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Commit 7b5f8272 authored by Suraj Jitindar Singh's avatar Suraj Jitindar Singh Committed by Paul Mackerras
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KVM: PPC: Book3S HV: Change vcore element runnable_threads from linked-list to array 



The struct kvmppc_vcore is a structure used to store various information
about a virtual core for a kvm guest. The runnable_threads element of the
struct provides a list of all of the currently runnable vcpus on the core
(those in the KVMPPC_VCPU_RUNNABLE state). The previous implementation of
this list was a linked_list. The next patch requires that the list be able
to be iterated over without holding the vcore lock.

Reimplement the runnable_threads list in the kvmppc_vcore struct as an
array. Implement function to iterate over valid entries in the array and
update access sites accordingly.

Signed-off-by: default avatarSuraj Jitindar Singh <sjitindarsingh@gmail.com>
Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
parent e64fb7e2

arch/powerpc/include/asm/kvm_book3s.h

+1 −1
Original line number Diff line number Diff line
@@ -87,7 +87,7 @@ struct kvmppc_vcore { 
	u8 vcore_state;

	u8 in_guest;

	struct kvmppc_vcore *master_vcore;

	struct list_head runnable_threads;

	struct kvm_vcpu *runnable_threads[MAX_SMT_THREADS];

	struct list_head preempt_list;

	spinlock_t lock;

	struct swait_queue_head wq;

arch/powerpc/include/asm/kvm_host.h

+0 −1
Original line number Diff line number Diff line
@@ -635,7 +635,6 @@ struct kvm_vcpu_arch { 
	long pgfault_index;

	unsigned long pgfault_hpte[2];



	struct list_head run_list;

	struct task_struct *run_task;

	struct kvm_run *kvm_run;

arch/powerpc/kvm/book3s_hv.c

+42 −26
Original line number Diff line number Diff line
@@ -58,6 +58,7 @@ 
#include <linux/highmem.h>

#include <linux/hugetlb.h>

#include <linux/module.h>

#include <linux/compiler.h>



#include "book3s.h"
@@ -97,6 +98,26 @@ MODULE_PARM_DESC(h_ipi_redirect, "Redirect H_IPI wakeup to a free host core"); 
static void kvmppc_end_cede(struct kvm_vcpu *vcpu);

static int kvmppc_hv_setup_htab_rma(struct kvm_vcpu *vcpu);



static inline struct kvm_vcpu *next_runnable_thread(struct kvmppc_vcore *vc,

		int *ip)

{

	int i = *ip;

	struct kvm_vcpu *vcpu;



	while (++i < MAX_SMT_THREADS) {

		vcpu = READ_ONCE(vc->runnable_threads[i]);

		if (vcpu) {

			*ip = i;

			return vcpu;

		}

	}

	return NULL;

}



/* Used to traverse the list of runnable threads for a given vcore */

#define for_each_runnable_thread(i, vcpu, vc) \

	for (i = -1; (vcpu = next_runnable_thread(vc, &i)); )



static bool kvmppc_ipi_thread(int cpu)

{

	/* On POWER8 for IPIs to threads in the same core, use msgsnd */
@@ -1493,7 +1514,6 @@ static struct kvmppc_vcore *kvmppc_vcore_create(struct kvm *kvm, int core) 
	if (vcore == NULL)

		return NULL;



	INIT_LIST_HEAD(&vcore->runnable_threads);

	spin_lock_init(&vcore->lock);

	spin_lock_init(&vcore->stoltb_lock);

	init_swait_queue_head(&vcore->wq);
@@ -1802,7 +1822,7 @@ static void kvmppc_remove_runnable(struct kvmppc_vcore *vc, 
	vcpu->arch.state = KVMPPC_VCPU_BUSY_IN_HOST;

	spin_unlock_irq(&vcpu->arch.tbacct_lock);

	--vc->n_runnable;

	list_del(&vcpu->arch.run_list);

	WRITE_ONCE(vc->runnable_threads[vcpu->arch.ptid], NULL);

}



static int kvmppc_grab_hwthread(int cpu)
@@ -2209,10 +2229,10 @@ static bool can_piggyback(struct kvmppc_vcore *pvc, struct core_info *cip, 


static void prepare_threads(struct kvmppc_vcore *vc)

{

	struct kvm_vcpu *vcpu, *vnext;

	int i;

	struct kvm_vcpu *vcpu;



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

				 arch.run_list) {

	for_each_runnable_thread(i, vcpu, vc) {

		if (signal_pending(vcpu->arch.run_task))

			vcpu->arch.ret = -EINTR;

		else if (vcpu->arch.vpa.update_pending ||
@@ -2259,15 +2279,14 @@ static void collect_piggybacks(struct core_info *cip, int target_threads) 


static void post_guest_process(struct kvmppc_vcore *vc, bool is_master)

{

	int still_running = 0;

	int still_running = 0, i;

	u64 now;

	long ret;

	struct kvm_vcpu *vcpu, *vnext;

	struct kvm_vcpu *vcpu;



	spin_lock(&vc->lock);

	now = get_tb();

