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linux/arch/x86/kernel/irq.c
Sean Christopherson 6ff53f6a43 x86/irq: Ensure PI wakeup handler is unregistered before module unload 
Add a synchronize_rcu() after clearing the posted interrupt wakeup handler
to ensure all readers, i.e. in-flight IRQ handlers, see the new handler
before returning to the caller.  If the caller is an exiting module and
is unregistering its handler, failure to wait could result in the IRQ
handler jumping into an unloaded module.

The registration path doesn't require synchronization, as it's the
caller's responsibility to not generate interrupts it cares about until
after its handler is registered.

Fixes: f6b3c72c23 ("x86/irq: Define a global vector for VT-d Posted-Interrupts")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211009001107.3936588-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-10-22 12:45:35 -04:00

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// SPDX-License-Identifier: GPL-2.0-only
/*
* Common interrupt code for 32 and 64 bit
*/
#include <linux/cpu.h>
#include <linux/interrupt.h>
#include <linux/kernel_stat.h>
#include <linux/of.h>
#include <linux/seq_file.h>
#include <linux/smp.h>
#include <linux/ftrace.h>
#include <linux/delay.h>
#include <linux/export.h>
#include <linux/irq.h>
#include <asm/irq_stack.h>
#include <asm/apic.h>
#include <asm/io_apic.h>
#include <asm/irq.h>
#include <asm/mce.h>
#include <asm/hw_irq.h>
#include <asm/desc.h>
#include <asm/traps.h>
#include <asm/thermal.h>
#define CREATE_TRACE_POINTS
#include <asm/trace/irq_vectors.h>
DEFINE_PER_CPU_SHARED_ALIGNED(irq_cpustat_t, irq_stat);
EXPORT_PER_CPU_SYMBOL(irq_stat);
atomic_t irq_err_count;
/*
* 'what should we do if we get a hw irq event on an illegal vector'.
* each architecture has to answer this themselves.
*/
void ack_bad_irq(unsigned int irq)
{
if (printk_ratelimit())
pr_err("unexpected IRQ trap at vector %02x\n", irq);
/*
* Currently unexpected vectors happen only on SMP and APIC.
* We _must_ ack these because every local APIC has only N
* irq slots per priority level, and a 'hanging, unacked' IRQ
* holds up an irq slot - in excessive cases (when multiple
* unexpected vectors occur) that might lock up the APIC
* completely.
* But only ack when the APIC is enabled -AK
*/
ack_APIC_irq();
}
#define irq_stats(x) (&per_cpu(irq_stat, x))
/*
* /proc/interrupts printing for arch specific interrupts
*/
int arch_show_interrupts(struct seq_file *p, int prec)
{
int j;
seq_printf(p, "%*s: ", prec, "NMI");
for_each_online_cpu(j)
seq_printf(p, "%10u ", irq_stats(j)->__nmi_count);
seq_puts(p, " Non-maskable interrupts\n");
#ifdef CONFIG_X86_LOCAL_APIC
seq_printf(p, "%*s: ", prec, "LOC");
for_each_online_cpu(j)
seq_printf(p, "%10u ", irq_stats(j)->apic_timer_irqs);
seq_puts(p, " Local timer interrupts\n");
seq_printf(p, "%*s: ", prec, "SPU");
