[Xen-devel,v3,16/39] ARM: new VGIC: Add MMIO handling framework

Message ID 20180321163235.12529-17-andre.przywara@linaro.org
State New
Headers show
Series
  • New VGIC(-v2) implementation
Related show

Commit Message

Andre Przywara March 21, 2018, 4:32 p.m.
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 Xen's MMIO handling framework and binary-search for the responsible
register handler based on the offset address within the region.

The register handler prototype are courtesy of Christoffer Dall.

This is based on Linux commit 4493b1c4866a, written by Marc Zyngier.

Signed-off-by: Andre Przywara <andre.przywara@linaro.org>
Reviewed-by: Julien Grall <julien.grall@arm.com>
---
 xen/arch/arm/vgic/vgic-mmio.c | 180 ++++++++++++++++++++++++++++++++++++++++++
 xen/arch/arm/vgic/vgic-mmio.h |  89 +++++++++++++++++++++
 2 files changed, 269 insertions(+)
 create mode 100644 xen/arch/arm/vgic/vgic-mmio.c
 create mode 100644 xen/arch/arm/vgic/vgic-mmio.h

Comments

Stefano Stabellini March 27, 2018, 8:07 p.m. | #1
On Wed, 21 Mar 2018, Andre Przywara wrote:
> 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 Xen's MMIO handling framework and binary-search for the responsible
> register handler based on the offset address within the region.
> 
> The register handler prototype are courtesy of Christoffer Dall.
> 
> This is based on Linux commit 4493b1c4866a, written by Marc Zyngier.
> 
> Signed-off-by: Andre Przywara <andre.przywara@linaro.org>
> Reviewed-by: Julien Grall <julien.grall@arm.com>

Acked-by: Stefano Stabellini <sstabellini@kernel.org>

One comment below (the ack still stands anyway).

> ---
>  xen/arch/arm/vgic/vgic-mmio.c | 180 ++++++++++++++++++++++++++++++++++++++++++
>  xen/arch/arm/vgic/vgic-mmio.h |  89 +++++++++++++++++++++
>  2 files changed, 269 insertions(+)
>  create mode 100644 xen/arch/arm/vgic/vgic-mmio.c
>  create mode 100644 xen/arch/arm/vgic/vgic-mmio.h
> 
> diff --git a/xen/arch/arm/vgic/vgic-mmio.c b/xen/arch/arm/vgic/vgic-mmio.c
> new file mode 100644
> index 0000000000..866023a84d
> --- /dev/null
> +++ b/xen/arch/arm/vgic/vgic-mmio.c
> @@ -0,0 +1,180 @@
> +/*
> + * VGIC MMIO handling functions
> + * Imported from Linux ("new" KVM VGIC) and heavily adapted to Xen.
> + *
> + * 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 <xen/bitops.h>
> +#include <xen/lib.h>
> +#include <xen/sched.h>
> +#include <asm/new_vgic.h>
> +#include <asm/byteorder.h>
> +
> +#include "vgic.h"
> +#include "vgic-mmio.h"
> +
> +unsigned long vgic_mmio_read_raz(struct vcpu *vcpu,
> +                                 paddr_t addr, unsigned int len)
> +{
> +    return 0;
> +}
> +
> +unsigned long vgic_mmio_read_rao(struct vcpu *vcpu,
> +                                 paddr_t addr, unsigned int len)
> +{
> +    return -1UL;
> +}
> +
> +void vgic_mmio_write_wi(struct vcpu *vcpu, paddr_t addr,
> +                        unsigned int len, unsigned long val)
> +{
> +    /* Ignore */
> +}

Would these make sense a static inline?


