[GIT PULL] x86/apic changes for v4.5

From: Ingo Molnar
Date: Mon Jan 11 2016 - 08:16:36 EST

Linus,

Please pull the latest x86-apic-for-linus git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86-apic-for-linus

# HEAD: c8f3e518d3444ee9200a4987421fcee60f768f11 x86/irq: Export functions to allow MSI domains in modules

The main changes in this cycle were:

- introduce optimized single IPI sending methods on modern APICs (Linus Torvalds, Thomas Gleixner)

- kexec/crash APIC handling fixes and enhancements (Hidehiro Kawai)

- extend lapic vector saving/restoring to the CMCI (MCE) vector as well (Juergen Gross)

- various fixes and enhancements (Jake Oshins, Len Brown)

out-of-topic modifications in x86-apic-for-linus:
---------------------------------------------------
include/linux/kernel.h # 58c5661f2144: panic, x86: Allow CPUs to sa
# 1717f2096b54: panic, x86: Fix re-entrance
include/linux/kexec.h # 7bbee5ca3896: kexec: Fix race between pani
kernel/kexec_core.c # 7bbee5ca3896: kexec: Fix race between pani
kernel/watchdog.c # 58c5661f2144: panic, x86: Allow CPUs to sa
# 1717f2096b54: panic, x86: Fix re-entrance

Thanks,

Ingo

------------------>
Hidehiro Kawai (6):
panic, x86: Fix re-entrance problem due to panic on NMI
panic, x86: Allow CPUs to save registers even if looping in NMI context
kexec: Fix race between panic() and crash_kexec()
x86/apic: Introduce apic_extnmi command line parameter
x86/nmi: Save regs in crash dump on external NMI
Documentation: Document kernel.panic_on_io_nmi sysctl

Jake Oshins (1):
x86/irq: Export functions to allow MSI domains in modules

Juergen Gross (1):
x86/apic: Fix the saving and restoring of lapic vectors during suspend/resume

Len Brown (1):
x86/smpboot: Re-enable init_udelay=0 by default on modern CPUs

Linus Torvalds (2):
x86/apic: Add a single-target IPI function to the apic
x86/apic: Implement single target IPI function for x2apic_cluster

Thomas Gleixner (12):
x86/apic: Implement default single target IPI function
x86/apic: Remove pointless indirections from apic_physflat
x86/apic: Wire up single IPI for apic_physflat
x86/apic: Remove pointless indirections from bigsmp_apic
x86/apic: Wire up single IPI for bigsmp_apic
x86/apic: Implement single IPI for x2apic_phys
x86/apic: Wire up single IPI for x2apic_uv
x86/apic: Wire up single IPI for apic_numachip
x86/apic: Implement single IPI for apic_noop
x86/apic: Provide default send single IPI wrapper
x86/apic: Use default send single IPI wrapper
x86/smp: Remove single IPI wrapper


Documentation/kernel-parameters.txt | 9 +++++++
Documentation/sysctl/kernel.txt | 15 ++++++++++++
arch/x86/include/asm/apic.h | 6 +++++
arch/x86/include/asm/ipi.h | 2 ++
arch/x86/include/asm/msi.h | 6 +++++
arch/x86/include/asm/reboot.h | 1 +
arch/x86/kernel/apic/apic.c | 45 ++++++++++++++++++++++++++++++++---
arch/x86/kernel/apic/apic_flat_64.c | 19 ++++-----------
arch/x86/kernel/apic/apic_noop.c | 2 ++
arch/x86/kernel/apic/apic_numachip.c | 2 ++
arch/x86/kernel/apic/bigsmp_32.c | 10 +++-----
arch/x86/kernel/apic/ipi.c | 18 ++++++++++++++
arch/x86/kernel/apic/msi.c | 8 ++++---
arch/x86/kernel/apic/probe_32.c | 1 +
arch/x86/kernel/apic/vector.c | 2 ++
arch/x86/kernel/apic/x2apic_cluster.c | 9 +++++++
arch/x86/kernel/apic/x2apic_phys.c | 9 +++++++
arch/x86/kernel/apic/x2apic_uv_x.c | 1 +
arch/x86/kernel/nmi.c | 32 ++++++++++++++++++++-----
arch/x86/kernel/reboot.c | 30 +++++++++++++++++++++++
arch/x86/kernel/smp.c | 4 ++--
include/linux/kernel.h | 28 ++++++++++++++++++++++
include/linux/kexec.h | 2 ++
kernel/kexec_core.c | 30 ++++++++++++++++++++++-
kernel/panic.c | 33 +++++++++++++++++++++----
kernel/watchdog.c | 2 +-
26 files changed, 284 insertions(+), 42 deletions(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 742f69d18fc8..74acea53e9e3 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -472,6 +472,15 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
Change the amount of debugging information output
when initialising the APIC and IO-APIC components.