for_each_online_cpu(j)
seq_printf(p, "%10u ", irq_stats(j)->irq_spurious_count);
seq_puts(p, " Spurious interrupts\n");
seq_printf(p, "%*s: ", prec, "PMI");
for_each_online_cpu(j)
seq_printf(p, "%10u ", irq_stats(j)->apic_perf_irqs);
seq_puts(p, " Performance monitoring interrupts\n");
seq_printf(p, "%*s: ", prec, "IWI");
for_each_online_cpu(j)
seq_printf(p, "%10u ", irq_stats(j)->apic_irq_work_irqs);
seq_puts(p, " IRQ work interrupts\n");
seq_printf(p, "%*s: ", prec, "RTR");
for_each_online_cpu(j)
seq_printf(p, "%10u ", irq_stats(j)->icr_read_retry_count);
seq_puts(p, " APIC ICR read retries\n");
if (x86_platform_ipi_callback) {
seq_printf(p, "%*s: ", prec, "PLT");
for_each_online_cpu(j)
seq_printf(p, "%10u ", irq_stats(j)->x86_platform_ipis);
seq_puts(p, " Platform interrupts\n");
}
#endif
#ifdef CONFIG_SMP
seq_printf(p, "%*s: ", prec, "RES");
for_each_online_cpu(j)
seq_printf(p, "%10u ", irq_stats(j)->irq_resched_count);
seq_puts(p, " Rescheduling interrupts\n");
seq_printf(p, "%*s: ", prec, "CAL");
for_each_online_cpu(j)
seq_printf(p, "%10u ", irq_stats(j)->irq_call_count);
seq_puts(p, " Function call interrupts\n");
seq_printf(p, "%*s: ", prec, "TLB");
for_each_online_cpu(j)
seq_printf(p, "%10u ", irq_stats(j)->irq_tlb_count);
seq_puts(p, " TLB shootdowns\n");
#endif
#ifdef CONFIG_X86_THERMAL_VECTOR
seq_printf(p, "%*s: ", prec, "TRM");
for_each_online_cpu(j)
seq_printf(p, "%10u ", irq_stats(j)->irq_thermal_count);
seq_puts(p, " Thermal event interrupts\n");
#endif
#ifdef CONFIG_X86_MCE_THRESHOLD
seq_printf(p, "%*s: ", prec, "THR");
for_each_online_cpu(j)
seq_printf(p, "%10u ", irq_stats(j)->irq_threshold_count);
seq_puts(p, " Threshold APIC interrupts\n");
#endif
#ifdef CONFIG_X86_MCE_AMD
seq_printf(p, "%*s: ", prec, "DFR");
for_each_online_cpu(j)
seq_printf(p, "%10u ", irq_stats(j)->irq_deferred_error_count);
seq_puts(p, " Deferred Error APIC interrupts\n");
#endif
#ifdef CONFIG_X86_MCE
seq_printf(p, "%*s: ", prec, "MCE");
for_each_online_cpu(j)
seq_printf(p, "%10u ", per_cpu(mce_exception_count, j));
seq_puts(p, " Machine check exceptions\n");
seq_printf(p, "%*s: ", prec, "MCP");
for_each_online_cpu(j)
seq_printf(p, "%10u ", per_cpu(mce_poll_count, j));
seq_puts(p, " Machine check polls\n");
#endif
#ifdef CONFIG_X86_HV_CALLBACK_VECTOR
if (test_bit(HYPERVISOR_CALLBACK_VECTOR, system_vectors)) {
seq_printf(p, "%*s: ", prec, "HYP");
for_each_online_cpu(j)
seq_printf(p, "%10u ",
irq_stats(j)->irq_hv_callback_count);
seq_puts(p, " Hypervisor callback interrupts\n");
}
#endif
#if IS_ENABLED(CONFIG_HYPERV)
if (test_bit(HYPERV_REENLIGHTENMENT_VECTOR, system_vectors)) {
seq_printf(p, "%*s: ", prec, "HRE");
for_each_online_cpu(j)
seq_printf(p, "%10u ",
irq_stats(j)->irq_hv_reenlightenment_count);
seq_puts(p, " Hyper-V reenlightenment interrupts\n");
}
if (test_bit(HYPERV_STIMER0_VECTOR, system_vectors)) {
seq_printf(p, "%*s: ", prec, "HVS");