> +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;
> +}
> +
> +static const struct vgic_register_region *
> +vgic_find_mmio_region(const struct vgic_register_region *regions,
> +                      int nr_regions, unsigned int offset)
> +{
> +    return bsearch((void *)(uintptr_t)offset, regions, nr_regions,
> +                   sizeof(regions[0]), match_region);
> +}
> +
> +static bool check_region(const struct domain *d,
> +                         const struct vgic_register_region *region,
> +                         paddr_t addr, int len)
> +{
> +    unsigned int flags, nr_irqs = d->arch.vgic.nr_spis + VGIC_NR_PRIVATE_IRQS;
> +
> +    switch ( len )
> +    {
> +    case sizeof(uint8_t):
> +        flags = VGIC_ACCESS_8bit;
> +        break;
> +    case sizeof(uint32_t):
> +        flags = VGIC_ACCESS_32bit;
> +        break;
> +    case sizeof(uint64_t):
> +        flags = VGIC_ACCESS_64bit;
> +        break;
> +    default:
> +        return false;
> +    }
> +
> +    if ( (region->access_flags & flags) && IS_ALIGNED(addr, len) )
> +    {
> +        if ( !region->bits_per_irq )
> +            return true;
> +
> +        /* Do we access a non-allocated IRQ? */
> +        return VGIC_ADDR_TO_INTID(addr, region->bits_per_irq) < nr_irqs;
> +    }
> +
> +    return false;
> +}
> +
> +static const struct vgic_register_region *
> +vgic_get_mmio_region(struct vcpu *vcpu, struct vgic_io_device *iodev,
> +                     paddr_t addr, unsigned int len)
> +{
> +    const struct vgic_register_region *region;
> +
> +    region = vgic_find_mmio_region(iodev->regions, iodev->nr_regions,
> +                                   addr - gfn_to_gaddr(iodev->base_fn));
> +    if ( !region || !check_region(vcpu->domain, region, addr, len) )
> +        return NULL;
> +
> +    return region;
> +}
> +
> +static int dispatch_mmio_read(struct vcpu *vcpu, mmio_info_t *info,
> +                              register_t *r, void *priv)
> +{
> +    struct vgic_io_device *iodev = priv;
> +    const struct vgic_register_region *region;
> +    unsigned long data = 0;
> +    paddr_t addr = info->gpa;
> +    int len = 1U << info->dabt.size;
> +
> +    region = vgic_get_mmio_region(vcpu, iodev, addr, len);
> +    if ( !region )
> +    {
> +        memset(r, 0, len);
> +        return 0;
> +    }
> +
> +    switch (iodev->iodev_type)
> +    {
> +    case IODEV_DIST:
> +        data = region->read(vcpu, addr, len);
> +        break;
> +    case IODEV_REDIST:
> +        data = region->read(iodev->redist_vcpu, addr, len);
> +        break;
> +    }
> +
> +    memcpy(r, &data, len);
> +
> +    return 1;
> +}
> +
> +static int dispatch_mmio_write(struct vcpu *vcpu, mmio_info_t *info,
> +                               register_t r, void *priv)
> +{
> +    struct vgic_io_device *iodev = priv;
> +    const struct vgic_register_region *region;
> +    unsigned long data = r;
> +    paddr_t addr = info->gpa;
> +    int len = 1U << info->dabt.size;
> +
> +    region = vgic_get_mmio_region(vcpu, iodev, addr, len);
> +    if ( !region )
> +        return 0;
> +
> +    switch (iodev->iodev_type)
> +    {
> +    case IODEV_DIST:
> +        region->write(vcpu, addr, len, data);
> +        break;
> +    case IODEV_REDIST:
> +        region->write(iodev->redist_vcpu, addr, len, data);
> +        break;
> +    }
> +
> +    return 1;
> +}
> +
> +struct mmio_handler_ops vgic_io_ops = {
> +    .read = dispatch_mmio_read,
> +    .write = dispatch_mmio_write,
> +};
> +
> +/*
> + * Local variables:
> + * mode: C
> + * c-file-style: "BSD"
> + * c-basic-offset: 4
> + * indent-tabs-mode: nil
> + * End:
> + */
> diff --git a/xen/arch/arm/vgic/vgic-mmio.h b/xen/arch/arm/vgic/vgic-mmio.h
> new file mode 100644
> index 0000000000..bf062a27ca
> --- /dev/null
> +++ b/xen/arch/arm/vgic/vgic-mmio.h
> @@ -0,0 +1,89 @@
> +/*
> + * 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 __XEN_ARM_VGIC_VGIC_MMIO_H__
> +#define __XEN_ARM_VGIC_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 vcpu *vcpu, paddr_t addr,
> +                          unsigned int len);
> +    void (*write)(struct vcpu *vcpu, paddr_t addr,
> +                  unsigned int len, unsigned long val);
> +};
> +
> +extern struct mmio_handler_ops vgic_io_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.
> + * We multiply this by 8 the get the _bit_ offset, then divide this by
> + * the number of bits to learn the actual INT ID.
> + * But instead of a division (which requires a "long long div" implementation),
> + * we shift by the binary logarithm of <bits>.
> + * This assumes that <bits> is a power of two.
> + */
> +#define VGIC_ADDR_TO_INTID(addr, bits)  (((addr) & VGIC_ADDR_IRQ_MASK(bits)) * \
> +                                         8 >> ilog2(bits))
> +
> +/*
> + * 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,                                            \
> +    }
> +
> +unsigned long vgic_mmio_read_raz(struct vcpu *vcpu,
> +                                 paddr_t addr, unsigned int len);
> +
> +unsigned long vgic_mmio_read_rao(struct vcpu *vcpu,
> +                                 paddr_t addr, unsigned int len);
> +
> +void vgic_mmio_write_wi(struct vcpu *vcpu, paddr_t addr,
> +                        unsigned int len, unsigned long val);
> +
> +#endif
> -- 
> 2.14.1
>
Andre Przywara March 28, 2018, 9:28 a.m. | #2
Hi,

