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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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