Commit f2bb0b4f authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Dave Hansen
Browse files

x86/apic/32: Remove x86_cpu_to_logical_apicid 



This per CPU variable is just yet another form of voodoo programming. The
boot ordering is:

  per_cpu(x86_cpu_to_logical_apicid, cpu) = 1U << cpu;

  .....

  setup_apic()
     apic->init_apic_ldr()
       default_init_apic_ldr()
         apic_write(SET_APIC_LOGICAL_ID(1UL << smp_processor_id(), APIC_LDR);

     id = GET_APIC_LOGICAL_ID(apic_read(APIC_LDR);
     WARN_ON(id != per_cpu(x86_cpu_to_logical_apicid, cpu));
     per_cpu(x86_cpu_to_logical_apicid, cpu) = id;

So first write the default into LDR and then validate it against the same default
which was set up during early boot APIC enumeration.

Brilliant, isn't it?

The comment above the per CPU variable declaration describes it well:
'Let's keep it ugly for now.'

Remove the useless gunk and use '1U << cpu' consistently all over the place.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: default avatarMichael Kelley <mikelley@microsoft.com>
Tested-by: default avatarSohil Mehta <sohil.mehta@intel.com>
Tested-by: Juergen Gross <jgross@suse.com> # Xen PV (dom0 and unpriv. guest)
parent e120e58e

arch/x86/include/asm/smp.h

+0 −3
Original line number Diff line number Diff line
@@ -22,9 +22,6 @@ DECLARE_PER_CPU_READ_MOSTLY(u16, cpu_l2c_id); 


DECLARE_EARLY_PER_CPU_READ_MOSTLY(u16, x86_cpu_to_apicid);

DECLARE_EARLY_PER_CPU_READ_MOSTLY(u32, x86_cpu_to_acpiid);

#if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_X86_32)

DECLARE_EARLY_PER_CPU_READ_MOSTLY(int, x86_cpu_to_logical_apicid);

#endif



struct task_struct;

arch/x86/kernel/apic/apic.c

+0 −31
Original line number Diff line number Diff line
@@ -113,15 +113,6 @@ EXPORT_EARLY_PER_CPU_SYMBOL(x86_cpu_to_apicid); 
EXPORT_EARLY_PER_CPU_SYMBOL(x86_cpu_to_acpiid);



#ifdef CONFIG_X86_32



/*

 * On x86_32, the mapping between cpu and logical apicid may vary

 * depending on apic in use.  The following early percpu variable is

 * used for the mapping.  This is where the behaviors of x86_64 and 32

 * actually diverge.  Let's keep it ugly for now.

 */

DEFINE_EARLY_PER_CPU_READ_MOSTLY(int, x86_cpu_to_logical_apicid, BAD_APICID);



/* Local APIC was disabled by the BIOS and enabled by the kernel */

static int enabled_via_apicbase __ro_after_init;
@@ -1589,24 +1580,6 @@ static void setup_local_APIC(void) 
	 */

	apic->init_apic_ldr();



#ifdef CONFIG_X86_32

	if (apic->dest_mode_logical) {

		int logical_apicid, ldr_apicid;



		/*

		 * APIC LDR is initialized.  If logical_apicid mapping was

		 * initialized during get_smp_config(), make sure it matches

		 * the actual value.

		 */

		logical_apicid = early_per_cpu(x86_cpu_to_logical_apicid, cpu);

		ldr_apicid = GET_APIC_LOGICAL_ID(apic_read(APIC_LDR));

		if (logical_apicid != BAD_APICID)

			WARN_ON(logical_apicid != ldr_apicid);

		/* Always use the value from LDR. */

		early_per_cpu(x86_cpu_to_logical_apicid, cpu) = ldr_apicid;

	}

#endif



	/*

	 * Set Task Priority to 'accept all except vectors 0-31'.  An APIC

	 * vector in the 16-31 range could be delivered if TPR == 0, but we
@@ -2433,10 +2406,6 @@ static void cpu_update_apic(int cpu, int apicid) 
{

