[PATCH v11 20/26] virt: gunyah: Add resource tickets
Alex Elder
elder at linaro.org
Fri Mar 31 07:27:01 PDT 2023
On 3/3/23 7:06 PM, Elliot Berman wrote:
> Some VM functions need to acquire Gunyah resources. For instance, Gunyah
> vCPUs are exposed to the host as a resource. The Gunyah vCPU function
> will register a resource ticket and be able to interact with the
> hypervisor once the resource ticket is filled.
>
> Resource tickets are the mechanism for functions to acquire ownership of
> Gunyah resources. Gunyah functions can be created before the VM's
> resources are created and made available to Linux. A resource ticket
> identifies a type of resource and a label of a resource which the ticket
> holder is interested in.
>
> Resources are created by Gunyah as configured in the VM's devicetree
> configuration. Gunyah doesn't process the label and that makes it
> possible for userspace to create multiple resources with the same label.
> Resource ticket owners need to be prepared for populate to be called
> multiple times if userspace created multiple resources with the same
> label.
>
> Signed-off-by: Elliot Berman <quic_eberman at quicinc.com>
One possibly substantive suggestion here, plus a couple suggestions
to add or revise comments.
-Alex
> ---
> drivers/virt/gunyah/vm_mgr.c | 112 +++++++++++++++++++++++++++++++++-
> drivers/virt/gunyah/vm_mgr.h | 4 ++
> include/linux/gunyah_vm_mgr.h | 14 +++++
> 3 files changed, 129 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/virt/gunyah/vm_mgr.c b/drivers/virt/gunyah/vm_mgr.c
> index 88db011395ec..0269bcdaf692 100644
> --- a/drivers/virt/gunyah/vm_mgr.c
> +++ b/drivers/virt/gunyah/vm_mgr.c
> @@ -165,6 +165,74 @@ static long gh_vm_rm_function(struct gh_vm *ghvm, struct gh_fn_desc *f)
> return r;
> }
>
> +int gh_vm_add_resource_ticket(struct gh_vm *ghvm, struct gh_vm_resource_ticket *ticket)
> +{
> + struct gh_vm_resource_ticket *iter;
> + struct gh_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);
> + }
> + }
> +out:
> + mutex_unlock(&ghvm->resources_lock);
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(gh_vm_add_resource_ticket);
> +
> +void gh_vm_remove_resource_ticket(struct gh_vm *ghvm, struct gh_vm_resource_ticket *ticket)
> +{
> + struct gh_resource *ghrsc, *iter;
> +
> + mutex_lock(&ghvm->resources_lock);
> + list_for_each_entry_safe(ghrsc, iter, &ticket->resources, list) {
> + ticket->unpopulate(ticket, ghrsc);
> + list_move(&ghrsc->list, &ghvm->resources);
> + }
> +
> + module_put(ticket->owner);
> + list_del(&ticket->list);
> + mutex_unlock(&ghvm->resources_lock);
> +}
> +EXPORT_SYMBOL_GPL(gh_vm_remove_resource_ticket);
> +
> +static void gh_vm_add_resource(struct gh_vm *ghvm, struct gh_resource *ghrsc)
> +{
> + struct gh_vm_resource_ticket *ticket;
> +
> + mutex_lock(&ghvm->resources_lock);
> + list_for_each_entry(ticket, &ghvm->resource_tickets, list) {
> + if (ghrsc->type == ticket->resource_type && ghrsc->rm_label == ticket->label) {
> + if (!ticket->populate(ticket, ghrsc)) {
> + list_add(&ghrsc->list, &ticket->resources);
> + goto found;
> + }
I think the "goto found" belongs here, unconditionally.
You disallow adding more than one ticket of a given type
with the same label. So you will never match another
ticket once you've matched this one.
The populate function generally shouldn't fail. I think
it only fails if you find a duplicate, and again, I think
you prevent that from happening. (But if it does, you
silently ignore it...)
