On 27/09/2019 13:53, Greg Kurz wrote:
> Reduce code duplication by consolidating the checking of vCPU ids and VP
> ids to a common helper used by both legacy and native XIVE KVM devices.
> And explain the magic with a comment.
>
> Signed-off-by: Greg Kurz <groug@xxxxxxxx>
Looks fine. One question below,
> ---
> arch/powerpc/kvm/book3s_xive.c | 42 ++++++++++++++++++++++++++-------
> arch/powerpc/kvm/book3s_xive.h | 1 +
> arch/powerpc/kvm/book3s_xive_native.c | 11 ++-------
> 3 files changed, 36 insertions(+), 18 deletions(-)
>
> diff --git a/arch/powerpc/kvm/book3s_xive.c b/arch/powerpc/kvm/book3s_xive.c
> index 0b7859e40f66..d84da9f6ee88 100644
> --- a/arch/powerpc/kvm/book3s_xive.c
> +++ b/arch/powerpc/kvm/book3s_xive.c
> @@ -1211,6 +1211,37 @@ void kvmppc_xive_cleanup_vcpu(struct kvm_vcpu *vcpu)
> vcpu->arch.xive_vcpu = NULL;
> }
>
> +static bool kvmppc_xive_vcpu_id_valid(struct kvmppc_xive *xive, u32 cpu)
> +{
> + /* We have a block of KVM_MAX_VCPUS VPs. We just need to check
> + * raw vCPU ids are below the expected limit for this guest's
> + * core stride ; kvmppc_pack_vcpu_id() will pack them down to an
> + * index that can be safely used to compute a VP id that belongs
> + * to the VP block.
> + */
> + return cpu < KVM_MAX_VCPUS * xive->kvm->arch.emul_smt_mode;
> +}
> +
> +int kvmppc_xive_compute_vp_id(struct kvmppc_xive *xive, u32 cpu, u32 *vp)
> +{
> + u32 vp_id;
> +
> + if (!kvmppc_xive_vcpu_id_valid(xive, cpu)) {
> + pr_devel("Out of bounds !\n");
> + return -EINVAL;
> + }
> +
> + vp_id = kvmppc_xive_vp(xive, cpu);
> + if (kvmppc_xive_vp_in_use(xive->kvm, vp_id)) {
> + pr_devel("Duplicate !\n");
> + return -EEXIST;
> + }
> +
> + *vp = vp_id;
> +
> + return 0;
why not return vp_id ? and test for a negative value in callers.
C.
> +}
> +
> int kvmppc_xive_connect_vcpu(struct kvm_device *dev,
> struct kvm_vcpu *vcpu, u32 cpu)
> {
> @@ -1229,20 +1260,13 @@ int kvmppc_xive_connect_vcpu(struct kvm_device *dev,
> return -EPERM;
> if (vcpu->arch.irq_type != KVMPPC_IRQ_DEFAULT)
> return -EBUSY;
> - if (cpu >= (KVM_MAX_VCPUS * vcpu->kvm->arch.emul_smt_mode)) {
> - pr_devel("Out of bounds !\n");
> - return -EINVAL;
> - }
>
> /* We need to synchronize with queue provisioning */
> mutex_lock(&xive->lock);
>
> - vp_id = kvmppc_xive_vp(xive, cpu);
> - if (kvmppc_xive_vp_in_use(xive->kvm, vp_id)) {
> - pr_devel("Duplicate !\n");
> - r = -EEXIST;
> + r = kvmppc_xive_compute_vp_id(xive, cpu, &vp_id);
> + if (r)
> goto bail;
> - }
>
> xc = kzalloc(sizeof(*xc), GFP_KERNEL);
> if (!xc) {
> diff --git a/arch/powerpc/kvm/book3s_xive.h b/arch/powerpc/kvm/book3s_xive.h
> index fe3ed50e0818..90cf6ec35a68 100644
> --- a/arch/powerpc/kvm/book3s_xive.h
> +++ b/arch/powerpc/kvm/book3s_xive.h
> @@ -296,6 +296,7 @@ int kvmppc_xive_attach_escalation(struct kvm_vcpu *vcpu, u8 prio,
> struct kvmppc_xive *kvmppc_xive_get_device(struct kvm *kvm, u32 type);
> void xive_cleanup_single_escalation(struct kvm_vcpu *vcpu,
> struct kvmppc_xive_vcpu *xc, int irq);
> +int kvmppc_xive_compute_vp_id(struct kvmppc_xive *xive, u32 cpu, u32 *vp);
>
> #endif /* CONFIG_KVM_XICS */
> #endif /* _KVM_PPC_BOOK3S_XICS_H */
> diff --git a/arch/powerpc/kvm/book3s_xive_native.c b/arch/powerpc/kvm/book3s_xive_native.c
> index 43a86858390a..5bb480b2aafd 100644
> --- a/arch/powerpc/kvm/book3s_xive_native.c
> +++ b/arch/powerpc/kvm/book3s_xive_native.c
> @@ -118,19 +118,12 @@ int kvmppc_xive_native_connect_vcpu(struct kvm_device *dev,
> return -EPERM;
> if (vcpu->arch.irq_type != KVMPPC_IRQ_DEFAULT)
> return -EBUSY;
> - if (server_num >= (KVM_MAX_VCPUS * vcpu->kvm->arch.emul_smt_mode)) {
> - pr_devel("Out of bounds !\n");
> - return -EINVAL;
> - }
>
> mutex_lock(&xive->lock);
>
> - vp_id = kvmppc_xive_vp(xive, server_num);
> - if (kvmppc_xive_vp_in_use(xive->kvm, vp_id)) {
> - pr_devel("Duplicate !\n");
> - rc = -EEXIST;
> + rc = kvmppc_xive_compute_vp_id(xive, server_num, &vp_id);
> + if (rc)
> goto bail;
> - }
>
> xc = kzalloc(sizeof(*xc), GFP_KERNEL);
> if (!xc) {
>
