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/*
* Copyright 2021 Google LLC
* SPDX-License-Identifier: MIT
*/
#ifndef VKR_RING_H
#define VKR_RING_H
#include "vkr_common.h"
/* We read from the ring buffer to a temporary buffer for
* virgl_context::submit_cmd. Until that is changed, we want to put a limit
* on the size of the temporary buffer. It also makes no sense to have huge
* rings.
*
* This must not exceed UINT32_MAX because the ring head and tail are 32-bit.
*/
#define VKR_RING_BUFFER_MAX_SIZE (16u * 1024 * 1024)
/* The layout of a ring in a virgl_resource. This is parsed and discarded by
* vkr_ring_create.
*/
struct vkr_ring_layout {
struct virgl_resource *resource;
struct vkr_region head;
struct vkr_region tail;
struct vkr_region status;
struct vkr_region buffer;
struct vkr_region extra;
};
static_assert(ATOMIC_INT_LOCK_FREE == 2 && sizeof(atomic_uint) == 4,
"vkr_ring_control requires lock-free 32-bit atomic_uint");
/* the control region of a ring */
struct vkr_ring_control {
/* Pointers to ring head, tail, and status.
*
* Clients increment the tail after commands are added. We increment the
* head after commands are executed. The status is updated when there is a
* status change to the ring thread.
*/
volatile atomic_uint *head;
const volatile atomic_uint *tail;
volatile atomic_uint *status;
};
/* the buffer region of a ring */
struct vkr_ring_buffer {
/* the base of the region in the resource */
int base_iov_index;
size_t base_iov_offset;
uint32_t size;
uint32_t mask;
/* The current offset in the buffer region. It is free-running and must be
* masked to be between [0, size).
*/
uint32_t cur;
/* The current iov and iov offset in the resource. */
const struct iovec *cur_iov;
int cur_iov_index;
size_t cur_iov_offset;
};
/* the extra region of a ring */
struct vkr_ring_extra {
/* the base of the region in the resource */
int base_iov_index;
size_t base_iov_offset;
/* used for offset validation */
struct vkr_region region;
/* cache the latest offset->pointer result */
size_t cached_offset;
volatile atomic_uint *cached_data;
};
struct vkr_ring {
/* used by the caller */
vkr_object_id id;
struct list_head head;
/* ring regions */
struct virgl_resource *resource;
struct vkr_ring_control control;
struct vkr_ring_buffer buffer;
struct vkr_ring_extra extra;
/* ring thread */
struct virgl_context *context;
uint64_t idle_timeout;
void *cmd;
mtx_t mutex;
cnd_t cond;
thrd_t thread;
atomic_bool started;
atomic_bool pending_notify;
};
struct vkr_ring *
vkr_ring_create(const struct vkr_ring_layout *layout,
struct virgl_context *ctx,
uint64_t idle_timeout);
void
vkr_ring_destroy(struct vkr_ring *ring);
void
vkr_ring_start(struct vkr_ring *ring);
bool
vkr_ring_stop(struct vkr_ring *ring);
void
vkr_ring_notify(struct vkr_ring *ring);
bool
vkr_ring_write_extra(struct vkr_ring *ring, size_t offset, uint32_t val);
#endif /* VKR_RING_H */
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