> + }
> + }
> + list_add(&ghrsc->list, &ghvm->resources);
> +found:
> + mutex_unlock(&ghvm->resources_lock);
> +}
> +
> static int gh_vm_rm_notification_status(struct gh_vm *ghvm, void *data)
> {
> struct gh_rm_vm_status_payload *payload = data;
> @@ -230,6 +298,8 @@ static void gh_vm_free(struct work_struct *work)
> {
> struct gh_vm *ghvm = container_of(work, struct gh_vm, free_work);
> struct gh_vm_function_instance *inst, *iiter;
> + struct gh_vm_resource_ticket *ticket, *titer;
> + struct gh_resource *ghrsc, *riter;
> struct gh_vm_mem *mapping, *tmp;
> int ret;
>
> @@ -246,6 +316,25 @@ static void gh_vm_free(struct work_struct *work)
> }
> mutex_unlock(&ghvm->fn_lock);
>
> + mutex_lock(&ghvm->resources_lock);
> + if (!list_empty(&ghvm->resource_tickets)) {
> + dev_warn(ghvm->parent, "Dangling resource tickets:\n");
> + list_for_each_entry_safe(ticket, titer, &ghvm->resource_tickets, list) {
> + dev_warn(ghvm->parent, " %pS\n", ticket->populate);
> + gh_vm_remove_resource_ticket(ghvm, ticket);
> + }
> + }
> +
> + list_for_each_entry_safe(ghrsc, riter, &ghvm->resources, list) {
> + gh_rm_free_resource(ghrsc);
> + }
> + mutex_unlock(&ghvm->resources_lock);
> +
> + ret = gh_rm_vm_reset(ghvm->rm, ghvm->vmid);
> + if (ret)
> + dev_err(ghvm->parent, "Failed to reset the vm: %d\n", ret);
> + wait_event(ghvm->vm_status_wait, ghvm->vm_status == GH_RM_VM_STATUS_RESET);
> +
> mutex_lock(&ghvm->mm_lock);
> list_for_each_entry_safe(mapping, tmp, &ghvm->memory_mappings, list) {
> gh_vm_mem_reclaim(ghvm, mapping);
> @@ -329,6 +418,9 @@ static __must_check struct gh_vm *gh_vm_alloc(struct gh_rm *rm)
> init_rwsem(&ghvm->status_lock);
> INIT_WORK(&ghvm->free_work, gh_vm_free);
> kref_init(&ghvm->kref);
> + mutex_init(&ghvm->resources_lock);
> + INIT_LIST_HEAD(&ghvm->resources);
> + INIT_LIST_HEAD(&ghvm->resource_tickets);
> INIT_LIST_HEAD(&ghvm->functions);
> ghvm->vm_status = GH_RM_VM_STATUS_LOAD;
>
> @@ -338,9 +430,11 @@ static __must_check struct gh_vm *gh_vm_alloc(struct gh_rm *rm)
> static int gh_vm_start(struct gh_vm *ghvm)
> {
> struct gh_vm_mem *mapping;
> + struct gh_rm_hyp_resources *resources;
> + struct gh_resource *ghrsc;
> u64 dtb_offset;
> u32 mem_handle;
> - int ret;
> + int ret, i, n;
>
> down_write(&ghvm->status_lock);
> if (ghvm->vm_status != GH_RM_VM_STATUS_LOAD) {
> @@ -394,6 +488,22 @@ static int gh_vm_start(struct gh_vm *ghvm)
> goto err;
> }
>
> + ret = gh_rm_get_hyp_resources(ghvm->rm, ghvm->vmid, &resources);
> + if (ret) {
> + dev_warn(ghvm->parent, "Failed to get hypervisor resources for VM: %d\n", ret);
> + goto err;
> + }
> +
> + for (i = 0, n = le32_to_cpu(resources->n_entries); i < n; i++) {
> + ghrsc = gh_rm_alloc_resource(ghvm->rm, &resources->entries[i]);
> + if (!ghrsc) {
> + ret = -ENOMEM;
> + goto err;
> + }
> +
> + gh_vm_add_resource(ghvm, ghrsc);
> + }
> +
> ret = gh_rm_vm_start(ghvm->rm, ghvm->vmid);
> if (ret) {
> dev_warn(ghvm->parent, "Failed to start VM: %d\n", ret);
> diff --git a/drivers/virt/gunyah/vm_mgr.h b/drivers/virt/gunyah/vm_mgr.h
> index 7bd271bad721..18d0e1effd25 100644
> --- a/drivers/virt/gunyah/vm_mgr.h
> +++ b/drivers/virt/gunyah/vm_mgr.h
> @@ -7,6 +7,7 @@
> #define _GH_PRIV_VM_MGR_H
>
> #include <linux/gunyah_rsc_mgr.h>
> +#include <linux/gunyah_vm_mgr.h>
> #include <linux/list.h>
> #include <linux/kref.h>
> #include <linux/miscdevice.h>
> @@ -51,6 +52,9 @@ struct gh_vm {
> struct list_head memory_mappings;
> struct mutex fn_lock;
> struct list_head functions;
> + struct mutex resources_lock;
> + struct list_head resources;
> + struct list_head resource_tickets;
> };
>
> int gh_vm_mem_alloc(struct gh_vm *ghvm, struct gh_userspace_memory_region *region);
> diff --git a/include/linux/gunyah_vm_mgr.h b/include/linux/gunyah_vm_mgr.h
> index 3825c951790a..01b1761b5923 100644
> --- a/include/linux/gunyah_vm_mgr.h
> +++ b/include/linux/gunyah_vm_mgr.h
> @@ -70,4 +70,18 @@ void gh_vm_function_unregister(struct gh_vm_function *f);
> DECLARE_GH_VM_FUNCTION(_name, _type, _bind, _unbind); \
> module_gh_vm_function(_name)
>
> +struct gh_vm_resource_ticket {
> + struct list_head list; /* for gh_vm's resources list */
Maybe "resource lists" above (it's for the resources list and
resource_tickets list).
> + struct list_head resources; /* for gh_resources's list */
Maybe: /* resources associated with this ticket */
> + enum gh_resource_type resource_type;
> + u32 label;
> +
> + struct module *owner;
> + int (*populate)(struct gh_vm_resource_ticket *ticket, struct gh_resource *ghrsc);
> + void (*unpopulate)(struct gh_vm_resource_ticket *ticket, struct gh_resource *ghrsc);
> +};
> +
> +int gh_vm_add_resource_ticket(struct gh_vm *ghvm, struct gh_vm_resource_ticket *ticket);
> +void gh_vm_remove_resource_ticket(struct gh_vm *ghvm, struct gh_vm_resource_ticket *ticket);
> +
> #endif
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