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SubjectRe: [tip:x86/urgent] x86, apic: Don't use logical-flat mode when CPU hotplug may exceed 8 CPUs
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@intel.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@intel.com>
> Acked-by: Shaohui Zheng <shaohui.zheng@intel.com>
> Cc: <stable@kernel.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.

YH

> +}
> +
> +void setup_apic_flat_routing(void)
> +{
> #ifdef CONFIG_X86_IO_APIC
> printk(KERN_INFO
> "Enabling APIC mode: Flat. Using %d I/O APICs\n",
> @@ -103,7 +128,7 @@ struct apic apic_default = {
> .init_apic_ldr = default_init_apic_ldr,
>
> .ioapic_phys_id_map = default_ioapic_phys_id_map,
> - .setup_apic_routing = default_setup_apic_routing,
> + .setup_apic_routing = setup_apic_flat_routing,
> .multi_timer_check = NULL,
> .apicid_to_node = default_apicid_to_node,
> .cpu_to_logical_apicid = default_cpu_to_logical_apicid,
> diff --git a/arch/x86/kernel/apic/probe_64.c b/arch/x86/kernel/apic/probe_64.c
> index 450fe20..83e9be4 100644
> --- a/arch/x86/kernel/apic/probe_64.c
> +++ b/arch/x86/kernel/apic/probe_64.c
> @@ -67,7 +67,7 @@ void __init default_setup_apic_routing(void)
> }
> #endif
>
> - if (apic == &apic_flat && num_processors > 8)
> + if (apic == &apic_flat && num_possible_cpus() > 8)
> apic = &apic_physflat;
>
> printk(KERN_INFO "Setting APIC routing to %s\n", apic->name);
> diff --git a/arch/x86/kernel/mpparse.c b/arch/x86/kernel/mpparse.c
> index 40b54ce..a2c1edd 100644
> --- a/arch/x86/kernel/mpparse.c
> +++ b/arch/x86/kernel/mpparse.c
> @@ -359,13 +359,6 @@ static int __init smp_read_mpc(struct mpc_table *mpc, unsigned early)
> x86_init.mpparse.mpc_record(1);
> }
>
> -#ifdef CONFIG_X86_BIGSMP
> - generic_bigsmp_probe();
> -#endif
> -
> - if (apic->setup_apic_routing)
> - apic->setup_apic_routing();
> -
> if (!num_processors)
> printk(KERN_ERR "MPTABLE: no processors registered!\n");
> return num_processors;
> diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
> index b2ebcba..c08829a 100644
> --- a/arch/x86/kernel/smpboot.c
> +++ b/arch/x86/kernel/smpboot.c
> @@ -1087,9 +1087,7 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus)
> set_cpu_sibling_map(0);
>
> enable_IR_x2apic();
> -#ifdef CONFIG_X86_64
> default_setup_apic_routing();
> -#endif
>
> if (smp_sanity_check(max_cpus) < 0) {
> printk(KERN_INFO "SMP disabled\n");
>
>
> --
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