x86/irq: Use cached IOAPIC entry instead of reading from hardware

Use cached IOAPIC entry instead of reading data from IOAPIC hardware
registers to improve performance.

Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Tested-by: Joerg Roedel <jroedel@suse.de>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: David Cohen <david.a.cohen@linux.intel.com>
Cc: Sander Eikelenboom <linux@eikelenboom.it>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dimitri Sivanich <sivanich@sgi.com>
Cc: Grant Likely <grant.likely@linaro.org>
Link: http://lkml.kernel.org/r/1428978610-28986-21-git-send-email-jiang.liu@linux.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 4c7da84..4fb347f 100644 (file)
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -67,8 +67,13 @@
        list_for_each_entry(entry, &head, list)
 
 /*
- *      Is the SiS APIC rmw bug present ?
+ * Is the SiS APIC rmw bug present ?
  *      -1 = don't know, 0 = no, 1 = yes
+ * When doing a read-modify-write operation on IOAPIC registers, older SiS APIC
+ * requires we rewrite the index register again where the read already set up
+ * the index register.
+ * The code to make use of sis_apic_bug has been removed, but we don't want to
+ * lose this knowledge.
  */
 int sis_apic_bug = -1;
 
@@ -293,22 +298,6 @@ static void io_apic_write(unsigned int apic, unsigned int reg,
        writel(value, &io_apic->data);
 }
 
-/*
- * Re-write a value: to be used for read-modify-write
- * cycles where the read already set up the index register.
- *
- * Older SiS APIC requires we rewrite the index register
- */
-static void io_apic_modify(unsigned int apic, unsigned int reg,
-                          unsigned int value)
-{
-       struct io_apic __iomem *io_apic = io_apic_base(apic);
-
-       if (sis_apic_bug)
-               writel(reg, &io_apic->index);
-       writel(value, &io_apic->data);
-}
-
 union entry_union {
        struct { u32 w1, w2; };
        struct IO_APIC_route_entry entry;
@@ -445,29 +434,23 @@ static void __init replace_pin_at_irq_node(struct mp_chip_data *data, int node,
        add_pin_to_irq_node(data, node, newapic, newpin);
 }
 
-static void __io_apic_modify_irq(struct irq_pin_list *entry,
-                                int mask_and, int mask_or,
-                                void (*final)(struct irq_pin_list *entry))
-{
-       unsigned int reg, pin;
-
-       pin = entry->pin;
-       reg = io_apic_read(entry->apic, 0x10 + pin * 2);
-       reg &= mask_and;
-       reg |= mask_or;
-       io_apic_modify(entry->apic, 0x10 + pin * 2, reg);
-       if (final)
-               final(entry);
-}
-
 static void io_apic_modify_irq(struct mp_chip_data *data,
                               int mask_and, int mask_or,
                               void (*final)(struct irq_pin_list *entry))
 {
+       union entry_union eu;
        struct irq_pin_list *entry;
 
-       for_each_irq_pin(entry, data->irq_2_pin)
-               __io_apic_modify_irq(entry, mask_and, mask_or, final);
+       eu.entry = data->entry;
+       eu.w1 &= mask_and;
+       eu.w1 |= mask_or;
+       data->entry = eu.entry;
+
+       for_each_irq_pin(entry, data->irq_2_pin) {
+               io_apic_write(entry->apic, 0x10 + 2 * entry->pin, eu.w1);
+               if (final)
+                       final(entry);
+       }
 }
 
 static void io_apic_sync(struct irq_pin_list *entry)
@@ -1739,28 +1722,6 @@ static unsigned int startup_ioapic_irq(struct irq_data *data)
        return was_pending;
 }
 
-static void __target_IO_APIC_irq(unsigned int irq, struct irq_cfg *cfg,
-                                struct mp_chip_data *data)
-{
-       int apic, pin;
-       struct irq_pin_list *entry;
-       u8 vector = cfg->vector;
-       unsigned int dest = SET_APIC_LOGICAL_ID(cfg->dest_apicid);
-
-       for_each_irq_pin(entry, data->irq_2_pin) {
-               unsigned int reg;
-
-               apic = entry->apic;
-               pin = entry->pin;
-
-               io_apic_write(apic, 0x11 + pin*2, dest);
-               reg = io_apic_read(apic, 0x10 + pin*2);
-               reg &= ~IO_APIC_REDIR_VECTOR_MASK;
-               reg |= vector;
-               io_apic_modify(apic, 0x10 + pin*2, reg);
-       }
-}
-
 atomic_t irq_mis_count;
 
 #ifdef CONFIG_GENERIC_PENDING_IRQ
@@ -1926,6 +1887,7 @@ static int ioapic_set_affinity(struct irq_data *irq_data,
 {
        struct irq_data *parent = irq_data->parent_data;
        struct mp_chip_data *data = irq_data->chip_data;
+       struct irq_pin_list *entry;
        struct irq_cfg *cfg;
        unsigned long flags;
        int ret;
@@ -1936,7 +1898,9 @@ static int ioapic_set_affinity(struct irq_data *irq_data,
                cfg = irqd_cfg(irq_data);
                data->entry.dest = cfg->dest_apicid;
                data->entry.vector = cfg->vector;
-               __target_IO_APIC_irq(irq_data->irq, cfg, irq_data->chip_data);
+               for_each_irq_pin(entry, data->irq_2_pin)
+                       __ioapic_write_entry(entry->apic, entry->pin,
+                                            data->entry);
        }
        raw_spin_unlock_irqrestore(&ioapic_lock, flags);