#if defined(CONFIG_SMP) || defined(CONFIG_X86_64)

	early_per_cpu(x86_cpu_to_apicid, cpu) = apicid;

#endif

#ifdef CONFIG_X86_32

	if (cpu < 8)

		early_per_cpu(x86_cpu_to_logical_apicid, cpu) = 1U << cpu;

#endif

	set_cpu_possible(cpu, true);

	physid_set(apicid, phys_cpu_present_map);

arch/x86/kernel/apic/ipi.c

+9 −27
Original line number Diff line number Diff line
@@ -243,50 +243,32 @@ void default_send_IPI_self(int vector) 
}



#ifdef CONFIG_X86_32



void default_send_IPI_mask_sequence_logical(const struct cpumask *mask,

						 int vector)

void default_send_IPI_mask_sequence_logical(const struct cpumask *mask, int vector)

{

	unsigned long flags;

	unsigned int query_cpu;



	/*

	 * Hack. The clustered APIC addressing mode doesn't allow us to send

	 * to an arbitrary mask, so I do a unicasts to each CPU instead. This

	 * should be modified to do 1 message per cluster ID - mbligh

	 */

	unsigned int cpu;



	local_irq_save(flags);

	for_each_cpu(query_cpu, mask)

		__default_send_IPI_dest_field(

			early_per_cpu(x86_cpu_to_logical_apicid, query_cpu),

			vector, APIC_DEST_LOGICAL);

	for_each_cpu(cpu, mask)

		__default_send_IPI_dest_field(1U << cpu, vector, APIC_DEST_LOGICAL);

	local_irq_restore(flags);

}



void default_send_IPI_mask_allbutself_logical(const struct cpumask *mask,

						 int vector)

{

	unsigned int cpu, this_cpu = smp_processor_id();

	unsigned long flags;

	unsigned int query_cpu;

	unsigned int this_cpu = smp_processor_id();



	/* See Hack comment above */



	local_irq_save(flags);

	for_each_cpu(query_cpu, mask) {

		if (query_cpu == this_cpu)

	for_each_cpu(cpu, mask) {

		if (cpu == this_cpu)

			continue;

		__default_send_IPI_dest_field(

			early_per_cpu(x86_cpu_to_logical_apicid, query_cpu),

			vector, APIC_DEST_LOGICAL);

		__default_send_IPI_dest_field(1U << cpu, vector, APIC_DEST_LOGICAL);

	}

	local_irq_restore(flags);

}



/*

 * This is only used on smaller machines.

 */

void default_send_IPI_mask_logical(const struct cpumask *cpumask, int vector)

{

	unsigned long mask = cpumask_bits(cpumask)[0];

arch/x86/kernel/setup_percpu.c

+0 −7
Original line number Diff line number Diff line
@@ -184,10 +184,6 @@ void __init setup_per_cpu_areas(void) 
		per_cpu(x86_cpu_to_acpiid, cpu) =

			early_per_cpu_map(x86_cpu_to_acpiid, cpu);

#endif

#ifdef CONFIG_X86_32

		per_cpu(x86_cpu_to_logical_apicid, cpu) =

			early_per_cpu_map(x86_cpu_to_logical_apicid, cpu);

#endif

#ifdef CONFIG_NUMA

		per_cpu(x86_cpu_to_node_map, cpu) =

			early_per_cpu_map(x86_cpu_to_node_map, cpu);
@@ -214,9 +210,6 @@ void __init setup_per_cpu_areas(void) 
	early_per_cpu_ptr(x86_cpu_to_apicid) = NULL;

	early_per_cpu_ptr(x86_cpu_to_acpiid) = NULL;

#endif

#ifdef CONFIG_X86_32

	early_per_cpu_ptr(x86_cpu_to_logical_apicid) = NULL;

#endif

#ifdef CONFIG_NUMA

	early_per_cpu_ptr(x86_cpu_to_node_map) = NULL;

#endif