+ apic_extnmi= [APIC,X86] External NMI delivery setting
+ Format: { bsp (default) | all | none }
+ bsp: External NMI is delivered only to CPU 0
+ all: External NMIs are broadcast to all CPUs as a
+ backup of CPU 0
+ none: External NMI is masked for all CPUs. This is
+ useful so that a dump capture kernel won't be
+ shot down by NMI
+
autoconf= [IPV6]
See Documentation/networking/ipv6.txt.

diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
index af70d1541d3a..73c6b1ef0e84 100644
--- a/Documentation/sysctl/kernel.txt
+++ b/Documentation/sysctl/kernel.txt
@@ -551,6 +551,21 @@ the recommended setting is 60.

==============================================================

+panic_on_io_nmi:
+
+Controls the kernel's behavior when a CPU receives an NMI caused by
+an IO error.
+
+0: try to continue operation (default)
+
+1: panic immediately. The IO error triggered an NMI. This indicates a
+ serious system condition which could result in IO data corruption.
+ Rather than continuing, panicking might be a better choice. Some
+ servers issue this sort of NMI when the dump button is pushed,
+ and you can use this option to take a crash dump.
+
+==============================================================
+
panic_on_oops:

Controls the kernel's behaviour when an oops or BUG is encountered.
diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
index a30316bf801a..c80f6b6f3da2 100644
--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -23,6 +23,11 @@
#define APIC_VERBOSE 1
#define APIC_DEBUG 2

+/* Macros for apic_extnmi which controls external NMI masking */
+#define APIC_EXTNMI_BSP 0 /* Default */
+#define APIC_EXTNMI_ALL 1
+#define APIC_EXTNMI_NONE 2
+
/*
* Define the default level of output to be very little
* This can be turned up by using apic=verbose for more
@@ -303,6 +308,7 @@ struct apic {
unsigned int *apicid);

/* ipi */
+ void (*send_IPI)(int cpu, int vector);
void (*send_IPI_mask)(const struct cpumask *mask, int vector);
void (*send_IPI_mask_allbutself)(const struct cpumask *mask,
int vector);
diff --git a/arch/x86/include/asm/ipi.h b/arch/x86/include/asm/ipi.h
index 615fa9061b57..cfc9a0d2d07c 100644
--- a/arch/x86/include/asm/ipi.h
+++ b/arch/x86/include/asm/ipi.h
@@ -119,6 +119,8 @@ static inline void
native_apic_mem_write(APIC_ICR, cfg);
}

+extern void default_send_IPI_single(int cpu, int vector);
+extern void default_send_IPI_single_phys(int cpu, int vector);
extern void default_send_IPI_mask_sequence_phys(const struct cpumask *mask,
int vector);
extern void default_send_IPI_mask_allbutself_phys(const struct cpumask *mask,
diff --git a/arch/x86/include/asm/msi.h b/arch/x86/include/asm/msi.h
index 93724cc62177..eb4b09b41df5 100644
--- a/arch/x86/include/asm/msi.h
+++ b/arch/x86/include/asm/msi.h
@@ -1,7 +1,13 @@
#ifndef _ASM_X86_MSI_H
#define _ASM_X86_MSI_H
#include <asm/hw_irq.h>
+#include <asm/irqdomain.h>

typedef struct irq_alloc_info msi_alloc_info_t;

+int pci_msi_prepare(struct irq_domain *domain, struct device *dev, int nvec,
+ msi_alloc_info_t *arg);
+
+void pci_msi_set_desc(msi_alloc_info_t *arg, struct msi_desc *desc);
+
#endif /* _ASM_X86_MSI_H */
diff --git a/arch/x86/include/asm/reboot.h b/arch/x86/include/asm/reboot.h
index a82c4f1b4d83..2cb1cc253d51 100644
--- a/arch/x86/include/asm/reboot.h
+++ b/arch/x86/include/asm/reboot.h
@@ -25,5 +25,6 @@ void __noreturn machine_real_restart(unsigned int type);

typedef void (*nmi_shootdown_cb)(int, struct pt_regs*);
void nmi_shootdown_cpus(nmi_shootdown_cb callback);
+void run_crash_ipi_callback(struct pt_regs *regs);

#endif /* _ASM_X86_REBOOT_H */
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 2f69e3b184f6..8a5cddac7d44 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -82,6 +82,12 @@ physid_mask_t phys_cpu_present_map;
static unsigned int disabled_cpu_apicid __read_mostly = BAD_APICID;

/*
+ * This variable controls which CPUs receive external NMIs. By default,
+ * external NMIs are delivered only to the BSP.
+ */
+static int apic_extnmi = APIC_EXTNMI_BSP;
+
+/*
* Map cpu index to physical APIC ID
*/
DEFINE_EARLY_PER_CPU_READ_MOSTLY(u16, x86_cpu_to_apicid, BAD_APICID);
@@ -1161,6 +1167,8 @@ void __init init_bsp_APIC(void)
value = APIC_DM_NMI;
if (!lapic_is_integrated()) /* 82489DX */
value |= APIC_LVT_LEVEL_TRIGGER;
+ if (apic_extnmi == APIC_EXTNMI_NONE)
+ value |= APIC_LVT_MASKED;
apic_write(APIC_LVT1, value);
}

@@ -1378,9 +1386,11 @@ void setup_local_APIC(void)
apic_write(APIC_LVT0, value);

