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>

arch/x86/include/asm/apic.h

@@ -351,6 +351,14 @@ struct apic {
 	/* 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 @@ static inline void apic_write(u32 reg, u32 val)
 	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 safe_apic_wait_icr_idle(void)
 
 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 @@ static inline void ack_APIC_irq(void)
 	 * 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)

arch/x86/kernel/apic/apic_flat_64.c

@@ -227,6 +227,7 @@ static struct apic apic_flat =  {
 
 	.read				= native_apic_mem_read,
 	.write				= native_apic_mem_write,
+	.eoi_write			= native_apic_mem_write,
 	.icr_read			= native_apic_icr_read,
 	.icr_write			= native_apic_icr_write,
 	.wait_icr_idle			= native_apic_wait_icr_idle,
@@ -386,6 +387,7 @@ static struct apic apic_physflat =  {
 
 	.read				= native_apic_mem_read,
 	.write				= native_apic_mem_write,
+	.eoi_write			= native_apic_mem_write,
 	.icr_read			= native_apic_icr_read,
 	.icr_write			= native_apic_icr_write,
 	.wait_icr_idle			= native_apic_wait_icr_idle,

arch/x86/kernel/apic/apic_noop.c

@@ -181,6 +181,7 @@ struct apic apic_noop = {
 
 	.read				= noop_apic_read,
 	.write				= noop_apic_write,
+	.eoi_write			= noop_apic_write,
 	.icr_read			= noop_apic_icr_read,
 	.icr_write			= noop_apic_icr_write,
 	.wait_icr_idle			= noop_apic_wait_icr_idle,

arch/x86/kernel/apic/apic_numachip.c

@@ -295,6 +295,7 @@ static struct apic apic_numachip __refconst = {
 
 	.read				= native_apic_mem_read,
 	.write				= native_apic_mem_write,
+	.eoi_write			= native_apic_mem_write,
 	.icr_read			= native_apic_icr_read,
 	.icr_write			= native_apic_icr_write,
 	.wait_icr_idle			= native_apic_wait_icr_idle,

arch/x86/kernel/apic/bigsmp_32.c

@@ -248,6 +248,7 @@ static struct apic apic_bigsmp = {
 
 	.read				= native_apic_mem_read,
 	.write				= native_apic_mem_write,
+	.eoi_write			= native_apic_mem_write,
 	.icr_read			= native_apic_icr_read,
 	.icr_write			= native_apic_icr_write,
 	.wait_icr_idle			= native_apic_wait_icr_idle,

arch/x86/kernel/apic/es7000_32.c

@@ -678,6 +678,7 @@ static struct apic __refdata apic_es7000_cluster = {
 
 	.read				= native_apic_mem_read,
 	.write				= native_apic_mem_write,
+	.eoi_write			= native_apic_mem_write,
 	.icr_read			= native_apic_icr_read,
 	.icr_write			= native_apic_icr_write,
 	.wait_icr_idle			= native_apic_wait_icr_idle,
@@ -742,6 +743,7 @@ static struct apic __refdata apic_es7000 = {
 
 	.read				= native_apic_mem_read,
 	.write				= native_apic_mem_write,
+	.eoi_write			= native_apic_mem_write,
 	.icr_read			= native_apic_icr_read,
 	.icr_write			= native_apic_icr_write,
 	.wait_icr_idle			= native_apic_wait_icr_idle,

arch/x86/kernel/apic/numaq_32.c

@@ -530,6 +530,7 @@ static struct apic __refdata apic_numaq = {
 
 	.read				= native_apic_mem_read,
 	.write				= native_apic_mem_write,
+	.eoi_write			= native_apic_mem_write,
 	.icr_read			= native_apic_icr_read,
 	.icr_write			= native_apic_icr_write,
 	.wait_icr_idle			= native_apic_wait_icr_idle,

arch/x86/kernel/apic/probe_32.c

@@ -142,6 +142,7 @@ static struct apic apic_default = {
 
 	.read				= native_apic_mem_read,
 	.write				= native_apic_mem_write,
+	.eoi_write			= native_apic_mem_write,
 	.icr_read			= native_apic_icr_read,
 	.icr_write			= native_apic_icr_write,
 	.wait_icr_idle			= native_apic_wait_icr_idle,

arch/x86/kernel/apic/summit_32.c

@@ -546,6 +546,7 @@ static struct apic apic_summit = {
 
 	.read				= native_apic_mem_read,
 	.write				= native_apic_mem_write,
+	.eoi_write			= native_apic_mem_write,
 	.icr_read			= native_apic_icr_read,
 	.icr_write			= native_apic_icr_write,
 	.wait_icr_idle			= native_apic_wait_icr_idle,

arch/x86/kernel/apic/x2apic_cluster.c

@@ -260,6 +260,7 @@ static struct apic apic_x2apic_cluster = {
 
 	.read				= native_apic_msr_read,
 	.write				= native_apic_msr_write,
+	.eoi_write			= native_apic_msr_write,
 	.icr_read			= native_x2apic_icr_read,
 	.icr_write			= native_x2apic_icr_write,
 	.wait_icr_idle			= native_x2apic_wait_icr_idle,

arch/x86/kernel/apic/x2apic_phys.c

@@ -172,6 +172,7 @@ static struct apic apic_x2apic_phys = {
 
 	.read				= native_apic_msr_read,
 	.write				= native_apic_msr_write,
+	.eoi_write			= native_apic_msr_write,
 	.icr_read			= native_x2apic_icr_read,
 	.icr_write			= native_x2apic_icr_write,
 	.wait_icr_idle			= native_x2apic_wait_icr_idle,

arch/x86/kernel/apic/x2apic_uv_x.c

@@ -404,6 +404,7 @@ static struct apic __refdata apic_x2apic_uv_x = {
 
 	.read				= native_apic_msr_read,
 	.write				= native_apic_msr_write,
+	.eoi_write			= native_apic_msr_write,
 	.icr_read			= native_x2apic_icr_read,
 	.icr_write			= native_x2apic_icr_write,
 	.wait_icr_idle			= native_x2apic_wait_icr_idle,