arch/powerpc/kvm/book3s_hv_rm_xics.c

Source file repositories/reference/linux-study-clean/arch/powerpc/kvm/book3s_hv_rm_xics.c

File Facts

System
Linux kernel
Corpus path
arch/powerpc/kvm/book3s_hv_rm_xics.c
Extension
.c
Size
24074 bytes
Lines
925
Domain
Architecture Layer
Bucket
arch/powerpc
Inferred role
Architecture Layer: exported/initcall integration point
Status
integration 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

static inline void icp_send_hcore_msg(int hcore, struct kvm_vcpu *vcpu) { }
#endif

/*
 * We start the search from our current CPU Id in the core map
 * and go in a circle until we get back to our ID looking for a
 * core that is running in host context and that hasn't already
 * been targeted for another rm_host_ops.
 *
 * In the future, could consider using a fairer algorithm (one
 * that distributes the IPIs better)
 *
 * Returns -1, if no CPU could be found in the host
 * Else, returns a CPU Id which has been reserved for use
 */
static inline int grab_next_hostcore(int start,
		struct kvmppc_host_rm_core *rm_core, int max, int action)
{
	bool success;
	int core;
	union kvmppc_rm_state old, new;

	for (core = start + 1; core < max; core++)  {
		old = new = READ_ONCE(rm_core[core].rm_state);

		if (!old.in_host || old.rm_action)
			continue;

		/* Try to grab this host core if not taken already. */
		new.rm_action = action;

		success = cmpxchg64(&rm_core[core].rm_state.raw,
						old.raw, new.raw) == old.raw;
		if (success) {
			/*
			 * Make sure that the store to the rm_action is made
			 * visible before we return to caller (and the
			 * subsequent store to rm_data) to synchronize with
			 * the IPI handler.
			 */
			smp_wmb();
			return core;
		}
	}

	return -1;
}

static inline int find_available_hostcore(int action)
{
	int core;
	int my_core = smp_processor_id() >> threads_shift;
	struct kvmppc_host_rm_core *rm_core = kvmppc_host_rm_ops_hv->rm_core;

	core = grab_next_hostcore(my_core, rm_core, cpu_nr_cores(), action);
	if (core == -1)
		core = grab_next_hostcore(core, rm_core, my_core, action);

	return core;
}

static void icp_rm_set_vcpu_irq(struct kvm_vcpu *vcpu,
				struct kvm_vcpu *this_vcpu)
{
	struct kvmppc_icp *this_icp = this_vcpu->arch.icp;
	int cpu;
	int hcore;

	/* Mark the target VCPU as having an interrupt pending */
	vcpu->stat.queue_intr++;
	set_bit(BOOK3S_IRQPRIO_EXTERNAL, &vcpu->arch.pending_exceptions);

	/* Kick self ? Just set MER and return */
	if (vcpu == this_vcpu) {
		mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) | LPCR_MER);
		return;
	}

	/*
	 * Check if the core is loaded,
	 * if not, find an available host core to post to wake the VCPU,
	 * if we can't find one, set up state to eventually return too hard.
	 */
	cpu = vcpu->arch.thread_cpu;
	if (cpu < 0 || cpu >= nr_cpu_ids) {
		hcore = -1;
		if (kvmppc_host_rm_ops_hv && h_ipi_redirect)
			hcore = find_available_hostcore(XICS_RM_KICK_VCPU);
		if (hcore != -1) {
			icp_send_hcore_msg(hcore, vcpu);

Annotation

Implementation Notes