[PATCH 13/16] per-vcpu lguest task management

Glauber de Oliveira Costa
2007-12-20T13:40:17Z

lguest uses tasks to control its running behaviour (like sending
breaks, controlling halted state, etc). In a per-vcpu environment,
each vcpu will have its own underlying task. So this patch
makes the infrastructure for that possible

Signed-off-by: Glauber de Oliveira Costa <gcosta@redhat.com>
---
drivers/lguest/core.c | 4 +-
drivers/lguest/hypercalls.c | 2 +-
drivers/lguest/interrupts_and_traps.c | 8 ++--
drivers/lguest/lg.h | 14 ++++----
drivers/lguest/lguest_user.c | 56 ++++++++++++++++++--------------
5 files changed, 45 insertions(+), 39 deletions(-)

diff --git a/drivers/lguest/core.c b/drivers/lguest/core.c
index 4d0102d..285a465 100644
--- a/drivers/lguest/core.c
+++ b/drivers/lguest/core.c
@@ -197,7 +197,7 @@ int run_guest(struct lguest_vcpu *vcpu, unsigned long __user *user)
return -ERESTARTSYS;

/* If Waker set break_out, return to Launcher. */
- if (lg->break_out)
+ if (vcpu->break_out)
return -EAGAIN;

/* Check if there are any interrupts which can be delivered
@@ -217,7 +217,7 @@ int run_guest(struct lguest_vcpu *vcpu, unsigned long __user *user)

/* 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 (vcpu->halted) {
set_current_state(TASK_INTERRUPTIBLE);
schedule();
continue;
diff --git a/drivers/lguest/hypercalls.c b/drivers/lguest/hypercalls.c
index 4364bc2..41ea2e2 100644
--- a/drivers/lguest/hypercalls.c
+++ b/drivers/lguest/hypercalls.c
@@ -86,7 +86,7 @@ static void do_hcall(struct lguest_vcpu *vcpu, struct hcall_args *args)
break;
case LHCALL_HALT:
/* Similarly, this sets the halted flag for run_guest(). */
- lg->halted = 1;
+ vcpu->halted = 1;
break;
case LHCALL_NOTIFY:
lg->pending_notify = args->arg1;
diff --git a/drivers/lguest/interrupts_and_traps.c b/drivers/lguest/interrupts_and_traps.c
index b3d444a..10c9aea 100644
--- a/drivers/lguest/interrupts_and_traps.c
+++ b/drivers/lguest/interrupts_and_traps.c
@@ -163,11 +163,11 @@ void maybe_do_interrupt(struct lguest_vcpu *vcpu)
return;

/* If they're halted, interrupts restart them. */
- if (lg->halted) {
+ if (vcpu->halted) {
/* Re-enable interrupts. */
if (put_user(X86_EFLAGS_IF, &lg->lguest_data->irq_enabled))
kill_guest(lg, "Re-enabling interrupts");
- lg->halted = 0;
+ vcpu->halted = 0;
} else {
/* Otherwise we check if they have interrupts disabled. */
u32 irq_enabled;
@@ -500,8 +500,8 @@ static enum hrtimer_restart clockdev_fn(struct hrtimer *timer)
/* Remember the first interrupt is the timer interrupt. */
set_bit(0, vcpu->irqs_pending);
/* If the Guest is actually stopped, we need to wake it up. */
- if (vcpu->lg->halted)
- wake_up_process(vcpu->lg->tsk);
+ if (vcpu->halted)
+ wake_up_process(vcpu->tsk);
return HRTIMER_NORESTART;
}

diff --git a/drivers/lguest/lg.h b/drivers/lguest/lg.h
index f9429ff..b23694e 100644
--- a/drivers/lguest/lg.h
+++ b/drivers/lguest/lg.h
@@ -43,6 +43,8 @@ struct lguest;
struct lguest_vcpu {
int vcpu_id;
struct lguest *lg;
+ struct task_struct *tsk;
+ struct mm_struct *mm; /* == tsk->mm, but that becomes NULL on exit */

/* At end of a page shared mapped over lguest_pages in guest. */
unsigned long regs_page;
@@ -55,6 +57,11 @@ struct lguest_vcpu {
/* Virtual clock device */
struct hrtimer hrt;

+ /* Do we need to stop what we're doing and return to userspace? */
+ int break_out;
+ wait_queue_head_t break_wq;
+ int halted;
+
/* Pending virtual interrupts */
DECLARE_BITMAP(irqs_pending, LGUEST_IRQS);

@@ -65,8 +72,6 @@ struct lguest_vcpu {
struct lguest
{
struct lguest_data __user *lguest_data;
- struct task_struct *tsk;
- struct mm_struct *mm; /* == tsk->mm, but that becomes NULL on exit */
struct lguest_vcpu vcpus[NR_CPUS];
unsigned int nr_vcpus;

@@ -76,15 +81,10 @@ struct lguest
void __user *mem_base;
unsigned long kernel_address;
u32 cr2;
- int halted;
int ts;
u32 esp1;
u8 ss1;

