Merge branch 'kvm-ppc-next' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc into HEAD

The main thing here is a new implementation of the in-kernel
XICS interrupt controller emulation for POWER9 machines, from Ben
Herrenschmidt.

POWER9 has a new interrupt controller called XIVE (eXternal Interrupt
Virtualization Engine) which is able to deliver interrupts directly
to guest virtual CPUs in hardware without hypervisor intervention.
With this new code, the guest still sees the old XICS interface but
performance is better because the XICS emulation in the host uses the
XIVE directly rather than going through a XICS emulation in firmware.

Conflicts:
	arch/powerpc/kernel/cpu_setup_power.S [cherry-picked fix]
	arch/powerpc/kvm/book3s_xive.c [include asm/debugfs.h]

1 files changed, 136 insertions, 6 deletions

diff --git a/arch/powerpc/sysdev/xive/common.c b/arch/powerpc/sysdev/xive/common.c
index 6a98efb14264..913825086b8d 100644
--- a/arch/powerpc/sysdev/xive/common.c
+++ b/arch/powerpc/sysdev/xive/common.c
@@ -46,13 +46,15 @@
 #endif
 
 bool __xive_enabled;
+EXPORT_SYMBOL_GPL(__xive_enabled);
 bool xive_cmdline_disabled;
 
 /* We use only one priority for now */
 static u8 xive_irq_priority;
 
-/* TIMA */
+/* TIMA exported to KVM */
 void __iomem *xive_tima;
+EXPORT_SYMBOL_GPL(xive_tima);
 u32 xive_tima_offset;
 
 /* Backend ops */
@@ -345,8 +347,11 @@ static void xive_irq_eoi(struct irq_data *d)
 	DBG_VERBOSE("eoi_irq: irq=%d [0x%lx] pending=%02x\n",
 		    d->irq, irqd_to_hwirq(d), xc->pending_prio);
 
-	/* EOI the source if it hasn't been disabled */
-	if (!irqd_irq_disabled(d))
+	/*
+	 * EOI the source if it hasn't been disabled and hasn't
+	 * been passed-through to a KVM guest
+	 */
+	if (!irqd_irq_disabled(d) && !irqd_is_forwarded_to_vcpu(d))
 		xive_do_source_eoi(irqd_to_hwirq(d), xd);
 
 	/*
@@ -689,9 +694,14 @@ static int xive_irq_set_affinity(struct irq_data *d,
 
 	old_target = xd->target;
 
-	rc = xive_ops->configure_irq(hw_irq,
-				     get_hard_smp_processor_id(target),
-				     xive_irq_priority, d->irq);
+	/*
+	 * Only configure the irq if it's not currently passed-through to
+	 * a KVM guest
+	 */
+	if (!irqd_is_forwarded_to_vcpu(d))
+		rc = xive_ops->configure_irq(hw_irq,
+					     get_hard_smp_processor_id(target),
+					     xive_irq_priority, d->irq);
 	if (rc < 0) {
 		pr_err("Error %d reconfiguring irq %d\n", rc, d->irq);
 		return rc;
@@ -771,6 +781,123 @@ static int xive_irq_retrigger(struct irq_data *d)
 	return 1;
 }
 