/*
- * only the BP should see the LINT1 NMI signal, obviously.
+ * Only the BSP sees the LINT1 NMI signal by default. This can be
+ * modified by apic_extnmi= boot option.
*/
- if (!cpu)
+ if ((!cpu && apic_extnmi != APIC_EXTNMI_NONE) ||
+ apic_extnmi == APIC_EXTNMI_ALL)
value = APIC_DM_NMI;
else
value = APIC_DM_NMI | APIC_LVT_MASKED;
@@ -2270,6 +2280,7 @@ static struct {
unsigned int apic_tmict;
unsigned int apic_tdcr;
unsigned int apic_thmr;
+ unsigned int apic_cmci;
} apic_pm_state;

static int lapic_suspend(void)
@@ -2299,6 +2310,10 @@ static int lapic_suspend(void)
if (maxlvt >= 5)
apic_pm_state.apic_thmr = apic_read(APIC_LVTTHMR);
#endif
+#ifdef CONFIG_X86_MCE_INTEL
+ if (maxlvt >= 6)
+ apic_pm_state.apic_cmci = apic_read(APIC_LVTCMCI);
+#endif

local_irq_save(flags);
disable_local_APIC();
@@ -2355,10 +2370,14 @@ static void lapic_resume(void)
apic_write(APIC_SPIV, apic_pm_state.apic_spiv);
apic_write(APIC_LVT0, apic_pm_state.apic_lvt0);
apic_write(APIC_LVT1, apic_pm_state.apic_lvt1);
-#if defined(CONFIG_X86_MCE_INTEL)
+#ifdef CONFIG_X86_THERMAL_VECTOR
if (maxlvt >= 5)
apic_write(APIC_LVTTHMR, apic_pm_state.apic_thmr);
#endif
+#ifdef CONFIG_X86_MCE_INTEL
+ if (maxlvt >= 6)
+ apic_write(APIC_LVTCMCI, apic_pm_state.apic_cmci);
+#endif
if (maxlvt >= 4)
apic_write(APIC_LVTPC, apic_pm_state.apic_lvtpc);
apic_write(APIC_LVTT, apic_pm_state.apic_lvtt);
@@ -2548,3 +2567,23 @@ static int __init apic_set_disabled_cpu_apicid(char *arg)
return 0;
}
early_param("disable_cpu_apicid", apic_set_disabled_cpu_apicid);
+
+static int __init apic_set_extnmi(char *arg)
+{
+ if (!arg)
+ return -EINVAL;
+
+ if (!strncmp("all", arg, 3))
+ apic_extnmi = APIC_EXTNMI_ALL;
+ else if (!strncmp("none", arg, 4))
+ apic_extnmi = APIC_EXTNMI_NONE;
+ else if (!strncmp("bsp", arg, 3))
+ apic_extnmi = APIC_EXTNMI_BSP;
+ else {
+ pr_warn("Unknown external NMI delivery mode `%s' ignored\n", arg);
+ return -EINVAL;
+ }
+
+ return 0;
+}
+early_param("apic_extnmi", apic_set_extnmi);
diff --git a/arch/x86/kernel/apic/apic_flat_64.c b/arch/x86/kernel/apic/apic_flat_64.c
index f92ab36979a2..9968f30cca3e 100644
--- a/arch/x86/kernel/apic/apic_flat_64.c
+++ b/arch/x86/kernel/apic/apic_flat_64.c
@@ -185,6 +185,7 @@ static struct apic apic_flat = {

.cpu_mask_to_apicid_and = flat_cpu_mask_to_apicid_and,

+ .send_IPI = default_send_IPI_single,
.send_IPI_mask = flat_send_IPI_mask,
.send_IPI_mask_allbutself = flat_send_IPI_mask_allbutself,
.send_IPI_allbutself = flat_send_IPI_allbutself,
@@ -230,17 +231,6 @@ static int physflat_acpi_madt_oem_check(char *oem_id, char *oem_table_id)
return 0;
}

-static void physflat_send_IPI_mask(const struct cpumask *cpumask, int vector)
-{
- default_send_IPI_mask_sequence_phys(cpumask, vector);
-}
-
-static void physflat_send_IPI_mask_allbutself(const struct cpumask *cpumask,
- int vector)
-{
- default_send_IPI_mask_allbutself_phys(cpumask, vector);
-}
-
static void physflat_send_IPI_allbutself(int vector)
{
default_send_IPI_mask_allbutself_phys(cpu_online_mask, vector);
@@ -248,7 +238,7 @@ static void physflat_send_IPI_allbutself(int vector)

static void physflat_send_IPI_all(int vector)
{
- physflat_send_IPI_mask(cpu_online_mask, vector);
+ default_send_IPI_mask_sequence_phys(cpu_online_mask, vector);
}

static int physflat_probe(void)
@@ -292,8 +282,9 @@ static struct apic apic_physflat = {

