Convert lguest to the hrtimer framework, enabling dynamic ticks and high
resolution timers.
Signed-off-by: James Morris <jmorris@xxxxxxxxx>
---
drivers/lguest/hypercalls.c | 13 +----
drivers/lguest/interrupts_and_traps.c | 32 +++++++++++--
drivers/lguest/lg.h | 6 ++-
drivers/lguest/lguest.c | 82 +++++++++++++++++++++++++-------
drivers/lguest/lguest_user.c | 7 +++
include/linux/lguest.h | 5 ++-
6 files changed, 111 insertions(+), 34 deletions(-)
diff --git a/drivers/lguest/hypercalls.c b/drivers/lguest/hypercalls.c
index a8c0b86..e2e8047 100644
--- a/drivers/lguest/hypercalls.c
+++ b/drivers/lguest/hypercalls.c
@@ -65,16 +65,6 @@ static void do_hcall(struct lguest *lg, struct lguest_regs *regs)
else
guest_pagetable_flush_user(lg);
break;
- case LHCALL_TIMER_READ: {
- /* The "timer" returns the number of clock ticks since the
- * Guest last asked. */
- u32 now = jiffies;
- mb();
- regs->eax = now - lg->last_timer;
- /* Remember the clock ticks for next time */
- lg->last_timer = now;
- break;
- }
case LHCALL_GET_WALLCLOCK: {
/* The Guest wants to know the real time in seconds since 1970,
* in good Unix tradition. */
@@ -120,6 +110,9 @@ static void do_hcall(struct lguest *lg, struct lguest_regs *regs)
case LHCALL_LOAD_TLS:
guest_load_tls(lg, (struct desc_struct __user*)regs->edx);
break;
+ case LHCALL_SET_CLOCKEVENT:
+ guest_set_clockevent(lg, regs->edx);
+ break;
case LHCALL_TS:
/* This sets the TS flag, as we saw used in run_guest(). */
diff --git a/drivers/lguest/interrupts_and_traps.c b/drivers/lguest/interrupts_and_traps.c
index ece6e2a..409d174 100644
--- a/drivers/lguest/interrupts_and_traps.c
+++ b/drivers/lguest/interrupts_and_traps.c
@@ -131,10 +131,6 @@ void maybe_do_interrupt(struct lguest *lg)
if (!lg->lguest_data)
return;
- /* If the timer has changed, we set the timer interrupt (0). */
- if (jiffies != lg->last_timer)
- set_bit(0, lg->irqs_pending);
-
/* Take our "irqs_pending" array and remove any interrupts the Guest
* wants blocked: the result ends up in "blk". */
if (copy_from_user(&blk, lg->lguest_data->blocked_interrupts,
@@ -408,3 +404,31 @@ void copy_traps(const struct lguest *lg, struct desc_struct *idt,
else
default_idt_entry(&idt[i], i, def[i]);
}
+
+void guest_set_clockevent(struct lguest *lg, unsigned long delta)
+{
+ ktime_t expires;
+
+ if (unlikely(delta == 0)) {
+ /* Clock event device is shutting down. */
+ hrtimer_cancel(&lg->hrt);
+ return;
+ }
+
+ expires = ktime_add_ns(ktime_get_real(), delta);
+ hrtimer_start(&lg->hrt, expires, HRTIMER_MODE_ABS);
+}
+
+static enum hrtimer_restart clockdev_fn(struct hrtimer *timer)
+{
+ struct lguest *lg = container_of(timer, struct lguest, hrt);
+
+ set_bit(0, lg->irqs_pending);
+ return HRTIMER_NORESTART;
+}
+
+void init_clockdev(struct lguest *lg)
+{
+ hrtimer_init(&lg->hrt, CLOCK_REALTIME, HRTIMER_MODE_ABS);
+ lg->hrt.function = clockdev_fn;
+}
diff --git a/drivers/lguest/lg.h b/drivers/lguest/lg.h
index be506c8..d4c3fb9 100644
