KVM: arm64/sve: Make register ioctl access errors more consistent
Currently, the way error codes are generated when processing the SVE register access ioctls in a bit haphazard. This patch refactors the code so that the behaviour is more consistent: now, -EINVAL should be returned only for unrecognised register IDs or when some other runtime error occurs. -ENOENT is returned for register IDs that are recognised, but whose corresponding register (or slice) does not exist for the vcpu. To this end, in {get,set}_sve_reg() we now delegate the vcpu_has_sve() check down into {get,set}_sve_vls() and sve_reg_to_region(). The KVM_REG_ARM64_SVE_VLS special case is picked off first, then sve_reg_to_region() plays the role of exhaustively validating or rejecting the register ID and (where accepted) computing the applicable register region as before. sve_reg_to_region() is rearranged so that -ENOENT or -EPERM is not returned prematurely, before checking whether reg->id is in a recognised range. -EPERM is now only returned when an attempt is made to access an actually existing register slice on an unfinalized vcpu. Fixes:e1c9c98345
("KVM: arm64/sve: Add SVE support to register access ioctl interface") Fixes:9033bba4b5
("KVM: arm64/sve: Add pseudo-register for the guest's vector lengths") Suggested-by: Andrew Jones <drjones@redhat.com> Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Andrew Jones <drjones@redhat.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
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@ -221,6 +221,9 @@ static int get_sve_vls(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
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unsigned int max_vq, vq;
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u64 vqs[DIV_ROUND_UP(SVE_VQ_MAX - SVE_VQ_MIN + 1, 64)];
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if (!vcpu_has_sve(vcpu))
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return -ENOENT;
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if (WARN_ON(!sve_vl_valid(vcpu->arch.sve_max_vl)))
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return -EINVAL;
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@ -242,6 +245,9 @@ static int set_sve_vls(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
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unsigned int max_vq, vq;
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u64 vqs[DIV_ROUND_UP(SVE_VQ_MAX - SVE_VQ_MIN + 1, 64)];
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if (!vcpu_has_sve(vcpu))
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return -ENOENT;
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if (kvm_arm_vcpu_sve_finalized(vcpu))
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return -EPERM; /* too late! */
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@ -304,7 +310,10 @@ struct sve_state_reg_region {
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unsigned int upad; /* extra trailing padding in user memory */
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};
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/* Get sanitised bounds for user/kernel SVE register copy */
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/*
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* Validate SVE register ID and get sanitised bounds for user/kernel SVE
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* register copy
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*/
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static int sve_reg_to_region(struct sve_state_reg_region *region,
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struct kvm_vcpu *vcpu,
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const struct kvm_one_reg *reg)
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@ -335,25 +344,30 @@ static int sve_reg_to_region(struct sve_state_reg_region *region,
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/* Verify that we match the UAPI header: */
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BUILD_BUG_ON(SVE_NUM_SLICES != KVM_ARM64_SVE_MAX_SLICES);
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if ((reg->id & SVE_REG_SLICE_MASK) > 0)
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return -ENOENT;
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vq = sve_vq_from_vl(vcpu->arch.sve_max_vl);
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reg_num = (reg->id & SVE_REG_ID_MASK) >> SVE_REG_ID_SHIFT;
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if (reg->id >= zreg_id_min && reg->id <= zreg_id_max) {
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if (!vcpu_has_sve(vcpu) || (reg->id & SVE_REG_SLICE_MASK) > 0)
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return -ENOENT;
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vq = sve_vq_from_vl(vcpu->arch.sve_max_vl);
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reqoffset = SVE_SIG_ZREG_OFFSET(vq, reg_num) -
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SVE_SIG_REGS_OFFSET;
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reqlen = KVM_SVE_ZREG_SIZE;
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maxlen = SVE_SIG_ZREG_SIZE(vq);
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} else if (reg->id >= preg_id_min && reg->id <= preg_id_max) {
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if (!vcpu_has_sve(vcpu) || (reg->id & SVE_REG_SLICE_MASK) > 0)
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return -ENOENT;
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vq = sve_vq_from_vl(vcpu->arch.sve_max_vl);
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reqoffset = SVE_SIG_PREG_OFFSET(vq, reg_num) -
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SVE_SIG_REGS_OFFSET;
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reqlen = KVM_SVE_PREG_SIZE;
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maxlen = SVE_SIG_PREG_SIZE(vq);
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} else {
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return -ENOENT;
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return -EINVAL;
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}
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sve_state_size = vcpu_sve_state_size(vcpu);
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@ -369,24 +383,22 @@ static int sve_reg_to_region(struct sve_state_reg_region *region,
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static int get_sve_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
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{
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int ret;
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struct sve_state_reg_region region;
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char __user *uptr = (char __user *)reg->addr;
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if (!vcpu_has_sve(vcpu))
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return -ENOENT;
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/* Handle the KVM_REG_ARM64_SVE_VLS pseudo-reg as a special case: */
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if (reg->id == KVM_REG_ARM64_SVE_VLS)
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return get_sve_vls(vcpu, reg);
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/* Otherwise, reg is an architectural SVE register... */
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/* Try to interpret reg ID as an architectural SVE register... */
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ret = sve_reg_to_region(®ion, vcpu, reg);
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if (ret)
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return ret;
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if (!kvm_arm_vcpu_sve_finalized(vcpu))
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return -EPERM;
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if (sve_reg_to_region(®ion, vcpu, reg))
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return -ENOENT;
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if (copy_to_user(uptr, vcpu->arch.sve_state + region.koffset,
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region.klen) ||
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clear_user(uptr + region.klen, region.upad))
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@ -397,24 +409,22 @@ static int get_sve_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
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static int set_sve_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
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{
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int ret;
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struct sve_state_reg_region region;
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const char __user *uptr = (const char __user *)reg->addr;
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if (!vcpu_has_sve(vcpu))
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return -ENOENT;
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/* Handle the KVM_REG_ARM64_SVE_VLS pseudo-reg as a special case: */
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if (reg->id == KVM_REG_ARM64_SVE_VLS)
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return set_sve_vls(vcpu, reg);
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/* Otherwise, reg is an architectural SVE register... */
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/* Try to interpret reg ID as an architectural SVE register... */
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ret = sve_reg_to_region(®ion, vcpu, reg);
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if (ret)
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return ret;
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if (!kvm_arm_vcpu_sve_finalized(vcpu))
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return -EPERM;
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if (sve_reg_to_region(®ion, vcpu, reg))
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return -ENOENT;
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if (copy_from_user(vcpu->arch.sve_state + region.koffset, uptr,
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region.klen))
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return -EFAULT;
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