.cpu_mask_to_apicid_and = default_cpu_mask_to_apicid_and,

- .send_IPI_mask = physflat_send_IPI_mask,
- .send_IPI_mask_allbutself = physflat_send_IPI_mask_allbutself,
+ .send_IPI = default_send_IPI_single_phys,
+ .send_IPI_mask = default_send_IPI_mask_sequence_phys,
+ .send_IPI_mask_allbutself = default_send_IPI_mask_allbutself_phys,
.send_IPI_allbutself = physflat_send_IPI_allbutself,
.send_IPI_all = physflat_send_IPI_all,
.send_IPI_self = apic_send_IPI_self,
diff --git a/arch/x86/kernel/apic/apic_noop.c b/arch/x86/kernel/apic/apic_noop.c
index 0d96749cfcac..331a7a07c48f 100644
--- a/arch/x86/kernel/apic/apic_noop.c
+++ b/arch/x86/kernel/apic/apic_noop.c
@@ -30,6 +30,7 @@
#include <asm/e820.h>

static void noop_init_apic_ldr(void) { }
+static void noop_send_IPI(int cpu, int vector) { }
static void noop_send_IPI_mask(const struct cpumask *cpumask, int vector) { }
static void noop_send_IPI_mask_allbutself(const struct cpumask *cpumask, int vector) { }
static void noop_send_IPI_allbutself(int vector) { }
@@ -144,6 +145,7 @@ struct apic apic_noop = {

.cpu_mask_to_apicid_and = flat_cpu_mask_to_apicid_and,

+ .send_IPI = noop_send_IPI,
.send_IPI_mask = noop_send_IPI_mask,
.send_IPI_mask_allbutself = noop_send_IPI_mask_allbutself,
.send_IPI_allbutself = noop_send_IPI_allbutself,
diff --git a/arch/x86/kernel/apic/apic_numachip.c b/arch/x86/kernel/apic/apic_numachip.c
index 38dd5efdd04c..69329a6e1dc0 100644
--- a/arch/x86/kernel/apic/apic_numachip.c
+++ b/arch/x86/kernel/apic/apic_numachip.c
@@ -276,6 +276,7 @@ static const struct apic apic_numachip1 __refconst = {

.cpu_mask_to_apicid_and = default_cpu_mask_to_apicid_and,

+ .send_IPI = numachip_send_IPI_one,
.send_IPI_mask = numachip_send_IPI_mask,
.send_IPI_mask_allbutself = numachip_send_IPI_mask_allbutself,
.send_IPI_allbutself = numachip_send_IPI_allbutself,
@@ -327,6 +328,7 @@ static const struct apic apic_numachip2 __refconst = {

.cpu_mask_to_apicid_and = default_cpu_mask_to_apicid_and,

+ .send_IPI = numachip_send_IPI_one,
.send_IPI_mask = numachip_send_IPI_mask,
.send_IPI_mask_allbutself = numachip_send_IPI_mask_allbutself,
.send_IPI_allbutself = numachip_send_IPI_allbutself,
diff --git a/arch/x86/kernel/apic/bigsmp_32.c b/arch/x86/kernel/apic/bigsmp_32.c
index 971cf8875939..cf9bd896c12d 100644
--- a/arch/x86/kernel/apic/bigsmp_32.c
+++ b/arch/x86/kernel/apic/bigsmp_32.c
@@ -96,11 +96,6 @@ static int bigsmp_phys_pkg_id(int cpuid_apic, int index_msb)
return cpuid_apic >> index_msb;
}

-static inline void bigsmp_send_IPI_mask(const struct cpumask *mask, int vector)
-{
- default_send_IPI_mask_sequence_phys(mask, vector);
-}
-
static void bigsmp_send_IPI_allbutself(int vector)
{
default_send_IPI_mask_allbutself_phys(cpu_online_mask, vector);
@@ -108,7 +103,7 @@ static void bigsmp_send_IPI_allbutself(int vector)

static void bigsmp_send_IPI_all(int vector)
{
- bigsmp_send_IPI_mask(cpu_online_mask, vector);
+ default_send_IPI_mask_sequence_phys(cpu_online_mask, vector);
}

static int dmi_bigsmp; /* can be set by dmi scanners */
@@ -180,7 +175,8 @@ static struct apic apic_bigsmp = {

.cpu_mask_to_apicid_and = default_cpu_mask_to_apicid_and,

- .send_IPI_mask = bigsmp_send_IPI_mask,
+ .send_IPI = default_send_IPI_single_phys,
+ .send_IPI_mask = default_send_IPI_mask_sequence_phys,
.send_IPI_mask_allbutself = NULL,
.send_IPI_allbutself = bigsmp_send_IPI_allbutself,
.send_IPI_all = bigsmp_send_IPI_all,
diff --git a/arch/x86/kernel/apic/ipi.c b/arch/x86/kernel/apic/ipi.c
index 62071569bd50..eb45fc9b6124 100644
--- a/arch/x86/kernel/apic/ipi.c
+++ b/arch/x86/kernel/apic/ipi.c
@@ -18,6 +18,16 @@
#include <asm/proto.h>
#include <asm/ipi.h>

