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KVM: PPC: Book 3S: XICS: Implement ICS P/Q states
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This patch implements P(Presented)/Q(Queued) states for ICS irqs.

When the interrupt is presented, set P. Present if P was not set.
If P is already set, don't present again, set Q.
When the interrupt is EOI'ed, move Q into P (and clear Q). If it is
set, re-present.

The asserted flag used by LSI is also incorporated into the P bit.

When the irq state is saved, P/Q bits are also saved, they need some
qemu modifications to be recognized and passed around to be restored.
KVM_XICS_PENDING bit set and saved should also indicate
KVM_XICS_PRESENTED bit set and saved. But it is possible some old
code doesn't have/recognize the P bit, so when we restore, we set P
for PENDING bit, too.

The idea and much of the code come from Ben.

Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
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Li Zhong authored and Paul Mackerras committed Jan 26, 2017
1 parent bf5a71d commit 17d4861
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Showing 4 changed files with 161 additions and 71 deletions.
2 changes: 2 additions & 0 deletions arch/powerpc/include/uapi/asm/kvm.h
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Original file line number Diff line number Diff line change
Expand Up @@ -613,5 +613,7 @@ struct kvm_get_htab_header {
#define KVM_XICS_LEVEL_SENSITIVE (1ULL << 40)
#define KVM_XICS_MASKED (1ULL << 41)
#define KVM_XICS_PENDING (1ULL << 42)
#define KVM_XICS_PRESENTED (1ULL << 43)
#define KVM_XICS_QUEUED (1ULL << 44)

#endif /* __LINUX_KVM_POWERPC_H */
100 changes: 70 additions & 30 deletions arch/powerpc/kvm/book3s_hv_rm_xics.c
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Original file line number Diff line number Diff line change
Expand Up @@ -672,51 +672,39 @@ int kvmppc_rm_h_cppr(struct kvm_vcpu *vcpu, unsigned long cppr)
return check_too_hard(xics, icp);
}

int kvmppc_rm_h_eoi(struct kvm_vcpu *vcpu, unsigned long xirr)
static int ics_rm_eoi(struct kvm_vcpu *vcpu, u32 irq)
{
struct kvmppc_xics *xics = vcpu->kvm->arch.xics;
struct kvmppc_icp *icp = vcpu->arch.icp;
struct kvmppc_ics *ics;
struct ics_irq_state *state;
u32 irq = xirr & 0x00ffffff;
u16 src;

if (!xics || !xics->real_mode)
return H_TOO_HARD;
u32 pq_old, pq_new;

/*
* ICP State: EOI
*
* Note: If EOI is incorrectly used by SW to lower the CPPR
* value (ie more favored), we do not check for rejection of
* a pending interrupt, this is a SW error and PAPR sepcifies
* that we don't have to deal with it.
* ICS EOI handling: For LSI, if P bit is still set, we need to
* resend it.
*
* The sending of an EOI to the ICS is handled after the
* CPPR update
*
* ICP State: Down_CPPR which we handle
* in a separate function as it's shared with H_CPPR.
* For MSI, we move Q bit into P (and clear Q). If it is set,
* resend it.
*/
icp_rm_down_cppr(xics, icp, xirr >> 24);

/* IPIs have no EOI */
if (irq == XICS_IPI)
goto bail;
/*
* EOI handling: If the interrupt is still asserted, we need to
* resend it. We can take a lockless "peek" at the ICS state here.
*
* "Message" interrupts will never have "asserted" set
*/
ics = kvmppc_xics_find_ics(xics, irq, &src);
if (!ics)
goto bail;

state = &ics->irq_state[src];

/* Still asserted, resend it */
if (state->asserted)
icp_rm_deliver_irq(xics, icp, irq);
if (state->lsi)
pq_new = state->pq_state;
else
do {
pq_old = state->pq_state;
pq_new = pq_old >> 1;
} while (cmpxchg(&state->pq_state, pq_old, pq_new) != pq_old);

if (pq_new & PQ_PRESENTED)
icp_rm_deliver_irq(xics, NULL, irq);

if (!hlist_empty(&vcpu->kvm->irq_ack_notifier_list)) {
icp->rm_action |= XICS_RM_NOTIFY_EOI;
Expand All @@ -737,10 +725,43 @@ int kvmppc_rm_h_eoi(struct kvm_vcpu *vcpu, unsigned long xirr)
state->intr_cpu = -1;
}
}

bail:
return check_too_hard(xics, icp);
}

int kvmppc_rm_h_eoi(struct kvm_vcpu *vcpu, unsigned long xirr)
{
struct kvmppc_xics *xics = vcpu->kvm->arch.xics;
struct kvmppc_icp *icp = vcpu->arch.icp;
u32 irq = xirr & 0x00ffffff;

if (!xics || !xics->real_mode)
return H_TOO_HARD;

/*
* ICP State: EOI
*
* Note: If EOI is incorrectly used by SW to lower the CPPR
* value (ie more favored), we do not check for rejection of
* a pending interrupt, this is a SW error and PAPR specifies
* that we don't have to deal with it.
*
* The sending of an EOI to the ICS is handled after the
* CPPR update
*
* ICP State: Down_CPPR which we handle
* in a separate function as it's shared with H_CPPR.
*/
icp_rm_down_cppr(xics, icp, xirr >> 24);

