From 52110aa95948deba724739fc9933070c3e2c7239 Mon Sep 17 00:00:00 2001 From: Dave Martin Date: Thu, 11 Apr 2019 16:13:39 +0100 Subject: [PATCH] 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: e1c9c98345b3 ("KVM: arm64/sve: Add SVE support to register access ioctl interface") Fixes: 9033bba4b535 ("KVM: arm64/sve: Add pseudo-register for the guest's vector lengths") Suggested-by: Andrew Jones Signed-off-by: Dave Martin Reviewed-by: Andrew Jones Signed-off-by: Marc Zyngier --- arch/arm64/kvm/guest.c | 52 +++++++++++++++++++++++++----------------- 1 file changed, 31 insertions(+), 21 deletions(-) diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c index f5ff7aea25aa..e45a042c0628 100644 --- a/arch/arm64/kvm/guest.c +++ b/arch/arm64/kvm/guest.c @@ -221,6 +221,9 @@ static int get_sve_vls(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg) unsigned int max_vq, vq; u64 vqs[DIV_ROUND_UP(SVE_VQ_MAX - SVE_VQ_MIN + 1, 64)]; + if (!vcpu_has_sve(vcpu)) + return -ENOENT; + if (WARN_ON(!sve_vl_valid(vcpu->arch.sve_max_vl))) return -EINVAL; @@ -242,6 +245,9 @@ static int set_sve_vls(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg) unsigned int max_vq, vq; u64 vqs[DIV_ROUND_UP(SVE_VQ_MAX - SVE_VQ_MIN + 1, 64)]; + if (!vcpu_has_sve(vcpu)) + return -ENOENT; + if (kvm_arm_vcpu_sve_finalized(vcpu)) return -EPERM; /* too late! */ @@ -304,7 +310,10 @@ struct sve_state_reg_region { unsigned int upad; /* extra trailing padding in user memory */ }; -/* Get sanitised bounds for user/kernel SVE register copy */ +/* + * Validate SVE register ID and get sanitised bounds for user/kernel SVE + * register copy + */ static int sve_reg_to_region(struct sve_state_reg_region *region, struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg) @@ -335,25 +344,30 @@ static int sve_reg_to_region(struct sve_state_reg_region *region, /* Verify that we match the UAPI header: */ BUILD_BUG_ON(SVE_NUM_SLICES != KVM_ARM64_SVE_MAX_SLICES); - if ((reg->id & SVE_REG_SLICE_MASK) > 0) - return -ENOENT; - - vq = sve_vq_from_vl(vcpu->arch.sve_max_vl); - reg_num = (reg->id & SVE_REG_ID_MASK) >> SVE_REG_ID_SHIFT; if (reg->id >= zreg_id_min && reg->id <= zreg_id_max) { + if (!vcpu_has_sve(vcpu) || (reg->id & SVE_REG_SLICE_MASK) > 0) + return -ENOENT; + + vq = sve_vq_from_vl(vcpu->arch.sve_max_vl); + reqoffset = SVE_SIG_ZREG_OFFSET(vq, reg_num) - SVE_SIG_REGS_OFFSET; reqlen = KVM_SVE_ZREG_SIZE; maxlen = SVE_SIG_ZREG_SIZE(vq); } else if (reg->id >= preg_id_min && reg->id <= preg_id_max) { + if (!vcpu_has_sve(vcpu) || (reg->id & SVE_REG_SLICE_MASK) > 0) + return -ENOENT; + + vq = sve_vq_from_vl(vcpu->arch.sve_max_vl); + reqoffset = SVE_SIG_PREG_OFFSET(vq, reg_num) - SVE_SIG_REGS_OFFSET; reqlen = KVM_SVE_PREG_SIZE; maxlen = SVE_SIG_PREG_SIZE(vq); } else { - return -ENOENT; + return -EINVAL; } sve_state_size = vcpu_sve_state_size(vcpu); @@ -369,24 +383,22 @@ static int sve_reg_to_region(struct sve_state_reg_region *region, static int get_sve_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg) { + int ret; struct sve_state_reg_region region; char __user *uptr = (char __user *)reg->addr; - if (!vcpu_has_sve(vcpu)) - return -ENOENT; - /* Handle the KVM_REG_ARM64_SVE_VLS pseudo-reg as a special case: */ if (reg->id == KVM_REG_ARM64_SVE_VLS) return get_sve_vls(vcpu, reg); - /* Otherwise, reg is an architectural SVE register... */ + /* Try to interpret reg ID as an architectural SVE register... */ + ret = sve_reg_to_region(®ion, vcpu, reg); + if (ret) + return ret; if (!kvm_arm_vcpu_sve_finalized(vcpu)) return -EPERM; - if (sve_reg_to_region(®ion, vcpu, reg)) - return -ENOENT; - if (copy_to_user(uptr, vcpu->arch.sve_state + region.koffset, region.klen) || clear_user(uptr + region.klen, region.upad)) @@ -397,24 +409,22 @@ static int get_sve_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg) static int set_sve_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg) { + int ret; struct sve_state_reg_region region; const char __user *uptr = (const char __user *)reg->addr; - if (!vcpu_has_sve(vcpu)) - return -ENOENT; - /* Handle the KVM_REG_ARM64_SVE_VLS pseudo-reg as a special case: */ if (reg->id == KVM_REG_ARM64_SVE_VLS) return set_sve_vls(vcpu, reg); - /* Otherwise, reg is an architectural SVE register... */ + /* Try to interpret reg ID as an architectural SVE register... */ + ret = sve_reg_to_region(®ion, vcpu, reg); + if (ret) + return ret; if (!kvm_arm_vcpu_sve_finalized(vcpu)) return -EPERM; - if (sve_reg_to_region(®ion, vcpu, reg)) - return -ENOENT; - if (copy_from_user(vcpu->arch.sve_state + region.koffset, uptr, region.klen)) return -EFAULT; -- 2.30.2