+void default_send_IPI_single_phys(int cpu, int vector)
+{
+ unsigned long flags;
+
+ local_irq_save(flags);
+ __default_send_IPI_dest_field(per_cpu(x86_cpu_to_apicid, cpu),
+ vector, APIC_DEST_PHYSICAL);
+ local_irq_restore(flags);
+}
+
void default_send_IPI_mask_sequence_phys(const struct cpumask *mask, int vector)
{
unsigned long query_cpu;
@@ -55,6 +65,14 @@ void default_send_IPI_mask_allbutself_phys(const struct cpumask *mask,
local_irq_restore(flags);
}

+/*
+ * Helper function for APICs which insist on cpumasks
+ */
+void default_send_IPI_single(int cpu, int vector)
+{
+ apic->send_IPI_mask(cpumask_of(cpu), vector);
+}
+
#ifdef CONFIG_X86_32

void default_send_IPI_mask_sequence_logical(const struct cpumask *mask,
diff --git a/arch/x86/kernel/apic/msi.c b/arch/x86/kernel/apic/msi.c
index 5f1feb6854af..ade25320df96 100644
--- a/arch/x86/kernel/apic/msi.c
+++ b/arch/x86/kernel/apic/msi.c
@@ -96,8 +96,8 @@ static irq_hw_number_t pci_msi_get_hwirq(struct msi_domain_info *info,
return arg->msi_hwirq;
}

-static int pci_msi_prepare(struct irq_domain *domain, struct device *dev,
- int nvec, msi_alloc_info_t *arg)
+int pci_msi_prepare(struct irq_domain *domain, struct device *dev, int nvec,
+ msi_alloc_info_t *arg)
{
struct pci_dev *pdev = to_pci_dev(dev);
struct msi_desc *desc = first_pci_msi_entry(pdev);
@@ -113,11 +113,13 @@ static int pci_msi_prepare(struct irq_domain *domain, struct device *dev,

return 0;
}
+EXPORT_SYMBOL_GPL(pci_msi_prepare);

-static void pci_msi_set_desc(msi_alloc_info_t *arg, struct msi_desc *desc)
+void pci_msi_set_desc(msi_alloc_info_t *arg, struct msi_desc *desc)
{
arg->msi_hwirq = pci_msi_domain_calc_hwirq(arg->msi_dev, desc);
}
+EXPORT_SYMBOL_GPL(pci_msi_set_desc);

static struct msi_domain_ops pci_msi_domain_ops = {
.get_hwirq = pci_msi_get_hwirq,
diff --git a/arch/x86/kernel/apic/probe_32.c b/arch/x86/kernel/apic/probe_32.c
index 7694ae6c1199..f316e34abb42 100644
--- a/arch/x86/kernel/apic/probe_32.c
+++ b/arch/x86/kernel/apic/probe_32.c
@@ -105,6 +105,7 @@ static struct apic apic_default = {

.cpu_mask_to_apicid_and = flat_cpu_mask_to_apicid_and,

+ .send_IPI = default_send_IPI_single,
.send_IPI_mask = default_send_IPI_mask_logical,
.send_IPI_mask_allbutself = default_send_IPI_mask_allbutself_logical,
.send_IPI_allbutself = default_send_IPI_allbutself,
diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c
index 861bc59c8f25..908cb37da171 100644
--- a/arch/x86/kernel/apic/vector.c
+++ b/arch/x86/kernel/apic/vector.c
@@ -29,6 +29,7 @@ struct apic_chip_data {
};

struct irq_domain *x86_vector_domain;
+EXPORT_SYMBOL_GPL(x86_vector_domain);
static DEFINE_RAW_SPINLOCK(vector_lock);
static cpumask_var_t vector_cpumask;
static struct irq_chip lapic_controller;
@@ -66,6 +67,7 @@ struct irq_cfg *irqd_cfg(struct irq_data *irq_data)

return data ? &data->cfg : NULL;
}
+EXPORT_SYMBOL_GPL(irqd_cfg);

struct irq_cfg *irq_cfg(unsigned int irq)
{
diff --git a/arch/x86/kernel/apic/x2apic_cluster.c b/arch/x86/kernel/apic/x2apic_cluster.c
index cc8311c4d298..aca8b75c1552 100644
--- a/arch/x86/kernel/apic/x2apic_cluster.c
+++ b/arch/x86/kernel/apic/x2apic_cluster.c
@@ -23,6 +23,14 @@ static inline u32 x2apic_cluster(int cpu)
return per_cpu(x86_cpu_to_logical_apicid, cpu) >> 16;
}

+static void x2apic_send_IPI(int cpu, int vector)
+{
+ u32 dest = per_cpu(x86_cpu_to_logical_apicid, cpu);
+
+ x2apic_wrmsr_fence();
+ __x2apic_send_IPI_dest(dest, vector, APIC_DEST_LOGICAL);
+}
+
static void
__x2apic_send_IPI_mask(const struct cpumask *mask, int vector, int apic_dest)
{
@@ -266,6 +274,7 @@ static struct apic apic_x2apic_cluster = {

