Merge branch 'topic/ppc-kvm' into next

Merge our ppc-kvm topic branch. This contains several fixes for the XIVE
interrupt controller that we are sharing with the KVM tree.

arch/powerpc/include/asm/xive.h

@@ -46,7 +46,15 @@ struct xive_irq_data {
 
 	/* Setup/used by frontend */
 	int target;
+	/*
+	 * saved_p means that there is a queue entry for this interrupt
+	 * in some CPU's queue (not including guest vcpu queues), even
+	 * if P is not set in the source ESB.
+	 * stale_p means that there is no queue entry for this interrupt
+	 * in some CPU's queue, even if P is set in the source ESB.
+	 */
 	bool saved_p;
+	bool stale_p;
 };
 #define XIVE_IRQ_FLAG_STORE_EOI	0x01
 #define XIVE_IRQ_FLAG_LSI	0x02

arch/powerpc/kvm/book3s_hv_rmhandlers.S

@@ -942,6 +942,8 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_ARCH_300)
 	ld	r11, VCPU_XIVE_SAVED_STATE(r4)
 	li	r9, TM_QW1_OS
 	lwz	r8, VCPU_XIVE_CAM_WORD(r4)
+	cmpwi	r8, 0
+	beq	no_xive
 	li	r7, TM_QW1_OS + TM_WORD2
 	mfmsr	r0
 	andi.	r0, r0, MSR_DR		/* in real mode? */
@@ -2831,29 +2833,39 @@ kvm_cede_prodded:
 kvm_cede_exit:
 	ld	r9, HSTATE_KVM_VCPU(r13)
 #ifdef CONFIG_KVM_XICS
-	/* Abort if we still have a pending escalation */
+	/* are we using XIVE with single escalation? */
+	ld	r10, VCPU_XIVE_ESC_VADDR(r9)
+	cmpdi	r10, 0
+	beq	3f
+	li	r6, XIVE_ESB_SET_PQ_00
+	/*
+	 * If we still have a pending escalation, abort the cede,
+	 * and we must set PQ to 10 rather than 00 so that we don't
+	 * potentially end up with two entries for the escalation
+	 * interrupt in the XIVE interrupt queue.  In that case
+	 * we also don't want to set xive_esc_on to 1 here in
+	 * case we race with xive_esc_irq().
+	 */
 	lbz	r5, VCPU_XIVE_ESC_ON(r9)
 	cmpwi	r5, 0
-	beq	1f
+	beq	4f
 	li	r0, 0
 	stb	r0, VCPU_CEDED(r9)
-1:	/* Enable XIVE escalation */
-	li	r5, XIVE_ESB_SET_PQ_00
+	li	r6, XIVE_ESB_SET_PQ_10
+	b	5f
+4:	li	r0, 1
+	stb	r0, VCPU_XIVE_ESC_ON(r9)
+	/* make sure store to xive_esc_on is seen before xive_esc_irq runs */
+	sync
+5:	/* Enable XIVE escalation */
 	mfmsr	r0
 	andi.	r0, r0, MSR_DR		/* in real mode? */
 	beq	1f
-	ld	r10, VCPU_XIVE_ESC_VADDR(r9)
-	cmpdi	r10, 0
-	beq	3f
-	ldx	r0, r10, r5
+	ldx	r0, r10, r6
 	b	2f
 1:	ld	r10, VCPU_XIVE_ESC_RADDR(r9)
-	cmpdi	r10, 0
-	beq	3f
-	ldcix	r0, r10, r5
+	ldcix	r0, r10, r6
 2:	sync
-	li	r0, 1
-	stb	r0, VCPU_XIVE_ESC_ON(r9)
 #endif /* CONFIG_KVM_XICS */
 3:	b	guest_exit_cont
 

arch/powerpc/kvm/book3s_xive.c

@@ -67,8 +67,14 @@ void kvmppc_xive_push_vcpu(struct kvm_vcpu *vcpu)
 	void __iomem *tima = local_paca->kvm_hstate.xive_tima_virt;
 	u64 pq;
 
-	if (!tima)
+	/*
+	 * Nothing to do if the platform doesn't have a XIVE
+	 * or this vCPU doesn't have its own XIVE context
+	 * (e.g. because it's not using an in-kernel interrupt controller).
+	 */
+	if (!tima || !vcpu->arch.xive_cam_word)
 		return;
+
 	eieio();
 	__raw_writeq(vcpu->arch.xive_saved_state.w01, tima + TM_QW1_OS);
 	__raw_writel(vcpu->arch.xive_cam_word, tima + TM_QW1_OS + TM_WORD2);
@@ -160,6 +166,9 @@ static irqreturn_t xive_esc_irq(int irq, void *data)
 	 */
 	vcpu->arch.xive_esc_on = false;
 
