Re: [PATCH] kexec: force x86_64 arches to boot kdump kernels on boot cpu

Eric W. Biederman
2007-12-11T15:32:48Z

Neil Horman <nhorman@tuxdriver.com> writes:

> On Mon, Dec 10, 2007 at 09:48:11PM -0700, Eric W. Biederman wrote:
>> Neil Horman <nhorman@tuxdriver.com> writes:
>>
>> Almost there.
> cool! :)
>
> <snip>
>>
>> We should not need check_hypertransport_config as the generic loop
>> now does the work for us.
>> > +
>> > static void __init nvidia_bugs(void)
>> > {
>> > #ifdef CONFIG_ACPI
>> > @@ -83,15 +127,25 @@ static void __init ati_bugs(void)
>> > #endif
>> > }
>> >
>> > +static void __init amd_host_bugs(void)
>> > +{
>> > + printk(KERN_CRIT "IN AMD_HOST_BUGS\n");
>> > + check_hypertransport_config();
>> > +}
>>
>> Likewise this function is unneeded and the printk is likely confusing
>> for users.
>>
> Copy that. Fixed
>
> <snip>
>> > {}
>> So make that fix_hypertransport_config and we should be good.
> Done
>
>>
>> We don't need to shift device. Although we can do:
>> device_vendor = read_pci_config(num, slot, func, PCI_VENDOR_ID);
>> device = device_vendor >> 16;
>> vendor = device_vendor & 0xffff;
>>
> I'm not so sure about this. In my testing, it was clear that I needed to do a
> shift on device to make valid comparisons to the defined PCI_DEVICE_* macros.
> The origional code had to do the same thing with the class field, which is
> simmilarly positioned in the pci config space.

Ok. I just looked at read_pci_config. It doesn't do the right thing for
a non-aligned 32bit access. (Not that I am convinced there is a right
thing we can do). Please make this read_pci_config_16 instead
and you won't need the shift.

Either that or as I earlier suggested just do a 32bit read from offset 0
and use shifts and masks to get vendor and device fields.

The current code doing a shift where none should be needed (because
we ignore the two low order bits in our read) is totally weird
when looking at it.

> Other than that, new patch attached. Enables the detection of AMD
> hypertransport functions and checks for the proper quirk just as before, and
> incoporates your comments above Eric, as well as yours Yinghai.

You almost got YH's comment. You need return 2 for the old functions
so we don't try and apply a per chipset fixup for every device in
the system.

I'm actually inclined to remove the return magic and just do something
like:
static fix_applied;
if (fix_applied++)
return;
In those functions that should be called only once.

Eric

>
> Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
>
>
> early-quirks.c | 76 +++++++++++++++++++++++++++++++++++++++++++++------------
> 1 file changed, 61 insertions(+), 15 deletions(-)
>
>
>
> diff --git a/arch/x86/kernel/early-quirks.c b/arch/x86/kernel/early-quirks.c
> index 88bb83e..e13c999 100644
> --- a/arch/x86/kernel/early-quirks.c
> +++ b/arch/x86/kernel/early-quirks.c
> @@ -21,7 +21,7 @@
> #include <asm/gart.h>
> #endif
>
> -static void __init via_bugs(void)
> +static int __init via_bugs(int num, int slot, int func)
> {
> #ifdef CONFIG_GART_IOMMU
> if ((end_pfn > MAX_DMA32_PFN || force_iommu) &&
> @@ -32,6 +32,7 @@ static void __init via_bugs(void)
> gart_iommu_aperture_disabled = 1;
> }
> #endif
> + return 1;
return 2;
> }
>
> #ifdef CONFIG_ACPI
> @@ -44,7 +45,31 @@ static int __init nvidia_hpet_check(struct acpi_table_header
> *header)
> #endif /* CONFIG_X86_IO_APIC */
> #endif /* CONFIG_ACPI */
>
> -static void __init nvidia_bugs(void)
> +static int __init fix_hypertransport_config(int num, int slot, int func)
> +{
> + u32 htcfg;
> + /*
> + *we found a hypertransport bus
> + *make sure that are broadcasting
> + *interrupts to all cpus on the ht bus
> + *if we're using extended apic ids
> + */
> + htcfg = read_pci_config(num, slot, func, 0x68);
> + if (htcfg & (1 << 18)) {
> + printk(KERN_INFO "Detected use of extended apic ids on hypertransport bus\n");
> + if ((htcfg & (1 << 17)) == 0) {
> + printk(KERN_INFO "Enabling hypertransport extended apic interrupt
> broadcast\n");
> + printk(KERN_INFO "Note this is a bios bug, please contact your hw vendor\n");
> + htcfg |= (1 << 17);
> + write_pci_config(num, slot, func, 0x68, htcfg);
> + }
> + }
> +
> + return 1;
> +
> +}
> +

Hmm. I don't think we want this code positioned in the middle of the
nvidia bug checks.