for_each_online_cpu(j)
seq_printf(p, "%10u ",
irq_stats(j)->hyperv_stimer0_count);
seq_puts(p, " Hyper-V stimer0 interrupts\n");
}
#endif
seq_printf(p, "%*s: %10u\n", prec, "ERR", atomic_read(&irq_err_count));
#if defined(CONFIG_X86_IO_APIC)
seq_printf(p, "%*s: %10u\n", prec, "MIS", atomic_read(&irq_mis_count));
#endif
#ifdef CONFIG_HAVE_KVM
seq_printf(p, "%*s: ", prec, "PIN");
for_each_online_cpu(j)
seq_printf(p, "%10u ", irq_stats(j)->kvm_posted_intr_ipis);
seq_puts(p, " Posted-interrupt notification event\n");
seq_printf(p, "%*s: ", prec, "NPI");
for_each_online_cpu(j)
seq_printf(p, "%10u ",
irq_stats(j)->kvm_posted_intr_nested_ipis);
seq_puts(p, " Nested posted-interrupt event\n");
seq_printf(p, "%*s: ", prec, "PIW");
for_each_online_cpu(j)
seq_printf(p, "%10u ",
irq_stats(j)->kvm_posted_intr_wakeup_ipis);
seq_puts(p, " Posted-interrupt wakeup event\n");
#endif
return 0;
}
/*
* /proc/stat helpers
*/
u64 arch_irq_stat_cpu(unsigned int cpu)
{
u64 sum = irq_stats(cpu)->__nmi_count;
#ifdef CONFIG_X86_LOCAL_APIC
sum += irq_stats(cpu)->apic_timer_irqs;
sum += irq_stats(cpu)->irq_spurious_count;
sum += irq_stats(cpu)->apic_perf_irqs;
sum += irq_stats(cpu)->apic_irq_work_irqs;
sum += irq_stats(cpu)->icr_read_retry_count;
if (x86_platform_ipi_callback)
sum += irq_stats(cpu)->x86_platform_ipis;
#endif
#ifdef CONFIG_SMP
sum += irq_stats(cpu)->irq_resched_count;
sum += irq_stats(cpu)->irq_call_count;
#endif
#ifdef CONFIG_X86_THERMAL_VECTOR
sum += irq_stats(cpu)->irq_thermal_count;
#endif
#ifdef CONFIG_X86_MCE_THRESHOLD
sum += irq_stats(cpu)->irq_threshold_count;
#endif
#ifdef CONFIG_X86_MCE
sum += per_cpu(mce_exception_count, cpu);
sum += per_cpu(mce_poll_count, cpu);
#endif
return sum;
}
u64 arch_irq_stat(void)
{
u64 sum = atomic_read(&irq_err_count);
return sum;
}
static __always_inline void handle_irq(struct irq_desc *desc,
struct pt_regs *regs)
{
if (IS_ENABLED(CONFIG_X86_64))
generic_handle_irq_desc(desc);
else
__handle_irq(desc, regs);
}
/*
* common_interrupt() handles all normal device IRQ's (the special SMP
* cross-CPU interrupts have their own entry points).
*/
DEFINE_IDTENTRY_IRQ(common_interrupt)
{
struct pt_regs *old_regs = set_irq_regs(regs);
struct irq_desc *desc;
/* entry code tells RCU that we're not quiescent. Check it. */
RCU_LOCKDEP_WARN(!rcu_is_watching(), "IRQ failed to wake up RCU");
desc = __this_cpu_read(vector_irq[vector]);
if (likely(!IS_ERR_OR_NULL(desc))) {
handle_irq(desc, regs);
} else {
ack_APIC_irq();
if (desc == VECTOR_UNUSED) {
pr_emerg_ratelimited("%s: %d.%u No irq handler for vector\n",
__func__, smp_processor_id(),
vector);
} else {
__this_cpu_write(vector_irq[vector], VECTOR_UNUSED);
}
}
set_irq_regs(old_regs);
}
#ifdef CONFIG_X86_LOCAL_APIC
/* Function pointer for generic interrupt vector handling */
void (*x86_platform_ipi_callback)(void) = NULL;
/*
* Handler for X86_PLATFORM_IPI_VECTOR.