.cpu_mask_to_apicid_and = x2apic_cpu_mask_to_apicid_and,

+ .send_IPI = x2apic_send_IPI,
.send_IPI_mask = x2apic_send_IPI_mask,
.send_IPI_mask_allbutself = x2apic_send_IPI_mask_allbutself,
.send_IPI_allbutself = x2apic_send_IPI_allbutself,
diff --git a/arch/x86/kernel/apic/x2apic_phys.c b/arch/x86/kernel/apic/x2apic_phys.c
index 662e9150ea6f..a1242e2c12e6 100644
--- a/arch/x86/kernel/apic/x2apic_phys.c
+++ b/arch/x86/kernel/apic/x2apic_phys.c
@@ -36,6 +36,14 @@ static int x2apic_acpi_madt_oem_check(char *oem_id, char *oem_table_id)
return x2apic_enabled() && (x2apic_phys || x2apic_fadt_phys());
}

+static void x2apic_send_IPI(int cpu, int vector)
+{
+ u32 dest = per_cpu(x86_cpu_to_apicid, cpu);
+
+ x2apic_wrmsr_fence();
+ __x2apic_send_IPI_dest(dest, vector, APIC_DEST_PHYSICAL);
+}
+
static void
__x2apic_send_IPI_mask(const struct cpumask *mask, int vector, int apic_dest)
{
@@ -122,6 +130,7 @@ static struct apic apic_x2apic_phys = {

.cpu_mask_to_apicid_and = default_cpu_mask_to_apicid_and,

+ .send_IPI = x2apic_send_IPI,
.send_IPI_mask = x2apic_send_IPI_mask,
.send_IPI_mask_allbutself = x2apic_send_IPI_mask_allbutself,
.send_IPI_allbutself = x2apic_send_IPI_allbutself,
diff --git a/arch/x86/kernel/apic/x2apic_uv_x.c b/arch/x86/kernel/apic/x2apic_uv_x.c
index 4a139465f1d4..d760c6bb37b5 100644
--- a/arch/x86/kernel/apic/x2apic_uv_x.c
+++ b/arch/x86/kernel/apic/x2apic_uv_x.c
@@ -406,6 +406,7 @@ static struct apic __refdata apic_x2apic_uv_x = {

.cpu_mask_to_apicid_and = uv_cpu_mask_to_apicid_and,

+ .send_IPI = uv_send_IPI_one,
.send_IPI_mask = uv_send_IPI_mask,
.send_IPI_mask_allbutself = uv_send_IPI_mask_allbutself,
.send_IPI_allbutself = uv_send_IPI_allbutself,
diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
index 697f90db0e37..8a2cdd736fa4 100644
--- a/arch/x86/kernel/nmi.c
+++ b/arch/x86/kernel/nmi.c
@@ -29,6 +29,7 @@
#include <asm/mach_traps.h>
#include <asm/nmi.h>
#include <asm/x86_init.h>
+#include <asm/reboot.h>

#define CREATE_TRACE_POINTS
#include <trace/events/nmi.h>
@@ -231,7 +232,7 @@ pci_serr_error(unsigned char reason, struct pt_regs *regs)
#endif

if (panic_on_unrecovered_nmi)
- panic("NMI: Not continuing");
+ nmi_panic(regs, "NMI: Not continuing");

pr_emerg("Dazed and confused, but trying to continue\n");

@@ -255,8 +256,16 @@ io_check_error(unsigned char reason, struct pt_regs *regs)
reason, smp_processor_id());
show_regs(regs);

- if (panic_on_io_nmi)
- panic("NMI IOCK error: Not continuing");
+ if (panic_on_io_nmi) {
+ nmi_panic(regs, "NMI IOCK error: Not continuing");
+
+ /*
+ * If we end up here, it means we have received an NMI while
+ * processing panic(). Simply return without delaying and
+ * re-enabling NMIs.
+ */
+ return;
+ }

/* Re-enable the IOCK line, wait for a few seconds */
reason = (reason & NMI_REASON_CLEAR_MASK) | NMI_REASON_CLEAR_IOCHK;
@@ -297,7 +306,7 @@ unknown_nmi_error(unsigned char reason, struct pt_regs *regs)

pr_emerg("Do you have a strange power saving mode enabled?\n");
if (unknown_nmi_panic || panic_on_unrecovered_nmi)
- panic("NMI: Not continuing");
+ nmi_panic(regs, "NMI: Not continuing");

pr_emerg("Dazed and confused, but trying to continue\n");
}
@@ -348,8 +357,19 @@ static void default_do_nmi(struct pt_regs *regs)
return;
}

- /* Non-CPU-specific NMI: NMI sources can be processed on any CPU */
- raw_spin_lock(&nmi_reason_lock);
+ /*
+ * Non-CPU-specific NMI: NMI sources can be processed on any CPU.
+ *
+ * Another CPU may be processing panic routines while holding
+ * nmi_reason_lock. Check if the CPU issued the IPI for crash dumping,
+ * and if so, call its callback directly. If there is no CPU preparing
+ * crash dump, we simply loop here.
+ */
+ while (!raw_spin_trylock(&nmi_reason_lock)) {
+ run_crash_ipi_callback(regs);
+ cpu_relax();
+ }
+
reason = x86_platform.get_nmi_reason();

if (reason & NMI_REASON_MASK) {
diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index 02693dd9a079..d64889aa2d46 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -718,6 +718,7 @@ static int crashing_cpu;
static nmi_shootdown_cb shootdown_callback;

static atomic_t waiting_for_crash_ipi;
+static int crash_ipi_issued;

static int crash_nmi_callback(unsigned int val, struct pt_regs *regs)
{
@@ -780,6 +781,9 @@ void nmi_shootdown_cpus(nmi_shootdown_cb callback)

smp_send_nmi_allbutself();

