Author: kib
Date: Tue Mar 29 19:54:13 2016
New Revision: 297398
URL: https://svnweb.freebsd.org/changeset/base/297398
Log:
Fix several bugs in r297374:
- fix UP build [1]
- do not obliterate initial reading of rdtsc by the loop counter [2]
- restore the meaning of the argument -1 to native_lapic_ipi_wait()
as wait until LAPIC acknowledge without timeout
- correct formula for calculating loop iteration count for 1us, it was
inverted, and ensure that even on unlikely slow CPUs at least one
check for ack is performed.
Reported by: Michael Butler <i...@protected-networks.net> [1], rpokala[2],
jhb[3]
Tested by: Michael Butler
Pointy hat to: kib
Sponsored by: The FreeBSD Foundation
Modified:
head/sys/x86/x86/local_apic.c
Modified: head/sys/x86/x86/local_apic.c
==============================================================================
--- head/sys/x86/x86/local_apic.c Tue Mar 29 19:23:00 2016
(r297397)
+++ head/sys/x86/x86/local_apic.c Tue Mar 29 19:54:13 2016
(r297398)
@@ -172,7 +172,9 @@ int lapic_eoi_suppression;
static int lapic_timer_tsc_deadline;
static u_long lapic_timer_divisor;
static struct eventtimer lapic_et;
+#ifdef SMP
static uint64_t lapic_ipi_wait_mult;
+#endif
SYSCTL_NODE(_hw, OID_AUTO, apic, CTLFLAG_RD, 0, "APIC options");
SYSCTL_INT(_hw_apic, OID_AUTO, x2apic_mode, CTLFLAG_RD, &x2apic_mode, 0, "");
@@ -404,7 +406,9 @@ lvt_mode(struct lapic *la, u_int pin, ui
static void
native_lapic_init(vm_paddr_t addr)
{
- uint64_t r;
+#ifdef SMP
+ uint64_t r, r1, r2, rx;
+#endif
uint32_t ver;
u_int regs[4];
int i, arat;
@@ -506,6 +510,7 @@ native_lapic_init(vm_paddr_t addr)
&lapic_eoi_suppression);
}
+#ifdef SMP
#define LOOPS 1000000
/*
* Calibrate the busy loop waiting for IPI ack in xAPIC mode.
@@ -521,18 +526,21 @@ native_lapic_init(vm_paddr_t addr)
KASSERT((cpu_feature & CPUID_TSC) != 0 && tsc_freq != 0,
("TSC not initialized"));
r = rdtsc();
- for (r = 0; r < LOOPS; r++) {
+ for (rx = 0; rx < LOOPS; rx++) {
(void)lapic_read_icr_lo();
ia32_pause();
}
r = rdtsc() - r;
- lapic_ipi_wait_mult = (r * 1000000) / tsc_freq / LOOPS;
+ r1 = tsc_freq * LOOPS;
+ r2 = r * 1000000;
+ lapic_ipi_wait_mult = r1 >= r2 ? r1 / r2 : 1;
if (bootverbose) {
printf("LAPIC: ipi_wait() us multiplier %jd (r %jd tsc %jd)\n",
(uintmax_t)lapic_ipi_wait_mult, (uintmax_t)r,
(uintmax_t)tsc_freq);
}
#undef LOOPS
+#endif /* SMP */
}
/*
@@ -1757,11 +1765,11 @@ native_lapic_ipi_wait(int delay)
uint64_t i, counter;
/* LAPIC_ICR.APIC_DELSTAT_MASK is undefined in x2APIC mode */
- if (x2apic_mode || delay == -1)
+ if (x2apic_mode)
return (1);
counter = lapic_ipi_wait_mult * delay;
- for (i = 0; i < counter; i++) {
+ for (i = 0; delay == -1 || i < counter; i++) {
if ((lapic_read_icr_lo() & APIC_DELSTAT_MASK) ==
APIC_DELSTAT_IDLE)
return (1);
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