*/
DEFINE_IDTENTRY_SYSVEC(sysvec_x86_platform_ipi)
{
struct pt_regs *old_regs = set_irq_regs(regs);
ack_APIC_irq();
trace_x86_platform_ipi_entry(X86_PLATFORM_IPI_VECTOR);
inc_irq_stat(x86_platform_ipis);
if (x86_platform_ipi_callback)
x86_platform_ipi_callback();
trace_x86_platform_ipi_exit(X86_PLATFORM_IPI_VECTOR);
set_irq_regs(old_regs);
}
#endif
#ifdef CONFIG_HAVE_KVM
static void dummy_handler(void) {}
static void (*kvm_posted_intr_wakeup_handler)(void) = dummy_handler;
void kvm_set_posted_intr_wakeup_handler(void (*handler)(void))
{
if (handler)
kvm_posted_intr_wakeup_handler = handler;
else {
kvm_posted_intr_wakeup_handler = dummy_handler;
synchronize_rcu();
}
}
EXPORT_SYMBOL_GPL(kvm_set_posted_intr_wakeup_handler);
/*
* Handler for POSTED_INTERRUPT_VECTOR.
*/
DEFINE_IDTENTRY_SYSVEC_SIMPLE(sysvec_kvm_posted_intr_ipi)
{
ack_APIC_irq();
inc_irq_stat(kvm_posted_intr_ipis);
}
/*
* Handler for POSTED_INTERRUPT_WAKEUP_VECTOR.
*/
DEFINE_IDTENTRY_SYSVEC(sysvec_kvm_posted_intr_wakeup_ipi)
{
ack_APIC_irq();
inc_irq_stat(kvm_posted_intr_wakeup_ipis);
kvm_posted_intr_wakeup_handler();
}
/*
* Handler for POSTED_INTERRUPT_NESTED_VECTOR.
*/
DEFINE_IDTENTRY_SYSVEC_SIMPLE(sysvec_kvm_posted_intr_nested_ipi)
{
ack_APIC_irq();
inc_irq_stat(kvm_posted_intr_nested_ipis);
}
#endif
#ifdef CONFIG_HOTPLUG_CPU
/* A cpu has been removed from cpu_online_mask. Reset irq affinities. */
void fixup_irqs(void)
{
unsigned int irr, vector;
struct irq_desc *desc;
struct irq_data *data;
struct irq_chip *chip;
irq_migrate_all_off_this_cpu();
/*
* We can remove mdelay() and then send spurious interrupts to
* new cpu targets for all the irqs that were handled previously by
* this cpu. While it works, I have seen spurious interrupt messages
* (nothing wrong but still...).
*
* So for now, retain mdelay(1) and check the IRR and then send those
* interrupts to new targets as this cpu is already offlined...
*/
mdelay(1);
/*
* We can walk the vector array of this cpu without holding
* vector_lock because the cpu is already marked !online, so
* nothing else will touch it.
*/
for (vector = FIRST_EXTERNAL_VECTOR; vector < NR_VECTORS; vector++) {
if (IS_ERR_OR_NULL(__this_cpu_read(vector_irq[vector])))
continue;
irr = apic_read(APIC_IRR + (vector / 32 * 0x10));
if (irr & (1 << (vector % 32))) {
desc = __this_cpu_read(vector_irq[vector]);
raw_spin_lock(&desc->lock);
data = irq_desc_get_irq_data(desc);
chip = irq_data_get_irq_chip(data);
if (chip->irq_retrigger) {
chip->irq_retrigger(data);
__this_cpu_write(vector_irq[vector], VECTOR_RETRIGGERED);
}
raw_spin_unlock(&desc->lock);
}
if (__this_cpu_read(vector_irq[vector]) != VECTOR_RETRIGGERED)
__this_cpu_write(vector_irq[vector], VECTOR_UNUSED);
}
}
#endif
#ifdef CONFIG_X86_THERMAL_VECTOR
static void smp_thermal_vector(void)
{
if (x86_thermal_enabled())
intel_thermal_interrupt();
else
pr_err("CPU%d: Unexpected LVT thermal interrupt!\n",
smp_processor_id());
}
DEFINE_IDTENTRY_SYSVEC(sysvec_thermal)
{
trace_thermal_apic_entry(THERMAL_APIC_VECTOR);
inc_irq_stat(irq_thermal_count);
smp_thermal_vector();
trace_thermal_apic_exit(THERMAL_APIC_VECTOR);
ack_APIC_irq();
}
#endif
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