/* IPIs have no EOI */
if (irq == XICS_IPI)
return check_too_hard(xics, icp);

return ics_rm_eoi(vcpu, irq);
}

unsigned long eoi_rc;

static void icp_eoi(struct irq_chip *c, u32 hwirq, __be32 xirr, bool *again)
Expand Down Expand Up @@ -827,14 +848,33 @@ long kvmppc_deliver_irq_passthru(struct kvm_vcpu *vcpu,
{
struct kvmppc_xics *xics;
struct kvmppc_icp *icp;
struct kvmppc_ics *ics;
struct ics_irq_state *state;
u32 irq;
u16 src;
u32 pq_old, pq_new;

irq = irq_map->v_hwirq;
xics = vcpu->kvm->arch.xics;
icp = vcpu->arch.icp;

kvmppc_rm_handle_irq_desc(irq_map->desc);
icp_rm_deliver_irq(xics, icp, irq);

ics = kvmppc_xics_find_ics(xics, irq, &src);
if (!ics)
return 2;

state = &ics->irq_state[src];

/* only MSIs register bypass producers, so it must be MSI here */
do {
pq_old = state->pq_state;
pq_new = ((pq_old << 1) & 3) | PQ_PRESENTED;
} while (cmpxchg(&state->pq_state, pq_old, pq_new) != pq_old);

/* Test P=1, Q=0, this is the only case where we present */
if (pq_new == PQ_PRESENTED)
icp_rm_deliver_irq(xics, icp, irq);

/* EOI the interrupt */
icp_eoi(irq_desc_get_chip(irq_map->desc), irq_map->r_hwirq, xirr,
Expand Down
125 changes: 85 additions & 40 deletions arch/powerpc/kvm/book3s_xics.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -75,6 +75,7 @@ static int ics_deliver_irq(struct kvmppc_xics *xics, u32 irq, u32 level)
struct ics_irq_state *state;
struct kvmppc_ics *ics;
u16 src;
u32 pq_old, pq_new;

XICS_DBG("ics deliver %#x (level: %d)\n", irq, level);

Expand All @@ -87,25 +88,41 @@ static int ics_deliver_irq(struct kvmppc_xics *xics, u32 irq, u32 level)
if (!state->exists)
return -EINVAL;

if (level == KVM_INTERRUPT_SET_LEVEL || level == KVM_INTERRUPT_SET)
level = 1;
else if (level == KVM_INTERRUPT_UNSET)
level = 0;
/*
* We set state->asserted locklessly. This should be fine as
* we are the only setter, thus concurrent access is undefined
* to begin with.
* Take other values the same as 1, consistent with original code.
* maybe WARN here?
*/
if ((level == 1 && state->lsi) || level == KVM_INTERRUPT_SET_LEVEL)
state->asserted = 1;
else if (level == 0 || level == KVM_INTERRUPT_UNSET) {
state->asserted = 0;

if (!state->lsi && level == 0) /* noop for MSI */
return 0;
}

do {
pq_old = state->pq_state;
if (state->lsi) {
if (level) {
if (pq_old & PQ_PRESENTED)
/* Setting already set LSI ... */
return 0;

pq_new = PQ_PRESENTED;
} else
pq_new = 0;
} else
pq_new = ((pq_old << 1) & 3) | PQ_PRESENTED;
} while (cmpxchg(&state->pq_state, pq_old, pq_new) != pq_old);

/* Test P=1, Q=0, this is the only case where we present */
if (pq_new == PQ_PRESENTED)
icp_deliver_irq(xics, NULL, irq);

/* Record which CPU this arrived on for passed-through interrupts */
if (state->host_irq)
state->intr_cpu = raw_smp_processor_id();

/* Attempt delivery */
icp_deliver_irq(xics, NULL, irq);

return 0;
}

Expand Down Expand Up @@ -768,14 +785,51 @@ static noinline void kvmppc_h_cppr(struct kvm_vcpu *vcpu, unsigned long cppr)
icp_deliver_irq(xics, icp, reject);
}

static noinline int kvmppc_h_eoi(struct kvm_vcpu *vcpu, unsigned long xirr)
static int ics_eoi(struct kvm_vcpu *vcpu, u32 irq)
{
struct kvmppc_xics *xics = vcpu->kvm->arch.xics;
struct kvmppc_icp *icp = vcpu->arch.icp;
struct kvmppc_ics *ics;
struct ics_irq_state *state;
u32 irq = xirr & 0x00ffffff;
u16 src;
u32 pq_old, pq_new;

