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KVM: PPC: Book3S HV P9: Remove most of the vcore logic
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The P9 path always uses one vcpu per vcore, so none of the vcore, locks,
stolen time, blocking logic, shared waitq, etc., is required.

Remove most of it.

Signed-off-by: Nicholas Piggin <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
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@npiggin @mpe
npiggin authored and mpe committed Nov 24, 2021
1 parent 434398a commit ecb6a72
Showing 1 changed file with 85 additions and 62 deletions.
147 changes: 85 additions & 62 deletions arch/powerpc/kvm/book3s_hv.c
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Original file line number Diff line number Diff line change
Expand Up @@ -276,6 +276,8 @@ static void kvmppc_core_start_stolen(struct kvmppc_vcore *vc, u64 tb)
{
unsigned long flags;

WARN_ON_ONCE(cpu_has_feature(CPU_FTR_ARCH_300));

spin_lock_irqsave(&vc->stoltb_lock, flags);
vc->preempt_tb = tb;
spin_unlock_irqrestore(&vc->stoltb_lock, flags);
Expand All @@ -285,6 +287,8 @@ static void kvmppc_core_end_stolen(struct kvmppc_vcore *vc, u64 tb)
{
unsigned long flags;

WARN_ON_ONCE(cpu_has_feature(CPU_FTR_ARCH_300));

spin_lock_irqsave(&vc->stoltb_lock, flags);
if (vc->preempt_tb != TB_NIL) {
vc->stolen_tb += tb - vc->preempt_tb;
Expand All @@ -297,7 +301,12 @@ static void kvmppc_core_vcpu_load_hv(struct kvm_vcpu *vcpu, int cpu)
{
struct kvmppc_vcore *vc = vcpu->arch.vcore;
unsigned long flags;
u64 now = mftb();
u64 now;

if (cpu_has_feature(CPU_FTR_ARCH_300))
return;

now = mftb();

/*
* We can test vc->runner without taking the vcore lock,
Expand All @@ -321,7 +330,12 @@ static void kvmppc_core_vcpu_put_hv(struct kvm_vcpu *vcpu)
{
struct kvmppc_vcore *vc = vcpu->arch.vcore;
unsigned long flags;
u64 now = mftb();
u64 now;

if (cpu_has_feature(CPU_FTR_ARCH_300))
return;

now = mftb();

if (vc->runner == vcpu && vc->vcore_state >= VCORE_SLEEPING)
kvmppc_core_start_stolen(vc, now);
Expand Down Expand Up @@ -673,6 +687,8 @@ static u64 vcore_stolen_time(struct kvmppc_vcore *vc, u64 now)
u64 p;
unsigned long flags;

WARN_ON_ONCE(cpu_has_feature(CPU_FTR_ARCH_300));

spin_lock_irqsave(&vc->stoltb_lock, flags);
p = vc->stolen_tb;
if (vc->vcore_state != VCORE_INACTIVE &&
Expand All @@ -695,13 +711,19 @@ static void kvmppc_create_dtl_entry(struct kvm_vcpu *vcpu,
dt = vcpu->arch.dtl_ptr;
vpa = vcpu->arch.vpa.pinned_addr;
now = tb;
core_stolen = vcore_stolen_time(vc, now);
stolen = core_stolen - vcpu->arch.stolen_logged;
vcpu->arch.stolen_logged = core_stolen;
spin_lock_irqsave(&vcpu->arch.tbacct_lock, flags);
stolen += vcpu->arch.busy_stolen;
vcpu->arch.busy_stolen = 0;
spin_unlock_irqrestore(&vcpu->arch.tbacct_lock, flags);

if (cpu_has_feature(CPU_FTR_ARCH_300)) {
stolen = 0;
} else {
core_stolen = vcore_stolen_time(vc, now);
stolen = core_stolen - vcpu->arch.stolen_logged;
vcpu->arch.stolen_logged = core_stolen;
spin_lock_irqsave(&vcpu->arch.tbacct_lock, flags);
stolen += vcpu->arch.busy_stolen;
vcpu->arch.busy_stolen = 0;
spin_unlock_irqrestore(&vcpu->arch.tbacct_lock, flags);
}

if (!dt || !vpa)
return;
memset(dt, 0, sizeof(struct dtl_entry));
Expand Down Expand Up @@ -898,13 +920,14 @@ static int kvm_arch_vcpu_yield_to(struct kvm_vcpu *target)
* mode handler is not called but no other threads are in the
* source vcore.
*/

spin_lock(&vcore->lock);
if (target->arch.state == KVMPPC_VCPU_RUNNABLE &&
vcore->vcore_state != VCORE_INACTIVE &&
vcore->runner)
target = vcore->runner;
spin_unlock(&vcore->lock);
if (!cpu_has_feature(CPU_FTR_ARCH_300)) {
spin_lock(&vcore->lock);
if (target->arch.state == KVMPPC_VCPU_RUNNABLE &&
vcore->vcore_state != VCORE_INACTIVE &&
vcore->runner)
target = vcore->runner;
spin_unlock(&vcore->lock);
}

return kvm_vcpu_yield_to(target);
}
Expand Down Expand Up @@ -3131,13 +3154,6 @@ static void kvmppc_start_thread(struct kvm_vcpu *vcpu, struct kvmppc_vcore *vc)
kvmppc_ipi_thread(cpu);
}

