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Commit 898b25b2 authored by Paul Mackerras's avatar Paul Mackerras
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KVM: PPC: Book3S HV: Simplify dynamic micro-threading code 



Since commit b009031f ("KVM: PPC: Book3S HV: Take out virtual
core piggybacking code", 2016-09-15), we only have at most one
vcore per subcore.  Previously, the fact that there might be more
than one vcore per subcore meant that we had the notion of a
"master vcore", which was the vcore that controlled thread 0 of
the subcore.  We also needed a list per subcore in the core_info
struct to record which vcores belonged to each subcore.  Now that
there can only be one vcore in the subcore, we can replace the
list with a simple pointer and get rid of the notion of the
master vcore (and in fact treat every vcore as a master vcore).

We can also get rid of the subcore_vm[] field in the core_info
struct since it is never read.

Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
parent 2ed4f9dd

arch/powerpc/include/asm/kvm_book3s.h

+0 −1
Original line number Diff line number Diff line
@@ -86,7 +86,6 @@ struct kvmppc_vcore { 
	u16 last_cpu;

	u8 vcore_state;

	u8 in_guest;

	struct kvmppc_vcore *master_vcore;

	struct kvm_vcpu *runnable_threads[MAX_SMT_THREADS];

	struct list_head preempt_list;

	spinlock_t lock;

arch/powerpc/include/asm/kvm_book3s_asm.h

+1 −1
Original line number Diff line number Diff line
@@ -81,7 +81,7 @@ struct kvm_split_mode { 
	u8		subcore_size;

	u8		do_nap;

	u8		napped[MAX_SMT_THREADS];

	struct kvmppc_vcore *master_vcs[MAX_SUBCORES];

	struct kvmppc_vcore *vc[MAX_SUBCORES];

};



/*

arch/powerpc/kvm/book3s_hv.c

+37 −51
Original line number Diff line number Diff line
@@ -2171,7 +2171,6 @@ static void kvmppc_start_thread(struct kvm_vcpu *vcpu, struct kvmppc_vcore *vc) 
{

	int cpu;

	struct paca_struct *tpaca;

	struct kvmppc_vcore *mvc = vc->master_vcore;

	struct kvm *kvm = vc->kvm;



	cpu = vc->pcpu;
@@ -2181,7 +2180,7 @@ static void kvmppc_start_thread(struct kvm_vcpu *vcpu, struct kvmppc_vcore *vc) 
			vcpu->arch.timer_running = 0;

		}

		cpu += vcpu->arch.ptid;

		vcpu->cpu = mvc->pcpu;

		vcpu->cpu = vc->pcpu;

		vcpu->arch.thread_cpu = cpu;



		/*
@@ -2207,10 +2206,10 @@ static void kvmppc_start_thread(struct kvm_vcpu *vcpu, struct kvmppc_vcore *vc) 
	}

	tpaca = &paca[cpu];

	tpaca->kvm_hstate.kvm_vcpu = vcpu;

	tpaca->kvm_hstate.ptid = cpu - mvc->pcpu;

	tpaca->kvm_hstate.ptid = cpu - vc->pcpu;

	/* Order stores to hstate.kvm_vcpu etc. before store to kvm_vcore */

	smp_wmb();

	tpaca->kvm_hstate.kvm_vcore = mvc;

	tpaca->kvm_hstate.kvm_vcore = vc;

	if (cpu != smp_processor_id())

		kvmppc_ipi_thread(cpu);

}
@@ -2339,8 +2338,7 @@ struct core_info { 
	int		max_subcore_threads;

	int		total_threads;

	int		subcore_threads[MAX_SUBCORES];

	struct kvm	*subcore_vm[MAX_SUBCORES];

	struct list_head vcs[MAX_SUBCORES];

	struct kvmppc_vcore *vc[MAX_SUBCORES];

};



/*
@@ -2351,17 +2349,12 @@ static int subcore_thread_map[MAX_SUBCORES] = { 0, 4, 2, 6 }; 


static void init_core_info(struct core_info *cip, struct kvmppc_vcore *vc)

{

	int sub;



	memset(cip, 0, sizeof(*cip));

	cip->n_subcores = 1;

	cip->max_subcore_threads = vc->num_threads;

	cip->total_threads = vc->num_threads;

	cip->subcore_threads[0] = vc->num_threads;

	cip->subcore_vm[0] = vc->kvm;

	for (sub = 0; sub < MAX_SUBCORES; ++sub)

		INIT_LIST_HEAD(&cip->vcs[sub]);

	list_add_tail(&vc->preempt_list, &cip->vcs[0]);

	cip->vc[0] = vc;

}



static bool subcore_config_ok(int n_subcores, int n_threads)
@@ -2381,9 +2374,8 @@ static bool subcore_config_ok(int n_subcores, int n_threads) 
	return n_subcores * roundup_pow_of_two(n_threads) <= MAX_SMT_THREADS;

}



static void init_master_vcore(struct kvmppc_vcore *vc)

static void init_vcore_to_run(struct kvmppc_vcore *vc)

{

	vc->master_vcore = vc;

	vc->entry_exit_map = 0;

	vc->in_guest = 0;

	vc->napping_threads = 0;
@@ -2408,9 +2400,9 @@ static bool can_dynamic_split(struct kvmppc_vcore *vc, struct core_info *cip) 
	++cip->n_subcores;

	cip->total_threads += vc->num_threads;

	cip->subcore_threads[sub] = vc->num_threads;

	cip->subcore_vm[sub] = vc->kvm;

	init_master_vcore(vc);

	list_move_tail(&vc->preempt_list, &cip->vcs[sub]);

	cip->vc[sub] = vc;

	init_vcore_to_run(vc);

	list_del_init(&vc->preempt_list);



	return true;

