lguest: write more information to userspace about pending traps.

This is preparation for userspace handling MMIO and ioport accesses.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2015-02-11 15:15:09 +10:30
parent 18c137371b
commit 69a09dc174
6 changed files with 42 additions and 18 deletions

View File

@ -229,16 +229,17 @@ int run_guest(struct lg_cpu *cpu, unsigned long __user *user)
* It's possible the Guest did a NOTIFY hypercall to the
* Launcher.
*/
if (cpu->pending_notify) {
if (cpu->pending.trap) {
/*
* 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 Launcher. */
if (put_user(cpu->pending_notify, user))
if (copy_to_user(user, &cpu->pending,
sizeof(cpu->pending)))
return -EFAULT;
return sizeof(cpu->pending_notify);
return sizeof(cpu->pending);
}
}

View File

@ -118,7 +118,8 @@ static void do_hcall(struct lg_cpu *cpu, struct hcall_args *args)
cpu->halted = 1;
break;
case LHCALL_NOTIFY:
cpu->pending_notify = args->arg1;
cpu->pending.trap = LGUEST_TRAP_ENTRY;
cpu->pending.addr = args->arg1;
break;
default:
/* It should be an architecture-specific hypercall. */
@ -189,7 +190,7 @@ static void do_async_hcalls(struct lg_cpu *cpu)
* Stop doing hypercalls if they want to notify the Launcher:
* it needs to service this first.
*/
if (cpu->pending_notify)
if (cpu->pending.trap)
break;
}
}
@ -280,7 +281,7 @@ void do_hypercalls(struct lg_cpu *cpu)
* NOTIFY to the Launcher, we want to return now. Otherwise we do
* the hypercall.
*/
if (!cpu->pending_notify) {
if (!cpu->pending.trap) {
do_hcall(cpu, cpu->hcall);
/*
* Tricky point: we reset the hcall pointer to mark the

View File

@ -50,7 +50,8 @@ struct lg_cpu {
/* Bitmap of what has changed: see CHANGED_* above. */
int changed;
unsigned long pending_notify; /* pfn from LHCALL_NOTIFY */
/* Pending operation. */
struct lguest_pending pending;
unsigned long *reg_read; /* register from LHREQ_GETREG */

View File

@ -29,6 +29,10 @@ bool send_notify_to_eventfd(struct lg_cpu *cpu)
unsigned int i;
struct lg_eventfd_map *map;
/* We only connect LHCALL_NOTIFY to event fds, not other traps. */
if (cpu->pending.trap != LGUEST_TRAP_ENTRY)
return false;
/*
* This "rcu_read_lock()" helps track when someone is still looking at
* the (RCU-using) eventfds array. It's not actually a lock at all;
@ -52,9 +56,9 @@ bool send_notify_to_eventfd(struct lg_cpu *cpu)
* we'll continue to use the old array and just won't see the new one.
*/
for (i = 0; i < map->num; i++) {
if (map->map[i].addr == cpu->pending_notify) {
if (map->map[i].addr == cpu->pending.addr) {
eventfd_signal(map->map[i].event, 1);
cpu->pending_notify = 0;
cpu->pending.trap = 0;
break;
}
}
@ -62,7 +66,7 @@ bool send_notify_to_eventfd(struct lg_cpu *cpu)
rcu_read_unlock();
/* If we cleared the notification, it's because we found a match. */
return cpu->pending_notify == 0;
return cpu->pending.trap == 0;
}
/*L:055
@ -282,8 +286,8 @@ static ssize_t read(struct file *file, char __user *user, size_t size,loff_t*o)
* If we returned from read() last time because the Guest sent I/O,
* clear the flag.
*/
if (cpu->pending_notify)
cpu->pending_notify = 0;
if (cpu->pending.trap)
cpu->pending.trap = 0;
/* Run the Guest until something interesting happens. */
return run_guest(cpu, (unsigned long __user *)user);

View File

@ -67,6 +67,19 @@ enum lguest_req
LHREQ_SETREG, /* + offset within struct pt_regs, value. */
};
/*
* This is what read() of the lguest fd populates. trap ==
* LGUEST_TRAP_ENTRY for an LHCALL_NOTIFY (addr is the
* argument), 14 for a page fault in the MMIO region (addr is
* the trap address, insn is the instruction), or 13 for a GPF
* (insn is the instruction).
*/
struct lguest_pending {
__u8 trap;
__u8 insn[7];
__u32 addr;
};
/*
* The alignment to use between consumer and producer parts of vring.
* x86 pagesize for historical reasons.

View File

@ -1820,17 +1820,21 @@ static void __attribute__((noreturn)) restart_guest(void)
static void __attribute__((noreturn)) run_guest(void)
{
for (;;) {
unsigned long notify_addr;
struct lguest_pending notify;
int readval;
/* We read from the /dev/lguest device to run the Guest. */
readval = pread(lguest_fd, &notify_addr,
sizeof(notify_addr), cpu_id);
readval = pread(lguest_fd, &notify, sizeof(notify), cpu_id);
/* One unsigned long means the Guest did HCALL_NOTIFY */
if (readval == sizeof(notify_addr)) {
verbose("Notify on address %#lx\n", notify_addr);
handle_output(notify_addr);
if (readval == sizeof(notify)) {
if (notify.trap == 0x1F) {
verbose("Notify on address %#08x\n",
notify.addr);
handle_output(notify.addr);
} else
errx(1, "Unknown trap %i addr %#08x\n",
notify.trap, notify.addr);
/* ENOENT means the Guest died. Reading tells us why. */
} else if (errno == ENOENT) {
char reason[1024] = { 0 };