/* Old path does this in asm */
static void kvmppc_stop_thread(struct kvm_vcpu *vcpu)
{
vcpu->cpu = -1;
vcpu->arch.thread_cpu = -1;
}

static void kvmppc_wait_for_nap(int n_threads)
{
int cpu = smp_processor_id();
Expand Down Expand Up @@ -3226,6 +3242,8 @@ static void kvmppc_vcore_preempt(struct kvmppc_vcore *vc)
{
struct preempted_vcore_list *lp = this_cpu_ptr(&preempted_vcores);

WARN_ON_ONCE(cpu_has_feature(CPU_FTR_ARCH_300));

vc->vcore_state = VCORE_PREEMPT;
vc->pcpu = smp_processor_id();
if (vc->num_threads < threads_per_vcore(vc->kvm)) {
Expand All @@ -3242,6 +3260,8 @@ static void kvmppc_vcore_end_preempt(struct kvmppc_vcore *vc)
{
struct preempted_vcore_list *lp;

WARN_ON_ONCE(cpu_has_feature(CPU_FTR_ARCH_300));

kvmppc_core_end_stolen(vc, mftb());
if (!list_empty(&vc->preempt_list)) {
lp = &per_cpu(preempted_vcores, vc->pcpu);
Expand Down Expand Up @@ -3983,7 +4003,6 @@ static int kvmhv_vcpu_entry_p9_nested(struct kvm_vcpu *vcpu, u64 time_limit, uns
static int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit,
unsigned long lpcr, u64 *tb)
{
struct kvmppc_vcore *vc = vcpu->arch.vcore;
u64 next_timer;
int trap;

Expand All @@ -3999,9 +4018,6 @@ static int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit,

kvmppc_subcore_enter_guest();

vc->entry_exit_map = 1;
vc->in_guest = 1;

vcpu_vpa_increment_dispatch(vcpu);

if (kvmhv_on_pseries()) {
Expand Down Expand Up @@ -4054,9 +4070,6 @@ static int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit,

vcpu_vpa_increment_dispatch(vcpu);

vc->entry_exit_map = 0x101;
vc->in_guest = 0;

kvmppc_subcore_exit_guest();

return trap;
Expand Down Expand Up @@ -4122,6 +4135,13 @@ static bool kvmppc_vcpu_woken(struct kvm_vcpu *vcpu)
return false;
}

static bool kvmppc_vcpu_check_block(struct kvm_vcpu *vcpu)
{
if (!vcpu->arch.ceded || kvmppc_vcpu_woken(vcpu))
return true;
return false;
}

/*
* Check to see if any of the runnable vcpus on the vcore have pending
* exceptions or are no longer ceded
Expand All @@ -4132,7 +4152,7 @@ static int kvmppc_vcore_check_block(struct kvmppc_vcore *vc)
int i;

for_each_runnable_thread(i, vcpu, vc) {
if (!vcpu->arch.ceded || kvmppc_vcpu_woken(vcpu))
if (kvmppc_vcpu_check_block(vcpu))
return 1;
}

Expand All @@ -4149,6 +4169,8 @@ static void kvmppc_vcore_blocked(struct kvmppc_vcore *vc)
int do_sleep = 1;
u64 block_ns;

WARN_ON_ONCE(cpu_has_feature(CPU_FTR_ARCH_300));

/* Poll for pending exceptions and ceded state */
cur = start_poll = ktime_get();
if (vc->halt_poll_ns) {
Expand Down Expand Up @@ -4426,11 +4448,7 @@ int kvmhv_run_single_vcpu(struct kvm_vcpu *vcpu, u64 time_limit,
vcpu->arch.ceded = 0;
vcpu->arch.run_task = current;
vcpu->arch.state = KVMPPC_VCPU_RUNNABLE;
vcpu->arch.busy_preempt = TB_NIL;
vcpu->arch.last_inst = KVM_INST_FETCH_FAILED;
vc->runnable_threads[0] = vcpu;
vc->n_runnable = 1;
vc->runner = vcpu;

/* See if the MMU is ready to go */
if (unlikely(!kvm->arch.mmu_ready)) {
Expand All @@ -4448,11 +4466,8 @@ int kvmhv_run_single_vcpu(struct kvm_vcpu *vcpu, u64 time_limit,

kvmppc_update_vpas(vcpu);

init_vcore_to_run(vc);

preempt_disable();
pcpu = smp_processor_id();
vc->pcpu = pcpu;
if (kvm_is_radix(kvm))
kvmppc_prepare_radix_vcpu(vcpu, pcpu);

