The branch main has been updated by vangyzen:
URL:
https://cgit.FreeBSD.org/src/commit/?id=2f32a971b7f936170b4d61318238e6cf89f198b5
commit 2f32a971b7f936170b4d61318238e6cf89f198b5
Author: Eric van Gyzen <vangy...@freebsd.org>
AuthorDate: 2021-04-26 15:01:17 +0000
Commit: Eric van Gyzen <vangy...@freebsd.org>
CommitDate: 2021-04-30 18:32:29 +0000
Wait longer for a previous IPI to be sent
When sending an IPI, if a previous IPI is still pending delivery,
native_lapic_ipi_vectored() waits for the previous IPI to be sent.
We've seen a few inexplicable panics with the current timeout of 50 ms.
Increase the timeout to 1 second and make it tunable.
No hardware specification mentions a timeout in this case; I checked
the Intel SDM, Intel MP spec, and Intel x2APIC spec. Linux and illumos
wait forever. In Linux, see __default_send_IPI_shortcut() in
arch/x86/kernel/apic/ipi.c. In illumos, see apic_send_ipi() in
usr/src/uts/i86pc/io/pcplusmp/apic_common.c. However, misbehaving hardware
could hang the system if we wait forever.
Reviewed by: mav kib
MFC after: 1 week
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D29942
---
sys/x86/x86/local_apic.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/sys/x86/x86/local_apic.c b/sys/x86/x86/local_apic.c
index 85c3cfb69277..36010fe38102 100644
--- a/sys/x86/x86/local_apic.c
+++ b/sys/x86/x86/local_apic.c
@@ -202,6 +202,7 @@ static u_long lapic_timer_divisor, count_freq;
static struct eventtimer lapic_et;
#ifdef SMP
static uint64_t lapic_ipi_wait_mult;
+static int __read_mostly lapic_ds_idle_timeout = 1000000;
#endif
unsigned int max_apic_id;
@@ -212,6 +213,11 @@ SYSCTL_INT(_hw_apic, OID_AUTO, eoi_suppression, CTLFLAG_RD,
&lapic_eoi_suppression, 0, "");
SYSCTL_INT(_hw_apic, OID_AUTO, timer_tsc_deadline, CTLFLAG_RD,
&lapic_timer_tsc_deadline, 0, "");
+#ifdef SMP
+SYSCTL_INT(_hw_apic, OID_AUTO, ds_idle_timeout, CTLFLAG_RWTUN,
+ &lapic_ds_idle_timeout, 0,
+ "timeout (in us) for APIC Delivery Status to become Idle (xAPIC only)");
+#endif
static void lapic_calibrate_initcount(struct lapic *la);
static void lapic_calibrate_deadline(struct lapic *la);
@@ -2035,7 +2041,6 @@ native_lapic_ipi_raw(register_t icrlo, u_int dest)
}
}
-#define BEFORE_SPIN 50000
#ifdef DETECT_DEADLOCK
#define AFTER_SPIN 50
#endif
@@ -2082,7 +2087,7 @@ native_lapic_ipi_vectored(u_int vector, int dest)
icrlo |= APIC_DESTMODE_PHY | APIC_TRIGMOD_EDGE | APIC_LEVEL_ASSERT;
/* Wait for an earlier IPI to finish. */
- if (!lapic_ipi_wait(BEFORE_SPIN)) {
+ if (!lapic_ipi_wait(lapic_ds_idle_timeout)) {
if (KERNEL_PANICKED())
return;
else
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