KVM: PPC: Book3S HV: Native usage of the XIVE interrupt controller

This patch makes KVM capable of using the XIVE interrupt controller
to provide the standard PAPR "XICS" style hypercalls. It is necessary
for proper operations when the host uses XIVE natively.

This has been lightly tested on an actual system, including PCI
pass-through with a TG3 device.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
[mpe: Cleanup pr_xxx(), unsplit pr_xxx() strings, etc., fix build
 failures by adding KVM_XIVE which depends on KVM_XICS and XIVE, and
 adding empty stubs for the kvm_xive_xxx() routines, fixup subject,
 integrate fixes from Paul for building PR=y HV=n]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 503 insertions, 0 deletions

diff --git a/arch/powerpc/kvm/book3s_xive_template.c b/arch/powerpc/kvm/book3s_xive_template.c
new file mode 100644
index 000000000000..023a31133c37
--- /dev/null
+++ b/arch/powerpc/kvm/book3s_xive_template.c
@@ -0,0 +1,503 @@
+/*
+ * Copyright 2017 Benjamin Herrenschmidt, IBM Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License, version 2, as
+ * published by the Free Software Foundation.
+ */
+
+/* File to be included by other .c files */
+
+#define XGLUE(a,b) a##b
+#define GLUE(a,b) XGLUE(a,b)
+
+static void GLUE(X_PFX,ack_pending)(struct kvmppc_xive_vcpu *xc)
+{
+	u8 cppr;
+	u16 ack;
+
+	/* XXX DD1 bug workaround: Check PIPR vs. CPPR first ! */
+
+	/* Perform the acknowledge OS to register cycle. */
+	ack = be16_to_cpu(__x_readw(__x_tima + TM_SPC_ACK_OS_REG));
+
+	/* Synchronize subsequent queue accesses */
+	mb();
+
+	/* XXX Check grouping level */
+
+	/* Anything ? */
+	if (!((ack >> 8) & TM_QW1_NSR_EO))
+		return;
+
+	/* Grab CPPR of the most favored pending interrupt */
+	cppr = ack & 0xff;
+	if (cppr < 8)
+		xc->pending |= 1 << cppr;
+
+#ifdef XIVE_RUNTIME_CHECKS
+	/* Check consistency */
+	if (cppr >= xc->hw_cppr)
+		pr_warn("KVM-XIVE: CPU %d odd ack CPPR, got %d at %d\n",
+			smp_processor_id(), cppr, xc->hw_cppr);
+#endif
+
+	/*
+	 * Update our image of the HW CPPR. We don't yet modify
+	 * xc->cppr, this will be done as we scan for interrupts
+	 * in the queues.
+	 */
+	xc->hw_cppr = cppr;
+}
+
+static u8 GLUE(X_PFX,esb_load)(struct xive_irq_data *xd, u32 offset)
+{
+	u64 val;
+
+	if (xd->flags & XIVE_IRQ_FLAG_SHIFT_BUG)
+		offset |= offset << 4;
+
+	val =__x_readq(__x_eoi_page(xd) + offset);
+#ifdef __LITTLE_ENDIAN__
+	val >>= 64-8;
+#endif
+	return (u8)val;
+}
+
+
+static void GLUE(X_PFX,source_eoi)(u32 hw_irq, struct xive_irq_data *xd)
+{
+	/* If the XIVE supports the new "store EOI facility, use it */
+	if (xd->flags & XIVE_IRQ_FLAG_STORE_EOI)
+		__x_writeq(0, __x_eoi_page(xd));
+	else if (hw_irq && xd->flags & XIVE_IRQ_FLAG_EOI_FW) {
+		opal_int_eoi(hw_irq);
+	} else {
+		uint64_t eoi_val;
+
+		/*
+		 * Otherwise for EOI, we use the special MMIO that does
+		 * a clear of both P and Q and returns the old Q,
+		 * except for LSIs where we use the "EOI cycle" special
+		 * load.
+		 *
+		 * This allows us to then do a re-trigger if Q was set
+		 * rather than synthetizing an interrupt in software
+		 *
+		 * For LSIs, using the HW EOI cycle works around a problem
+		 * on P9 DD1 PHBs where the other ESB accesses don't work
+		 * properly.