On 27/03/18 21:07, Stefano Stabellini wrote:
> On Wed, 21 Mar 2018, Andre Przywara wrote:
>> 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 Xen's MMIO handling framework and binary-search for the responsible
>> register handler based on the offset address within the region.
>>
>> The register handler prototype are courtesy of Christoffer Dall.
>>
>> This is based on Linux commit 4493b1c4866a, written by Marc Zyngier.
>>
>> Signed-off-by: Andre Przywara <andre.przywara@linaro.org>
>> Reviewed-by: Julien Grall <julien.grall@arm.com>
> 
> Acked-by: Stefano Stabellini <sstabellini@kernel.org>

Thanks!

> 
> One comment below (the ack still stands anyway).
> 
>> ---
>>  xen/arch/arm/vgic/vgic-mmio.c | 180 ++++++++++++++++++++++++++++++++++++++++++
>>  xen/arch/arm/vgic/vgic-mmio.h |  89 +++++++++++++++++++++
>>  2 files changed, 269 insertions(+)
>>  create mode 100644 xen/arch/arm/vgic/vgic-mmio.c
>>  create mode 100644 xen/arch/arm/vgic/vgic-mmio.h
>>
>> diff --git a/xen/arch/arm/vgic/vgic-mmio.c b/xen/arch/arm/vgic/vgic-mmio.c
>> new file mode 100644
>> index 0000000000..866023a84d
>> --- /dev/null
>> +++ b/xen/arch/arm/vgic/vgic-mmio.c
>> @@ -0,0 +1,180 @@
>> +/*
>> + * VGIC MMIO handling functions
>> + * Imported from Linux ("new" KVM VGIC) and heavily adapted to Xen.
>> + *
>> + * 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 <xen/bitops.h>
>> +#include <xen/lib.h>
>> +#include <xen/sched.h>
>> +#include <asm/new_vgic.h>
>> +#include <asm/byteorder.h>
>> +
>> +#include "vgic.h"
>> +#include "vgic-mmio.h"
>> +
>> +unsigned long vgic_mmio_read_raz(struct vcpu *vcpu,
>> +                                 paddr_t addr, unsigned int len)
>> +{
>> +    return 0;
>> +}
>> +
>> +unsigned long vgic_mmio_read_rao(struct vcpu *vcpu,
>> +                                 paddr_t addr, unsigned int len)
>> +{
>> +    return -1UL;
>> +}
>> +
>> +void vgic_mmio_write_wi(struct vcpu *vcpu, paddr_t addr,
>> +                        unsigned int len, unsigned long val)
>> +{
>> +    /* Ignore */
>> +}
> 
> Would these make sense a static inline?

We take function pointers to those functions.

Besides: are you really concerned about performance of write_ignore? ;-)

Cheers,
Andre.

