We create an "lguest_clock" which the guest uses: either TSC or
jiffies, depending on whether the host tells us the TSC frequency.
Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
---
drivers/lguest/lguest.c | 51 +++++++++++++++++++++++------------------------
1 file changed, 26 insertions(+), 25 deletions(-)
===================================================================
--- a/drivers/lguest/lguest.c
+++ b/drivers/lguest/lguest.c
@@ -212,8 +212,8 @@ static void lguest_cpuid(unsigned int *e
case 1: /* Basic feature request. */
/* We only allow kernel to see SSE3, CMPXCHG16B and SSSE3 */
*ecx &= 0x00002201;
- /* SSE, SSE2, FXSR, MMX, CMOV, CMPXCHG8B, TSC, FPU. */
- *edx &= 0x07808111;
+ /* SSE, SSE2, FXSR, MMX, CMOV, CMPXCHG8B, FPU. */
+ *edx &= 0x07808101;
/* Host wants to know when we flush kernel pages: set PGE. */
*edx |= 0x00002000;
break;
@@ -348,16 +348,19 @@ static unsigned long lguest_get_wallcloc
return hcall(LHCALL_GET_WALLCLOCK, 0, 0, 0);
}
-/* This is what we tell the kernel is our clocksource. It's the normal "Time
- * Stamp Counter": the Host tells us what speed it's going at. */
+static cycle_t lguest_clock_read(void)
+{
+ if (lguest_data.tsc_khz)
+ return native_read_tsc();
+ else
+ return jiffies;
+}
+
+/* This is what we tell the kernel is our clocksource. */
static struct clocksource lguest_clock = {
.name = "lguest",
.rating = 400,
- .read = native_read_tsc,
- .mask = CLOCKSOURCE_MASK(64),
- .mult = 0, /* to be set */
- .shift = 22,
- .flags = CLOCK_SOURCE_IS_CONTINUOUS,
+ .read = lguest_clock_read,
};
/* We also need a "struct clock_event_device": Linux asks us to set it to go
@@ -414,14 +417,6 @@ static void lguest_time_irq(unsigned int
{
unsigned long flags;
- /* Check in case host TSC has changed rate. */
- if (unlikely(tsc_khz != lguest_data.tsc_khz)) {
- tsc_khz = lguest_data.tsc_khz;
- lguest_clock.mult = clocksource_khz2mult(tsc_khz, 22);
- __get_cpu_var(sc_data).cyc2ns_scale
- = (1000000 << CYC2NS_SCALE_FACTOR) / tsc_khz;
- }
-
/* Don't interrupt us while this is running. */
local_irq_save(flags);
lguest_clockevent.event_handler(&lguest_clockevent);
@@ -432,7 +427,20 @@ static void lguest_time_init(void)
{
set_irq_handler(0, lguest_time_irq);
- lguest_clock.mult = clocksource_khz2mult(tsc_khz, 22);
+ /* We use the TSC if the Host tells us we can, otherwise a dumb
+ * jiffies-based clock. */
+ if (lguest_data.tsc_khz) {
+ lguest_clock.shift = 22;
+ lguest_clock.mult = clocksource_khz2mult(lguest_data.tsc_khz,
+ lguest_clock.shift);
+ lguest_clock.mask = CLOCKSOURCE_MASK(64);
+ lguest_clock.flags = CLOCK_SOURCE_IS_CONTINUOUS;
+ } else {
+ /* To understand this, start at kernel/time/jiffies.c... */
+ lguest_clock.shift = 8;
+ lguest_clock.mult = (((u64)NSEC_PER_SEC<<8)/ACTHZ) << 8;
+ lguest_clock.mask = CLOCKSOURCE_MASK(32);
+ }
clocksource_register(&lguest_clock);
/* We can't set cpumask in the initializer: damn C limitations! */
@@ -440,12 +448,6 @@ static void lguest_time_init(void)
clockevents_register_device(&lguest_clockevent);
enable_lguest_irq(0);
-}
-
-static unsigned long lguest_get_cpu_khz(void)
-{
- /* The Host tells us the TSC speed */
- return lguest_data.tsc_khz;
}
static void lguest_load_esp0(struct tss_struct *tss,
@@ -584,7 +586,6 @@ __init void lguest_init(void *boot)
paravirt_ops.time_init = lguest_time_init;
paravirt_ops.set_lazy_mode = lguest_lazy_mode;
paravirt_ops.wbinvd = lguest_wbinvd;
- paravirt_ops.get_cpu_khz = lguest_get_cpu_khz;
hcall(LHCALL_LGUEST_INIT, __pa(&lguest_data), 0, 0);
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