Re: [Xen-devel] Workings/effectiveness of the xen-acpi-processor driver

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Wed, May 02, 2012 at 02:31:07PM -0700, Boris Ostrovsky wrote:
> On 05/02/2012 01:14 PM, Konrad Rzeszutek Wilk wrote:
> >On Wed, May 02, 2012 at 01:06:34PM -0400, Boris Ostrovsky wrote:
> >>On 05/02/2012 12:08 PM, Konrad Rzeszutek Wilk wrote:
> >>>diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
> >>>index a8f8844..d816448 100644
> >>>--- a/arch/x86/xen/enlighten.c
> >>>+++ b/arch/x86/xen/enlighten.c
> >>>@@ -811,7 +811,29 @@ static void xen_io_delay(void)
> >>>  #ifdef CONFIG_X86_LOCAL_APIC
> >>>  static u32 xen_apic_read(u32 reg)
> >>>  {
> >>>-  return 0;
> >>>+  struct xen_platform_op op = {
> >>>+          .cmd = XENPF_get_cpuinfo,
> >>>+          .interface_version = XENPF_INTERFACE_VERSION,
> >>>+          .u.pcpu_info.xen_cpuid = 0,
> >>
> >>
> >>Is this always zero? This will probably solve the current problem
> >
> >Its a CPU number (not tied in to APIC or ACPI IDs).
> 
> Why not use CPU number instead of zero here?

The issue was only with the bootup CPU - so was using the Xen's 
bootup CPU number - which is zero (as is Linux's).

> 
> >
> >>but I am wondering whether in the future we might hit another bug
> >>because this routine will return the same APICID for all VCPUs.
> >
> >  Later on it does a check for 'smp_processor_id()' - and if
> >that is anything but zero it will bail out.
> 
> Can you point me to the check you are referring to?

if (!xen_initial_domain() || smp_processor_id())


> 
> -boris
> 
> 
> >
> >So this shoudl solve the problem for the bootup processor.
> >>
> >>-boris
> >>
> >>
> >>>+  };
> >>>+  int ret = 0;
> >>>+
> >>>+  /* Shouldn't need this as APIC is turned off for PV, and we only
> >>>+   * get called on the bootup processor. But just in case. */
> >>>+  if (!xen_initial_domain() || smp_processor_id())
> >>>+          return 0;
> >>>+
> >>>+  if (reg == APIC_LVR)
> >>>+          return 0x10;
> >>>+
> >>>+  if (reg != APIC_ID)
> >>>+          return 0;
> >>>+
> >>>+  ret = HYPERVISOR_dom0_op(&op);
> >>>+  if (ret)
> >>>+          return 0;
> >>>+
> >>>+  return op.u.pcpu_info.apic_id;
> >>>  }
> >>>
> >>>  static void xen_apic_write(u32 reg, u32 val)
> >>>
> >>
> >
> 
> 
> 
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