--- a/drivers/lguest/lg.h
+++ b/drivers/lguest/lg.h
@@ -147,7 +147,6 @@ struct lguest
u32 cr2;
int halted;
int ts;
- u32 last_timer;
u32 next_hcall;
u32 esp1;
u8 ss1;
@@ -186,6 +185,9 @@ struct lguest
struct desc_struct idt[FIRST_EXTERNAL_VECTOR+LGUEST_IRQS];
struct desc_struct syscall_idt;
+ /* Virtual clock device */
+ struct hrtimer hrt;
+
/* Pending virtual interrupts */
DECLARE_BITMAP(irqs_pending, LGUEST_IRQS);
};
@@ -214,6 +216,8 @@ void setup_default_idt_entries(struct lguest_ro_state *state,
const unsigned long *def);
void copy_traps(const struct lguest *lg, struct desc_struct *idt,
const unsigned long *def);
+void guest_set_clockevent(struct lguest *lg, unsigned long delta);
+void init_clockdev(struct lguest *lg);
/* segments.c: */
void setup_default_gdt_entries(struct lguest_ro_state *state);
diff --git a/drivers/lguest/lguest.c b/drivers/lguest/lguest.c
index e102c35..0f4edf1 100644
--- a/drivers/lguest/lguest.c
+++ b/drivers/lguest/lguest.c
@@ -53,6 +53,7 @@
#include <linux/irq.h>
#include <linux/interrupt.h>
#include <linux/clocksource.h>
+#include <linux/clockchips.h>
#include <linux/lguest.h>
#include <linux/lguest_launcher.h>
#include <asm/paravirt.h>
@@ -605,19 +606,6 @@ static unsigned long lguest_get_wallclock(void)
return hcall(LHCALL_GET_WALLCLOCK, 0, 0, 0);
}
-/* This is the Guest timer interrupt handler (hardware interrupt 0). I copied
- * this from some old code which has since been bulldozed, but it still
- * works. */
-static void lguest_time_irq(unsigned int irq, struct irq_desc *desc)
-{
- /* We call do_timer() with the number of ticks which have passed since
- * we last called do_timer(). Fortunately, that's exactly what the
- * TIMER_READ hypercall returns (if the Guest and Host have different
- * CONFIG_HZ values, this will give strange results). */
- do_timer(hcall(LHCALL_TIMER_READ, 0, 0, 0));
- /* We are expected to update process times from here as well. */
- update_process_times(user_mode_vm(get_irq_regs()));
-}
static cycle_t lguest_clock_read(void)
{
@@ -642,6 +630,68 @@ static void lguest_setup_clocksource(void)
clocksource_register(&lguest_clock);
}
+static void lguest_clockevent_shutdown(void)
+{
+ hcall(LHCALL_SET_CLOCKEVENT, 0, 0, 0);
+}
+
+static int lguest_clockevent_set_next_event(unsigned long delta,
+ struct clock_event_device *evt)
+{
+ if (delta < LG_CLOCK_MIN_DELTA) {
+ if (printk_ratelimit())
+ printk(KERN_DEBUG "%s: small delta %lu ns\n",
+ __FUNCTION__, delta);
+ return -ETIME;
+ }
+ hcall(LHCALL_SET_CLOCKEVENT, delta, 0, 0);
+ return 0;
+}
+
+static void lguest_clockevent_set_mode(enum clock_event_mode mode,
+ struct clock_event_device *evt)
+{
+ switch (mode) {
+ case CLOCK_EVT_MODE_UNUSED:
+ case CLOCK_EVT_MODE_SHUTDOWN:
+ lguest_clockevent_shutdown();
+ break;
+ case CLOCK_EVT_MODE_ONESHOT:
+ break;
+ case CLOCK_EVT_MODE_PERIODIC:
+ BUG();
+ }
+}
+
+static struct clock_event_device lguest_clockevent = {
+ .name = "lguest",
