ARM: KVM: Initial VGIC infrastructure code

Wire the basic framework code for VGIC support and the initial in-kernel
MMIO support code for the VGIC, used for the distributor emulation.

Reviewed-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Christoffer Dall <c.dall@virtualopensystems.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

1 files changed, 153 insertions, 0 deletions

diff --git a/arch/arm/kvm/vgic.c b/arch/arm/kvm/vgic.c
new file mode 100644
index 00000000000..c400661409a
--- /dev/null
+++ b/arch/arm/kvm/vgic.c
@@ -0,0 +1,153 @@
+/*
+ * Copyright (C) 2012 ARM Ltd.
+ * Author: Marc Zyngier <marc.zyngier@arm.com>
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#include <linux/kvm.h>
+#include <linux/kvm_host.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <asm/kvm_emulate.h>
+
+#define ACCESS_READ_VALUE	(1 << 0)
+#define ACCESS_READ_RAZ		(0 << 0)
+#define ACCESS_READ_MASK(x)	((x) & (1 << 0))
+#define ACCESS_WRITE_IGNORED	(0 << 1)
+#define ACCESS_WRITE_SETBIT	(1 << 1)
+#define ACCESS_WRITE_CLEARBIT	(2 << 1)
+#define ACCESS_WRITE_VALUE	(3 << 1)
+#define ACCESS_WRITE_MASK(x)	((x) & (3 << 1))
+
+static u32 mmio_data_read(struct kvm_exit_mmio *mmio, u32 mask)
+{
+	return *((u32 *)mmio->data) & mask;
+}
+
+static void mmio_data_write(struct kvm_exit_mmio *mmio, u32 mask, u32 value)
+{
+	*((u32 *)mmio->data) = value & mask;
+}
+
+/**
+ * vgic_reg_access - access vgic register
+ * @mmio:   pointer to the data describing the mmio access
+ * @reg:    pointer to the virtual backing of vgic distributor data
+ * @offset: least significant 2 bits used for word offset
+ * @mode:   ACCESS_ mode (see defines above)
+ *
+ * Helper to make vgic register access easier using one of the access
+ * modes defined for vgic register access
+ * (read,raz,write-ignored,setbit,clearbit,write)
+ */
+static void vgic_reg_access(struct kvm_exit_mmio *mmio, u32 *reg,
+			    phys_addr_t offset, int mode)
+{
+	int word_offset = (offset & 3) * 8;
+	u32 mask = (1UL << (mmio->len * 8)) - 1;
+	u32 regval;
+
+	/*
+	 * Any alignment fault should have been delivered to the guest
+	 * directly (ARM ARM B3.12.7 "Prioritization of aborts").
+	 */
+
+	if (reg) {
+		regval = *reg;
+	} else {
+		BUG_ON(mode != (ACCESS_READ_RAZ | ACCESS_WRITE_IGNORED));
+		regval = 0;
+	}
+
+	if (mmio->is_write) {
+		u32 data = mmio_data_read(mmio, mask) << word_offset;
+		switch (ACCESS_WRITE_MASK(mode)) {
+		case ACCESS_WRITE_IGNORED:
+			return;
+
+		case ACCESS_WRITE_SETBIT:
+			regval |= data;
+			break;
+
+		case ACCESS_WRITE_CLEARBIT:
+			regval &= ~data;
+			break;
+
+		case ACCESS_WRITE_VALUE:
+			regval = (regval & ~(mask << word_offset)) | data;
+			break;
+		}
+		*reg = regval;
+	} else {
+		switch (ACCESS_READ_MASK(mode)) {
+		case ACCESS_READ_RAZ:
+			regval = 0;
+			/* fall through */
+
+		case ACCESS_READ_VALUE:
+			mmio_data_write(mmio, mask, regval >> word_offset);
+		}
+	}
+}
+
+/*
+ * I would have liked to use the kvm_bus_io_*() API instead, but it
+ * cannot cope with banked registers (only the VM pointer is passed
+ * around, and we need the vcpu). One of these days, someone please
+ * fix it!
+ */
+struct mmio_range {
+	phys_addr_t base;
+	unsigned long len;
+	bool (*handle_mmio)(struct kvm_vcpu *vcpu, struct kvm_exit_mmio *mmio,
+			    phys_addr_t offset);
+};
+
+static const struct mmio_range vgic_ranges[] = {
+	{}
+};
+
+static const
+struct mmio_range *find_matching_range(const struct mmio_range *ranges,
+				       struct kvm_exit_mmio *mmio,
+				       phys_addr_t base)
+{
+	const struct mmio_range *r = ranges;
+	phys_addr_t addr = mmio->phys_addr - base;
+
+	while (r->len) {
+		if (addr >= r->base &&
+		    (addr + mmio->len) <= (r->base + r->len))
+			return r;
+		r++;
+	}
+
+	return NULL;
+}
+
+/**
+ * vgic_handle_mmio - handle an in-kernel MMIO access
+ * @vcpu:	pointer to the vcpu performing the access
+ * @run:	pointer to the kvm_run structure
+ * @mmio:	pointer to the data describing the access
+ *
+ * returns true if the MMIO access has been performed in kernel space,
+ * and false if it needs to be emulated in user space.
+ */
+bool vgic_handle_mmio(struct kvm_vcpu *vcpu, struct kvm_run *run,
+		      struct kvm_exit_mmio *mmio)
+{
+	return KVM_EXIT_MMIO;
+}