>> +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;
>> +}
>> +
>> +static const struct vgic_register_region *
>> +vgic_find_mmio_region(const struct vgic_register_region *regions,
>> +                      int nr_regions, unsigned int offset)
>> +{
>> +    return bsearch((void *)(uintptr_t)offset, regions, nr_regions,
>> +                   sizeof(regions[0]), match_region);
>> +}
>> +
>> +static bool check_region(const struct domain *d,
>> +                         const struct vgic_register_region *region,
>> +                         paddr_t addr, int len)
>> +{
>> +    unsigned int flags, nr_irqs = d->arch.vgic.nr_spis + VGIC_NR_PRIVATE_IRQS;
>> +
>> +    switch ( len )
>> +    {
>> +    case sizeof(uint8_t):
>> +        flags = VGIC_ACCESS_8bit;
>> +        break;
>> +    case sizeof(uint32_t):
>> +        flags = VGIC_ACCESS_32bit;
>> +        break;
>> +    case sizeof(uint64_t):
>> +        flags = VGIC_ACCESS_64bit;
>> +        break;
>> +    default:
>> +        return false;
>> +    }
>> +
>> +    if ( (region->access_flags & flags) && IS_ALIGNED(addr, len) )
>> +    {
>> +        if ( !region->bits_per_irq )
>> +            return true;
>> +
>> +        /* Do we access a non-allocated IRQ? */
>> +        return VGIC_ADDR_TO_INTID(addr, region->bits_per_irq) < nr_irqs;
>> +    }
>> +
>> +    return false;
>> +}
>> +
>> +static const struct vgic_register_region *
>> +vgic_get_mmio_region(struct vcpu *vcpu, struct vgic_io_device *iodev,
>> +                     paddr_t addr, unsigned int len)
>> +{
>> +    const struct vgic_register_region *region;
>> +
>> +    region = vgic_find_mmio_region(iodev->regions, iodev->nr_regions,
>> +                                   addr - gfn_to_gaddr(iodev->base_fn));
>> +    if ( !region || !check_region(vcpu->domain, region, addr, len) )
>> +        return NULL;
>> +
>> +    return region;
>> +}
>> +
>> +static int dispatch_mmio_read(struct vcpu *vcpu, mmio_info_t *info,
>> +                              register_t *r, void *priv)
>> +{
>> +    struct vgic_io_device *iodev = priv;
>> +    const struct vgic_register_region *region;
>> +    unsigned long data = 0;
>> +    paddr_t addr = info->gpa;
>> +    int len = 1U << info->dabt.size;
>> +
>> +    region = vgic_get_mmio_region(vcpu, iodev, addr, len);
>> +    if ( !region )
>> +    {
>> +        memset(r, 0, len);
>> +        return 0;
>> +    }
>> +
>> +    switch (iodev->iodev_type)
>> +    {
>> +    case IODEV_DIST:
>> +        data = region->read(vcpu, addr, len);
>> +        break;
>> +    case IODEV_REDIST:
>> +        data = region->read(iodev->redist_vcpu, addr, len);
>> +        break;
>> +    }
>> +
>> +    memcpy(r, &data, len);
>> +
>> +    return 1;
>> +}
>> +
>> +static int dispatch_mmio_write(struct vcpu *vcpu, mmio_info_t *info,
>> +                               register_t r, void *priv)
>> +{
>> +    struct vgic_io_device *iodev = priv;
>> +    const struct vgic_register_region *region;
>> +    unsigned long data = r;
>> +    paddr_t addr = info->gpa;
>> +    int len = 1U << info->dabt.size;
>> +
>> +    region = vgic_get_mmio_region(vcpu, iodev, addr, len);
>> +    if ( !region )
>> +        return 0;
>> +
>> +    switch (iodev->iodev_type)
>> +    {
>> +    case IODEV_DIST:
>> +        region->write(vcpu, addr, len, data);
>> +        break;
>> +    case IODEV_REDIST:
>> +        region->write(iodev->redist_vcpu, addr, len, data);
>> +        break;
>> +    }
>> +
>> +    return 1;
>> +}
>> +
>> +struct mmio_handler_ops vgic_io_ops = {
>> +    .read = dispatch_mmio_read,
>> +    .write = dispatch_mmio_write,
>> +};
>> +
>> +/*
>> + * Local variables:
>> + * mode: C
>> + * c-file-style: "BSD"
>> + * c-basic-offset: 4
>> + * indent-tabs-mode: nil
>> + * End:
>> + */
>> diff --git a/xen/arch/arm/vgic/vgic-mmio.h b/xen/arch/arm/vgic/vgic-mmio.h
>> new file mode 100644
>> index 0000000000..bf062a27ca
>> --- /dev/null
>> +++ b/xen/arch/arm/vgic/vgic-mmio.h
>> @@ -0,0 +1,89 @@
>> +/*
>> + * 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 __XEN_ARM_VGIC_VGIC_MMIO_H__
>> +#define __XEN_ARM_VGIC_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 vcpu *vcpu, paddr_t addr,
>> +                          unsigned int len);
>> +    void (*write)(struct vcpu *vcpu, paddr_t addr,
>> +                  unsigned int len, unsigned long val);
>> +};
>> +
>> +extern struct mmio_handler_ops vgic_io_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.
>> + * We multiply this by 8 the get the _bit_ offset, then divide this by
>> + * the number of bits to learn the actual INT ID.
>> + * But instead of a division (which requires a "long long div" implementation),
>> + * we shift by the binary logarithm of <bits>.
>> + * This assumes that <bits> is a power of two.
>> + */
>> +#define VGIC_ADDR_TO_INTID(addr, bits)  (((addr) & VGIC_ADDR_IRQ_MASK(bits)) * \
>> +                                         8 >> ilog2(bits))
>> +
>> +/*
>> + * 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,                                            \
>> +    }
>> +
>> +unsigned long vgic_mmio_read_raz(struct vcpu *vcpu,
>> +                                 paddr_t addr, unsigned int len);
>> +
>> +unsigned long vgic_mmio_read_rao(struct vcpu *vcpu,
>> +                                 paddr_t addr, unsigned int len);
>> +
>> +void vgic_mmio_write_wi(struct vcpu *vcpu, paddr_t addr,
>> +                        unsigned int len, unsigned long val);
>> +
>> +#endif
>> -- 
>> 2.14.1
>>

