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Subject[PATCH 02/10] xen: hook io_apic read/write operations
Date
In Xen, writes to the IO APIC are paravirtualized via hypercalls, so
implement the appropriate operations.

This version of the patch just hooks the io_apic read/write functions
directly, rather than introducing another layer of indirection. The
xen_initial_domain() tests compile to 0 if CONFIG_XEN_DOM0 isn't set,
and are cheap if it is.

(An alternative would be to add io_apic_ops, and point them to the Xen
implementation as needed. HPA deemed this extra level of indirection to
be excessive.)

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
---
arch/x86/include/asm/io_apic.h | 6 ++++
arch/x86/kernel/io_apic.c | 32 ++++++++++++++++++++--
arch/x86/xen/Makefile | 2 +-
arch/x86/xen/apic.c | 57 ++++++++++++++++++++++++++++++++++++++++
arch/x86/xen/enlighten.c | 2 +
arch/x86/xen/xen-ops.h | 6 ++++
6 files changed, 101 insertions(+), 4 deletions(-)
create mode 100644 arch/x86/xen/apic.c
diff --git a/arch/x86/include/asm/io_apic.h b/arch/x86/include/asm/io_apic.h
index 309d0e2..685f21b 100644
--- a/arch/x86/include/asm/io_apic.h
+++ b/arch/x86/include/asm/io_apic.h
@@ -177,4 +177,10 @@ static inline void ioapic_init_mappings(void) { }
static inline void probe_nr_irqs_gsi(void) { }
#endif

+void xen_io_apic_init(void);
+unsigned int xen_io_apic_read(unsigned apic, unsigned reg);
+void xen_io_apic_write(unsigned int apic,
+ unsigned int reg, unsigned int value);
+
+
#endif /* _ASM_X86_IO_APIC_H */
diff --git a/arch/x86/kernel/io_apic.c b/arch/x86/kernel/io_apic.c
index 56e51eb..6366384 100644
--- a/arch/x86/kernel/io_apic.c
+++ b/arch/x86/kernel/io_apic.c
@@ -62,6 +62,8 @@
#include <asm/uv/uv_hub.h>
#include <asm/uv/uv_irq.h>

+#include <asm/xen/hypervisor.h>
+
#include <asm/genapic.h>

#define __apicdebuginit(type) static type __init
@@ -399,14 +401,26 @@ static __attribute_const__ struct io_apic __iomem *io_apic_base(int idx)

static inline unsigned int io_apic_read(unsigned int apic, unsigned int reg)
{
- struct io_apic __iomem *io_apic = io_apic_base(apic);
+ struct io_apic __iomem *io_apic;
+
+ if (xen_initial_domain())
+ return xen_io_apic_read(apic, reg);
+
+ 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)
{
- struct io_apic __iomem *io_apic = io_apic_base(apic);
+ struct io_apic __iomem *io_apic;
+
+ if (xen_initial_domain()) {
+ xen_io_apic_write(apic, reg, value);
+ return;
+ }
+
+ io_apic = io_apic_base(apic);
writel(reg, &io_apic->index);
writel(value, &io_apic->data);
}
@@ -419,7 +433,14 @@ static inline void io_apic_write(unsigned int apic, unsigned int reg, unsigned i
*/
static inline void io_apic_modify(unsigned int apic, unsigned int reg, unsigned int value)
{
- struct io_apic __iomem *io_apic = io_apic_base(apic);
+ struct io_apic __iomem *io_apic;
+
+ if (xen_initial_domain()) {
+ xen_io_apic_write(apic, reg, value);
+ return;
+ }
+
+ io_apic = io_apic_base(apic);

if (sis_apic_bug)
writel(reg, &io_apic->index);
@@ -4113,6 +4134,11 @@ void __init ioapic_init_mappings(void)
struct resource *ioapic_res;
int i;

+ if (xen_initial_domain()) {
+ xen_io_apic_init();
+ return;
+ }
+
ioapic_res = ioapic_setup_resources();
for (i = 0; i < nr_ioapics; i++) {
if (smp_found_config) {
diff --git a/arch/x86/xen/Makefile b/arch/x86/xen/Makefile
index c4cda96..73ecb74 100644
--- a/arch/x86/xen/Makefile
+++ b/arch/x86/xen/Makefile
@@ -11,4 +11,4 @@ obj-y := enlighten.o setup.o multicalls.o mmu.o irq.o \

obj-$(CONFIG_SMP) += smp.o spinlock.o
obj-$(CONFIG_XEN_DEBUG_FS) += debugfs.o
-obj-$(CONFIG_XEN_DOM0) += vga.o
+obj-$(CONFIG_XEN_DOM0) += vga.o apic.o
diff --git a/arch/x86/xen/apic.c b/arch/x86/xen/apic.c
new file mode 100644
index 0000000..17736a0
--- /dev/null
+++ b/arch/x86/xen/apic.c
@@ -0,0 +1,57 @@
+#include <linux/kernel.h>
+#include <linux/threads.h>
+#include <linux/bitmap.h>
+
+#include <asm/io_apic.h>
+#include <asm/acpi.h>
+
+#include <asm/xen/hypervisor.h>
+#include <asm/xen/hypercall.h>
+
+#include <xen/interface/xen.h>
+#include <xen/interface/physdev.h>
+
+void __init xen_io_apic_init(void)
+{
+ printk("xen apic init\n");
+ dump_stack();
+}
+
+unsigned int xen_io_apic_read(unsigned apic, unsigned reg)
+{
+ struct physdev_apic apic_op;
+ int ret;
+
+ apic_op.apic_physbase = mp_ioapics[apic].apicaddr;
+ apic_op.reg = reg;
+ ret = HYPERVISOR_physdev_op(PHYSDEVOP_apic_read, &apic_op);
+ if (ret)
+ BUG();
+ return apic_op.value;
+}
+
+
+void xen_io_apic_write(unsigned int apic, unsigned int reg, unsigned int value)
+{
+ struct physdev_apic apic_op;
+
+ apic_op.apic_physbase = mp_ioapics[apic].apicaddr;
+ apic_op.reg = reg;
+ apic_op.value = value;
+ if (HYPERVISOR_physdev_op(PHYSDEVOP_apic_write, &apic_op))
+ BUG();
+}
+
+void xen_init_apic(void)
+{
+ if (!xen_initial_domain())
+ return;
+
+#ifdef CONFIG_ACPI
+ /*
+ * Pretend ACPI found our lapic even though we've disabled it,
+ * to prevent MP tables from setting up lapics.
+ */
+ acpi_lapic = 1;
+#endif
+}
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index cf0e081..60e2de9 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -970,6 +970,8 @@ asmlinkage void __init xen_start_kernel(void)
set_iopl.iopl = 1;
if (HYPERVISOR_physdev_op(PHYSDEVOP_set_iopl, &set_iopl) == -1)
BUG();
+
+ xen_init_apic();
}

/* set the limit of our address space */
diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
index dea44b0..3337712 100644
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -86,6 +86,12 @@ static inline void xen_init_vga(const struct dom0_vga_console_info *info,
}
#endif

+#ifdef CONFIG_XEN_DOM0
+void xen_init_apic(void);
+#else
+static inline void xen_init_apic(void) {}
+#endif
+
/* Declare an asm function, along with symbols needed to make it
inlineable */
#define DECL_ASM(ret, name, ...) \
--
1.6.0.6


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