[PATCH 1/3] x86/asm/irq: Rearrange definitoin of specical irq vectors and cleanup.

[Jianyu Zhan]

Currently special(system) irq definition layout is a bit random, due to quite
a long period of code shuffle and refactorization, making native_init_IRQ()
quit hard to follow.

Besides, there are also some leftovers on the vector layout comment.
For example, INVALIDATE_TLB_VECTOR_START vectors have gone by using generic IPI
mechanism(see commit 52aec3308db8). VSYSCALL_EMU_VECTOR is also gone because
vsyscalls are emulated by instruction fault traps(see commit 3ae36655b97a).

So this patch aims at refactoring the special(system) irq vector layout and cleanup.

New system irq vectors layout are now look like:

0xff, 0xfe:
	Two highest vectors, assigned to spurious vector and error vector.
	Also add sanity check for error vector definition:

	SPURIOUS_APIC_VECTOR           0xff
	ERROR_APIC_VECTOR              0xfe

0xfd - 0xf9:
	CONFIG_SMP dependent vectors. On morden machines these are achieved
	via local APIC, but not neccessary:

   	RESCHEDULE_VECTOR     		0xfd
	CALL_FUNCTION_VECTOR		0xfc
	CALL_FUNCTION_SINGLE_VECTOR	0xfb
	REBOOT_VECTOR			0xfa
	X86_PLATFORM_IPI_VECTOR		0xf9

0xf8 - 0xf0:
	Local APIC dependent vectors. Some are only depending on Local ACPI,
	but some are depending on more.

	IRQ_WORK is not neccessarily depending on SMP, but currently it depends
	on X86_LOCAL_APIC. Werid, just leav it as-is:

	IRQ_WORK_VECTOR			0xf8

	Below are all depending on X86_LOCAL_APIC, some depend on more(MCE, Virt, etc):

	THERMAL_APIC_VECTOR             0xf7
	THRESHOLD_APIC_VECTOR           0xf6
	UV_BAU_MESSAGE                  0xf5
	DEFERRED_ERROR_VECTOR           0xf4
	HYPERVISOR_CALLBACK_VECTOR      0xf3

	POSTED_INTR_VECTOR              0xf2
	POSTED_INTR_WAKEUP_VECTOR       0xf1
	/* 0xf0 is currently not used */

0xef:
	Local APIC timer vector		0xef

Once this layout is applied, next patch will arrange native_init_IRQ() per this layout.

Signed-off-by: Jianyu Zhan <nasa4836@xxxxxxxxx>
---
 arch/x86/include/asm/irq_vectors.h | 72 +++++++++++++++++++++++++++++---------
 1 file changed, 55 insertions(+), 17 deletions(-)

diff --git a/arch/x86/include/asm/irq_vectors.h b/arch/x86/include/asm/irq_vectors.h
index 6ca9fd6..b785a19 100644
--- a/arch/x86/include/asm/irq_vectors.h
+++ b/arch/x86/include/asm/irq_vectors.h
@@ -17,8 +17,9 @@
  *  Vectors   0 ...  31 : system traps and exceptions - hardcoded events
  *  Vectors  32 ... 127 : device interrupts
  *  Vector  128         : legacy int80 syscall interface
- *  Vectors 129 ... INVALIDATE_TLB_VECTOR_START-1 except 204 : device interrupts
- *  Vectors INVALIDATE_TLB_VECTOR_START ... 255 : special interrupts
+ *  Vectors 129 ... 238 : device interrupts
+ *  Vectors 239(0xef)   : special(system) interrupt LOCAL_TIMER_VECTOR
+ *  Vectors 240 ... 255 : special(system) interrupts, see definition below for details.
  *
  * 64-bit x86 has per CPU IDT tables, 32-bit has one shared IDT table.
  *
@@ -55,40 +56,71 @@
 #define ISA_IRQ_VECTOR(irq)		(((FIRST_EXTERNAL_VECTOR + 16) & ~15) + irq)
 