+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);
+	unsigned int hw_irq = (unsigned int)irqd_to_hwirq(d);
+	int rc;
+	u8 pq;
+
+	/*
+	 * We only support this on interrupts that do not require
+	 * firmware calls for masking and unmasking
+	 */
+	if (xd->flags & XIVE_IRQ_FLAG_MASK_FW)
+		return -EIO;
+
+	/*
+	 * This is called by KVM with state non-NULL for enabling
+	 * pass-through or NULL for disabling it
+	 */
+	if (state) {
+		irqd_set_forwarded_to_vcpu(d);
+
+		/* Set it to PQ=10 state to prevent further sends */
+		pq = xive_poke_esb(xd, XIVE_ESB_SET_PQ_10);
+
+		/* No target ? nothing to do */
+		if (xd->target == XIVE_INVALID_TARGET) {
+			/*
+			 * An untargetted interrupt should have been
+			 * also masked at the source
+			 */
+			WARN_ON(pq & 2);
+
+			return 0;
+		}
+
+		/*
+		 * If P was set, adjust state to PQ=11 to indicate
+		 * that a resend is needed for the interrupt to reach
+		 * the guest. Also remember the value of P.
+		 *
+		 * This also tells us that it's in flight to a host queue
+		 * or has already been fetched but hasn't been EOIed yet
+		 * by the host. This it's potentially using up a host
+		 * queue slot. This is important to know because as long
+		 * as this is the case, we must not hard-unmask it when
+		 * "returning" that interrupt to the host.
+		 *
+		 * 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_poke_esb(xd, XIVE_ESB_SET_PQ_11);
+			xd->saved_p = true;
+
+			/*
+			 * Sync the XIVE source HW to ensure the interrupt
+			 * has gone through the EAS before we change its
+			 * target to the guest. That should guarantee us
+			 * that we *will* eventually get an EOI for it on
+			 * the host. Otherwise there would be a small window
+			 * for P to be seen here but the interrupt going
+			 * to the guest queue.
+			 */
+			if (xive_ops->sync_source)
+				xive_ops->sync_source(hw_irq);
+		} else
+			xd->saved_p = false;
+	} else {
+		irqd_clr_forwarded_to_vcpu(d);
+
+		/* No host target ? hard mask and return */
+		if (xd->target == XIVE_INVALID_TARGET) {
+			xive_do_source_set_mask(xd, true);
+			return 0;
+		}
+
+		/*
+		 * Sync the XIVE source HW to ensure the interrupt
+		 * has gone through the EAS before we change its
+		 * target to the host.
+		 */
+		if (xive_ops->sync_source)
+			xive_ops->sync_source(hw_irq);
+
+		/*
+		 * By convention we are called with the interrupt in
+		 * a PQ=10 or PQ=11 state, ie, it won't fire and will
+		 * have latched in Q whether there's a pending HW
+		 * interrupt or not.
+		 *
+		 * First reconfigure the target.
+		 */
+		rc = xive_ops->configure_irq(hw_irq,
+					     get_hard_smp_processor_id(xd->target),
+					     xive_irq_priority, d->irq);
+		if (rc)
+			return rc;
+
+		/*
+		 * Then if saved_p is not set, effectively re-enable the
+		 * interrupt with an EOI. If it is set, we know there is
+		 * still a message in a host queue somewhere that will be
+		 * EOId eventually.
+		 *
+		 * Note: We don't check irqd_irq_disabled(). Effectively,
+		 * we *will* let the irq get through even if masked if the
+		 * HW is still firing it in order to deal with the whole
+		 * saved_p business properly. If the interrupt triggers
+		 * while masked, the generic code will re-mask it anyway.
+		 */
+		if (!xd->saved_p)
+			xive_do_source_eoi(hw_irq, xd);
+
+	}
+	return 0;
+}
+
 static struct irq_chip xive_irq_chip = {
 	.name = "XIVE-IRQ",
 	.irq_startup = xive_irq_startup,
@@ -781,12 +908,14 @@ static struct irq_chip xive_irq_chip = {
 	.irq_set_affinity = xive_irq_set_affinity,
 	.irq_set_type = xive_irq_set_type,
 	.irq_retrigger = xive_irq_retrigger,
+	.irq_set_vcpu_affinity = xive_irq_set_vcpu_affinity,
 };
 
 bool is_xive_irq(struct irq_chip *chip)
 {
 	return chip == &xive_irq_chip;
 }
+EXPORT_SYMBOL_GPL(is_xive_irq);
 
 void xive_cleanup_irq_data(struct xive_irq_data *xd)
 {
@@ -801,6 +930,7 @@ void xive_cleanup_irq_data(struct xive_irq_data *xd)
 		xd->trig_mmio = NULL;
 	}
 }
+EXPORT_SYMBOL_GPL(xive_cleanup_irq_data);
 
 static int xive_irq_alloc_data(unsigned int virq, irq_hw_number_t hw)
 {