}
@@ -2515,7 +2507,6 @@ static void post_guest_process(struct kvmppc_vcore *vc, bool is_master) 
			wake_up(&vcpu->arch.cpu_run);

		}

	}

	list_del_init(&vc->preempt_list);

	if (!is_master) {

		if (still_running > 0) {

			kvmppc_vcore_preempt(vc);
@@ -2587,7 +2578,7 @@ static noinline void kvmppc_run_core(struct kvmppc_vcore *vc) 
	int i;

	int srcu_idx;

	struct core_info core_info;

	struct kvmppc_vcore *pvc, *vcnext;

	struct kvmppc_vcore *pvc;

	struct kvm_split_mode split_info, *sip;

	int split, subcore_size, active;

	int sub;
@@ -2610,7 +2601,7 @@ static noinline void kvmppc_run_core(struct kvmppc_vcore *vc) 
	/*

	 * Initialize *vc.

	 */

	init_master_vcore(vc);

	init_vcore_to_run(vc);

	vc->preempt_tb = TB_NIL;



	/*
@@ -2670,9 +2661,7 @@ static noinline void kvmppc_run_core(struct kvmppc_vcore *vc) 
		split_info.ldbar = mfspr(SPRN_LDBAR);

		split_info.subcore_size = subcore_size;

		for (sub = 0; sub < core_info.n_subcores; ++sub)

			split_info.master_vcs[sub] =

				list_first_entry(&core_info.vcs[sub],

					struct kvmppc_vcore, preempt_list);

			split_info.vc[sub] = core_info.vc[sub];

		/* order writes to split_info before kvm_split_mode pointer */

		smp_wmb();

	}
@@ -2704,7 +2693,7 @@ static noinline void kvmppc_run_core(struct kvmppc_vcore *vc) 
		thr = subcore_thread_map[sub];

		thr0_done = false;

		active |= 1 << thr;

		list_for_each_entry(pvc, &core_info.vcs[sub], preempt_list) {

		pvc = core_info.vc[sub];

		pvc->pcpu = pcpu + thr;

		for_each_runnable_thread(i, vcpu, pvc) {

			kvmppc_start_thread(vcpu, pvc);
@@ -2718,11 +2707,10 @@ static noinline void kvmppc_run_core(struct kvmppc_vcore *vc) 
		 * We need to start the first thread of each subcore

		 * even if it doesn't have a vcpu.

		 */

			if (pvc->master_vcore == pvc && !thr0_done)

		if (!thr0_done)

			kvmppc_start_thread(NULL, pvc);

		thr += pvc->num_threads;

	}

	}



	/*

	 * Ensure that split_info.do_nap is set after setting
@@ -2748,8 +2736,7 @@ static noinline void kvmppc_run_core(struct kvmppc_vcore *vc) 
	trace_kvmppc_run_core(vc, 0);



	for (sub = 0; sub < core_info.n_subcores; ++sub)

		list_for_each_entry(pvc, &core_info.vcs[sub], preempt_list)

			spin_unlock(&pvc->lock);

		spin_unlock(&core_info.vc[sub]->lock);



	guest_enter();
@@ -2802,10 +2789,10 @@ static noinline void kvmppc_run_core(struct kvmppc_vcore *vc) 
	smp_mb();

	guest_exit();



	for (sub = 0; sub < core_info.n_subcores; ++sub)

		list_for_each_entry_safe(pvc, vcnext, &core_info.vcs[sub],

					 preempt_list)

	for (sub = 0; sub < core_info.n_subcores; ++sub) {

		pvc = core_info.vc[sub];

		post_guest_process(pvc, pvc == vc);

	}



	spin_lock(&vc->lock);

	preempt_enable();
@@ -3026,15 +3013,14 @@ static int kvmppc_run_vcpu(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu) 
	 */

	if (!signal_pending(current)) {

		if (vc->vcore_state == VCORE_PIGGYBACK) {

			struct kvmppc_vcore *mvc = vc->master_vcore;

			if (spin_trylock(&mvc->lock)) {

				if (mvc->vcore_state == VCORE_RUNNING &&

				    !VCORE_IS_EXITING(mvc)) {

			if (spin_trylock(&vc->lock)) {

				if (vc->vcore_state == VCORE_RUNNING &&

				    !VCORE_IS_EXITING(vc)) {

					kvmppc_create_dtl_entry(vcpu, vc);

					kvmppc_start_thread(vcpu, vc);

					trace_kvm_guest_enter(vcpu);

				}

				spin_unlock(&mvc->lock);

				spin_unlock(&vc->lock);

			}

		} else if (vc->vcore_state == VCORE_RUNNING &&

			   !VCORE_IS_EXITING(vc)) {

arch/powerpc/kvm/book3s_hv_builtin.c

+1 −1
Original line number Diff line number Diff line
@@ -307,7 +307,7 @@ void kvmhv_commence_exit(int trap) 
		return;



	for (i = 0; i < MAX_SUBCORES; ++i) {

		vc = sip->master_vcs[i];

		vc = sip->vc[i];

		if (!vc)

			break;

		do {