x86/irq: Demote irq_cpustat_t::__softirq_pending to u16

nicstange · KAGA-KOKO · commit 9aee5f8a7e30 · 2018-08-05T09:53:12.000+02:00
An upcoming patch will extend KVM's L1TF mitigation in conditional mode
to also cover interrupts after VMEXITs. For tracking those, stores to a
new per-cpu flag from interrupt handlers will become necessary.

In order to improve cache locality, this new flag will be added to x86's
irq_cpustat_t.

Make some space available there by shrinking the -&gt;softirq_pending bitfield
from 32 to 16 bits: the number of bits actually used is only NR_SOFTIRQS,
i.e. 10.

Suggested-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
Signed-off-by: Nicolai Stange &lt;nstange@suse.de&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Reviewed-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
diff --git a/arch/x86/include/asm/hardirq.h b/arch/x86/include/asm/hardirq.h
@@ -6,7 +6,7 @@
 #include <linux/irq.h>
 
 typedef struct {
-	unsigned int __softirq_pending;
+	u16	     __softirq_pending;
 	unsigned int __nmi_count;	/* arch dependent */
 #ifdef CONFIG_X86_LOCAL_APIC
 	unsigned int apic_timer_irqs;	/* arch dependent */
