On Fri, Apr 14, 2017 at 12:15:19PM +0200, Eric Auger wrote:
> This patch implements vgic_its_has_attr_regs and vgic_its_attr_regs_access
> upon the MMIO framework. VGIC ITS KVM device KVM_DEV_ARM_VGIC_GRP_ITS_REGS
> group becomes functional.
>
> At least GITS_CREADR and GITS_IIDR require to differentiate a guest write
> action from a user access. As such let's introduce a new uaccess_its_write
> vgic_register_region callback.
>
> Signed-off-by: Eric Auger <eric.auger@xxxxxxxxxx>
>
> ---
> v4 -> v5:
> - use GITS_TYPER instead of offset 0x8
> - uaccess_its_write now can return an error
>
> v3 -> v4:
> - remove changes to the REGISTER_ITS_DESC macro. This will be handled in
> subsequent patch with the introduction of a new REGISTER_ITS_DESC_UACCESS
> macro
> - fix IIDR access and add a comment wrt full length access
> - handle endianness
> - add kvm lock and vcpus lock
> ---
> virt/kvm/arm/vgic/vgic-its.c | 79 +++++++++++++++++++++++++++++++++++++++++--
> virt/kvm/arm/vgic/vgic-mmio.h | 9 +++--
> 2 files changed, 84 insertions(+), 4 deletions(-)
>
> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
> index f687e91..a9a2c12 100644
> --- a/virt/kvm/arm/vgic/vgic-its.c
> +++ b/virt/kvm/arm/vgic/vgic-its.c
> @@ -1469,14 +1469,89 @@ static void vgic_its_destroy(struct kvm_device *kvm_dev)
> int vgic_its_has_attr_regs(struct kvm_device *dev,
> struct kvm_device_attr *attr)
> {
> - return -ENXIO;
> + const struct vgic_register_region *region;
> + struct vgic_io_device iodev = {
> + .regions = its_registers,
> + .nr_regions = ARRAY_SIZE(its_registers),
> + };
> + gpa_t offset = attr->attr;
> +
> + region = vgic_find_mmio_region(iodev.regions,
> + iodev.nr_regions,
> + offset);
why do you need to define the iodev here? Can't you just pass
its_registers and ARRAY_SIZE(its_registers) directly?
> + if (!region)
> + return -ENXIO;
> +
> + return 0;
> }
>
> int vgic_its_attr_regs_access(struct kvm_device *dev,
> struct kvm_device_attr *attr,
> u64 *reg, bool is_write)
> {
> - return -ENXIO;
> + const struct vgic_register_region *region;
> + struct vgic_io_device iodev = {
> + .regions = its_registers,
> + .nr_regions = ARRAY_SIZE(its_registers),
> + };
> + struct vgic_its *its = dev->private;
> + gpa_t addr, offset = attr->attr;
> + unsigned int len;
> + unsigned long data = 0;
> + int ret = 0;
nit: you could structure this whole declaration block more nicely by
having a separate line for the declaration and initialization of offset,
and by moving the iodev declaration/initialization to the end.
It might also be cleaner to do any non-zero initialization in a separate
block following the declarations.
> +
> + /*
> + * Among supported registers, only GITS_CTLR (0x0) and GITS_IIDR (0x4)
> + * are 32 bits. Others are 64 bits.
> + */
> + if ((offset < GITS_TYPER && offset & 0x3) ||
> + (offset >= GITS_TYPER && offset & 0x7))
> + return -EINVAL;
> +
> + mutex_lock(&dev->kvm->lock);
> +
> + if (IS_VGIC_ADDR_UNDEF(its->vgic_its_base)) {
> + ret = -ENXIO;
> + goto out;
> + }
> +
> + region = vgic_find_mmio_region(iodev.regions,
> + iodev.nr_regions,
> + offset);
> + if (!region) {
> + ret = -ENXIO;
> + goto out;
> + }
> +
> + if (!lock_all_vcpus(dev->kvm)) {
> + ret = -EBUSY;
> + goto out;
> + }
> +
> + addr = its->vgic_its_base + offset;
> +
> + /*
> + * Only full length register accesses are supported although
> + * the architecture spec theoretically allows upper/lower 32
does the spec allow 32-bit accesses, or only theoretically ? :)
> + * bits to be accessed independently
> + */
In any case, the comment is a bit confusing, because it seems to imply
that we only support 64-bit accesses, but we do set the length below to
4 or 8.
Did you mean:
/*
* Althought the spec supports upper/lower 32-bit accesses to
* 64-bit ITS registers, the userspace ABI requires 64-bit
* accesses to all 64-bit wide registers. We therefore only 32-bit
* accesses to the GITS_CTLR, GITS_IIDR registers.
*/
Also, I don't understand how this works with the ID registers? For
example, if userspace wants to read GITS_PIDR1 does it have to read
GITS_PIDR0 as a 64-bit register and split it afterwards? (that doesn't
work with this implementation)
> + len = region->access_flags & VGIC_ACCESS_64bit ? 8 : 4;
> +
> + if (is_write) {
> + data = vgic_data_mmio_bus_to_host(reg, len);
I don't think we need this anymore; we no longer share the guest
trapping MMIO path with uaccesses.
> + if (region->uaccess_its_write)
> + ret = region->uaccess_its_write(dev->kvm, its, addr,
> + len, data);
> + else
> + region->its_write(dev->kvm, its, addr, len, data);
> + } else {
> + data = region->its_read(dev->kvm, its, addr, len);
> + vgic_data_host_to_mmio_bus(reg, len, data);
same here.
> + }
> + unlock_all_vcpus(dev->kvm);
> +out:
> + mutex_unlock(&dev->kvm->lock);
> + return ret;
> }
>
> static int vgic_its_has_attr(struct kvm_device *dev,
> diff --git a/virt/kvm/arm/vgic/vgic-mmio.h b/virt/kvm/arm/vgic/vgic-mmio.h
> index 6eec91b..ea4171a 100644
> --- a/virt/kvm/arm/vgic/vgic-mmio.h
> +++ b/virt/kvm/arm/vgic/vgic-mmio.h
> @@ -36,8 +36,13 @@ struct vgic_register_region {
> };
> unsigned long (*uaccess_read)(struct kvm_vcpu *vcpu, gpa_t addr,
> unsigned int len);
> - void (*uaccess_write)(struct kvm_vcpu *vcpu, gpa_t addr,
> - unsigned int len, unsigned long val);
> + union {
> + void (*uaccess_write)(struct kvm_vcpu *vcpu, gpa_t addr,
> + unsigned int len, unsigned long val);
> + int (*uaccess_its_write)(struct kvm *kvm, struct vgic_its *its,
> + gpa_t addr, unsigned int len,
> + unsigned long val);
> + };
> };
>
> extern struct kvm_io_device_ops kvm_io_gic_ops;
> --
> 2.5.5
>
Thanks,
-Christoffer