Patch

diff --git a/xen/arch/arm/vgic/vgic-mmio.c b/xen/arch/arm/vgic/vgic-mmio.c
new file mode 100644
index 0000000000..866023a84d
--- /dev/null
+++ b/xen/arch/arm/vgic/vgic-mmio.c
@@ -0,0 +1,180 @@ 
+/*
+ * VGIC MMIO handling functions
+ * Imported from Linux ("new" KVM VGIC) and heavily adapted to Xen.
+ *
+ * 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 <xen/bitops.h>
+#include <xen/lib.h>
+#include <xen/sched.h>
+#include <asm/new_vgic.h>
+#include <asm/byteorder.h>
+
+#include "vgic.h"
+#include "vgic-mmio.h"
+
+unsigned long vgic_mmio_read_raz(struct vcpu *vcpu,
+                                 paddr_t addr, unsigned int len)
+{
+    return 0;
+}
+
+unsigned long vgic_mmio_read_rao(struct vcpu *vcpu,
+                                 paddr_t addr, unsigned int len)
+{
+    return -1UL;
+}
+
+void vgic_mmio_write_wi(struct vcpu *vcpu, paddr_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;
+}
+
+static const struct vgic_register_region *
+vgic_find_mmio_region(const struct vgic_register_region *regions,
+                      int nr_regions, unsigned int offset)
+{
+    return bsearch((void *)(uintptr_t)offset, regions, nr_regions,
+                   sizeof(regions[0]), match_region);
+}
+
+static bool check_region(const struct domain *d,
+                         const struct vgic_register_region *region,
+                         paddr_t addr, int len)
+{
+    unsigned int flags, nr_irqs = d->arch.vgic.nr_spis + VGIC_NR_PRIVATE_IRQS;
+
+    switch ( len )
+    {
+    case sizeof(uint8_t):
+        flags = VGIC_ACCESS_8bit;
+        break;
+    case sizeof(uint32_t):
+        flags = VGIC_ACCESS_32bit;
+        break;
+    case sizeof(uint64_t):
+        flags = VGIC_ACCESS_64bit;
+        break;
+    default:
+        return false;
+    }
+
+    if ( (region->access_flags & flags) && IS_ALIGNED(addr, len) )
+    {
+        if ( !region->bits_per_irq )
+            return true;
+
+        /* Do we access a non-allocated IRQ? */
+        return VGIC_ADDR_TO_INTID(addr, region->bits_per_irq) < nr_irqs;
+    }
+
+    return false;
+}
+
+static const struct vgic_register_region *
+vgic_get_mmio_region(struct vcpu *vcpu, struct vgic_io_device *iodev,
+                     paddr_t addr, unsigned int len)
+{
+    const struct vgic_register_region *region;
+
+    region = vgic_find_mmio_region(iodev->regions, iodev->nr_regions,
+                                   addr - gfn_to_gaddr(iodev->base_fn));
+    if ( !region || !check_region(vcpu->domain, region, addr, len) )
+        return NULL;
+
+    return region;
+}
+
+static int dispatch_mmio_read(struct vcpu *vcpu, mmio_info_t *info,
+                              register_t *r, void *priv)
+{
+    struct vgic_io_device *iodev = priv;
+    const struct vgic_register_region *region;
+    unsigned long data = 0;
+    paddr_t addr = info->gpa;
