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authorMarc Zyngier <marc.zyngier@arm.com>2016-04-26 11:06:12 +0100
committerChristoffer Dall <christoffer.dall@linaro.org>2016-05-20 15:39:49 +0200
commit4493b1c4866a03963a35be7d157c911a617a3694 (patch)
tree612e202d4d5c4f9536d38637b7b1f7afafbe6b85 /virt
parent90eee56c5f9081686035972dfcddfd6c85cafdf9 (diff)
downloadlinux-4493b1c4866a03963a35be7d157c911a617a3694.tar.gz
linux-4493b1c4866a03963a35be7d157c911a617a3694.tar.xz
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>
Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/arm/vgic/vgic-mmio.c184
-rw-r--r--virt/kvm/arm/vgic/vgic-mmio.h99
2 files changed, 283 insertions, 0 deletions
diff --git a/virt/kvm/arm/vgic/vgic-mmio.c b/virt/kvm/arm/vgic/vgic-mmio.c
new file mode 100644
index 0000000..012b82b
--- /dev/null
+++ b/virt/kvm/arm/vgic/vgic-mmio.c
@@ -0,0 +1,184 @@
+/*
+ * VGIC MMIO handling functions
+ *
+ * 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.
+ */
+
+#include <linux/bitops.h>
+#include <linux/bsearch.h>
+#include <linux/kvm.h>
+#include <linux/kvm_host.h>
+#include <kvm/iodev.h>
+#include <kvm/arm_vgic.h>
+
+#include "vgic.h"
+#include "vgic-mmio.h"
+
+unsigned long vgic_mmio_read_raz(struct kvm_vcpu *vcpu,
+ gpa_t addr, unsigned int len)
+{
+ return 0;
+}
+
+unsigned long vgic_mmio_read_rao(struct kvm_vcpu *vcpu,
+ gpa_t addr, unsigned int len)
+{
+ return -1UL;
+}
+
+void vgic_mmio_write_wi(struct kvm_vcpu *vcpu, gpa_t addr,
+ unsigned int len, unsigned long val)
+{
+ /* Ignore */
+}
+
+static int match_region(const void *key, const void *elt)
+{
+ const unsigned int offset = (unsigned long)key;
+ const struct vgic_register_region *region = elt;
+
+ if (offset < region->reg_offset)
+ return -1;
+
+ if (offset >= region->reg_offset + region->len)
+ return 1;
+
+ return 0;
+}
+
+/* Find the proper register handler entry given a certain address offset. */
+static const struct vgic_register_region *
+vgic_find_mmio_region(const struct vgic_register_region *region, int nr_regions,
+ unsigned int offset)
+{
+ return bsearch((void *)(uintptr_t)offset, region, nr_regions,
+ sizeof(region[0]), match_region);
+}
+
+/*
+ * kvm_mmio_read_buf() returns a value in a format where it can be converted
+ * to a byte array and be directly observed as the guest wanted it to appear
+ * in memory if it had done the store itself, which is LE for the GIC, as the
+ * guest knows the GIC is always LE.
+ *
+ * We convert this value to the CPUs native format to deal with it as a data
+ * value.
+ */
+unsigned long vgic_data_mmio_bus_to_host(const void *val, unsigned int len)
+{
+ unsigned long data = kvm_mmio_read_buf(val, len);
+
+ switch (len) {
+ case 1:
+ return data;
+ case 2:
+ return le16_to_cpu(data);
+ case 4:
+ return le32_to_cpu(data);
+ default:
+ return le64_to_cpu(data);
+ }
+}
+
+/*
+ * kvm_mmio_write_buf() expects a value in a format such that if converted to
+ * a byte array it is observed as the guest would see it if it could perform
+ * the load directly. Since the GIC is LE, and the guest knows this, the
+ * guest expects a value in little endian format.
+ *
+ * We convert the data value from the CPUs native format to LE so that the
+ * value is returned in the proper format.
+ */
+void vgic_data_host_to_mmio_bus(void *buf, unsigned int len,
+ unsigned long data)
+{
+ switch (len) {
+ case 1:
+ break;
+ case 2:
+ data = cpu_to_le16(data);
+ break;
+ case 4:
+ data = cpu_to_le32(data);
+ break;
+ default:
+ data = cpu_to_le64(data);
+ }
+
+ kvm_mmio_write_buf(buf, len, data);
+}
+
+static
+struct vgic_io_device *kvm_to_vgic_iodev(const struct kvm_io_device *dev)
+{
+ return container_of(dev, struct vgic_io_device, dev);
+}
+
+static bool check_region(const struct vgic_register_region *region,
+ gpa_t addr, int len)
+{
+ if ((region->access_flags & VGIC_ACCESS_8bit) && len == 1)
+ return true;
+ if ((region->access_flags & VGIC_ACCESS_32bit) &&
+ len == sizeof(u32) && !(addr & 3))
+ return true;
+ if ((region->access_flags & VGIC_ACCESS_64bit) &&
+ len == sizeof(u64) && !(addr & 7))
+ return true;
+
+ return false;
+}
+
+static int dispatch_mmio_read(struct kvm_vcpu *vcpu, struct kvm_io_device *dev,
+ gpa_t addr, int len, void *val)
+{
+ struct vgic_io_device *iodev = kvm_to_vgic_iodev(dev);
+ const struct vgic_register_region *region;
+ struct kvm_vcpu *r_vcpu;
+ unsigned long data;
+
+ region = vgic_find_mmio_region(iodev->regions, iodev->nr_regions,
+ addr - iodev->base_addr);
+ if (!region || !check_region(region, addr, len)) {
+ memset(val, 0, len);
+ return 0;
+ }
+
+ r_vcpu = iodev->redist_vcpu ? iodev->redist_vcpu : vcpu;
+ data = region->read(r_vcpu, addr, len);
+ vgic_data_host_to_mmio_bus(val, len, data);
+ return 0;
+}
+
+static int dispatch_mmio_write(struct kvm_vcpu *vcpu, struct kvm_io_device *dev,
+ gpa_t addr, int len, const void *val)
+{
+ struct vgic_io_device *iodev = kvm_to_vgic_iodev(dev);
+ const struct vgic_register_region *region;
+ struct kvm_vcpu *r_vcpu;
+ unsigned long data = vgic_data_mmio_bus_to_host(val, len);
+
+ region = vgic_find_mmio_region(iodev->regions, iodev->nr_regions,
+ addr - iodev->base_addr);
+ if (!region)
+ return 0;
+
+ if (!check_region(region, addr, len))
+ return 0;
+
+ r_vcpu = iodev->redist_vcpu ? iodev->redist_vcpu : vcpu;
+ region->write(r_vcpu, addr, len, data);
+ return 0;
+}
+
+struct kvm_io_device_ops kvm_io_gic_ops = {
+ .read = dispatch_mmio_read,
+ .write = dispatch_mmio_write,
+};
diff --git a/virt/kvm/arm/vgic/vgic-mmio.h b/virt/kvm/arm/vgic/vgic-mmio.h
new file mode 100644
index 0000000..3023ecf
--- /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