+		 */
+		if (xd->flags & XIVE_IRQ_FLAG_LSI)
+			__x_readq(__x_eoi_page(xd));
+		else {
+			eoi_val = GLUE(X_PFX,esb_load)(xd, XIVE_ESB_SET_PQ_00);
+
+			/* Re-trigger if needed */
+			if ((eoi_val & 1) && __x_trig_page(xd))
+				__x_writeq(0, __x_trig_page(xd));
+		}
+	}
+}
+
+enum {
+	scan_fetch,
+	scan_poll,
+	scan_eoi,
+};
+
+static u32 GLUE(X_PFX,scan_interrupts)(struct kvmppc_xive_vcpu *xc,
+				       u8 pending, int scan_type)
+{
+	u32 hirq = 0;
+	u8 prio = 0xff;
+
+	/* Find highest pending priority */
+	while ((xc->mfrr != 0xff || pending != 0) && hirq == 0) {
+		struct xive_q *q;
+		u32 idx, toggle;
+		__be32 *qpage;
+
+		/*
+		 * If pending is 0 this will return 0xff which is what
+		 * we want
+		 */
+		prio = ffs(pending) - 1;
+
+		/*
+		 * If the most favoured prio we found pending is less
+		 * favored (or equal) than a pending IPI, we return
+		 * the IPI instead.
+		 *
+		 * Note: If pending was 0 and mfrr is 0xff, we will
+		 * not spurriously take an IPI because mfrr cannot
+		 * then be smaller than cppr.
+		 */
+		if (prio >= xc->mfrr && xc->mfrr < xc->cppr) {
+			prio = xc->mfrr;
+			hirq = XICS_IPI;
+			break;
+		}
+
+		/* Don't scan past the guest cppr */
+		if (prio >= xc->cppr || prio > 7)
+			break;
+
+		/* Grab queue and pointers */
+		q = &xc->queues[prio];
+		idx = q->idx;
+		toggle = q->toggle;
+
+		/*
+		 * Snapshot the queue page. The test further down for EOI
+		 * must use the same "copy" that was used by __xive_read_eq
+		 * since qpage can be set concurrently and we don't want
+		 * to miss an EOI.
+		 */
+		qpage = READ_ONCE(q->qpage);
+
+skip_ipi:
+		/*
+		 * Try to fetch from the queue. Will return 0 for a
+		 * non-queueing priority (ie, qpage = 0).
+		 */
+		hirq = __xive_read_eq(qpage, q->msk, &idx, &toggle);
+
+		/*
+		 * If this was a signal for an MFFR change done by
+		 * H_IPI we skip it. Additionally, if we were fetching
+		 * we EOI it now, thus re-enabling reception of a new
+		 * such signal.
+		 *
+		 * We also need to do that if prio is 0 and we had no
+		 * page for the queue. In this case, we have non-queued
+		 * IPI that needs to be EOId.
+		 *
+		 * This is safe because if we have another pending MFRR
+		 * change that wasn't observed above, the Q bit will have
+		 * been set and another occurrence of the IPI will trigger.
+		 */
+		if (hirq == XICS_IPI || (prio == 0 && !qpage)) {
+			if (scan_type == scan_fetch)
+				GLUE(X_PFX,source_eoi)(xc->vp_ipi,
+						       &xc->vp_ipi_data);
+			/* Loop back on same queue with updated idx/toggle */
+#ifdef XIVE_RUNTIME_CHECKS
+			WARN_ON(hirq && hirq != XICS_IPI);
+#endif
+			if (hirq)
+				goto skip_ipi;
+		}
+
+		/* If fetching, update queue pointers */
+		if (scan_type == scan_fetch) {
+			q->idx = idx;
+			q->toggle = toggle;
+		}
+
+		/* Something found, stop searching */
+		if (hirq)
+			break;
+
+		/* Clear the pending bit on the now empty queue */
+		pending &= ~(1 << prio);
+
+		/*
+		 * Check if the queue count needs adjusting due to
+		 * interrupts being moved away.
+		 */
+		if (atomic_read(&q->pending_count)) {
+			int p = atomic_xchg(&q->pending_count, 0);
+			if (p) {
+#ifdef XIVE_RUNTIME_CHECKS
+				WARN_ON(p > atomic_read(&q->count));
+#endif
+				atomic_sub(p, &q->count);
+			}
+		}
+	}
+
+	/* If we are just taking a "peek", do nothing else */
+	if (scan_type == scan_poll)
+		return hirq;
+
+	/* Update the pending bits */
+	xc->pending = pending;
+
+	/*
+	 * If this is an EOI that's it, no CPPR adjustment done here,
+	 * all we needed was cleanup the stale pending bits and check
+	 * if there's anything left.
+	 */
+	if (scan_type == scan_eoi)
+		return hirq;
+
+	/*
+	 * If we found an interrupt, adjust what the guest CPPR should
+	 * be as if we had just fetched that interrupt from HW.
+	 */
+	if (hirq)
+		xc->cppr = prio;
+	/*
+	 * If it was an IPI the HW CPPR might have been lowered too much
+	 * as the HW interrupt we use for IPIs is routed to priority 0.
+	 *
+	 * We re-sync it here.
