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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: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Tested-by: Juergen Gross <jgross@suse.com> # Xen PV (dom0 and unpriv. guest)
This commit is contained in:
Thomas Gleixner 2023-08-08 15:03:53 -07:00 committed by Dave Hansen
parent e120e58ec2
commit f2bb0b4f15
4 changed files with 9 additions and 68 deletions
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3
arch/x86/include/asm/smp.h
View File

@ -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;

31
arch/x86/kernel/apic/apic.c
View File

@ -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);

36
arch/x86/kernel/apic/ipi.c
View File

@ -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];

7
arch/x86/kernel/setup_percpu.c
View File

@ -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