+	/* This orders xive_esc_on = false vs. subsequent stale_p = true */
+	smp_wmb();	/* goes with smp_mb() in cleanup_single_escalation */
+
 	return IRQ_HANDLED;
 }
 
@@ -1113,6 +1122,31 @@ void kvmppc_xive_disable_vcpu_interrupts(struct kvm_vcpu *vcpu)
 	vcpu->arch.xive_esc_raddr = 0;
 }
 
+/*
+ * In single escalation mode, the escalation interrupt is marked so
+ * that EOI doesn't re-enable it, but just sets the stale_p flag to
+ * indicate that the P bit has already been dealt with.  However, the
+ * assembly code that enters the guest sets PQ to 00 without clearing
+ * stale_p (because it has no easy way to address it).  Hence we have
+ * to adjust stale_p before shutting down the interrupt.
+ */
+void xive_cleanup_single_escalation(struct kvm_vcpu *vcpu,
+				    struct kvmppc_xive_vcpu *xc, int irq)
+{
+	struct irq_data *d = irq_get_irq_data(irq);
+	struct xive_irq_data *xd = irq_data_get_irq_handler_data(d);
+
+	/*
+	 * This slightly odd sequence gives the right result
+	 * (i.e. stale_p set if xive_esc_on is false) even if
+	 * we race with xive_esc_irq() and xive_irq_eoi().
+	 */
+	xd->stale_p = false;
+	smp_mb();		/* paired with smb_wmb in xive_esc_irq */
+	if (!vcpu->arch.xive_esc_on)
+		xd->stale_p = true;
+}
+
 void kvmppc_xive_cleanup_vcpu(struct kvm_vcpu *vcpu)
 {
 	struct kvmppc_xive_vcpu *xc = vcpu->arch.xive_vcpu;
@@ -1134,20 +1168,28 @@ void kvmppc_xive_cleanup_vcpu(struct kvm_vcpu *vcpu)
 	/* Mask the VP IPI */
 	xive_vm_esb_load(&xc->vp_ipi_data, XIVE_ESB_SET_PQ_01);
 
-	/* Disable the VP */
-	xive_native_disable_vp(xc->vp_id);
-
-	/* Free the queues & associated interrupts */
+	/* Free escalations */
 	for (i = 0; i < KVMPPC_XIVE_Q_COUNT; i++) {
-		struct xive_q *q = &xc->queues[i];
-
-		/* Free the escalation irq */
 		if (xc->esc_virq[i]) {
+			if (xc->xive->single_escalation)
+				xive_cleanup_single_escalation(vcpu, xc,
+							xc->esc_virq[i]);
 			free_irq(xc->esc_virq[i], vcpu);
 			irq_dispose_mapping(xc->esc_virq[i]);
 			kfree(xc->esc_virq_names[i]);
 		}
-		/* Free the queue */
+	}
+
+	/* Disable the VP */
+	xive_native_disable_vp(xc->vp_id);
+
+	/* Clear the cam word so guest entry won't try to push context */
+	vcpu->arch.xive_cam_word = 0;
+
+	/* Free the queues */
+	for (i = 0; i < KVMPPC_XIVE_Q_COUNT; i++) {
+		struct xive_q *q = &xc->queues[i];
+
 		xive_native_disable_queue(xc->vp_id, q, i);
 		if (q->qpage) {
 			free_pages((unsigned long)q->qpage,

arch/powerpc/kvm/book3s_xive.h

@@ -282,6 +282,8 @@ int kvmppc_xive_select_target(struct kvm *kvm, u32 *server, u8 prio);
 int kvmppc_xive_attach_escalation(struct kvm_vcpu *vcpu, u8 prio,
 				  bool single_escalation);
 struct kvmppc_xive *kvmppc_xive_get_device(struct kvm *kvm, u32 type);
+void xive_cleanup_single_escalation(struct kvm_vcpu *vcpu,
+				    struct kvmppc_xive_vcpu *xc, int irq);
 
 #endif /* CONFIG_KVM_XICS */
 #endif /* _KVM_PPC_BOOK3S_XICS_H */

arch/powerpc/kvm/book3s_xive_native.c

@@ -67,20 +67,28 @@ void kvmppc_xive_native_cleanup_vcpu(struct kvm_vcpu *vcpu)
 	xc->valid = false;
 	kvmppc_xive_disable_vcpu_interrupts(vcpu);
 
-	/* Disable the VP */
-	xive_native_disable_vp(xc->vp_id);
-
-	/* Free the queues & associated interrupts */
+	/* Free escalations */
 	for (i = 0; i < KVMPPC_XIVE_Q_COUNT; i++) {
 		/* Free the escalation irq */
 		if (xc->esc_virq[i]) {
+			if (xc->xive->single_escalation)
+				xive_cleanup_single_escalation(vcpu, xc,
+							xc->esc_virq[i]);
 			free_irq(xc->esc_virq[i], vcpu);
 			irq_dispose_mapping(xc->esc_virq[i]);
 			kfree(xc->esc_virq_names[i]);
 			xc->esc_virq[i] = 0;
 		}
+	}
 