+	 */
+	if (xc->cppr != xc->hw_cppr) {
+		xc->hw_cppr = xc->cppr;
+		__x_writeb(xc->cppr, __x_tima + TM_QW1_OS + TM_CPPR);
+	}
+
+	return hirq;
+}
+
+X_STATIC unsigned long GLUE(X_PFX,h_xirr)(struct kvm_vcpu *vcpu)
+{
+	struct kvmppc_xive_vcpu *xc = vcpu->arch.xive_vcpu;
+	u8 old_cppr;
+	u32 hirq;
+
+	pr_devel("H_XIRR\n");
+
+	xc->GLUE(X_STAT_PFX,h_xirr)++;
+
+	/* First collect pending bits from HW */
+	GLUE(X_PFX,ack_pending)(xc);
+
+	/*
+	 * Cleanup the old-style bits if needed (they may have been
+	 * set by pull or an escalation interrupts).
+	 */
+	if (test_bit(BOOK3S_IRQPRIO_EXTERNAL, &vcpu->arch.pending_exceptions))
+		clear_bit(BOOK3S_IRQPRIO_EXTERNAL_LEVEL,
+			  &vcpu->arch.pending_exceptions);
+
+	pr_devel(" new pending=0x%02x hw_cppr=%d cppr=%d\n",
+		 xc->pending, xc->hw_cppr, xc->cppr);
+
+	/* Grab previous CPPR and reverse map it */
+	old_cppr = xive_prio_to_guest(xc->cppr);
+
+	/* Scan for actual interrupts */
+	hirq = GLUE(X_PFX,scan_interrupts)(xc, xc->pending, scan_fetch);
+
+	pr_devel(" got hirq=0x%x hw_cppr=%d cppr=%d\n",
+		 hirq, xc->hw_cppr, xc->cppr);
+
+#ifdef XIVE_RUNTIME_CHECKS
+	/* That should never hit */
+	if (hirq & 0xff000000)
+		pr_warn("XIVE: Weird guest interrupt number 0x%08x\n", hirq);
+#endif
+
+	/*
+	 * XXX We could check if the interrupt is masked here and
+	 * filter it. If we chose to do so, we would need to do:
+	 *
+	 *    if (masked) {
+	 *        lock();
+	 *        if (masked) {
+	 *            old_Q = true;
+	 *            hirq = 0;
+	 *        }
+	 *        unlock();
+	 *    }
+	 */
+
+	/* Return interrupt and old CPPR in GPR4 */
+	vcpu->arch.gpr[4] = hirq | (old_cppr << 24);
+
+	return H_SUCCESS;
+}
+
+X_STATIC unsigned long GLUE(X_PFX,h_ipoll)(struct kvm_vcpu *vcpu, unsigned long server)
+{
+	struct kvmppc_xive_vcpu *xc = vcpu->arch.xive_vcpu;
+	u8 pending = xc->pending;
+	u32 hirq;
+	u8 pipr;
+
+	pr_devel("H_IPOLL(server=%ld)\n", server);
+
+	xc->GLUE(X_STAT_PFX,h_ipoll)++;
+
+	/* Grab the target VCPU if not the current one */
+	if (xc->server_num != server) {
+		vcpu = kvmppc_xive_find_server(vcpu->kvm, server);
+		if (!vcpu)
+			return H_PARAMETER;
+		xc = vcpu->arch.xive_vcpu;
+
+		/* Scan all priorities */
+		pending = 0xff;
+	} else {
+		/* Grab pending interrupt if any */
+		pipr = __x_readb(__x_tima + TM_QW1_OS + TM_PIPR);
+		if (pipr < 8)
+			pending |= 1 << pipr;
+	}
+
+	hirq = GLUE(X_PFX,scan_interrupts)(xc, pending, scan_poll);
+
+	/* Return interrupt and old CPPR in GPR4 */
+	vcpu->arch.gpr[4] = hirq | (xc->cppr << 24);
+
+	return H_SUCCESS;
+}
+
+static void GLUE(X_PFX,push_pending_to_hw)(struct kvmppc_xive_vcpu *xc)
+{
+	u8 pending, prio;
+
+	pending = xc->pending;
+	if (xc->mfrr != 0xff) {
+		if (xc->mfrr < 8)
+			pending |= 1 << xc->mfrr;
+		else
+			pending |= 0x80;
+	}
+	if (!pending)
+		return;
+	prio = ffs(pending) - 1;
+
+	__x_writeb(prio, __x_tima + TM_SPC_SET_OS_PENDING);
+}
+
+X_STATIC int GLUE(X_PFX,h_cppr)(struct kvm_vcpu *vcpu, unsigned long cppr)
+{
+	struct kvmppc_xive_vcpu *xc = vcpu->arch.xive_vcpu;
+	u8 old_cppr;
+
+	pr_devel("H_CPPR(cppr=%ld)\n", cppr);
+
+	xc->GLUE(X_STAT_PFX,h_cppr)++;
+
+	/* Map CPPR */
+	cppr = xive_prio_from_guest(cppr);
+
+	/* Remember old and update SW state */
+	old_cppr = xc->cppr;
+	xc->cppr = cppr;
+
+	/*
+	 * We are masking less, we need to look for pending things
+	 * to deliver and set VP pending bits accordingly to trigger
+	 * a new interrupt otherwise we might miss MFRR changes for
+	 * which we have optimized out sending an IPI signal.
