Re: [PATCH v9 22/27] virt: gunyah: Add resource tickets

Srivatsa Vaddagiri
2023-02-06T09:50:55Z

* Elliot Berman <quic_eberman@quicinc.com> [2023-01-20 14:46:21]:

> +int ghvm_add_resource_ticket(struct gunyah_vm *ghvm, struct gunyah_vm_resource_ticket *ticket)
> +{
> + struct gunyah_vm_resource_ticket *iter;
> + struct gunyah_resource *ghrsc;
> + int ret = 0;
> +
> + mutex_lock(&ghvm->resources_lock);
> + list_for_each_entry(iter, &ghvm->resource_tickets, list) {
> + if (iter->resource_type == ticket->resource_type && iter->label == ticket->label) {
> + ret = -EEXIST;
> + goto out;
> + }
> + }
> +
> + if (!try_module_get(ticket->owner)) {
> + ret = -ENODEV;
> + goto out;
> + }
> +
> + list_add(&ticket->list, &ghvm->resource_tickets);
> + INIT_LIST_HEAD(&ticket->resources);
> +
> + list_for_each_entry(ghrsc, &ghvm->resources, list) {
> + if (ghrsc->type == ticket->resource_type && ghrsc->rm_label == ticket->label) {
> + if (!ticket->populate(ticket, ghrsc))
> + list_move(&ghrsc->list, &ticket->resources);

Do we need the search to continue in case of a hit? 'gh_vm_add_resource' seems to
break loop on first occurrence.

Also do we have examples of more than one 'gunyah_resource' being associated
with same 'gunyah_vm_resource_ticket'? Both vcpu and irqfd tickets seem to deal
with just one resource?

> static int gh_vm_start(struct gunyah_vm *ghvm)
> {
> struct gunyah_vm_memory_mapping *mapping;
> u64 dtb_offset;
> u32 mem_handle;
> - int ret;
> + struct gunyah_resource *ghrsc;
> + struct gh_rm_hyp_resources *resources;
> + int ret, i;
>
> down_write(&ghvm->status_lock);
> if (ghvm->vm_status != GH_RM_VM_STATUS_NO_STATE) {
> @@ -241,6 +314,22 @@ static int gh_vm_start(struct gunyah_vm *ghvm)
> goto err;
> }
>
> + ret = gh_rm_get_hyp_resources(ghvm->rm, ghvm->vmid, &resources);
> + if (ret) {
> + pr_warn("Failed to get hypervisor resources for VM: %d\n", ret);
> + goto err;
> + }
> +
> + for (i = 0; i < le32_to_cpu(resources->n_entries); i++) {

minor nit: not sure if we can rely on compiler to optimize this, but it would
be better if we run le32_to_cpu once and use the result in loop.

> + ghrsc = gh_rm_alloc_resource(ghvm->rm, &resources->entries[i]);
> + if (!ghrsc) {
> + ret = -ENOMEM;
> + goto err;
> + }
> +
> + gh_vm_add_resource(ghvm, ghrsc);

Shouldn't we have gh_vm_add_resource()-> ticket->populate() return a result and
in case of failure we should bail out from this loop?

> + }
> +
> ret = gh_rm_vm_start(ghvm->rm, ghvm->vmid);
> if (ret) {
> pr_warn("Failed to start VM: %d\n", ret);