/*
* ICS EOI handling: For LSI, if P bit is still set, we need to
* resend it.
*
* For MSI, we move Q bit into P (and clear Q). If it is set,
* resend it.
*/

ics = kvmppc_xics_find_ics(xics, irq, &src);
if (!ics) {
XICS_DBG("ios_eoi: IRQ 0x%06x not found !\n", irq);
return H_PARAMETER;
}
state = &ics->irq_state[src];

if (state->lsi)
pq_new = state->pq_state;
else
do {
pq_old = state->pq_state;
pq_new = pq_old >> 1;
} while (cmpxchg(&state->pq_state, pq_old, pq_new) != pq_old);

if (pq_new & PQ_PRESENTED)
icp_deliver_irq(xics, icp, irq);

kvm_notify_acked_irq(vcpu->kvm, 0, irq);

return H_SUCCESS;
}

static noinline int kvmppc_h_eoi(struct kvm_vcpu *vcpu, unsigned long xirr)
{
struct kvmppc_xics *xics = vcpu->kvm->arch.xics;
struct kvmppc_icp *icp = vcpu->arch.icp;
u32 irq = xirr & 0x00ffffff;

XICS_DBG("h_eoi vcpu %d eoi %#lx\n", vcpu->vcpu_id, xirr);

Expand All @@ -798,26 +852,8 @@ static noinline int kvmppc_h_eoi(struct kvm_vcpu *vcpu, unsigned long xirr)
/* IPIs have no EOI */
if (irq == XICS_IPI)
return H_SUCCESS;
/*
* EOI handling: If the interrupt is still asserted, we need to
* resend it. We can take a lockless "peek" at the ICS state here.
*
* "Message" interrupts will never have "asserted" set
*/
ics = kvmppc_xics_find_ics(xics, irq, &src);
if (!ics) {
XICS_DBG("h_eoi: IRQ 0x%06x not found !\n", irq);
return H_PARAMETER;
}
state = &ics->irq_state[src];

/* Still asserted, resend it */
if (state->asserted)
icp_deliver_irq(xics, icp, irq);

kvm_notify_acked_irq(vcpu->kvm, 0, irq);

return H_SUCCESS;
return ics_eoi(vcpu, irq);
}

int kvmppc_xics_rm_complete(struct kvm_vcpu *vcpu, u32 hcall)
Expand Down Expand Up @@ -975,9 +1011,9 @@ static int xics_debug_show(struct seq_file *m, void *private)
for (i = 0; i < KVMPPC_XICS_IRQ_PER_ICS; i++) {
struct ics_irq_state *irq = &ics->irq_state[i];

seq_printf(m, "irq 0x%06x: server %#x prio %#x save prio %#x asserted %d resend %d masked pending %d\n",
seq_printf(m, "irq 0x%06x: server %#x prio %#x save prio %#x pq_state %d resend %d masked pending %d\n",
irq->number, irq->server, irq->priority,
irq->saved_priority, irq->asserted,
irq->saved_priority, irq->pq_state,
irq->resend, irq->masked_pending);

}
Expand Down Expand Up @@ -1196,10 +1232,17 @@ static int xics_get_source(struct kvmppc_xics *xics, long irq, u64 addr)
val |= prio << KVM_XICS_PRIORITY_SHIFT;
if (irqp->lsi) {
val |= KVM_XICS_LEVEL_SENSITIVE;
if (irqp->asserted)
if (irqp->pq_state & PQ_PRESENTED)
val |= KVM_XICS_PENDING;
} else if (irqp->masked_pending || irqp->resend)
val |= KVM_XICS_PENDING;

if (irqp->pq_state & PQ_PRESENTED)
val |= KVM_XICS_PRESENTED;

if (irqp->pq_state & PQ_QUEUED)
val |= KVM_XICS_QUEUED;

ret = 0;
}
arch_spin_unlock(&ics->lock);
Expand Down Expand Up @@ -1251,12 +1294,14 @@ static int xics_set_source(struct kvmppc_xics *xics, long irq, u64 addr)
irqp->resend = 0;
irqp->masked_pending = 0;
irqp->lsi = 0;
irqp->asserted = 0;
if (val & KVM_XICS_LEVEL_SENSITIVE) {
irqp->pq_state = 0;
if (val & KVM_XICS_LEVEL_SENSITIVE)
irqp->lsi = 1;
if (val & KVM_XICS_PENDING)
irqp->asserted = 1;
}
/* If PENDING, set P in case P is not saved because of old code */
if (val & KVM_XICS_PRESENTED || val & KVM_XICS_PENDING)
irqp->pq_state |= PQ_PRESENTED;
if (val & KVM_XICS_QUEUED)
irqp->pq_state |= PQ_QUEUED;
irqp->exists = 1;
arch_spin_unlock(&ics->lock);
local_irq_restore(flags);
Expand Down
5 changes: 4 additions & 1 deletion arch/powerpc/kvm/book3s_xics.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -31,16 +31,19 @@
/* Priority value to use for disabling an interrupt */
#define MASKED 0xff

#define PQ_PRESENTED 1
#define PQ_QUEUED 2

/* State for one irq source */
struct ics_irq_state {
u32 number;
u32 server;
u32 pq_state;
u8 priority;
u8 saved_priority;
u8 resend;
u8 masked_pending;
u8 lsi; /* level-sensitive interrupt */
u8 asserted; /* Only for LSI */
u8 exists;
int intr_cpu;
u32 host_irq;
Expand Down

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