+ /* Kick CPUs looping in NMI context. */
+ WRITE_ONCE(crash_ipi_issued, 1);
+
msecs = 1000; /* Wait at most a second for the other cpus to stop */
while ((atomic_read(&waiting_for_crash_ipi) > 0) && msecs) {
mdelay(1);
@@ -788,9 +792,35 @@ void nmi_shootdown_cpus(nmi_shootdown_cb callback)

/* Leave the nmi callback set */
}
+
+/*
+ * Check if the crash dumping IPI got issued and if so, call its callback
+ * directly. This function is used when we have already been in NMI handler.
+ * It doesn't return.
+ */
+void run_crash_ipi_callback(struct pt_regs *regs)
+{
+ if (crash_ipi_issued)
+ crash_nmi_callback(0, regs);
+}
+
+/* Override the weak function in kernel/panic.c */
+void nmi_panic_self_stop(struct pt_regs *regs)
+{
+ while (1) {
+ /* If no CPU is preparing crash dump, we simply loop here. */
+ run_crash_ipi_callback(regs);
+ cpu_relax();
+ }
+}
+
#else /* !CONFIG_SMP */
void nmi_shootdown_cpus(nmi_shootdown_cb callback)
{
/* No other CPUs to shoot down */
}
+
+void run_crash_ipi_callback(struct pt_regs *regs)
+{
+}
#endif
diff --git a/arch/x86/kernel/smp.c b/arch/x86/kernel/smp.c
index 12c8286206ce..658777cf3851 100644
--- a/arch/x86/kernel/smp.c
+++ b/arch/x86/kernel/smp.c
@@ -125,12 +125,12 @@ static void native_smp_send_reschedule(int cpu)
WARN_ON(1);
return;
}
- apic->send_IPI_mask(cpumask_of(cpu), RESCHEDULE_VECTOR);
+ apic->send_IPI(cpu, RESCHEDULE_VECTOR);
}

void native_send_call_func_single_ipi(int cpu)
{
- apic->send_IPI_mask(cpumask_of(cpu), CALL_FUNCTION_SINGLE_VECTOR);
+ apic->send_IPI(cpu, CALL_FUNCTION_SINGLE_VECTOR);
}

void native_send_call_func_ipi(const struct cpumask *mask)
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 350dfb08aee3..7311c3294e25 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -255,6 +255,7 @@ extern long (*panic_blink)(int state);
__printf(1, 2)
void panic(const char *fmt, ...)
__noreturn __cold;
+void nmi_panic_self_stop(struct pt_regs *);
extern void oops_enter(void);
extern void oops_exit(void);
void print_oops_end_marker(void);
@@ -446,6 +447,33 @@ extern int sysctl_panic_on_stackoverflow;
extern bool crash_kexec_post_notifiers;

/*
+ * panic_cpu is used for synchronizing panic() and crash_kexec() execution. It
+ * holds a CPU number which is executing panic() currently. A value of
+ * PANIC_CPU_INVALID means no CPU has entered panic() or crash_kexec().
+ */
+extern atomic_t panic_cpu;
+#define PANIC_CPU_INVALID -1
+
+/*
+ * A variant of panic() called from NMI context. We return if we've already
+ * panicked on this CPU. If another CPU already panicked, loop in
+ * nmi_panic_self_stop() which can provide architecture dependent code such
+ * as saving register state for crash dump.
+ */
+#define nmi_panic(regs, fmt, ...) \
+do { \
+ int old_cpu, cpu; \
+ \
+ cpu = raw_smp_processor_id(); \
+ old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, cpu); \
+ \
+ if (old_cpu == PANIC_CPU_INVALID) \
+ panic(fmt, ##__VA_ARGS__); \
+ else if (old_cpu != cpu) \
+ nmi_panic_self_stop(regs); \
+} while (0)
+
+/*
* Only to be used by arch init code. If the user over-wrote the default
* CONFIG_PANIC_TIMEOUT, honor it.
*/
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index d140b1e9faa7..7b68d2788a56 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -237,6 +237,7 @@ extern int kexec_purgatory_get_set_symbol(struct kimage *image,
unsigned int size, bool get_value);
extern void *kexec_purgatory_get_symbol_addr(struct kimage *image,
const char *name);
+extern void __crash_kexec(struct pt_regs *);
extern void crash_kexec(struct pt_regs *);
int kexec_should_crash(struct task_struct *);
void crash_save_cpu(struct pt_regs *regs, int cpu);
@@ -332,6 +333,7 @@ int __weak arch_kexec_apply_relocations(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
#else /* !CONFIG_KEXEC_CORE */
struct pt_regs;
struct task_struct;
+static inline void __crash_kexec(struct pt_regs *regs) { }
static inline void crash_kexec(struct pt_regs *regs) { }
static inline int kexec_should_crash(struct task_struct *p) { return 0; }
#define kexec_in_progress false
diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index 11b64a63c0f8..c823f3001e12 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -853,7 +853,12 @@ struct kimage *kexec_image;
struct kimage *kexec_crash_image;
int kexec_load_disabled;