 /*
- * Special IRQ vectors used by the SMP architecture, 0xf0-0xff
+ * Special IRQ vectors: 0xef - 0xff, for system vectors.
  *
  *  some of the following vectors are 'rare', they are merged
  *  into a single vector (CALL_FUNCTION_VECTOR) to save vector space.
  *  TLB, reschedule and local APIC vectors are performance-critical.
+ *
+ *  Layout:
+ *  0xff, 0xfe:
+ *	Two highest vectors, granted for spurious vector and error vector.
+ *  0xfd - 0xf9:
+ *	CONFIG_SMP dependent vectors. On morden machines these are achieved
+ *	via local APIC, but not neccessary.
+ *  0xf8 - 0xf0:
+ *      Local APIC dependent vectors. Some are only depending on Local ACPI,
+ *      but some are depending on more.
+ *  0xef:
+ *      Local APIC timer vector.
  */
 
-#define SPURIOUS_APIC_VECTOR		0xff
 /*
- * Sanity check
+ * Grant highest 2 vectors for two special vectors:
+ * Spurious Vector and Error Vector.
  */
-#if ((SPURIOUS_APIC_VECTOR & 0x0F) != 0x0F)
-# error SPURIOUS_APIC_VECTOR definition error
+#define SPURIOUS_APIC_VECTOR		0xff
+#define ERROR_APIC_VECTOR		0xfe
+
+#if SPURIOUS_APIC_VECTOR != 0xff
+# error SPURIOUS_APIC_VECTOR definition error, should grant it: 0xff
 #endif
 
-#define ERROR_APIC_VECTOR		0xfe
+#if ERROR_APIC_VECTOR  != 0xfe
+# error ERROR_APIC_VECTOR definition error, should grant it: 0xfe
+#endif
+
+
+/*
+ * SMP dependent vectors
+ */
+/* CPU-to-CPU reschedule-helper IPI, driven by wakeup.*/
 #define RESCHEDULE_VECTOR		0xfd
+
+/* IPI for generic function call */
 #define CALL_FUNCTION_VECTOR		0xfc
+
+/* IPI for generic single function call */
 #define CALL_FUNCTION_SINGLE_VECTOR	0xfb
-#define THERMAL_APIC_VECTOR		0xfa
-#define THRESHOLD_APIC_VECTOR		0xf9
-#define REBOOT_VECTOR			0xf8
+
+/* IPI used for rebooting/stopping */
+#define REBOOT_VECTOR			0xfa
+
+/* IPI for X86 platform specific use */
+#define X86_PLATFORM_IPI_VECTOR		0xf9
 
 /*
- * Generic system vector for platform specific use
+ * Local APCI dependent only vectors, these may or may not depend on SMP.
  */
-#define X86_PLATFORM_IPI_VECTOR		0xf7
+/* IRQ work vector: a mechanism that allows running code in IRQ context */
+#define IRQ_WORK_VECTOR			0xf8
 
-#define POSTED_INTR_WAKEUP_VECTOR	0xf1
 /*
- * IRQ work vector:
+ * Local APCI dependent vectors, but also depend on other configurations
+ * (MCE, virtualization, etc)
  */
-#define IRQ_WORK_VECTOR			0xf6
-
+#define THERMAL_APIC_VECTOR		0xf7
+#define THRESHOLD_APIC_VECTOR		0xf6
 #define UV_BAU_MESSAGE			0xf5
 #define DEFERRED_ERROR_VECTOR		0xf4
 
@@ -99,6 +131,9 @@
 #ifdef CONFIG_HAVE_KVM
 #define POSTED_INTR_VECTOR		0xf2
 #endif
+#define POSTED_INTR_WAKEUP_VECTOR	0xf1
+
+/* Vector 0xf0 is not used yet, reserved */
 
 /*
  * Local APIC timer IRQ vector is on a different priority level,
@@ -107,6 +142,9 @@
  */
 #define LOCAL_TIMER_VECTOR		0xef
 
+/* --- end of special vectors definitions ---  */
+
+
 #define NR_VECTORS			 256
 
 #ifdef CONFIG_X86_LOCAL_APIC
-- 
2.4.3