On 18/02/2019 19:52, Dave Martin wrote:
> In order to avoid the pointless complexity of maintaining two ioctl
> register access views of the same data, this patch blocks ioctl
> access to the FPSIMD V-registers on vcpus that support SVE.
>
> This will make it more straightforward to add SVE register access
> support.
>
> Since SVE is an opt-in feature for userspace, this will not affect
> existing users.
>
> Signed-off-by: Dave Martin <Dave.Martin at arm.com>
Reviewed-by: Julien Thierry <julien.thierry at arm.com>
> ---
> arch/arm64/kvm/guest.c | 38 +++++++++++++++++++++++++++-----------
> 1 file changed, 27 insertions(+), 11 deletions(-)
>
> diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
> index f83fe22..f491456 100644
> --- a/arch/arm64/kvm/guest.c
> +++ b/arch/arm64/kvm/guest.c
> @@ -95,7 +95,14 @@ static int core_reg_size_from_offset(u64 off)
> return -EINVAL;
> }
>
> -static int validate_core_offset(const struct kvm_one_reg *reg)
> +static bool core_reg_offset_is_vreg(u64 off)
> +{
> + return off >= KVM_REG_ARM_CORE_REG(fp_regs.vregs) &&
> + off < KVM_REG_ARM_CORE_REG(fp_regs.fpsr);
> +}
> +
> +static int validate_core_offset(const struct kvm_vcpu *vcpu,
> + const struct kvm_one_reg *reg)
> {
> u64 off = core_reg_offset_from_id(reg->id);
> int size = core_reg_size_from_offset(off);
> @@ -103,10 +110,18 @@ static int validate_core_offset(const struct kvm_one_reg *reg)
> if (size < 0)
> return -EINVAL;
>
> - if (KVM_REG_SIZE(reg->id) == size)
> - return 0;
> + if (KVM_REG_SIZE(reg->id) != size)
> + return -EINVAL;
>
> - return -EINVAL;
> + /*
> + * The KVM_REG_ARM64_SVE regs must be used instead of
> + * KVM_REG_ARM_CORE for accessing the FPSIMD V-registers on
> + * SVE-enabled vcpus:
> + */
> + if (vcpu_has_sve(vcpu) && core_reg_offset_is_vreg(off))
> + return -EINVAL;
> +
> + return 0;
> }
>
> static int get_core_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
> @@ -128,7 +143,7 @@ static int get_core_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
> (off + (KVM_REG_SIZE(reg->id) / sizeof(__u32))) >= nr_regs)
> return -ENOENT;
>
> - if (validate_core_offset(reg))
> + if (validate_core_offset(vcpu, reg))
> return -EINVAL;
>
> if (copy_to_user(uaddr, ((u32 *)regs) + off, KVM_REG_SIZE(reg->id)))
> @@ -153,7 +168,7 @@ static int set_core_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
> (off + (KVM_REG_SIZE(reg->id) / sizeof(__u32))) >= nr_regs)
> return -ENOENT;
>
> - if (validate_core_offset(reg))
> + if (validate_core_offset(vcpu, reg))
> return -EINVAL;
>
> if (KVM_REG_SIZE(reg->id) > sizeof(tmp))
> @@ -206,7 +221,8 @@ int kvm_arch_vcpu_ioctl_set_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs)
> return -EINVAL;
> }
>
> -static int copy_core_reg_indices(u64 __user **uind)
> +static int copy_core_reg_indices(const struct kvm_vcpu *vcpu,
> + u64 __user **uind)
> {
> unsigned int i;
> int n = 0;
> @@ -248,9 +264,9 @@ static int copy_core_reg_indices(u64 __user **uind)
> return n;
> }
>
> -static unsigned long num_core_regs(void)
> +static unsigned long num_core_regs(const struct kvm_vcpu *vcpu)
> {
> - return copy_core_reg_indices(NULL);
> + return copy_core_reg_indices(vcpu, NULL);
> }
>
> /**
> @@ -315,7 +331,7 @@ unsigned long kvm_arm_num_regs(struct kvm_vcpu *vcpu)
> {
> unsigned long res = 0;
>
> - res += num_core_regs();
> + res += num_core_regs(vcpu);
> res += kvm_arm_num_sys_reg_descs(vcpu);
> res += kvm_arm_get_fw_num_regs(vcpu);
> res += NUM_TIMER_REGS;
> @@ -332,7 +348,7 @@ int kvm_arm_copy_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices)
> {
> int ret;
>
> - ret = copy_core_reg_indices(&uindices);
> + ret = copy_core_reg_indices(vcpu, &uindices);
> if (ret < 0)
> return ret;
>
>
--
Julien Thierry
