KVM: arm/arm64: vgic-new: Add MMIO handling framework

Add an MMIO handling framework to the VGIC emulation:
Each register is described by its offset, size (or number of bits per
IRQ, if applicable) and the read/write handler functions. We provide
initialization macros to describe each GIC register later easily.

Separate dispatch functions for read and write accesses are connected
to the kvm_io_bus framework and binary-search for the responsible
register handler based on the offset address within the region.
We convert the incoming data (referenced by a pointer) to the host's
endianess and use pass-by-value to hand the data over to the actual
handler functions.

The register handler prototype and the endianess conversion are
courtesy of Christoffer Dall.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>

1 files changed, 99 insertions, 0 deletions

diff --git a/virt/kvm/arm/vgic/vgic-mmio.h b/virt/kvm/arm/vgic/vgic-mmio.h
new file mode 100644
index 000000000000..3023ecf221c6
--- /dev/null
+++ b/virt/kvm/arm/vgic/vgic-mmio.h
@@ -0,0 +1,99 @@
+/*
+ * Copyright (C) 2015, 2016 ARM Ltd.
+ *
+ * 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, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef __KVM_ARM_VGIC_MMIO_H__
+#define __KVM_ARM_VGIC_MMIO_H__
+
+struct vgic_register_region {
+	unsigned int reg_offset;
+	unsigned int len;
+	unsigned int bits_per_irq;
+	unsigned int access_flags;
+	unsigned long (*read)(struct kvm_vcpu *vcpu, gpa_t addr,
+			      unsigned int len);
+	void (*write)(struct kvm_vcpu *vcpu, gpa_t addr, unsigned int len,
+		      unsigned long val);
+};
+
+extern struct kvm_io_device_ops kvm_io_gic_ops;
+
+#define VGIC_ACCESS_8bit	1
+#define VGIC_ACCESS_32bit	2
+#define VGIC_ACCESS_64bit	4
+
+/*
+ * Generate a mask that covers the number of bytes required to address
+ * up to 1024 interrupts, each represented by <bits> bits. This assumes
+ * that <bits> is a power of two.
+ */
+#define VGIC_ADDR_IRQ_MASK(bits) (((bits) * 1024 / 8) - 1)
+
+/*
+ * (addr & mask) gives us the byte offset for the INT ID, so we want to
+ * divide this with 'bytes per irq' to get the INT ID, which is given
+ * by '(bits) / 8'.  But we do this with fixed-point-arithmetic and
+ * take advantage of the fact that division by a fraction equals
+ * multiplication with the inverted fraction, and scale up both the
+ * numerator and denominator with 8 to support at most 64 bits per IRQ:
+ */
+#define VGIC_ADDR_TO_INTID(addr, bits)  (((addr) & VGIC_ADDR_IRQ_MASK(bits)) * \
+					64 / (bits) / 8)
+
+/*
+ * Some VGIC registers store per-IRQ information, with a different number
+ * of bits per IRQ. For those registers this macro is used.
+ * The _WITH_LENGTH version instantiates registers with a fixed length
+ * and is mutually exclusive with the _PER_IRQ version.
+ */
+#define REGISTER_DESC_WITH_BITS_PER_IRQ(off, rd, wr, bpi, acc)		\
+	{								\
+		.reg_offset = off,					\
+		.bits_per_irq = bpi,					\
+		.len = bpi * 1024 / 8,					\
+		.access_flags = acc,					\
+		.read = rd,						\
+		.write = wr,						\
+	}
+
+#define REGISTER_DESC_WITH_LENGTH(off, rd, wr, length, acc)		\
+	{								\
+		.reg_offset = off,					\
+		.bits_per_irq = 0,					\
+		.len = length,						\
+		.access_flags = acc,					\
+		.read = rd,						\
+		.write = wr,						\
+	}
+
+int kvm_vgic_register_mmio_region(struct kvm *kvm, struct kvm_vcpu *vcpu,
+				  struct vgic_register_region *reg_desc,
+				  struct vgic_io_device *region,
+				  int nr_irqs, bool offset_private);
+
+unsigned long vgic_data_mmio_bus_to_host(const void *val, unsigned int len);
+
+void vgic_data_host_to_mmio_bus(void *buf, unsigned int len,
+				unsigned long data);
+
+unsigned long vgic_mmio_read_raz(struct kvm_vcpu *vcpu,
+				 gpa_t addr, unsigned int len);
+
+unsigned long vgic_mmio_read_rao(struct kvm_vcpu *vcpu,
+				 gpa_t addr, unsigned int len);
+
+void vgic_mmio_write_wi(struct kvm_vcpu *vcpu, gpa_t addr,
+			unsigned int len, unsigned long val);
+
+#endif