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KVM: PPC: Book3S HV: Change vcore element runnable_threads from linked-list to array

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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: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This commit is contained in:
Suraj Jitindar Singh 2016-08-02 14:03:20 +10:00 committed by Paul Mackerras
parent e64fb7e272
commit 7b5f8272c7
3 changed files with 43 additions and 28 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/powerpc/include/asm/kvm_book3s.h
View File

@ -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;

1
arch/powerpc/include/asm/kvm_host.h
View File

@ -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;

68
arch/powerpc/kvm/book3s_hv.c
View File

@ -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);
}