-void crash_kexec(struct pt_regs *regs)
+/*
+ * No panic_cpu check version of crash_kexec(). This function is called
+ * only when panic_cpu holds the current CPU number; this is the only CPU
+ * which processes crash_kexec routines.
+ */
+void __crash_kexec(struct pt_regs *regs)
{
/* Take the kexec_mutex here to prevent sys_kexec_load
* running on one cpu from replacing the crash kernel
@@ -876,6 +881,29 @@ void crash_kexec(struct pt_regs *regs)
}
}

+void crash_kexec(struct pt_regs *regs)
+{
+ int old_cpu, this_cpu;
+
+ /*
+ * Only one CPU is allowed to execute the crash_kexec() code as with
+ * panic(). Otherwise parallel calls of panic() and crash_kexec()
+ * may stop each other. To exclude them, we use panic_cpu here too.
+ */
+ this_cpu = raw_smp_processor_id();
+ old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, this_cpu);
+ if (old_cpu == PANIC_CPU_INVALID) {
+ /* This is the 1st CPU which comes here, so go ahead. */
+ __crash_kexec(regs);
+
+ /*
+ * Reset panic_cpu to allow another panic()/crash_kexec()
+ * call.
+ */
+ atomic_set(&panic_cpu, PANIC_CPU_INVALID);
+ }
+}
+
size_t crash_get_memory_size(void)
{
size_t size = 0;
diff --git a/kernel/panic.c b/kernel/panic.c
index 4b150bc0c6c1..b333380c6bb2 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -61,6 +61,17 @@ void __weak panic_smp_self_stop(void)
cpu_relax();
}

+/*
+ * Stop ourselves in NMI context if another CPU has already panicked. Arch code
+ * may override this to prepare for crash dumping, e.g. save regs info.
+ */
+void __weak nmi_panic_self_stop(struct pt_regs *regs)
+{
+ panic_smp_self_stop();
+}
+
+atomic_t panic_cpu = ATOMIC_INIT(PANIC_CPU_INVALID);
+
/**
* panic - halt the system
* @fmt: The text string to print
@@ -71,17 +82,17 @@ void __weak panic_smp_self_stop(void)
*/
void panic(const char *fmt, ...)
{
- static DEFINE_SPINLOCK(panic_lock);
static char buf[1024];
va_list args;
long i, i_next = 0;
int state = 0;
+ int old_cpu, this_cpu;

/*
* Disable local interrupts. This will prevent panic_smp_self_stop
* from deadlocking the first cpu that invokes the panic, since
* there is nothing to prevent an interrupt handler (that runs
- * after the panic_lock is acquired) from invoking panic again.
+ * after setting panic_cpu) from invoking panic() again.
*/
local_irq_disable();

@@ -94,8 +105,16 @@ void panic(const char *fmt, ...)
* multiple parallel invocations of panic, all other CPUs either
* stop themself or will wait until they are stopped by the 1st CPU
* with smp_send_stop().
+ *
+ * `old_cpu == PANIC_CPU_INVALID' means this is the 1st CPU which
+ * comes here, so go ahead.
+ * `old_cpu == this_cpu' means we came from nmi_panic() which sets
+ * panic_cpu to this CPU. In this case, this is also the 1st CPU.
*/
- if (!spin_trylock(&panic_lock))
+ this_cpu = raw_smp_processor_id();
+ old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, this_cpu);
+
+ if (old_cpu != PANIC_CPU_INVALID && old_cpu != this_cpu)
panic_smp_self_stop();

console_verbose();
@@ -117,9 +136,11 @@ void panic(const char *fmt, ...)
* everything else.
* If we want to run this after calling panic_notifiers, pass
* the "crash_kexec_post_notifiers" option to the kernel.
+ *
+ * Bypass the panic_cpu check and call __crash_kexec directly.
*/
if (!crash_kexec_post_notifiers)
- crash_kexec(NULL);
+ __crash_kexec(NULL);

/*
* Note smp_send_stop is the usual smp shutdown function, which
@@ -142,9 +163,11 @@ void panic(const char *fmt, ...)
* panic_notifiers and dumping kmsg before kdump.
* Note: since some panic_notifiers can make crashed kernel
* more unstable, it can increase risks of the kdump failure too.
+ *
+ * Bypass the panic_cpu check and call __crash_kexec directly.
*/
if (crash_kexec_post_notifiers)
- crash_kexec(NULL);
+ __crash_kexec(NULL);

bust_spinlocks(0);

diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 18f34cf75f74..84b5035cb6a5 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -351,7 +351,7 @@ static void watchdog_overflow_callback(struct perf_event *event,
trigger_allbutself_cpu_backtrace();

if (hardlockup_panic)
- panic("Hard LOCKUP");
+ nmi_panic(regs, "Hard LOCKUP");

__this_cpu_write(hard_watchdog_warn, true);
return;