- /* Do we need to stop what we're doing and return to userspace? */
- int break_out;
- wait_queue_head_t break_wq;
-
/* Bitmap of what has changed: see CHANGED_* above. */
int changed;
struct lguest_pages *last_pages;
diff --git a/drivers/lguest/lguest_user.c b/drivers/lguest/lguest_user.c
index 4f51e25..d081db4 100644
--- a/drivers/lguest/lguest_user.c
+++ b/drivers/lguest/lguest_user.c
@@ -13,7 +13,8 @@
* LHREQ_BREAK and the value "1" to /dev/lguest to do this. Once the Launcher
* has done whatever needs attention, it writes LHREQ_BREAK and "0" to release
* the Waker. */
-static int break_guest_out(struct lguest *lg, const unsigned long __user *input)
+static int break_guest_out(struct lguest_vcpu *vcpu,
+ const unsigned long __user *input)
{
unsigned long on;

@@ -22,14 +23,15 @@ static int break_guest_out(struct lguest *lg, const unsigned long __user *input)
return -EFAULT;

if (on) {
- lg->break_out = 1;
+ vcpu->break_out = 1;
/* Pop it out of the Guest (may be running on different CPU) */
- wake_up_process(lg->tsk);
+ wake_up_process(vcpu->tsk);
/* Wait for them to reset it */
- return wait_event_interruptible(lg->break_wq, !lg->break_out);
+ return wait_event_interruptible(vcpu->break_wq,
+ !vcpu->break_out);
} else {
- lg->break_out = 0;
- wake_up(&lg->break_wq);
+ vcpu->break_out = 0;
+ wake_up(&vcpu->break_wq);
return 0;
}
}
@@ -66,7 +68,7 @@ static ssize_t read(struct file *file, char __user *user, size_t size,loff_t*o)
vcpu = &lg->vcpus[vcpu_id];

/* If you're not the task which owns the Guest, go away. */
- if (current != lg->tsk)
+ if (current != vcpu->tsk)
return -EPERM;

/* If the guest is already dead, we indicate why */
@@ -114,6 +116,19 @@ static int vcpu_start(struct lguest_vcpu *vcpu, int vcpu_id,
* address. */
lguest_arch_setup_regs(vcpu, start_ip);

+ /* Initialize the queue for the waker to wait on */
+ init_waitqueue_head(&vcpu->break_wq);
+
+ /* We keep a pointer to the Launcher task (ie. current task) for when
+ * other Guests want to wake this one (inter-Guest I/O). */
+ vcpu->tsk = current;
+
+ /* We need to keep a pointer to the Launcher's memory map, because if
+ * the Launcher dies we need to clean it up. If we don't keep a
+ * reference, it is destroyed before close() is called. */
+ vcpu->mm = get_task_mm(vcpu->tsk);
+
+
vcpu->lg = container_of((vcpu - vcpu_id), struct lguest, vcpus[0]);
vcpu->lg->nr_vcpus++;

@@ -179,17 +194,6 @@ static int initialize(struct file *file, const unsigned long __user *input)
if (err)
goto free_regs;

- /* We keep a pointer to the Launcher task (ie. current task) for when
- * other Guests want to wake this one (inter-Guest I/O). */
- lg->tsk = current;
- /* We need to keep a pointer to the Launcher's memory map, because if
- * the Launcher dies we need to clean it up. If we don't keep a
- * reference, it is destroyed before close() is called. */
- lg->mm = get_task_mm(lg->tsk);
-
- /* Initialize the queue for the waker to wait on */
- init_waitqueue_head(&lg->break_wq);
-
/* We remember which CPU's pages this Guest used last, for optimization
* when the same Guest runs on the same CPU twice. */
lg->last_pages = NULL;
@@ -244,7 +248,7 @@ static ssize_t write(struct file *file, const char __user *in,
return -ENOENT;

/* If you're not the task which owns the Guest, you can only break */
- if (lg && current != lg->tsk && req != LHREQ_BREAK)
+ if (lg && current != vcpu->tsk && req != LHREQ_BREAK)
return -EPERM;

switch (req) {
@@ -253,7 +257,7 @@ static ssize_t write(struct file *file, const char __user *in,
case LHREQ_IRQ:
return user_send_irq(vcpu, input);
case LHREQ_BREAK:
- return break_guest_out(lg, input);
+ return break_guest_out(vcpu, input);
default:
return -EINVAL;
}
@@ -278,17 +282,19 @@ static int close(struct inode *inode, struct file *file)
/* We need the big lock, to protect from inter-guest I/O and other
* Launchers initializing guests. */
mutex_lock(&lguest_lock);
+
+ /* Free up the shadow page tables for the Guest. */
+ free_guest_pagetable(lg);
+
for (i = 0; i < lg->nr_vcpus; i++) {
/* Cancels the hrtimer set via LHCALL_SET_CLOCKEVENT. */
hrtimer_cancel(&lg->vcpus[i].hrt);
/* We can free up the register page we allocated. */
free_page(lg->vcpus[i].regs_page);
+ /* Now all the memory cleanups are done, it's safe to release
+ * the Launcher's memory management structure. */
+ mmput(lg->vcpus[i].mm);
}
- /* Free up the shadow page tables for the Guest. */
- free_guest_pagetable(lg);
- /* Now all the memory cleanups are done, it's safe to release the
- * Launcher's memory management structure. */
- mmput(lg->mm);
/* If lg->dead doesn't contain an error code it will be NULL or a
* kmalloc()ed string, either of which is ok to hand to kfree(). */
if (!IS_ERR(lg->dead))
--
1.5.0.6