IPI – Inter-Processor Interrupts

TLB shootdown and panic-halt IPI infrastructure. More...

Classes
struct	ipi_barrier_t

Functions
static void	ipi_barrier_ack (ipi_barrier_t *b)
	Atomically decrement the barrier's ack_count.
static void	ipi_barrier_wait (ipi_barrier_t *b)
	Spin until barrier->ack_count reaches 0.
void	ipi_tlb_shootdown (uint64_t virt)
	Broadcast TLB-shootdown IPI and wait for all CPUs to flush.
void	tlb_shootdown_isr (void *frame)
	ISR for TLB_SHOOTDOWN_VECTOR (51) on remote CPUs.
void	ipi_panic_halt (void)
	Broadcast halt IPI to all APs on kernel panic.
void	panic_halt_isr (void *frame)
	ISR for PANIC_HALT_VECTOR (52) on APs.

Variables
ipi_barrier_t	g_tlb_barrier

Detailed Description

TLB shootdown and panic-halt IPI infrastructure.

Implements two IPI paths:

• TLB shootdown (vector 51): vmm_unmap_page() calls ipi_tlb_shootdown() to ensure all CPUs flush the invalidated mapping before the caller continues.
• Panic halt (vector 52): kernel_panic() calls ipi_panic_halt() to halt all APs before the BSP prints the panic message and halts.

Function Documentation

ipi_barrier_ack()

void ipi_barrier_ack ( ipi_barrier_t * b )

inlinestatic

Atomically decrement the barrier's ack_count.

Parameters

b	Barrier to acknowledge. Called by ISR handlers BEFORE lapic_eoi().

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ipi_barrier_wait()

void ipi_barrier_wait ( ipi_barrier_t * b )

inlinestatic

Spin until barrier->ack_count reaches 0.

Parameters

b	Barrier to wait on. Called by the IPI initiator after broadcasting.

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ipi_panic_halt()

void ipi_panic_halt

(

void

)

Broadcast halt IPI to all APs on kernel panic.

Sends PANIC_HALT_VECTOR (52) to every CPU except the calling BSP via lapic_send_ipi. Waits up to one LAPIC timer period (lapic_bsp_timer_icr/2 CCR ticks) for APs to halt, then returns to allow the BSP to print the panic message and execute cli;hlt. Called from handle_exception().

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ipi_tlb_shootdown()

void ipi_tlb_shootdown

(

uint64_t

virt

)

Broadcast TLB-shootdown IPI and wait for all CPUs to flush.

Parameters

virt	Virtual address to invalidate on all CPUs.

Sets g_tlb_barrier.virt = @virt and g_tlb_barrier.ack_count = smp_cpu_count - 1, then broadcasts TLB_SHOOTDOWN_VECTOR (51) to all CPUs except self via lapic_send_ipi. Spins in ipi_barrier_wait() until all handlers have called ipi_barrier_ack(). Caller (sys_munmap) must have already called invlpg locally.

Context: Called with interrupts disabled or spinlock protection on g_tlb_barrier.

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panic_halt_isr()

void panic_halt_isr

(

void *

frame

)

ISR for PANIC_HALT_VECTOR (52) on APs.

Parameters

frame

Pointer to the interrupt frame (unused).

Executes cli; hlt. Does NOT send EOI – the halted CPU never needs the LAPIC unblocked for subsequent interrupts.

tlb_shootdown_isr()

void tlb_shootdown_isr

(

void *

frame

)

ISR for TLB_SHOOTDOWN_VECTOR (51) on remote CPUs.

Parameters

frame

Pointer to the interrupt frame (unused by this handler).

Executes invlpg(g_tlb_barrier.virt), then calls ipi_barrier_ack(&g_tlb_barrier) (decrement-before-EOI guarantees the initiator sees ack_count==0 only after the TLB flush is complete), then calls lapic_eoi_asm().

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Variable Documentation

g_tlb_barrier

ipi_barrier_t g_tlb_barrier

extern