KVM: PPC: Book3S: Add kernel emulation for the XICS interrupt controller

This adds in-kernel emulation of the XICS (eXternal Interrupt
Controller Specification) interrupt controller specified by PAPR, for
both HV and PR KVM guests.

The XICS emulation supports up to 1048560 interrupt sources.
Interrupt source numbers below 16 are reserved; 0 is used to mean no
interrupt and 2 is used for IPIs.  Internally these are represented in
blocks of 1024, called ICS (interrupt controller source) entities, but
that is not visible to userspace.

Each vcpu gets one ICP (interrupt controller presentation) entity,
used to store the per-vcpu state such as vcpu priority, pending
interrupt state, IPI request, etc.

This does not include any API or any way to connect vcpus to their
ICP state; that will be added in later patches.

This is based on an initial implementation by Michael Ellerman
<michael@ellerman.id.au> reworked by Benjamin Herrenschmidt and
Paul Mackerras.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
[agraf: fix typo, add dependency on !KVM_MPIC]
Signed-off-by: Alexander Graf <agraf@suse.de>

1 files changed, 113 insertions, 0 deletions

diff --git a/arch/powerpc/kvm/book3s_xics.h b/arch/powerpc/kvm/book3s_xics.h
new file mode 100644
index 000000000000..58ee190de5e5
--- /dev/null
+++ b/arch/powerpc/kvm/book3s_xics.h
@@ -0,0 +1,113 @@
+/*
+ * Copyright 2012 Michael Ellerman, IBM Corporation.
+ * Copyright 2012 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.
+ */
+
+#ifndef _KVM_PPC_BOOK3S_XICS_H
+#define _KVM_PPC_BOOK3S_XICS_H
+
+/*
+ * We use a two-level tree to store interrupt source information.
+ * There are up to 1024 ICS nodes, each of which can represent
+ * 1024 sources.
+ */
+#define KVMPPC_XICS_MAX_ICS_ID	1023
+#define KVMPPC_XICS_ICS_SHIFT	10
+#define KVMPPC_XICS_IRQ_PER_ICS	(1 << KVMPPC_XICS_ICS_SHIFT)
+#define KVMPPC_XICS_SRC_MASK	(KVMPPC_XICS_IRQ_PER_ICS - 1)
+
+/*
+ * Interrupt source numbers below this are reserved, for example
+ * 0 is "no interrupt", and 2 is used for IPIs.
+ */
+#define KVMPPC_XICS_FIRST_IRQ	16
+#define KVMPPC_XICS_NR_IRQS	((KVMPPC_XICS_MAX_ICS_ID + 1) * \
+				 KVMPPC_XICS_IRQ_PER_ICS)
+
+/* Priority value to use for disabling an interrupt */
+#define MASKED	0xff
+
+/* State for one irq source */
+struct ics_irq_state {
+	u32 number;
+	u32 server;
+	u8  priority;
+	u8  saved_priority; /* currently unused */
+	u8  resend;
+	u8  masked_pending;
+	u8  asserted; /* Only for LSI */
+	u8  exists;
+};
+
+/* Atomic ICP state, updated with a single compare & swap */
+union kvmppc_icp_state {
+	unsigned long raw;
+	struct {
+		u8 out_ee:1;
+		u8 need_resend:1;
+		u8 cppr;
+		u8 mfrr;
+		u8 pending_pri;
+		u32 xisr;
+	};
+};
+
+/* One bit per ICS */
+#define ICP_RESEND_MAP_SIZE	(KVMPPC_XICS_MAX_ICS_ID / BITS_PER_LONG + 1)
+
+struct kvmppc_icp {
+	struct kvm_vcpu *vcpu;
+	unsigned long server_num;
+	union kvmppc_icp_state state;
+	unsigned long resend_map[ICP_RESEND_MAP_SIZE];
+};
+
+struct kvmppc_ics {
+	struct mutex lock;
+	u16 icsid;
+	struct ics_irq_state irq_state[KVMPPC_XICS_IRQ_PER_ICS];
+};
+
+struct kvmppc_xics {
+	struct kvm *kvm;
+	struct dentry *dentry;
+	u32 max_icsid;
+	struct kvmppc_ics *ics[KVMPPC_XICS_MAX_ICS_ID + 1];
+};
+
+static inline struct kvmppc_icp *kvmppc_xics_find_server(struct kvm *kvm,
+							 u32 nr)
+{
+	struct kvm_vcpu *vcpu = NULL;
+	int i;
+
+	kvm_for_each_vcpu(i, vcpu, kvm) {
+		if (vcpu->arch.icp && nr == vcpu->arch.icp->server_num)
+			return vcpu->arch.icp;
+	}
+	return NULL;
+}
+
+static inline struct kvmppc_ics *kvmppc_xics_find_ics(struct kvmppc_xics *xics,
+						      u32 irq, u16 *source)
+{
+	u32 icsid = irq >> KVMPPC_XICS_ICS_SHIFT;
+	u16 src = irq & KVMPPC_XICS_SRC_MASK;
+	struct kvmppc_ics *ics;
+
+	if (source)
+		*source = src;
+	if (icsid > KVMPPC_XICS_MAX_ICS_ID)
+		return NULL;
+	ics = xics->ics[icsid];
+	if (!ics)
+		return NULL;
+	return ics;
+}
+
+
+#endif /* _KVM_PPC_BOOK3S_XICS_H */