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 <drjones@xxxxxxxxxx>
Signed-off-by: Dave Martin <Dave.Martin@xxxxxxx>
Reviewed-by: Andrew Jones <drjones@xxxxxxxxxx>
---
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 f5ff7ae..e45a042 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;
--
2.1.4
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