-		/* Free the queue */
+	/* Disable the VP */
+	xive_native_disable_vp(xc->vp_id);
+
+	/* Clear the cam word so guest entry won't try to push context */
+	vcpu->arch.xive_cam_word = 0;
+
+	/* Free the queues */
+	for (i = 0; i < KVMPPC_XIVE_Q_COUNT; i++) {
 		kvmppc_xive_native_cleanup_queue(vcpu, i);
 	}
 

arch/powerpc/sysdev/xive/common.c

@@ -135,7 +135,7 @@ static u32 xive_read_eq(struct xive_q *q, bool just_peek)
 static u32 xive_scan_interrupts(struct xive_cpu *xc, bool just_peek)
 {
 	u32 irq = 0;
-	u8 prio;
+	u8 prio = 0;
 
 	/* Find highest pending priority */
 	while (xc->pending_prio != 0) {
@@ -148,8 +148,19 @@ static u32 xive_scan_interrupts(struct xive_cpu *xc, bool just_peek)
 		irq = xive_read_eq(&xc->queue[prio], just_peek);
 
 		/* Found something ? That's it */
-		if (irq)
+		if (irq) {
+			if (just_peek || irq_to_desc(irq))
 				break;
+			/*
+			 * We should never get here; if we do then we must
+			 * have failed to synchronize the interrupt properly
+			 * when shutting it down.
+			 */
+			pr_crit("xive: got interrupt %d without descriptor, dropping\n",
+				irq);
+			WARN_ON(1);
+			continue;
+		}
 
 		/* Clear pending bits */
 		xc->pending_prio &= ~(1 << prio);
@@ -307,6 +318,7 @@ static void xive_do_queue_eoi(struct xive_cpu *xc)
  */
 static void xive_do_source_eoi(u32 hw_irq, struct xive_irq_data *xd)
 {
+	xd->stale_p = false;
 	/* If the XIVE supports the new "store EOI facility, use it */
 	if (xd->flags & XIVE_IRQ_FLAG_STORE_EOI)
 		xive_esb_write(xd, XIVE_ESB_STORE_EOI, 0);
@@ -350,7 +362,7 @@ static void xive_do_source_eoi(u32 hw_irq, struct xive_irq_data *xd)
 	}
 }
 
-/* irq_chip eoi callback */
+/* irq_chip eoi callback, called with irq descriptor lock held */
 static void xive_irq_eoi(struct irq_data *d)
 {
 	struct xive_irq_data *xd = irq_data_get_irq_handler_data(d);
@@ -366,6 +378,8 @@ static void xive_irq_eoi(struct irq_data *d)
 	if (!irqd_irq_disabled(d) && !irqd_is_forwarded_to_vcpu(d) &&
 	    !(xd->flags & XIVE_IRQ_NO_EOI))
 		xive_do_source_eoi(irqd_to_hwirq(d), xd);
+	else
+		xd->stale_p = true;
 
 	/*
 	 * Clear saved_p to indicate that it's no longer occupying
@@ -397,11 +411,16 @@ static void xive_do_source_set_mask(struct xive_irq_data *xd,
 	 */
 	if (mask) {
 		val = xive_esb_read(xd, XIVE_ESB_SET_PQ_01);
-		xd->saved_p = !!(val & XIVE_ESB_VAL_P);
-	} else if (xd->saved_p)
+		if (!xd->stale_p && !!(val & XIVE_ESB_VAL_P))
+			xd->saved_p = true;
+		xd->stale_p = false;
+	} else if (xd->saved_p) {
 		xive_esb_read(xd, XIVE_ESB_SET_PQ_10);
-	else
+		xd->saved_p = false;
+	} else {
 		xive_esb_read(xd, XIVE_ESB_SET_PQ_00);
+		xd->stale_p = false;
+	}
 }
 
 /*
@@ -541,6 +560,8 @@ static unsigned int xive_irq_startup(struct irq_data *d)
 	unsigned int hw_irq = (unsigned int)irqd_to_hwirq(d);
 	int target, rc;
 
+	xd->saved_p = false;
+	xd->stale_p = false;
 	pr_devel("xive_irq_startup: irq %d [0x%x] data @%p\n",
 		 d->irq, hw_irq, d);
 
@@ -587,6 +608,7 @@ static unsigned int xive_irq_startup(struct irq_data *d)
 	return 0;
 }
 
+/* called with irq descriptor lock held */
 static void xive_irq_shutdown(struct irq_data *d)
 {
 	struct xive_irq_data *xd = irq_data_get_irq_handler_data(d);
@@ -601,16 +623,6 @@ static void xive_irq_shutdown(struct irq_data *d)
 	/* Mask the interrupt at the source */
 	xive_do_source_set_mask(xd, true);
 
