been fatal, for example.
+ */
+ if (cpu->lg->dead)
break;
- /* If the Guest asked to be stopped, we sleep. The Guest's
- * clock timer or LHCALL_BREAK from the Waker will wake us. */
- if (lg->halted) {
+ /*
+ * If the Guest asked to be stopped, we sleep. The Guest's
+ * clock timer will wake us.
+ */
+ if (cpu->halted) {
set_current_state(TASK_INTERRUPTIBLE);
- schedule();
+ /*
+ * Just before we sleep, make sure no interrupt snuck in
+ * which we should be doing.
+ */
+ if (interrupt_pending(cpu, &more) < LGUEST_IRQS)
+ set_current_state(TASK_RUNNING);
+ else
+ schedule();
continue;
}
- /* OK, now we're ready to jump into the Guest. First we put up
- * the "Do Not Disturb" sign: */
+ /*
+ * OK, now we're ready to jump into the Guest. First we put up
+ * the "Do Not Disturb" sign:
+ */
local_irq_disable();
/* Actually run the Guest until something happens. */
local_irq_enable();
/* Now we deal with whatever happened to the Guest. */
- lguest_arch_handle_trap(lg);
+ lguest_arch_handle_trap(cpu);
}
- if (lg->dead == ERR_PTR(-ERESTART))
+ /* Special case: Guest is 'dead' but wants a reboot. */
+ if (cpu->lg->dead == ERR_PTR(-ERESTART))
return -ERESTART;
+
/* The Guest is dead => "No such file or directory" */
return -ENOENT;
}
}
/*:*/
-/* The Host side of lguest can be a module. This is a nice way for people to
- * play with it. */
+/*
+ * The Host side of lguest can be a module. This is a nice way for people to
+ * play with it.
+ */
module_init(init);
module_exit(fini);
MODULE_LICENSE("GPL");
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff