x86/apic: Add apic->eoi_write() callback
Add eoi_write callback so that kvm can override
eoi accesses without touching the rest of the apic.
As a side-effect, this will enable a micro-optimization
for apics using msr.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: gleb@redhat.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/0df425d746c49ac2ecc405174df87752869629d2.1337184153.git.mst@redhat.com
[ tidied it up a bit ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
index a09e9ab..bf8d065 100644
--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -351,6 +351,14 @@
/* apic ops */
u32 (*read)(u32 reg);
void (*write)(u32 reg, u32 v);
+ /*
+ * ->eoi_write() has the same signature as ->write().
+ *
+ * Drivers can support both ->eoi_write() and ->write() by passing the same
+ * callback value. Kernel can override ->eoi_write() and fall back
+ * on write for EOI.
+ */
+ void (*eoi_write)(u32 reg, u32 v);
u64 (*icr_read)(void);
void (*icr_write)(u32 low, u32 high);
void (*wait_icr_idle)(void);
@@ -426,6 +434,11 @@
apic->write(reg, val);
}
+static inline void apic_eoi(void)
+{
+ apic->eoi_write(APIC_EOI, APIC_EOI_ACK);
+}
+
static inline u64 apic_icr_read(void)
{
return apic->icr_read();
@@ -450,6 +463,7 @@
static inline u32 apic_read(u32 reg) { return 0; }
static inline void apic_write(u32 reg, u32 val) { }
+static inline void apic_eoi(void) { }
static inline u64 apic_icr_read(void) { return 0; }
static inline void apic_icr_write(u32 low, u32 high) { }
static inline void apic_wait_icr_idle(void) { }
@@ -463,7 +477,7 @@
* ack_APIC_irq() actually gets compiled as a single instruction
* ... yummie.
*/
- apic_write(APIC_EOI, APIC_EOI_ACK);
+ apic_eoi();
}
static inline unsigned default_get_apic_id(unsigned long x)