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>
This commit is contained in:
Marc Zyngier 2016-04-26 11:06:12 +01:00 committed by Christoffer Dall
parent 90eee56c5f
commit 4493b1c486
3 changed files with 296 additions and 0 deletions

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@ -106,6 +106,16 @@ struct vgic_irq {
enum vgic_irq_config config; /* Level or edge */
};
struct vgic_register_region;
struct vgic_io_device {
gpa_t base_addr;
struct kvm_vcpu *redist_vcpu;
const struct vgic_register_region *regions;
int nr_regions;
struct kvm_io_device dev;
};
struct vgic_dist {
bool in_kernel;
bool ready;
@ -132,6 +142,9 @@ struct vgic_dist {
bool enabled;
struct vgic_irq *spis;
struct vgic_io_device dist_iodev;
struct vgic_io_device *redist_iodevs;
};
struct vgic_v2_cpu_if {

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@ -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,
};

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@ -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