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Message-ID: <20120416154746.GC4654@phenom.dumpdata.com>
Date: Mon, 16 Apr 2012 11:47:46 -0400
From: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To: Lin Ming <mlin@...pku.edu.cn>
Cc: mingo@...e.hu, suresh.b.siddha@...el.com, jwboyer@...hat.com,
hpa@...or.com, yinghai@...nel.org, linux-kernel@...r.kernel.org,
xiantao.zhang@...el.com
Subject: Re: [PATCH 2/2] xen/x86: Implement x86_apic_ops
On Wed, Apr 11, 2012 at 12:49:02PM +0800, Lin Ming wrote:
> On Thu, Mar 29, 2012 at 1:37 AM, Konrad Rzeszutek Wilk
> <konrad.wilk@...cle.com> wrote:
> > Or rather just implement one different function as opposed
> > to the native one : the read function.
> >
> > We synthesize the values.
> >
> > Acked-by: Suresh Siddha <suresh.b.siddha@...el.com>
> > [v1: Rebased on top of tip/x86/urgent]
> > Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
> > ---
> > arch/x86/xen/Makefile | 2 +-
> > arch/x86/xen/apic.c | 17 +++++++++++++++++
> > arch/x86/xen/enlighten.c | 2 ++
> > arch/x86/xen/xen-ops.h | 4 ++++
> > 4 files changed, 24 insertions(+), 1 deletions(-)
> > create mode 100644 arch/x86/xen/apic.c
> >
> > diff --git a/arch/x86/xen/Makefile b/arch/x86/xen/Makefile
> > index add2c2d..96ab2c0 100644
> > --- a/arch/x86/xen/Makefile
> > +++ b/arch/x86/xen/Makefile
> > @@ -20,5 +20,5 @@ obj-$(CONFIG_EVENT_TRACING) += trace.o
> > obj-$(CONFIG_SMP) += smp.o
> > obj-$(CONFIG_PARAVIRT_SPINLOCKS)+= spinlock.o
> > obj-$(CONFIG_XEN_DEBUG_FS) += debugfs.o
> > -obj-$(CONFIG_XEN_DOM0) += vga.o
> > +obj-$(CONFIG_XEN_DOM0) += apic.o vga.o
> > obj-$(CONFIG_SWIOTLB_XEN) += pci-swiotlb-xen.o
> > diff --git a/arch/x86/xen/apic.c b/arch/x86/xen/apic.c
> > new file mode 100644
> > index 0000000..aee16ab
> > --- /dev/null
> > +++ b/arch/x86/xen/apic.c
> > @@ -0,0 +1,17 @@
> > +#include <linux/init.h>
> > +#include <asm/x86_init.h>
> > +
> > +unsigned int xen_io_apic_read(unsigned apic, unsigned reg)
> > +{
> > + if (reg == 0x1)
> > + return 0x00170020;
> > + else if (reg == 0x0)
> > + return apic << 24;
>
> Why is fixed value returned?
>
> Can't we implement it with hypercall(PHYSDEVOP_apic_read)?
We sure can. But this was meant to fix the regression - so I
figured we would do that later on. But the more important question
is - do we actually need to do the hypercall? We aren't using the
IOAPIC for anything - we don't program the pins from dom0.
>
> Lin Ming
>
> > +
> > + return 0xff;
> > +}
> > +
> > +void __init xen_init_apic(void)
> > +{
> > + x86_io_apic_ops.read = xen_io_apic_read;
> > +}
> > diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
> > index 4172af8..a7df080 100644
> > --- a/arch/x86/xen/enlighten.c
> > +++ b/arch/x86/xen/enlighten.c
> > @@ -1271,6 +1271,8 @@ asmlinkage void __init xen_start_kernel(void)
> > xen_start_info->console.domU.mfn = 0;
> > xen_start_info->console.domU.evtchn = 0;
> >
> > + xen_init_apic();
> > +
> > /* Make sure ACS will be enabled */
> > pci_request_acs();
> > }
> > diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
> > index b095739..45c0c06 100644
> > --- a/arch/x86/xen/xen-ops.h
> > +++ b/arch/x86/xen/xen-ops.h
> > @@ -92,11 +92,15 @@ struct dom0_vga_console_info;
> >
> > #ifdef CONFIG_XEN_DOM0
> > void __init xen_init_vga(const struct dom0_vga_console_info *, size_t size);
> > +void __init xen_init_apic(void);
> > #else
> > static inline void __init xen_init_vga(const struct dom0_vga_console_info *info,
> > size_t size)
> > {
> > }
> > +static inline void __init xen_init_apic(void)
> > +{
> > +}
> > #endif
> >
> > /* Declare an asm function, along with symbols needed to make it
> > --
> > 1.7.7.5
> --
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