+ .features = CLOCK_EVT_FEAT_ONESHOT,
+ .set_next_event = lguest_clockevent_set_next_event,
+ .set_mode = lguest_clockevent_set_mode,
+ .rating = INT_MAX,
+ .mult = 1,
+ .shift = 0,
+ .min_delta_ns = LG_CLOCK_MIN_DELTA,
+ .max_delta_ns = LG_CLOCK_MAX_DELTA,
+};
+
+/* TODO: make this per-cpu for SMP */
+static void lguest_setup_clockevent(void)
+{
+ lguest_clockevent.cpumask = cpumask_of_cpu(0);
+ clockevents_register_device(&lguest_clockevent);
+}
+
+/* This is the Guest timer interrupt handler (hardware interrupt 0). */
+static void lguest_time_irq(unsigned int irq, struct irq_desc *desc)
+{
+ unsigned long flags;
+
+ local_irq_save(flags);
+ lguest_clockevent.event_handler(&lguest_clockevent);
+ local_irq_restore(flags);
+}
+
/* At some point in the boot process, we get asked to set up our timing
* infrastructure. The kernel doesn't expect timer interrupts before this, but
* we cleverly initialized the "blocked_interrupts" field of "struct
@@ -652,11 +702,7 @@ static void lguest_time_init(void)
* routine */
set_irq_handler(0, lguest_time_irq);
lguest_setup_clocksource();
- /* Ask the Host for the time once. Since the TIMER_READ hypercall
- * returns the number of ticks since it was last called, this means it
- * will return the right thing when we call it next time, from
- * lguest_time_irq(). */
- hcall(LHCALL_TIMER_READ, 0, 0, 0);
+ lguest_setup_clockevent();
/* Finally, we unblock the timer interrupt. */
enable_lguest_irq(0);
}
diff --git a/drivers/lguest/lguest_user.c b/drivers/lguest/lguest_user.c
index 7c9440b..a439cdb 100644
--- a/drivers/lguest/lguest_user.c
+++ b/drivers/lguest/lguest_user.c
@@ -230,6 +230,11 @@ static int initialize(struct file *file, const u32 __user *input)
* when the same Guest runs on the same CPU twice. */
lg->last_pages = NULL;
+ /* The clock device is a hrtimer programmed via the SET_CLOCKEVENT
+ * hypercall. This comment is fully compliant with Rusty's commenting
+ * style 1.0. */
+ init_clockdev(lg);
+
/* We keep our "struct lguest" in the file's private_data. */
file->private_data = lg;
@@ -303,6 +308,8 @@ 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);
+ /* Cancels the hrtimer set via LHCALL_SET_CLOCKEVENT. */
+ hrtimer_cancel(&lg->hrt);
/* Free any DMA buffers the Guest had bound. */
release_all_dma(lg);
/* Free up the shadow page tables for the Guest. */
diff --git a/include/linux/lguest.h b/include/linux/lguest.h
index 6ce0865..99548c5 100644
--- a/include/linux/lguest.h
+++ b/include/linux/lguest.h
@@ -12,7 +12,7 @@
#define LHCALL_LOAD_IDT_ENTRY 6
#define LHCALL_SET_STACK 7
#define LHCALL_TS 8
-#define LHCALL_TIMER_READ 9
+#define LHCALL_SET_CLOCKEVENT 9
#define LHCALL_HALT 10
#define LHCALL_GET_WALLCLOCK 11
#define LHCALL_BIND_DMA 12
@@ -23,6 +23,9 @@
#define LGUEST_TRAP_ENTRY 0x1F
+#define LG_CLOCK_MIN_DELTA 100UL
+#define LG_CLOCK_MAX_DELTA ULONG_MAX
+
#ifndef __ASSEMBLY__
#include <asm/irq.h>
--
1.5.0.6
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