> +static int __init nvidia_bugs(int num, int slot, int func)
> {
> #ifdef CONFIG_ACPI
> #ifdef CONFIG_X86_IO_APIC
> @@ -56,7 +81,7 @@ static void __init nvidia_bugs(void)
> * at least allow a command line override.
> */
> if (acpi_use_timer_override)
> - return;
> + return 1;
>
> if (acpi_table_parse(ACPI_SIG_HPET, nvidia_hpet_check)) {
> acpi_skip_timer_override = 1;
> @@ -70,9 +95,10 @@ static void __init nvidia_bugs(void)
> #endif
> /* RED-PEN skip them on mptables too? */
>
> + return 1;
return 2;
> }
>
> -static void __init ati_bugs(void)
> +static int __init ati_bugs(int num, int slot, int func)
> {
> #ifdef CONFIG_X86_IO_APIC
> if (timer_over_8254 == 1) {
> @@ -81,17 +107,22 @@ static void __init ati_bugs(void)
> "ATI board detected. Disabling timer routing over 8254.\n");
> }
> #endif
> + return 1;
return 2;
> }
>
> struct chipset {
> - u16 vendor;
> - void (*f)(void);
> + u32 vendor;
> + u32 device;
> + u32 class;
> + u32 class_mask;
> + int (*f)(int num, int slot, int func);
> };
>
> static struct chipset early_qrk[] __initdata = {
> - { PCI_VENDOR_ID_NVIDIA, nvidia_bugs },
> - { PCI_VENDOR_ID_VIA, via_bugs },
> - { PCI_VENDOR_ID_ATI, ati_bugs },
> + { PCI_VENDOR_ID_NVIDIA, PCI_ANY_ID, PCI_CLASS_BRIDGE_PCI, PCI_ANY_ID,
> nvidia_bugs },
> + { PCI_VENDOR_ID_VIA, PCI_ANY_ID, PCI_CLASS_BRIDGE_PCI, PCI_ANY_ID, via_bugs },
> + { PCI_VENDOR_ID_ATI, PCI_ANY_ID, PCI_CLASS_BRIDGE_PCI, PCI_ANY_ID, ati_bugs },
> + { PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_K8_NB, PCI_CLASS_BRIDGE_HOST,
> PCI_ANY_ID, fix_hypertransport_config },
> {}
> };
>
> @@ -108,25 +139,40 @@ void __init early_quirks(void)
> for (func = 0; func < 8; func++) {
> u32 class;
> u32 vendor;
> + u32 device;
> u8 type;
> + int ret;
> int i;
> +
> class = read_pci_config(num,slot,func,
> PCI_CLASS_REVISION);
> if (class == 0xffffffff)
> break;
>
> - if ((class >> 16) != PCI_CLASS_BRIDGE_PCI)
> - continue;
> + class >>= 16;
>
> vendor = read_pci_config(num, slot, func,
> PCI_VENDOR_ID);
> vendor &= 0xffff;
vendor = read_pci_config_16(num, slot, func,
PCI_VENDOR_ID);
>
> - for (i = 0; early_qrk[i].f; i++)
> - if (early_qrk[i].vendor == vendor) {
> - early_qrk[i].f();
> - return;
> + device = read_pci_config(num, slot, func,
> + PCI_DEVICE_ID);
> + device >>= 16;

device = read_pci_config_16(num, slot, func,
PCI_DEVICE_ID);

> +
> + for(i=0;early_qrk[i].f != NULL;i++) {
> + if (((early_qrk[i].vendor == PCI_ANY_ID) ||
> + (early_qrk[i].vendor == vendor)) &&
> + ((early_qrk[i].device == PCI_ANY_ID) ||
> + (early_qrk[i].device == device)) &&
> + (!((early_qrk[i].class ^ class) &
> + early_qrk[i].class_mask))) {
> + ret = early_qrk[i].f(num, slot, func);
> + if (ret == 1)
> + break;
> + if (ret == 2)
> + return;

> }
> + }
>
> type = read_pci_config_byte(num, slot, func,
> PCI_HEADER_TYPE);