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

				 arch.run_list) {

	for_each_runnable_thread(i, vcpu, vc) {

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

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

		    kvmppc_core_pending_dec(vcpu))
@@ -2307,8 +2326,8 @@ static void post_guest_process(struct kvmppc_vcore *vc, bool is_master) 
		}

		if (vc->n_runnable > 0 && vc->runner == NULL) {

			/* make sure there's a candidate runner awake */

			vcpu = list_first_entry(&vc->runnable_threads,

						struct kvm_vcpu, arch.run_list);

			i = -1;

			vcpu = next_runnable_thread(vc, &i);

			wake_up(&vcpu->arch.cpu_run);

		}

	}
@@ -2361,7 +2380,7 @@ static inline void kvmppc_set_host_core(int cpu) 
 */

static noinline void kvmppc_run_core(struct kvmppc_vcore *vc)

{

	struct kvm_vcpu *vcpu, *vnext;

	struct kvm_vcpu *vcpu;

	int i;

	int srcu_idx;

	struct core_info core_info;
@@ -2397,8 +2416,7 @@ static noinline 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_safe(vcpu, vnext, &vc->runnable_threads,

					 arch.run_list) {

		for_each_runnable_thread(i, vcpu, vc) {

			vcpu->arch.ret = -EBUSY;

			kvmppc_remove_runnable(vc, vcpu);

			wake_up(&vcpu->arch.cpu_run);
@@ -2477,8 +2495,7 @@ static noinline void kvmppc_run_core(struct kvmppc_vcore *vc) 
		active |= 1 << thr;

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

			pvc->pcpu = pcpu + thr;

			list_for_each_entry(vcpu, &pvc->runnable_threads,

					    arch.run_list) {

			for_each_runnable_thread(i, vcpu, pvc) {

				kvmppc_start_thread(vcpu, pvc);

				kvmppc_create_dtl_entry(vcpu, pvc);

				trace_kvm_guest_enter(vcpu);
@@ -2611,7 +2628,7 @@ static void kvmppc_wait_for_exec(struct kvmppc_vcore *vc, 
static void kvmppc_vcore_blocked(struct kvmppc_vcore *vc)

{

	struct kvm_vcpu *vcpu;

	int do_sleep = 1;

	int do_sleep = 1, i;

	DECLARE_SWAITQUEUE(wait);



	prepare_to_swait(&vc->wq, &wait, TASK_INTERRUPTIBLE);
@@ -2620,7 +2637,7 @@ static void kvmppc_vcore_blocked(struct kvmppc_vcore *vc) 
	 * Check one last time for pending exceptions and ceded state after

	 * we put ourselves on the wait queue

	 */

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

	for_each_runnable_thread(i, vcpu, vc) {

		if (vcpu->arch.pending_exceptions || !vcpu->arch.ceded) {

			do_sleep = 0;

			break;
@@ -2644,9 +2661,9 @@ static void kvmppc_vcore_blocked(struct kvmppc_vcore *vc) 


static int kvmppc_run_vcpu(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)

{

	int n_ceded;

	int n_ceded, i;

	struct kvmppc_vcore *vc;

	struct kvm_vcpu *v, *vn;

	struct kvm_vcpu *v;



	trace_kvmppc_run_vcpu_enter(vcpu);
@@ -2666,7 +2683,7 @@ static int kvmppc_run_vcpu(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu) 
	vcpu->arch.stolen_logged = vcore_stolen_time(vc, mftb());

	vcpu->arch.state = KVMPPC_VCPU_RUNNABLE;

	vcpu->arch.busy_preempt = TB_NIL;

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

	WRITE_ONCE(vc->runnable_threads[vcpu->arch.ptid], vcpu);

	++vc->n_runnable;



	/*
@@ -2706,8 +2723,7 @@ static int kvmppc_run_vcpu(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu) 
			kvmppc_wait_for_exec(vc, vcpu, TASK_INTERRUPTIBLE);

			continue;

		}

		list_for_each_entry_safe(v, vn, &vc->runnable_threads,

					 arch.run_list) {

		for_each_runnable_thread(i, v, vc) {

			kvmppc_core_prepare_to_enter(v);

			if (signal_pending(v->arch.run_task)) {

				kvmppc_remove_runnable(vc, v);
@@ -2720,7 +2736,7 @@ 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;

		n_ceded = 0;

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

		for_each_runnable_thread(i, v, vc) {

			if (!v->arch.pending_exceptions)

				n_ceded += v->arch.ceded;

			else
@@ -2759,8 +2775,8 @@ static int kvmppc_run_vcpu(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu) 


	if (vc->n_runnable && vc->vcore_state == VCORE_INACTIVE) {

		/* Wake up some vcpu to run the core */

		v = list_first_entry(&vc->runnable_threads,

				     struct kvm_vcpu, arch.run_list);

		i = -1;

		v = next_runnable_thread(vc, &i);

		wake_up(&v->arch.cpu_run);

	}