x86/irq: Demote irq_cpustat_t::__softirq_pending to u16

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 ->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 <pbonzini@redhat.com>
Signed-off-by: Nicolai Stange <nstange@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/include/asm/hardirq.h b/arch/x86/include/asm/hardirq.h
index 740a428acf1e72b8228b5f9d39a2beb95b475ecf..e39c606de6f652962736ad51008a1d2807bf9232 100644 (file)
--- 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 */