arch/powerpc/include/asm/paravirt.h

Source file repositories/reference/linux-study-clean/arch/powerpc/include/asm/paravirt.h

File Facts

System
Linux kernel
Corpus path
arch/powerpc/include/asm/paravirt.h
Extension
.h
Size
6228 bytes
Lines
221
Domain
Architecture Layer
Bucket
arch/powerpc
Inferred role
Architecture Layer: implementation source
Status
source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

#ifndef _ASM_POWERPC_PARAVIRT_H
#define _ASM_POWERPC_PARAVIRT_H

#include <linux/jump_label.h>
#include <asm/smp.h>
#ifdef CONFIG_PPC64
#include <asm/paca.h>
#include <asm/lppaca.h>
#include <asm/hvcall.h>
#endif

#ifdef CONFIG_PPC_SPLPAR
#include <linux/smp.h>
#include <asm/kvm_guest.h>
#include <asm/cputhreads.h>

DECLARE_STATIC_KEY_FALSE(shared_processor);

static inline bool is_shared_processor(void)
{
	return static_branch_unlikely(&shared_processor);
}

#ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
u64 pseries_paravirt_steal_clock(int cpu);

static inline u64 paravirt_steal_clock(int cpu)
{
	return pseries_paravirt_steal_clock(cpu);
}
#endif

/* If bit 0 is set, the cpu has been ceded, conferred, or preempted */
static inline u32 yield_count_of(int cpu)
{
	__be32 yield_count = READ_ONCE(lppaca_of(cpu).yield_count);
	return be32_to_cpu(yield_count);
}

/*
 * Spinlock code confers and prods, so don't trace the hcalls because the
 * tracing code takes spinlocks which can cause recursion deadlocks.
 *
 * These calls are made while the lock is not held: the lock slowpath yields if
 * it can not acquire the lock, and unlock slow path might prod if a waiter has
 * yielded). So this may not be a problem for simple spin locks because the
 * tracing does not technically recurse on the lock, but we avoid it anyway.
 *
 * However the queued spin lock contended path is more strictly ordered: the
 * H_CONFER hcall is made after the task has queued itself on the lock, so then
 * recursing on that lock will cause the task to then queue up again behind the
 * first instance (or worse: queued spinlocks use tricks that assume a context
 * never waits on more than one spinlock, so such recursion may cause random
 * corruption in the lock code).
 */
static inline void yield_to_preempted(int cpu, u32 yield_count)
{
	plpar_hcall_norets_notrace(H_CONFER, get_hard_smp_processor_id(cpu), yield_count);
}

static inline void prod_cpu(int cpu)
{
	plpar_hcall_norets_notrace(H_PROD, get_hard_smp_processor_id(cpu));
}

static inline void yield_to_any(void)
{
	plpar_hcall_norets_notrace(H_CONFER, -1, 0);
}

static inline bool is_vcpu_idle(int vcpu)
{
	return lppaca_of(vcpu).idle;
}

static inline bool vcpu_is_dispatched(int vcpu)
{
	/*
	 * This is the yield_count.  An "odd" value (low bit on) means that
	 * the processor is yielded (either because of an OS yield or a
	 * hypervisor preempt).  An even value implies that the processor is
	 * currently executing.
	 */
	return (!(yield_count_of(vcpu) & 1));
}
#else
static inline bool is_shared_processor(void)
{
	return false;
}

Annotation

Implementation Notes