Re: [PATCH v2 2/5] x86/PCI: Support additional MMIO range capabilities

[Suravee Suthikulanit]

On 4/25/2014 5:24 PM, Myron Stowe wrote:
> On Sun, Apr 20, 2014 at 1:59 AM, Borislav Petkov <bp@xxxxxxx> wrote:
> > Drop Andreas' old email address from CC as it keeps bouncing.
> >
> > On Sat, Apr 19, 2014 at 03:52:20PM +0200, Borislav Petkov wrote:
> > > > -static void __init pci_enable_pci_io_ecs(void)
> > > > +static void __init pci_enable_pci_io_ecs(u8 bus, u8 slot)
> > > >   {
> > > >   #ifdef CONFIG_AMD_NB
> > > >      unsigned int i, n;
> > > > +   u8 limit;
> > > >
> > > >      for (n = i = 0; !n && amd_nb_bus_dev_ranges[i].dev_limit; ++i) {
> > > > -           u8 bus = amd_nb_bus_dev_ranges[i].bus;
> > > > -           u8 slot = amd_nb_bus_dev_ranges[i].dev_base;
> > > > -           u8 limit = amd_nb_bus_dev_ranges[i].dev_limit;
> > > > +           /* Try matching for the bus range */
> > > > +           if ((bus != amd_nb_bus_dev_ranges[i].bus) ||
> > > > +               (slot != amd_nb_bus_dev_ranges[i].dev_base))
> > > > +                   continue;
> > > > +
> > > > +           limit = amd_nb_bus_dev_ranges[i].dev_limit;
> > > >
> > > > +           /* Setup all northbridges within the range */
> > > >              for (; slot < limit; ++slot) {
> > > >                      u32 val = read_pci_config(bus, slot, 3, 0);
> > > > -
> > > > -                   if (!early_is_amd_nb(val))
> > > > +                   if (!val)
> > > >                              continue;
> > > >
> > > >                      val = read_pci_config(bus, slot, 3, 0x8c);
> > > > @@ -375,13 +457,14 @@ static void __init pci_enable_pci_io_ecs(void)
> > > >                              val |= ENABLE_CF8_EXT_CFG >> 32;
> > >
> > > What a fun shifting!
> > >
> > > Maybe you should do
> > >
> > > #define ENABLE_CF8_EXT_CFG    BIT(46 - 32)
> > >
> > > to show exactly what you mean and how the bit is defined in MSR NB_CFG1
> > > and also show how the high 32-bits are mapped into F3x8c, while at it.
> > >
> > > And then you can drop the shifting at the call site.
> >
> > Ok, I see another fun with this ECS enabling:
> >
> > There's a enable_pci_io_ecs() which enables ECS through the NB_CFG MSR
> > which is called as part of the notifier *and* there's a PCI write to
> > that same bit in pci_enable_pci_io_ecs() which iterates over all NBs.
> >
> > So, AFAICT, we do it twice and the second time is not needed. Which
> > means, you probably can drop pci_enable_pci_io_ecs() completely and use
> > solely the notifier?
>
> It does look as if there is some duplication with respect to setting
> MSR_AMD64_NB_CFG's (which is aliased at D18F3x8c [1])
> ENABLE_CF8_EXT_CFG enable bit but there are at least a couple of
> differences.
>
> enable_pci_io_ecs() only sets the bit on one NB whereas
> pci_enable_pci_io_ecs iterates over all the NBs (as you mentioned
> above).  The other difference has something to do with Xen; see the
> origin of pci_enable_pci_io_ecs - commit 24d9b70b8.
>
> > Yes, no?
>
> Suravee, Kim - either of you want to chime in here?

I believe the notifier is mainly for the cores which are initially 
offline, and then brought up online afterward.

Suravee

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