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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] [xen-unstable] Add acpi C3 support for x86.
# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1209635219 -3600
# Node ID 520519f5e346034585dfe65b2e6ca5ec3fc49687
# Parent 93bc6d9b5f3186ad5f0221a8e23e524284c3197e
Add acpi C3 support for x86.
C3 & deep C state will need to do ARB_DIS or cache flush. ARB_DIS
should be done within the last cpu which is ready for C3. Bus master
activities are checked and recorded for C state promotion/demotion
judgement.
C3 is disabled by default, till TSC/APIC stop issues resolved.
Adding cmdline option "max_cstate=3" can enable C3.
Signed-off-by: Wei Gang <gang.wei@xxxxxxxxx>
---
xen/arch/x86/acpi/cpu_idle.c | 280 +++++++++++++++++++++++++++++++++++++++++--
1 files changed, 273 insertions(+), 7 deletions(-)
diff -r 93bc6d9b5f31 -r 520519f5e346 xen/arch/x86/acpi/cpu_idle.c
--- a/xen/arch/x86/acpi/cpu_idle.c Thu May 01 10:41:51 2008 +0100
+++ b/xen/arch/x86/acpi/cpu_idle.c Thu May 01 10:46:59 2008 +0100
@@ -60,6 +60,16 @@ static void (*pm_idle_save) (void) __rea
static void (*pm_idle_save) (void) __read_mostly;
unsigned int max_cstate __read_mostly = 2;
integer_param("max_cstate", max_cstate);
+/*
+ * bm_history -- bit-mask with a bit per jiffy of bus-master activity
+ * 1000 HZ: 0xFFFFFFFF: 32 jiffies = 32ms
+ * 800 HZ: 0xFFFFFFFF: 32 jiffies = 40ms
+ * 100 HZ: 0x0000000F: 4 jiffies = 40ms
+ * reduce history for more aggressive entry into C3
+ */
+unsigned int bm_history __read_mostly =
+ (HZ >= 800 ? 0xFFFFFFFF : ((1U << (HZ / 25)) - 1));
+integer_param("bm_history", bm_history);
struct acpi_processor_cx;
@@ -91,10 +101,20 @@ struct acpi_processor_cx
struct acpi_processor_cx_policy demotion;
};
+struct acpi_processor_flags
+{
+ u8 bm_control:1;
+ u8 bm_check:1;
+ u8 has_cst:1;
+ u8 power_setup_done:1;
+ u8 bm_rld_set:1;
+};
+
struct acpi_processor_power
{
+ struct acpi_processor_flags flags;
struct acpi_processor_cx *state;
- u64 bm_check_timestamp;
+ s_time_t bm_check_timestamp;
u32 default_state;
u32 bm_activity;
u32 count;
@@ -185,6 +205,29 @@ static void acpi_processor_power_activat
old->promotion.count = 0;
new->demotion.count = 0;
+ /* Cleanup from old state. */
+ if ( old )
+ {
+ switch ( old->type )
+ {
+ case ACPI_STATE_C3:
+ /* Disable bus master reload */
+ if ( new->type != ACPI_STATE_C3 && power->flags.bm_check )
+ acpi_set_register(ACPI_BITREG_BUS_MASTER_RLD, 0);
+ break;
+ }
+ }
+
+ /* Prepare to use new state. */
+ switch ( new->type )
+ {
+ case ACPI_STATE_C3:
+ /* Enable bus master reload */
+ if ( old->type != ACPI_STATE_C3 && power->flags.bm_check )
+ acpi_set_register(ACPI_BITREG_BUS_MASTER_RLD, 1);
+ break;
+ }
+
power->state = new;
return;
@@ -196,7 +239,7 @@ static void acpi_safe_halt(void)
safe_halt();
}
-#define MWAIT_ECX_INTERRUPT_BREAK (0x1)
+#define MWAIT_ECX_INTERRUPT_BREAK (0x1)
static void mwait_idle_with_hints(unsigned long eax, unsigned long ecx)
{
@@ -229,6 +272,8 @@ static void acpi_idle_do_entry(struct ac
}
}
+static atomic_t c3_cpu_count;
+
static void acpi_processor_idle(void)
{
struct acpi_processor_power *power = NULL;
@@ -258,6 +303,62 @@ static void acpi_processor_idle(void)
acpi_safe_halt();
}
return;
+ }
+
+ /*
+ * Check BM Activity
+ * -----------------
+ * Check for bus mastering activity (if required), record, and check
+ * for demotion.