+	 */
+	if (cppr > old_cppr)
+		GLUE(X_PFX,push_pending_to_hw)(xc);
+
+	/* Apply new CPPR */
+	xc->hw_cppr = cppr;
+	__x_writeb(cppr, __x_tima + TM_QW1_OS + TM_CPPR);
+
+	return H_SUCCESS;
+}
+
+X_STATIC int GLUE(X_PFX,h_eoi)(struct kvm_vcpu *vcpu, unsigned long xirr)
+{
+	struct kvmppc_xive *xive = vcpu->kvm->arch.xive;
+	struct kvmppc_xive_src_block *sb;
+	struct kvmppc_xive_irq_state *state;
+	struct kvmppc_xive_vcpu *xc = vcpu->arch.xive_vcpu;
+	struct xive_irq_data *xd;
+	u8 new_cppr = xirr >> 24;
+	u32 irq = xirr & 0x00ffffff, hw_num;
+	u16 src;
+	int rc = 0;
+
+	pr_devel("H_EOI(xirr=%08lx)\n", xirr);
+
+	xc->GLUE(X_STAT_PFX,h_eoi)++;
+
+	xc->cppr = xive_prio_from_guest(new_cppr);
+
+	/*
+	 * IPIs are synthetized from MFRR and thus don't need
+	 * any special EOI handling. The underlying interrupt
+	 * used to signal MFRR changes is EOId when fetched from
+	 * the queue.
+	 */
+	if (irq == XICS_IPI || irq == 0)
+		goto bail;
+
+	/* Find interrupt source */
+	sb = kvmppc_xive_find_source(xive, irq, &src);
+	if (!sb) {
+		pr_devel(" source not found !\n");
+		rc = H_PARAMETER;
+		goto bail;
+	}
+	state = &sb->irq_state[src];
+	kvmppc_xive_select_irq(state, &hw_num, &xd);
+
+	state->in_eoi = true;
+	mb();
+
+again:
+	if (state->guest_priority == MASKED) {
+		arch_spin_lock(&sb->lock);
+		if (state->guest_priority != MASKED) {
+			arch_spin_unlock(&sb->lock);
+			goto again;
+		}
+		pr_devel(" EOI on saved P...\n");
+
+		/* Clear old_p, that will cause unmask to perform an EOI */
+		state->old_p = false;
+
+		arch_spin_unlock(&sb->lock);
+	} else {
+		pr_devel(" EOI on source...\n");
+
+		/* Perform EOI on the source */
+		GLUE(X_PFX,source_eoi)(hw_num, xd);
+
+		/* If it's an emulated LSI, check level and resend */
+		if (state->lsi && state->asserted)
+			__x_writeq(0, __x_trig_page(xd));
+
+	}
+
+	mb();
+	state->in_eoi = false;
+bail:
+
+	/* Re-evaluate pending IRQs and update HW */
+	GLUE(X_PFX,scan_interrupts)(xc, xc->pending, scan_eoi);
+	GLUE(X_PFX,push_pending_to_hw)(xc);
+	pr_devel(" after scan pending=%02x\n", xc->pending);
+
+	/* Apply new CPPR */
+	xc->hw_cppr = xc->cppr;
+	__x_writeb(xc->cppr, __x_tima + TM_QW1_OS + TM_CPPR);
+
+	return rc;
+}
+
+X_STATIC int GLUE(X_PFX,h_ipi)(struct kvm_vcpu *vcpu, unsigned long server,
+			       unsigned long mfrr)
+{
+	struct kvmppc_xive_vcpu *xc = vcpu->arch.xive_vcpu;
+
+	pr_devel("H_IPI(server=%08lx,mfrr=%ld)\n", server, mfrr);
+
+	xc->GLUE(X_STAT_PFX,h_ipi)++;
+
+	/* Find target */
+	vcpu = kvmppc_xive_find_server(vcpu->kvm, server);
+	if (!vcpu)
+		return H_PARAMETER;
+	xc = vcpu->arch.xive_vcpu;
+
+	/* Locklessly write over MFRR */
+	xc->mfrr = mfrr;
+
+	/* Shoot the IPI if most favored than target cppr */
+	if (mfrr < xc->cppr)
+		__x_writeq(0, __x_trig_page(&xc->vp_ipi_data));
+
+	return H_SUCCESS;
+}