Re: [PATCH v4 09/10] RISC-V: KVM: Improve vector save/restore errors

Andrew Jones
2023-08-03T17:16:25Z

On Thu, Aug 03, 2023 at 08:05:47PM +0300, Andrew Jones wrote:
> On Thu, Aug 03, 2023 at 01:33:01PM -0300, Daniel Henrique Barboza wrote:
> > From: Andrew Jones <ajones@ventanamicro.com>
> >
> > kvm_riscv_vcpu_(get/set)_reg_vector() now returns ENOENT if V is not
> > available, EINVAL if reg type is not of VECTOR type, and any error that
> > might be thrown by kvm_riscv_vcpu_vreg_addr().
> >
> > Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
> > ---
> > arch/riscv/kvm/vcpu_vector.c | 60 ++++++++++++++++++++----------------
> > 1 file changed, 33 insertions(+), 27 deletions(-)
> >
> > diff --git a/arch/riscv/kvm/vcpu_vector.c b/arch/riscv/kvm/vcpu_vector.c
> > index edd2eecbddc2..39c5bceb4d1b 100644
> > --- a/arch/riscv/kvm/vcpu_vector.c
> > +++ b/arch/riscv/kvm/vcpu_vector.c
> > @@ -91,44 +91,44 @@ void kvm_riscv_vcpu_free_vector_context(struct kvm_vcpu *vcpu)
> > }
> > #endif
> >
> > -static void *kvm_riscv_vcpu_vreg_addr(struct kvm_vcpu *vcpu,
> > +static int kvm_riscv_vcpu_vreg_addr(struct kvm_vcpu *vcpu,
> > unsigned long reg_num,
> > - size_t reg_size)
> > + size_t reg_size,
> > + void **reg_val)
> > {
> > struct kvm_cpu_context *cntx = &vcpu->arch.guest_context;
> > - void *reg_val;
> > size_t vlenb = riscv_v_vsize / 32;
> >
> > if (reg_num < KVM_REG_RISCV_VECTOR_REG(0)) {
> > if (reg_size != sizeof(unsigned long))
> > - return NULL;
> > + return -EINVAL;
> > switch (reg_num) {
> > case KVM_REG_RISCV_VECTOR_CSR_REG(vstart):
> > - reg_val = &cntx->vector.vstart;
> > + *reg_val = &cntx->vector.vstart;
> > break;
> > case KVM_REG_RISCV_VECTOR_CSR_REG(vl):
> > - reg_val = &cntx->vector.vl;
> > + *reg_val = &cntx->vector.vl;
> > break;
> > case KVM_REG_RISCV_VECTOR_CSR_REG(vtype):
> > - reg_val = &cntx->vector.vtype;
> > + *reg_val = &cntx->vector.vtype;
> > break;
> > case KVM_REG_RISCV_VECTOR_CSR_REG(vcsr):
> > - reg_val = &cntx->vector.vcsr;
> > + *reg_val = &cntx->vector.vcsr;
> > break;
> > case KVM_REG_RISCV_VECTOR_CSR_REG(datap):
> > default:
> > - return NULL;
> > + return -ENOENT;
> > }
> > } else if (reg_num <= KVM_REG_RISCV_VECTOR_REG(31)) {
> > if (reg_size != vlenb)
> > - return NULL;
> > - reg_val = cntx->vector.datap
> > + return -EINVAL;
> > + *reg_val = cntx->vector.datap
> > + (reg_num - KVM_REG_RISCV_VECTOR_REG(0)) * vlenb;
> > } else {
> > - return NULL;
> > + return -ENOENT;
> > }
> >
> > - return reg_val;
> > + return 0;
> > }
> >
> > int kvm_riscv_vcpu_get_reg_vector(struct kvm_vcpu *vcpu,
> > @@ -141,17 +141,20 @@ int kvm_riscv_vcpu_get_reg_vector(struct kvm_vcpu *vcpu,
> > unsigned long reg_num = reg->id & ~(KVM_REG_ARCH_MASK |
> > KVM_REG_SIZE_MASK |
> > rtype);
> > - void *reg_val = NULL;
> > size_t reg_size = KVM_REG_SIZE(reg->id);
> > + void *reg_val;
> > + int rc;
> >
> > - if (rtype == KVM_REG_RISCV_VECTOR &&
> > - riscv_isa_extension_available(isa, v)) {
> > - reg_val = kvm_riscv_vcpu_vreg_addr(vcpu, reg_num, reg_size);
> > - }
> > -
> > - if (!reg_val)
> > + if (rtype != KVM_REG_RISCV_VECTOR)
> > return -EINVAL;
> >
> > + if (!riscv_isa_extension_available(isa, v))
> > + return -ENOENT;
> > +
> > + rc = kvm_riscv_vcpu_vreg_addr(vcpu, reg_num, reg_size, &reg_val);
> > + if (rc)
> > + return rc;
> > +
> > if (copy_to_user(uaddr, reg_val, reg_size))
> > return -EFAULT;
> >
> > @@ -168,17 +171,20 @@ int kvm_riscv_vcpu_set_reg_vector(struct kvm_vcpu *vcpu,
> > unsigned long reg_num = reg->id & ~(KVM_REG_ARCH_MASK |
> > KVM_REG_SIZE_MASK |
> > rtype);
> > - void *reg_val = NULL;
> > size_t reg_size = KVM_REG_SIZE(reg->id);
> > + void *reg_val;
> > + int rc;
> >
> > - if (rtype == KVM_REG_RISCV_VECTOR &&
> > - riscv_isa_extension_available(isa, v)) {
> > - reg_val = kvm_riscv_vcpu_vreg_addr(vcpu, reg_num, reg_size);
> > - }
> > -
> > - if (!reg_val)
> > + if (rtype != KVM_REG_RISCV_VECTOR)
> > return -EINVAL;
> >
> > + if (!riscv_isa_extension_available(isa, v))
> > + return -ENOENT;
> > +
> > + rc = kvm_riscv_vcpu_vreg_addr(vcpu, reg_num, reg_size, &reg_val);
> > + if (rc)
> > + return rc;
> > +
> > if (copy_from_user(reg_val, uaddr, reg_size))
> > return -EFAULT;
>
> Ugh, this is totally wrong. We no longer set the register. I need to
> rework this rework...

Oh, never mind. Skimming over (my own patch) I forgot we were fetching the
address not the value. I should have renamed 'reg_val' to 'reg_addr'.
There's another change that can be made, which is to drop rtype and its
check from these functions and just use KVM_REG_RISCV_VECTOR directly in
the mask. I'll send a cleanup patch with that and the rename, but that's
separate from this series.

Thanks,
drew