+ */
+ if ( power->flags.bm_check )
+ {
+ u32 bm_status = 0;
+ unsigned long diff = (NOW() - power->bm_check_timestamp) >> 23;
+
+ if ( diff > 31 )
+ diff = 31;
+
+ power->bm_activity <<= diff;
+
+ acpi_get_register(ACPI_BITREG_BUS_MASTER_STATUS, &bm_status);
+ if ( bm_status )
+ {
+ power->bm_activity |= 0x1;
+ acpi_set_register(ACPI_BITREG_BUS_MASTER_STATUS, 1);
+ }
+ /*
+ * PIIX4 Erratum #18: Note that BM_STS doesn't always reflect
+ * the true state of bus mastering activity; forcing us to
+ * manually check the BMIDEA bit of each IDE channel.
+ */
+ /*else if ( errata.piix4.bmisx )
+ {
+ if ( (inb_p(errata.piix4.bmisx + 0x02) & 0x01)
+ || (inb_p(errata.piix4.bmisx + 0x0A) & 0x01) )
+ pr->power.bm_activity |= 0x1;
+ }*/
+
+ power->bm_check_timestamp = NOW();
+
+ /*
+ * If bus mastering is or was active this jiffy, demote
+ * to avoid a faulty transition. Note that the processor
+ * won't enter a low-power state during this call (to this
+ * function) but should upon the next.
+ *
+ * TBD: A better policy might be to fallback to the demotion
+ * state (use it for this quantum only) istead of
+ * demoting -- and rely on duration as our sole demotion
+ * qualification. This may, however, introduce DMA
+ * issues (e.g. floppy DMA transfer overrun/underrun).
+ */
+ if ( (power->bm_activity & 0x1) && cx->demotion.threshold.bm )
+ {
+ local_irq_enable();
+ next_state = cx->demotion.state;
+ goto end;
+ }
}
/*
@@ -303,6 +404,73 @@ static void acpi_processor_idle(void)
sleep_ticks =
ticks_elapsed(t1, t2) - cx->latency_ticks - C2_OVERHEAD;
break;
+
+ case ACPI_STATE_C3:
+ /*
+ * disable bus master
+ * bm_check implies we need ARB_DIS
+ * !bm_check implies we need cache flush
+ * bm_control implies whether we can do ARB_DIS
+ *
+ * That leaves a case where bm_check is set and bm_control is
+ * not set. In that case we cannot do much, we enter C3
+ * without doing anything.
+ */
+ if ( power->flags.bm_check && power->flags.bm_control )
+ {
+ atomic_inc(&c3_cpu_count);
+ if ( atomic_read(&c3_cpu_count) == num_online_cpus() )
+ {
+ /*
+ * All CPUs are trying to go to C3
+ * Disable bus master arbitration
+ */
+ acpi_set_register(ACPI_BITREG_ARB_DISABLE, 1);
+ }
+ }
+ else if ( !power->flags.bm_check )
+ {
+ /* SMP with no shared cache... Invalidate cache */
+ ACPI_FLUSH_CPU_CACHE();
+ }
+
+ /* Get start time (ticks) */
+ t1 = inl(pmtmr_ioport);
+
+ /*
+ * FIXME: Before invoking C3, be aware that TSC/APIC timer may be
+ * stopped by H/W. Without carefully handling of TSC/APIC stop issues,
+ * deep C state can't work correctly.
+ */
+ /* placeholder for preparing TSC stop */
+
+ /* placeholder for preparing APIC stop */
+
+ /* Invoke C3 */
+ acpi_idle_do_entry(cx);
+
+ /* placeholder for recovering APIC */
+
+ /* placeholder for recovering TSC */
+
+ /* Get end time (ticks) */
+ t2 = inl(pmtmr_ioport);
+ if ( power->flags.bm_check && power->flags.bm_control )
+ {
+ /* Enable bus master arbitration */
+ atomic_dec(&c3_cpu_count);
+ acpi_set_register(ACPI_BITREG_ARB_DISABLE, 0);
+ }
+
+ /* Compute time (ticks) that we were actually asleep */
+ sleep_ticks = ticks_elapsed(t1, t2);
+ /* Re-enable interrupts */
+ local_irq_enable();
+ /* Do not account our idle-switching overhead: */
+ sleep_ticks -= cx->latency_ticks + C3_OVERHEAD;
+
+ break;
+
default:
local_irq_enable();
return;
@@ -331,8 +499,19 @@ static void acpi_processor_idle(void)
cx->demotion.count = 0;
if ( cx->promotion.count >= cx->promotion.threshold.count )
{
- next_state = cx->promotion.state;
- goto end;
+ if ( power->flags.bm_check )
+ {
+ if ( !(power->bm_activity & cx->promotion.threshold.bm) )
+ {
+ next_state = cx->promotion.state;
+ goto end;
+ }
+ }
+ else
+ {
+ next_state = cx->promotion.state;
+ goto end;
+ }
}
}
}
@@ -425,6 +604,8 @@ static int acpi_processor_set_power_poli
cx->demotion.state = lower;
cx->demotion.threshold.ticks = cx->latency_ticks;
cx->demotion.threshold.count = 1;
+ if ( cx->type == ACPI_STATE_C3 )
+ cx->demotion.threshold.bm = bm_history;
}
lower = cx;
@@ -445,6 +626,8 @@ static int acpi_processor_set_power_poli
cx->promotion.threshold.count = 4;
else
cx->promotion.threshold.count = 10;
+ if ( higher->type == ACPI_STATE_C3 )
+ cx->promotion.threshold.bm = bm_history;
}
higher = cx;
@@ -511,11 +694,40 @@ static int acpi_processor_ffh_cstate_pro
return 0;
}
+/*
+ * Initialize bm_flags based on the CPU cache properties
+ * On SMP it depends on cache configuration
+ * - When cache is not shared among all CPUs, we flush cache
+ * before entering C3.
