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Date: Tue, 09 Feb 2010 19:00:03 -0800
From: Yinghai Lu <yinghai@...nel.org>
To: Suresh Siddha <suresh.b.siddha@...el.com>
CC: "mingo@...hat.com" <mingo@...hat.com>,
"hpa@...or.com" <hpa@...or.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"stable@...nel.org" <stable@...nel.org>,
"tglx@...utronix.de" <tglx@...utronix.de>,
"Zheng, Shaohui" <shaohui.zheng@...el.com>,
"linux-tip-commits@...r.kernel.org"
<linux-tip-commits@...r.kernel.org>
Subject: Re: [tip:x86/urgent] x86, apic: Don't use logical-flat mode when
CPU hotplug may exceed 8 CPUs
On 02/09/2010 06:26 PM, Yinghai Lu wrote:
> On 02/09/2010 06:01 PM, Suresh Siddha wrote:
>> On Tue, 2010-02-09 at 10:47 -0800, Yinghai Lu wrote:
>>>> #ifdef CONFIG_X86_32
>>>> - if (num_processors > 8) {
>>>> + if (num_possible_cpus() > 8) {
>>>
>>> for 32bit you can not use this function yet.
>>> that only can be used after prefill_possible_map()
>>
>> Yinghai, Agreed. How about the appended patch? I tested and it works.
>> Peter wants a small quick fix for this issue (to resolve the boot issue
>> reported in the virtualization guest context) so that we can queue it
>> for .33 and .32 kernels (as some distributions will be based on these
>> kernels).
>>
>> Can you please Ack if it is ok?
>>
>> thanks,
>> suresh
>> ---
>>
>> From: Suresh Siddha <suresh.b.siddha@...el.com>
>> Subject: x86, apic: Don't use logical-flat mode when CPU hotplug may exceed 8 CPUs
>>
>> We need to fall back from logical-flat APIC mode to physical-flat mode
>> when we have more than 8 CPUs. However, in the presence of CPU
>> hotplug(with bios listing not enabled but possible cpus as disabled cpus in
>> MADT), we have to consider the number of possible CPUs rather than
>> the number of current CPUs; otherwise we may cross the 8-CPU boundary
>> when CPUs are added later.
>>
>> 32bit apic code can use more cleanups (like the removal of vendor checks in
>> 32bit default_setup_apic_routing()) and more unifications with 64bit code.
>> Yinghai has some patches in works already. This patch addresses the boot issue
>> that is reported in the virtualization guest context.
>>
>> Signed-off-by: Suresh Siddha <suresh.b.siddha@...el.com>
>> Acked-by: Shaohui Zheng <shaohui.zheng@...el.com>
>> Cc: <stable@...nel.org>
>> ---
>>
>> diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
>> index 036d28a..0acbcdf 100644
>> --- a/arch/x86/kernel/acpi/boot.c
>> +++ b/arch/x86/kernel/acpi/boot.c
>> @@ -1185,9 +1185,6 @@ static void __init acpi_process_madt(void)
>> if (!error) {
>> acpi_lapic = 1;
>>
>> -#ifdef CONFIG_X86_BIGSMP
>> - generic_bigsmp_probe();
>> -#endif
>> /*
>> * Parse MADT IO-APIC entries
>> */
>> @@ -1197,8 +1194,6 @@ static void __init acpi_process_madt(void)
>> acpi_ioapic = 1;
>>
>> smp_found_config = 1;
>> - if (apic->setup_apic_routing)
>> - apic->setup_apic_routing();
>> }
>> }
>> if (error == -EINVAL) {
>> diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
>> index a85f216..6e29b2a 100644
>> --- a/arch/x86/kernel/apic/apic.c
>> +++ b/arch/x86/kernel/apic/apic.c
>> @@ -1641,9 +1641,7 @@ int __init APIC_init_uniprocessor(void)
>> #endif
>>
>> enable_IR_x2apic();
>> -#ifdef CONFIG_X86_64
>> default_setup_apic_routing();
>> -#endif
>>
>> verify_local_APIC();
>> connect_bsp_APIC();
>> @@ -1891,21 +1889,6 @@ void __cpuinit generic_processor_info(int apicid, int version)
>> if (apicid > max_physical_apicid)
>> max_physical_apicid = apicid;
>>
>> -#ifdef CONFIG_X86_32
>> - if (num_processors > 8) {
>> - switch (boot_cpu_data.x86_vendor) {
>> - case X86_VENDOR_INTEL:
>> - if (!APIC_XAPIC(version)) {
>> - def_to_bigsmp = 0;
>> - break;
>> - }
>> - /* If P4 and above fall through */
>> - case X86_VENDOR_AMD:
>> - def_to_bigsmp = 1;
>> - }
>> - }
>> -#endif
>> -
>> #if defined(CONFIG_SMP) || defined(CONFIG_X86_64)
>> early_per_cpu(x86_cpu_to_apicid, cpu) = apicid;
>> early_per_cpu(x86_bios_cpu_apicid, cpu) = apicid;
>> diff --git a/arch/x86/kernel/apic/probe_32.c b/arch/x86/kernel/apic/probe_32.c
>> index 1a6559f..88e78ae 100644
>> --- a/arch/x86/kernel/apic/probe_32.c
>> +++ b/arch/x86/kernel/apic/probe_32.c
>> @@ -54,6 +54,31 @@ late_initcall(print_ipi_mode);
>>
>> void default_setup_apic_routing(void)
>> {
>> + int version = apic_version[boot_cpu_physical_apicid];
>> +
>> + if (num_possible_cpus() > 8) {
>> + switch (boot_cpu_data.x86_vendor) {
>> + case X86_VENDOR_INTEL:
>> + if (!APIC_XAPIC(version)) {
>> + def_to_bigsmp = 0;
>> + break;
>> + }
>> + /* If P4 and above fall through */
>> + case X86_VENDOR_AMD:
>> + def_to_bigsmp = 1;
>> + }
>> + }
>> +
>> +#ifdef CONFIG_X86_BIGSMP
>> + generic_bigsmp_probe();
>> +#endif
>> +
>> + if (apic->setup_apic_routing)
>> + apic->setup_apic_routing();
>
> the main difference between this patch and
> http://patchwork.kernel.org/patch/74525/
>
> is moving apic->setup_apic_routing calling.
>
> wonder if it will affect subarch other than logical flat and physical flat.
other subarch setup_apic_routing is just pr_info...
so your patch should be ok.
YH
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