Commit 17d48610 authored by Li Zhong's avatar Li Zhong Committed by Paul Mackerras
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KVM: PPC: Book 3S: XICS: Implement ICS P/Q states 



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: default avatarLi Zhong <zhong@linux.vnet.ibm.com>
Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
parent bf5a71d5

arch/powerpc/include/uapi/asm/kvm.h

+2 −0
Original line number Diff line number Diff line
@@ -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 */

arch/powerpc/kvm/book3s_hv_rm_xics.c

+70 −30
Original line number Diff line number Diff line
@@ -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;
@@ -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)
@@ -827,13 +848,32 @@ 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);



	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 */

arch/powerpc/kvm/book3s_xics.c

+85 −40
Original line number Diff line number Diff line
@@ -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);
@@ -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;

}
@@ -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);
@@ -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)
@@ -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);



		}
@@ -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);
@@ -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);

arch/powerpc/kvm/book3s_xics.h

+4 −1
Original line number Diff line number Diff line
@@ -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;

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