Author: vangyzen Date: Sun Apr 26 00:41:29 2020 New Revision: 360328 URL: https://svnweb.freebsd.org/changeset/base/360328
Log: Fix handling of NMIs from unknown sources (BMC, hypervisor) Release kernels have no KDB backends enabled, so they discard an NMI if it is not due to a hardware failure. This includes NMIs from IPMI BMCs and hypervisors. Furthermore, the interaction of panic_on_nmi, kdb_on_nmi, and debugger_on_panic is confusing. Respond to all NMIs according to panic_on_nmi and debugger_on_panic. Remove kdb_on_nmi. Expand the meaning of panic_on_nmi by making it a bitfield. There are currently two bits: one for NMIs due to hardware failure, and one for all others. Leave room for more. If panic_on_nmi and debugger_on_panic are both true, don't actually panic, but directly enter the debugger, to allow someone to leave the debugger and [hopefully] resume normal execution. Reviewed by: kib MFC after: 2 weeks Relnotes: yes: machdep.kdb_on_nmi is gone; machdep.panic_on_nmi changed Sponsored by: Dell EMC Isilon Differential Revision: https://reviews.freebsd.org/D24558 Modified: head/sys/kern/kern_shutdown.c head/sys/sys/kdb.h head/sys/x86/x86/cpu_machdep.c Modified: head/sys/kern/kern_shutdown.c ============================================================================== --- head/sys/kern/kern_shutdown.c Sat Apr 25 23:35:49 2020 (r360327) +++ head/sys/kern/kern_shutdown.c Sun Apr 26 00:41:29 2020 (r360328) @@ -119,9 +119,9 @@ SYSCTL_INT(_kern, OID_AUTO, panic_reboot_wait_time, CT #ifdef KDB #ifdef KDB_UNATTENDED -static int debugger_on_panic = 0; +int debugger_on_panic = 0; #else -static int debugger_on_panic = 1; +int debugger_on_panic = 1; #endif SYSCTL_INT(_debug, OID_AUTO, debugger_on_panic, CTLFLAG_RWTUN | CTLFLAG_SECURE, Modified: head/sys/sys/kdb.h ============================================================================== --- head/sys/sys/kdb.h Sat Apr 25 23:35:49 2020 (r360327) +++ head/sys/sys/kdb.h Sun Apr 26 00:41:29 2020 (r360328) @@ -65,6 +65,7 @@ struct kdb_dbbe { SET_DECLARE(kdb_dbbe_set, struct kdb_dbbe); extern u_char kdb_active; /* Non-zero while in debugger. */ +extern int debugger_on_panic; /* enter the debugger on panic. */ extern int debugger_on_trap; /* enter the debugger on trap. */ extern struct kdb_dbbe *kdb_dbbe; /* Default debugger backend or NULL. */ extern struct trapframe *kdb_frame; /* Frame to kdb_trap(). */ Modified: head/sys/x86/x86/cpu_machdep.c ============================================================================== --- head/sys/x86/x86/cpu_machdep.c Sat Apr 25 23:35:49 2020 (r360327) +++ head/sys/x86/x86/cpu_machdep.c Sun Apr 26 00:41:29 2020 (r360328) @@ -823,20 +823,14 @@ cpu_idle_tun(void *unused __unused) } SYSINIT(cpu_idle_tun, SI_SUB_CPU, SI_ORDER_MIDDLE, cpu_idle_tun, NULL); -static int panic_on_nmi = 1; +static int panic_on_nmi = 0xff; SYSCTL_INT(_machdep, OID_AUTO, panic_on_nmi, CTLFLAG_RWTUN, &panic_on_nmi, 0, - "Panic on NMI raised by hardware failure"); + "Panic on NMI: 1 = H/W failure; 2 = unknown; 0xff = all"); int nmi_is_broadcast = 1; SYSCTL_INT(_machdep, OID_AUTO, nmi_is_broadcast, CTLFLAG_RWTUN, &nmi_is_broadcast, 0, "Chipset NMI is broadcast"); -#ifdef KDB -int kdb_on_nmi = 1; -SYSCTL_INT(_machdep, OID_AUTO, kdb_on_nmi, CTLFLAG_RWTUN, - &kdb_on_nmi, 0, - "Go to KDB on NMI with unknown source"); -#endif void nmi_call_kdb(u_int cpu, u_int type, struct trapframe *frame) @@ -847,19 +841,31 @@ nmi_call_kdb(u_int cpu, u_int type, struct trapframe * /* machine/parity/power fail/"kitchen sink" faults */ if (isa_nmi(frame->tf_err)) { claimed = true; - if (panic_on_nmi) + if ((panic_on_nmi & 1) != 0) panic("NMI indicates hardware failure"); } #endif /* DEV_ISA */ + + /* + * NMIs can be useful for debugging. They can be hooked up to a + * pushbutton, usually on an ISA, PCI, or PCIe card. They can also be + * generated by an IPMI BMC, either manually or in response to a + * watchdog timeout. For example, see the "power diag" command in + * ports/sysutils/ipmitool. They can also be generated by a + * hypervisor; see "bhyvectl --inject-nmi". + */ + #ifdef KDB - if (!claimed && kdb_on_nmi) { - /* - * NMI can be hooked up to a pushbutton for debugging. - */ - printf("NMI/cpu%d ... going to debugger\n", cpu); - kdb_trap(type, 0, frame); + if (!claimed && (panic_on_nmi & 2) != 0) { + if (debugger_on_panic) { + printf("NMI/cpu%d ... going to debugger\n", cpu); + claimed = kdb_trap(type, 0, frame); + } } #endif /* KDB */ + + if (!claimed && panic_on_nmi != 0) + panic("NMI"); } void _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
