Commit 25fedfca authored by Paul Mackerras's avatar Paul Mackerras Committed by Alexander Graf
Browse files

KVM: PPC: Book3S HV: Move vcore preemption point up into kvmppc_run_vcpu 



Rather than calling cond_resched() in kvmppc_run_core() before doing
the post-processing for the vcpus that we have just run (that is,
calling kvmppc_handle_exit_hv(), kvmppc_set_timer(), etc.), we now do
that post-processing before calling cond_resched(), and that post-
processing is moved out into its own function, post_guest_process().

The reschedule point is now in kvmppc_run_vcpu() and we define a new
vcore state, VCORE_PREEMPT, to indicate that that the vcore's runner
task is runnable but not running.  (Doing the reschedule with the
vcore in VCORE_INACTIVE state would be bad because there are potentially
other vcpus waiting for the runner in kvmppc_wait_for_exec() which
then wouldn't get woken up.)

Also, we make use of the handy cond_resched_lock() function, which
unlocks and relocks vc->lock for us around the reschedule.

Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
Signed-off-by: default avatarAlexander Graf <agraf@suse.de>
parent 1f09c3ed

arch/powerpc/include/asm/kvm_host.h

+3 −2
Original line number Diff line number Diff line
@@ -304,8 +304,9 @@ struct kvmppc_vcore { 
/* Values for vcore_state */

#define VCORE_INACTIVE	0

#define VCORE_SLEEPING	1

#define VCORE_RUNNING	2

#define VCORE_EXITING	3

#define VCORE_PREEMPT	2

#define VCORE_RUNNING	3

#define VCORE_EXITING	4



/*

 * Struct used to manage memory for a virtual processor area

arch/powerpc/kvm/book3s_hv.c

+52 −40
Original line number Diff line number Diff line
@@ -1882,15 +1882,50 @@ static void prepare_threads(struct kvmppc_vcore *vc) 
	}

}



static void post_guest_process(struct kvmppc_vcore *vc)

{

	u64 now;

	long ret;

	struct kvm_vcpu *vcpu, *vnext;



	now = get_tb();

	list_for_each_entry_safe(vcpu, vnext, &vc->runnable_threads,

				 arch.run_list) {

		/* cancel pending dec exception if dec is positive */

		if (now < vcpu->arch.dec_expires &&

		    kvmppc_core_pending_dec(vcpu))

			kvmppc_core_dequeue_dec(vcpu);



		trace_kvm_guest_exit(vcpu);



		ret = RESUME_GUEST;

		if (vcpu->arch.trap)

			ret = kvmppc_handle_exit_hv(vcpu->arch.kvm_run, vcpu,

						    vcpu->arch.run_task);



		vcpu->arch.ret = ret;

		vcpu->arch.trap = 0;



		if (vcpu->arch.ceded) {

			if (!is_kvmppc_resume_guest(ret))

				kvmppc_end_cede(vcpu);

			else

				kvmppc_set_timer(vcpu);

		}

		if (!is_kvmppc_resume_guest(vcpu->arch.ret)) {

			kvmppc_remove_runnable(vc, vcpu);

			wake_up(&vcpu->arch.cpu_run);

		}

	}

}



/*

 * Run a set of guest threads on a physical core.

 * Called with vc->lock held.

 */

static void kvmppc_run_core(struct kvmppc_vcore *vc)

{

	struct kvm_vcpu *vcpu, *vnext;

	long ret;

	u64 now;

	struct kvm_vcpu *vcpu;

	int i;

	int srcu_idx;
@@ -1922,8 +1957,11 @@ static void kvmppc_run_core(struct kvmppc_vcore *vc) 
	 */

	if ((threads_per_core > 1) &&

	    ((vc->num_threads > threads_per_subcore) || !on_primary_thread())) {

		list_for_each_entry(vcpu, &vc->runnable_threads, arch.run_list)

		list_for_each_entry(vcpu, &vc->runnable_threads, arch.run_list) {

			vcpu->arch.ret = -EBUSY;

			kvmppc_remove_runnable(vc, vcpu);

			wake_up(&vcpu->arch.cpu_run);

		}

		goto out;

	}
@@ -1979,44 +2017,12 @@ static void kvmppc_run_core(struct kvmppc_vcore *vc) 
	kvm_guest_exit();



	preempt_enable();

	cond_resched();



	spin_lock(&vc->lock);

	now = get_tb();

	list_for_each_entry(vcpu, &vc->runnable_threads, arch.run_list) {

		/* cancel pending dec exception if dec is positive */

		if (now < vcpu->arch.dec_expires &&

		    kvmppc_core_pending_dec(vcpu))

			kvmppc_core_dequeue_dec(vcpu);



		trace_kvm_guest_exit(vcpu);



		ret = RESUME_GUEST;

		if (vcpu->arch.trap)

			ret = kvmppc_handle_exit_hv(vcpu->arch.kvm_run, vcpu,

						    vcpu->arch.run_task);



		vcpu->arch.ret = ret;

		vcpu->arch.trap = 0;



		if (vcpu->arch.ceded) {

			if (!is_kvmppc_resume_guest(ret))

				kvmppc_end_cede(vcpu);

			else

				kvmppc_set_timer(vcpu);

		}

	}

	post_guest_process(vc);



 out:

	vc->vcore_state = VCORE_INACTIVE;

	list_for_each_entry_safe(vcpu, vnext, &vc->runnable_threads,

				 arch.run_list) {

		if (!is_kvmppc_resume_guest(vcpu->arch.ret)) {

			kvmppc_remove_runnable(vc, vcpu);

			wake_up(&vcpu->arch.cpu_run);

		}

	}



	trace_kvmppc_run_core(vc, 1);

}
@@ -2138,7 +2144,6 @@ static int kvmppc_run_vcpu(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu) 
		}

		if (!vc->n_runnable || vcpu->arch.state != KVMPPC_VCPU_RUNNABLE)

			break;

		vc->runner = vcpu;

		n_ceded = 0;

		list_for_each_entry(v, &vc->runnable_threads, arch.run_list) {

			if (!v->arch.pending_exceptions)
@@ -2146,10 +2151,17 @@ static int kvmppc_run_vcpu(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu) 
			else

				v->arch.ceded = 0;

		}

		if (n_ceded == vc->n_runnable)

		vc->runner = vcpu;

		if (n_ceded == vc->n_runnable) {

			kvmppc_vcore_blocked(vc);

		else

		} else if (should_resched()) {

			vc->vcore_state = VCORE_PREEMPT;

			/* Let something else run */

			cond_resched_lock(&vc->lock);

			vc->vcore_state = VCORE_INACTIVE;

		} else {

			kvmppc_run_core(vc);

		}

		vc->runner = NULL;

	}

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