+ * - When cache is shared among all CPUs, we use bm_check
+ * mechanism as in UP case
+ *
+ * This routine is called only after all the CPUs are online
+ */
+static void acpi_processor_power_init_bm_check(struct acpi_processor_flags
*flags)
+{
+ struct cpuinfo_x86 *c = ¤t_cpu_data;
+
+ flags->bm_check = 0;
+ if ( num_online_cpus() == 1 )
+ flags->bm_check = 1;
+ else if ( c->x86_vendor == X86_VENDOR_INTEL )
+ {
+ /*
+ * Today all CPUs that support C3 share cache.
+ * TBD: This needs to look at cache shared map, once
+ * multi-core detection patch makes to the base.
+ */
+ flags->bm_check = 1;
+ }
+}
+
#define VENDOR_INTEL (1)
#define NATIVE_CSTATE_BEYOND_HALT (2)
-static int check_cx(xen_processor_cx_t *cx)
-{
+static int check_cx(struct acpi_processor_power *power, xen_processor_cx_t *cx)
+{
+ static int bm_check_flag;
if ( cx == NULL )
return -EINVAL;
@@ -543,6 +755,56 @@ static int check_cx(xen_processor_cx_t *
return -ENODEV;
}
+ if ( cx->type == ACPI_STATE_C3 )
+ {
+ /* All the logic here assumes flags.bm_check is same across all CPUs */
+ if ( !bm_check_flag )
+ {
+ /* Determine whether bm_check is needed based on CPU */
+ acpi_processor_power_init_bm_check(&(power->flags));
+ bm_check_flag = power->flags.bm_check;
+ }
+ else
+ {
+ power->flags.bm_check = bm_check_flag;
+ }
+
+ if ( power->flags.bm_check )
+ {
+ if ( !power->flags.bm_control )
+ {
+ if ( power->flags.has_cst != 1 )
+ {
+ /* bus mastering control is necessary */
+ ACPI_DEBUG_PRINT((ACPI_DB_INFO,
+ "C3 support requires BM control\n"));
+ return -1;
+ }
+ else
+ {
+ /* Here we enter C3 without bus mastering */
+ ACPI_DEBUG_PRINT((ACPI_DB_INFO,
+ "C3 support without BM control\n"));
+ }
+ }
+ }
+ else
+ {
+ /*
+ * WBINVD should be set in fadt, for C3 state to be
+ * supported on when bm_check is not required.
+ */
+ if ( !(acpi_gbl_FADT.flags & ACPI_FADT_WBINVD) )
+ {
+ ACPI_DEBUG_PRINT((ACPI_DB_INFO,
+ "Cache invalidation should work properly"
+ " for C3 to be enabled on SMP systems\n"));
+ return -1;
+ }
+ acpi_set_register(ACPI_BITREG_BUS_MASTER_RLD, 0);
+ }
+ }
+
return 0;
}
@@ -552,7 +814,7 @@ static int set_cx(struct acpi_processor_
struct acpi_processor_cx *cx;
/* skip unsupported acpi cstate */
- if ( check_cx(xen_cx) )
+ if ( check_cx(acpi_power, xen_cx) )
return -EFAULT;
cx = &acpi_power->states[xen_cx->type];
@@ -663,6 +925,10 @@ long set_cx_pminfo(uint32_t cpu, struct
init_cx_pminfo(acpi_power);
+ acpi_power->flags.bm_check = power->flags.bm_check;
+ acpi_power->flags.bm_control = power->flags.bm_control;
+ acpi_power->flags.has_cst = power->flags.has_cst;
+
states = power->states;
for ( i = 0; i < power->count; i++ )
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