path: root/arch/x86/kernel
diff options
authorThomas Gleixner <tglx@linutronix.de>2019-06-24 13:34:06 +0200
committerThomas Gleixner <tglx@linutronix.de>2019-06-28 13:19:19 +0200
commit4fe1093305e304bb7cc429a91311d7be6948e817 (patch)
treedb22c3eaa5a2713c18bbc0f43aa4f06af746d1ea /arch/x86/kernel
parent17c3b756fec29fc5c70fe26a42a7220af6844e6a (diff)
x86/irq: Seperate unused system vectors from spurious entry againWIP.irq
Quite some time ago the interrupt entry stubs for unused vectors in the system vector range got removed and directly mapped to the spurious interrupt vector entry point. Sounds reasonable, but it's subtly broken. The spurious interrupt vector entry point pushes vector number 0xFF on the stack which makes the whole logic in __smp_spurious_interrupt() pointless. As a consequence any spurious interrupt which comes from a vector != 0xFF is treated as a real spurious interrupt (vector 0xFF) and not acknowledged. That subsequently stalls all interrupt vectors of equal and lower priority, which brings the system to a grinding halt. This can happen because even on 64-bit the system vector space is not guaranteed to be fully populated. A full compile time handling of the unused vectors is not possible because quite some of them are conditonally populated at runtime. Bring the entry stubs back, which wastes 160 bytes if all stubs are unused, but gains the proper handling back. There is no point to selectively spare some of the stubs which are known at compile time as the required code in the IDT management would be way larger and convoluted. Do not route the spurious entries through common_interrupt and do_IRQ() as the original code did. Route it to smp_spurious_interrupt() which evaluates the vector number and acts accordingly now that the real vector numbers are handed in. Fixup the pr_warn so the actual spurious vector (0xff) is clearly distiguished from the other vectors and also note for the vectored case whether it was pending in the ISR or not. "Spurious APIC interrupt (vector 0xFF) on CPU#0, should never happen." "Spurious interrupt vector 0xed on CPU#1. Acked." "Spurious interrupt vector 0xee on CPU#1. Not pending!." Fixes: 2414e021ac8d ("x86: Avoid building unused IRQ entry stubs") Reported-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Jan Beulich <jbeulich@suse.com>
Diffstat (limited to 'arch/x86/kernel')
2 files changed, 24 insertions, 12 deletions
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 177aa8ef2afa..5ca3c30b1333 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -2040,21 +2040,32 @@ __visible void __irq_entry smp_spurious_interrupt(struct pt_regs *regs)
+ inc_irq_stat(irq_spurious_count);
+ /*
+ * If this is a spurious interrupt then do not acknowledge
+ */
+ if (vector == SPURIOUS_APIC_VECTOR) {
+ /* See SDM vol 3 */
+ pr_info("Spurious APIC interrupt (vector 0xFF) on CPU#%d, should never happen.\n",
+ smp_processor_id());
+ goto out;
+ }
- * Check if this really is a spurious interrupt and ACK it
- * if it is a vectored one. Just in case...
- * Spurious interrupts should not be ACKed.
+ * If it is a vectored one, verify it's set in the ISR. If set,
+ * acknowledge it.
v = apic_read(APIC_ISR + ((vector & ~0x1f) >> 1));
- if (v & (1 << (vector & 0x1f)))
+ if (v & (1 << (vector & 0x1f))) {
+ pr_info("Spurious interrupt (vector 0x%02x) on CPU#%d. Acked\n",
+ vector, smp_processor_id());
- inc_irq_stat(irq_spurious_count);
- /* see sw-dev-man vol 3, chapter */
- pr_info("spurious APIC interrupt through vector %02x on CPU#%d, "
- "should never happen.\n", vector, smp_processor_id());
+ } else {
+ pr_info("Spurious interrupt (vector 0x%02x) on CPU#%d. Not pending!\n",
+ vector, smp_processor_id());
+ }
diff --git a/arch/x86/kernel/idt.c b/arch/x86/kernel/idt.c
index d2482bbbe3d0..87ef69a72c52 100644
--- a/arch/x86/kernel/idt.c
+++ b/arch/x86/kernel/idt.c
@@ -319,7 +319,8 @@ void __init idt_setup_apic_and_irq_gates(void)
for_each_clear_bit_from(i, system_vectors, NR_VECTORS) {
set_bit(i, system_vectors);
- set_intr_gate(i, spurious_interrupt);
+ entry = spurious_entries_start + 8 * (i - FIRST_SYSTEM_VECTOR);
+ set_intr_gate(i, entry);