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Subject[PATCH 1/3] x86: add io_apic_ops to allow interception
Date
From: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

Xen dom0 needs to paravirtualize IO operations to the IO APIC, so add
a io_apic_ops for it to intercept. Do this as ops structure because
there's at least some chance that another paravirtualized environment
may want to intercept these.

[ Impact: indirect IO APIC access via io_apic_ops ]

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
---
arch/x86/include/asm/io_apic.h | 9 +++++++
arch/x86/kernel/apic/io_apic.c | 50 +++++++++++++++++++++++++++++++++++++--
2 files changed, 56 insertions(+), 3 deletions(-)
diff --git a/arch/x86/include/asm/io_apic.h b/arch/x86/include/asm/io_apic.h
index 690d1cc..190d8c2 100644
--- a/arch/x86/include/asm/io_apic.h
+++ b/arch/x86/include/asm/io_apic.h
@@ -21,6 +21,15 @@
#define IO_APIC_REDIR_LEVEL_TRIGGER (1 << 15)
#define IO_APIC_REDIR_MASKED (1 << 16)

+struct io_apic_ops {
+ void (*init)(void);
+ unsigned int (*read)(unsigned int apic, unsigned int reg);
+ void (*write)(unsigned int apic, unsigned int reg, unsigned int value);
+ void (*modify)(unsigned int apic, unsigned int reg, unsigned int value);
+};
+
+void __init set_io_apic_ops(const struct io_apic_ops *);
+
/*
* The structure of the IO-APIC:
*/
diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index fb07275..bf120234 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -67,6 +67,25 @@
#define for_each_irq_pin(entry, head) \
for (entry = head; entry; entry = entry->next)

+static void __init __ioapic_init_mappings(void);
+static unsigned int __io_apic_read(unsigned int apic, unsigned int reg);
+static void __io_apic_write(unsigned int apic, unsigned int reg,
+ unsigned int val);
+static void __io_apic_modify(unsigned int apic, unsigned int reg,
+ unsigned int val);
+
+static struct io_apic_ops io_apic_ops = {
+ .init = __ioapic_init_mappings,
+ .read = __io_apic_read,
+ .write = __io_apic_write,
+ .modify = __io_apic_modify,
+};
+
+void __init set_io_apic_ops(const struct io_apic_ops *ops)
+{
+ io_apic_ops = *ops;
+}
+
/*
* Is the SiS APIC rmw bug present ?
* -1 = don't know, 0 = no, 1 = yes
@@ -294,6 +313,24 @@ static void free_irq_at(unsigned int at, struct irq_cfg *cfg)
irq_free_desc(at);
}

+static inline unsigned int io_apic_read(unsigned int apic, unsigned int reg)
+{
+ return io_apic_ops.read(apic, reg);
+}
+
+static inline void io_apic_write(unsigned int apic, unsigned int reg,
+ unsigned int value)
+{
+ io_apic_ops.write(apic, reg, value);
+}
+
+static inline void io_apic_modify(unsigned int apic, unsigned int reg,
+ unsigned int value)
+{
+ io_apic_ops.modify(apic, reg, value);
+}
+
+
struct io_apic {
unsigned int index;
unsigned int unused[3];
@@ -314,14 +351,15 @@ static inline void io_apic_eoi(unsigned int apic, unsigned int vector)
writel(vector, &io_apic->eoi);
}

-static inline unsigned int io_apic_read(unsigned int apic, unsigned int reg)
+static unsigned int __io_apic_read(unsigned int apic, unsigned int reg)
{
struct io_apic __iomem *io_apic = io_apic_base(apic);
writel(reg, &io_apic->index);
return readl(&io_apic->data);
}

-static inline void io_apic_write(unsigned int apic, unsigned int reg, unsigned int value)
+static void __io_apic_write(unsigned int apic, unsigned int reg,
+ unsigned int value)
{
struct io_apic __iomem *io_apic = io_apic_base(apic);
writel(reg, &io_apic->index);
@@ -334,7 +372,8 @@ static inline void io_apic_write(unsigned int apic, unsigned int reg, unsigned i
*
* Older SiS APIC requires we rewrite the index register
*/
-static inline void io_apic_modify(unsigned int apic, unsigned int reg, unsigned int value)
+static void __io_apic_modify(unsigned int apic, unsigned int reg,
+ unsigned int value)
{
struct io_apic __iomem *io_apic = io_apic_base(apic);

@@ -3873,6 +3912,11 @@ static struct resource * __init ioapic_setup_resources(int nr_ioapics)

void __init ioapic_and_gsi_init(void)
{
+ io_apic_ops.init();
+}
+
+static void __init __ioapic_init_mappings(void)
+{
unsigned long ioapic_phys, idx = FIX_IO_APIC_BASE_0;
struct resource *ioapic_res;
int i;
--
1.7.7.5


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