Re: [PATCH v6 08/24] KVM: arm64: vgic-its: Implement vgic_mmio_uaccess_write_its_creadr

Christoffer Dall
2017-05-04T17:09:42Z

On Thu, May 04, 2017 at 01:44:28PM +0200, Eric Auger wrote:
> GITS_CREADR needs to be restored so let's implement the associated
> uaccess_write_its callback. The write only is allowed if the its
> is disabled.
>
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
>
> ---
> v5 -> v6:
> - remove usage of update_64bit_reg and check alignment of cmd offset
>
> v4 -> v5:
> - keep Stalled bit
> - vgic_mmio_uaccess_write_its_creadr can now return an error
>
> v3 -> v4:
> - REGISTER_ITS_DESC_UACCESS now introduced in this patch
> - we now check the its is disabled
> ---
> virt/kvm/arm/vgic/vgic-its.c | 43 +++++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 41 insertions(+), 2 deletions(-)
>
> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
> index 222fad5..18588ef 100644
> --- a/virt/kvm/arm/vgic/vgic-its.c
> +++ b/virt/kvm/arm/vgic/vgic-its.c
> @@ -1213,6 +1213,34 @@ static unsigned long vgic_mmio_read_its_creadr(struct kvm *kvm,
> return extract_bytes(its->creadr, addr & 0x7, len);
> }
>
> +static int vgic_mmio_uaccess_write_its_creadr(struct kvm *kvm,
> + struct vgic_its *its,
> + gpa_t addr, unsigned int len,
> + unsigned long val)
> +{
> + u32 cmd_offset;
> + int ret = 0;
> +
> + mutex_lock(&its->cmd_lock);
> +
> + if (its->enabled) {
> + ret = -EBUSY;
> + goto out;
> + }
> +
> + cmd_offset = ITS_CMD_OFFSET(val);
> + if ((cmd_offset >= ITS_CMD_BUFFER_SIZE(its->cbaser)) ||
> + (cmd_offset & 0x1F)) {
> + ret = -EINVAL;
> + goto out;
> + }
> +
> + its->creadr = val;

do we let userspace decide the stalled bit or should we use
ITS_CMD_OFFSET() when assigning the field as well?

> +out:
> + mutex_unlock(&its->cmd_lock);
> + return ret;
> +}
> +
> #define BASER_INDEX(addr) (((addr) / sizeof(u64)) & 0x7)
> static unsigned long vgic_mmio_read_its_baser(struct kvm *kvm,
> struct vgic_its *its,
> @@ -1317,6 +1345,16 @@ static void vgic_mmio_write_its_ctlr(struct kvm *kvm, struct vgic_its *its,
> .its_write = wr, \
> }
>
> +#define REGISTER_ITS_DESC_UACCESS(off, rd, wr, uwr, length, acc)\
> +{ \
> + .reg_offset = off, \
> + .len = length, \
> + .access_flags = acc, \
> + .its_read = rd, \
> + .its_write = wr, \
> + .uaccess_its_write = uwr, \
> +}
> +
> static void its_mmio_write_wi(struct kvm *kvm, struct vgic_its *its,
> gpa_t addr, unsigned int len, unsigned long val)
> {
> @@ -1339,8 +1377,9 @@ static struct vgic_register_region its_registers[] = {
> REGISTER_ITS_DESC(GITS_CWRITER,
> vgic_mmio_read_its_cwriter, vgic_mmio_write_its_cwriter, 8,
> VGIC_ACCESS_64bit | VGIC_ACCESS_32bit),
> - REGISTER_ITS_DESC(GITS_CREADR,
> - vgic_mmio_read_its_creadr, its_mmio_write_wi, 8,
> + REGISTER_ITS_DESC_UACCESS(GITS_CREADR,
> + vgic_mmio_read_its_creadr, its_mmio_write_wi,
> + vgic_mmio_uaccess_write_its_creadr, 8,
> VGIC_ACCESS_64bit | VGIC_ACCESS_32bit),
> REGISTER_ITS_DESC(GITS_BASER,
> vgic_mmio_read_its_baser, vgic_mmio_write_its_baser, 0x40,
> --
> 2.5.5
>

Otherwise:

Reviewed-by: Christoffer Dall <cdall@linaro.org>