Expand Down Expand Up @@ -4481,21 +4496,23 @@ int kvmhv_run_single_vcpu(struct kvm_vcpu *vcpu, u64 time_limit,
goto out;
}

tb = mftb();
if (vcpu->arch.timer_running) {
hrtimer_try_to_cancel(&vcpu->arch.dec_timer);
vcpu->arch.timer_running = 0;
}

vcpu->arch.stolen_logged = vcore_stolen_time(vc, tb);
vc->preempt_tb = TB_NIL;
tb = mftb();

kvmppc_clear_host_core(pcpu);
vcpu->cpu = pcpu;
vcpu->arch.thread_cpu = pcpu;
vc->pcpu = pcpu;
local_paca->kvm_hstate.kvm_vcpu = vcpu;
local_paca->kvm_hstate.ptid = 0;
local_paca->kvm_hstate.fake_suspend = 0;

local_paca->kvm_hstate.napping = 0;
local_paca->kvm_hstate.kvm_split_mode = NULL;
kvmppc_start_thread(vcpu, vc);
kvmppc_create_dtl_entry(vcpu, vc, tb);
trace_kvm_guest_enter(vcpu);

vc->vcore_state = VCORE_RUNNING;
trace_kvmppc_run_core(vc, 0);
trace_kvm_guest_enter(vcpu);

guest_enter_irqoff();

Expand All @@ -4517,8 +4534,6 @@ int kvmhv_run_single_vcpu(struct kvm_vcpu *vcpu, u64 time_limit,

set_irq_happened(trap);

kvmppc_set_host_core(pcpu);

context_tracking_guest_exit();
if (!vtime_accounting_enabled_this_cpu()) {
local_irq_enable();
Expand All @@ -4534,7 +4549,8 @@ int kvmhv_run_single_vcpu(struct kvm_vcpu *vcpu, u64 time_limit,
}
vtime_account_guest_exit();

kvmppc_stop_thread(vcpu);
vcpu->cpu = -1;
vcpu->arch.thread_cpu = -1;

powerpc_local_irq_pmu_restore(flags);

Expand All @@ -4561,28 +4577,31 @@ int kvmhv_run_single_vcpu(struct kvm_vcpu *vcpu, u64 time_limit,
}
vcpu->arch.ret = r;

if (is_kvmppc_resume_guest(r) && vcpu->arch.ceded &&
!kvmppc_vcpu_woken(vcpu)) {
if (is_kvmppc_resume_guest(r) && !kvmppc_vcpu_check_block(vcpu)) {
kvmppc_set_timer(vcpu);
while (vcpu->arch.ceded && !kvmppc_vcpu_woken(vcpu)) {

prepare_to_rcuwait(&vcpu->wait);
for (;;) {
set_current_state(TASK_INTERRUPTIBLE);
if (signal_pending(current)) {
vcpu->stat.signal_exits++;
run->exit_reason = KVM_EXIT_INTR;
vcpu->arch.ret = -EINTR;
break;
}
spin_lock(&vc->lock);
kvmppc_vcore_blocked(vc);
spin_unlock(&vc->lock);

if (kvmppc_vcpu_check_block(vcpu))
break;

trace_kvmppc_vcore_blocked(vc, 0);
schedule();
trace_kvmppc_vcore_blocked(vc, 1);
}
finish_rcuwait(&vcpu->wait);
}
vcpu->arch.ceded = 0;

vc->vcore_state = VCORE_INACTIVE;
trace_kvmppc_run_core(vc, 1);

done:
kvmppc_remove_runnable(vc, vcpu, tb);
trace_kvmppc_run_vcpu_exit(vcpu);

return vcpu->arch.ret;
Expand Down Expand Up @@ -4664,7 +4683,8 @@ static int kvmppc_vcpu_run_hv(struct kvm_vcpu *vcpu)

kvmppc_save_current_sprs();

vcpu->arch.waitp = &vcpu->arch.vcore->wait;
if (!cpu_has_feature(CPU_FTR_ARCH_300))
vcpu->arch.waitp = &vcpu->arch.vcore->wait;
vcpu->arch.pgdir = kvm->mm->pgd;
vcpu->arch.state = KVMPPC_VCPU_BUSY_IN_HOST;

Expand Down Expand Up @@ -5126,6 +5146,9 @@ void kvmppc_alloc_host_rm_ops(void)
int cpu, core;
int size;

if (cpu_has_feature(CPU_FTR_ARCH_300))
return;

/* Not the first time here ? */
if (kvmppc_host_rm_ops_hv != NULL)
return;
Expand Down

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