+    int len = 1U << info->dabt.size;
+
+    region = vgic_get_mmio_region(vcpu, iodev, addr, len);
+    if ( !region )
+    {
+        memset(r, 0, len);
+        return 0;
+    }
+
+    switch (iodev->iodev_type)
+    {
+    case IODEV_DIST:
+        data = region->read(vcpu, addr, len);
+        break;
+    case IODEV_REDIST:
+        data = region->read(iodev->redist_vcpu, addr, len);
+        break;
+    }
+
+    memcpy(r, &data, len);
+
+    return 1;
+}
+
+static int dispatch_mmio_write(struct vcpu *vcpu, mmio_info_t *info,
+                               register_t r, void *priv)
+{
+    struct vgic_io_device *iodev = priv;
+    const struct vgic_register_region *region;
+    unsigned long data = r;
+    paddr_t addr = info->gpa;
+    int len = 1U << info->dabt.size;
+
+    region = vgic_get_mmio_region(vcpu, iodev, addr, len);
+    if ( !region )
+        return 0;
+
+    switch (iodev->iodev_type)
+    {
+    case IODEV_DIST:
+        region->write(vcpu, addr, len, data);
+        break;
+    case IODEV_REDIST:
+        region->write(iodev->redist_vcpu, addr, len, data);
+        break;
+    }
+
+    return 1;
+}
+
+struct mmio_handler_ops vgic_io_ops = {
+    .read = dispatch_mmio_read,
+    .write = dispatch_mmio_write,
+};
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/xen/arch/arm/vgic/vgic-mmio.h b/xen/arch/arm/vgic/vgic-mmio.h
new file mode 100644
index 0000000000..bf062a27ca
--- /dev/null
+++ b/xen/arch/arm/vgic/vgic-mmio.h
@@ -0,0 +1,89 @@ 
+/*
+ * 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 __XEN_ARM_VGIC_VGIC_MMIO_H__
+#define __XEN_ARM_VGIC_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 vcpu *vcpu, paddr_t addr,
+                          unsigned int len);
+    void (*write)(struct vcpu *vcpu, paddr_t addr,
+                  unsigned int len, unsigned long val);
+};
+
+extern struct mmio_handler_ops vgic_io_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.
+ * We multiply this by 8 the get the _bit_ offset, then divide this by
+ * the number of bits to learn the actual INT ID.
+ * But instead of a division (which requires a "long long div" implementation),
+ * we shift by the binary logarithm of <bits>.
+ * This assumes that <bits> is a power of two.
+ */
+#define VGIC_ADDR_TO_INTID(addr, bits)  (((addr) & VGIC_ADDR_IRQ_MASK(bits)) * \
+                                         8 >> ilog2(bits))
+
+/*
+ * 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,                                            \
+    }
+
+unsigned long vgic_mmio_read_raz(struct vcpu *vcpu,
+                                 paddr_t addr, unsigned int len);
+
+unsigned long vgic_mmio_read_rao(struct vcpu *vcpu,
+                                 paddr_t addr, unsigned int len);
+
+void vgic_mmio_write_wi(struct vcpu *vcpu, paddr_t addr,
+                        unsigned int len, unsigned long val);
+
+#endif