-	/*
-	 * The above may have set saved_p. We clear it otherwise it
-	 * will prevent re-enabling later on. It is ok to forget the
-	 * fact that the interrupt might be in a queue because we are
-	 * accounting that already in xive_dec_target_count() and will
-	 * be re-routing it to a new queue with proper accounting when
-	 * it's started up again
-	 */
-	xd->saved_p = false;
-
 	/*
 	 * Mask the interrupt in HW in the IVT/EAS and set the number
 	 * to be the "bad" IRQ number
@@ -797,6 +809,10 @@ static int xive_irq_retrigger(struct irq_data *d)
 	return 1;
 }
 
+/*
+ * Caller holds the irq descriptor lock, so this won't be called
+ * concurrently with xive_get_irqchip_state on the same interrupt.
+ */
 static int xive_irq_set_vcpu_affinity(struct irq_data *d, void *state)
 {
 	struct xive_irq_data *xd = irq_data_get_irq_handler_data(d);
@@ -820,6 +836,10 @@ static int xive_irq_set_vcpu_affinity(struct irq_data *d, void *state)
 
 		/* Set it to PQ=10 state to prevent further sends */
 		pq = xive_esb_read(xd, XIVE_ESB_SET_PQ_10);
+		if (!xd->stale_p) {
+			xd->saved_p = !!(pq & XIVE_ESB_VAL_P);
+			xd->stale_p = !xd->saved_p;
+		}
 
 		/* No target ? nothing to do */
 		if (xd->target == XIVE_INVALID_TARGET) {
@@ -827,7 +847,7 @@ static int xive_irq_set_vcpu_affinity(struct irq_data *d, void *state)
 			 * An untargetted interrupt should have been
 			 * also masked at the source
 			 */
-			WARN_ON(pq & 2);
+			WARN_ON(xd->saved_p);
 
 			return 0;
 		}
@@ -847,9 +867,8 @@ static int xive_irq_set_vcpu_affinity(struct irq_data *d, void *state)
 		 * This saved_p is cleared by the host EOI, when we know
 		 * for sure the queue slot is no longer in use.
 		 */
-		if (pq & 2) {
-			pq = xive_esb_read(xd, XIVE_ESB_SET_PQ_11);
-			xd->saved_p = true;
+		if (xd->saved_p) {
+			xive_esb_read(xd, XIVE_ESB_SET_PQ_11);
 
 			/*
 			 * Sync the XIVE source HW to ensure the interrupt
@@ -862,8 +881,7 @@ static int xive_irq_set_vcpu_affinity(struct irq_data *d, void *state)
 			 */
 			if (xive_ops->sync_source)
 				xive_ops->sync_source(hw_irq);
-		} else
-			xd->saved_p = false;
+		}
 	} else {
 		irqd_clr_forwarded_to_vcpu(d);
 
@@ -914,6 +932,23 @@ static int xive_irq_set_vcpu_affinity(struct irq_data *d, void *state)
 	return 0;
 }
 
+/* Called with irq descriptor lock held. */
+static int xive_get_irqchip_state(struct irq_data *data,
+				  enum irqchip_irq_state which, bool *state)
+{
+	struct xive_irq_data *xd = irq_data_get_irq_handler_data(data);
+
+	switch (which) {
+	case IRQCHIP_STATE_ACTIVE:
+		*state = !xd->stale_p &&
+			 (xd->saved_p ||
+			  !!(xive_esb_read(xd, XIVE_ESB_GET) & XIVE_ESB_VAL_P));
+		return 0;
+	default:
+		return -EINVAL;
+	}
+}
+
 static struct irq_chip xive_irq_chip = {
 	.name = "XIVE-IRQ",
 	.irq_startup = xive_irq_startup,
@@ -925,6 +960,7 @@ static struct irq_chip xive_irq_chip = {
 	.irq_set_type = xive_irq_set_type,
 	.irq_retrigger = xive_irq_retrigger,
 	.irq_set_vcpu_affinity = xive_irq_set_vcpu_affinity,
+	.irq_get_irqchip_state = xive_get_irqchip_state,
 };
 
 bool is_xive_irq(struct irq_chip *chip)
@@ -1337,6 +1373,11 @@ static void xive_flush_cpu_queue(unsigned int cpu, struct xive_cpu *xc)
 		raw_spin_lock(&desc->lock);
 		xd = irq_desc_get_handler_data(desc);
 
+		/*
+		 * Clear saved_p to indicate that it's no longer pending
+		 */
+		xd->saved_p = false;
+
 		/*
 		 * For LSIs, we EOI, this will cause a resend if it's
 		 * still asserted. Otherwise do an MSI retrigger.