kernel/include/linux/virtio_config.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_VIRTIO_CONFIG_H
#define _LINUX_VIRTIO_CONFIG_H

#include <linux/err.h>
#include <linux/bug.h>
#include <linux/virtio.h>
#include <linux/virtio_byteorder.h>
#include <linux/compiler_types.h>
#include <uapi/linux/virtio_config.h>

struct irq_affinity;

struct virtio_shm_region {
	u64 addr;
	u64 len;
};

typedef void vq_callback_t(struct virtqueue *);

/**
 * struct virtqueue_info - Info for a virtqueue passed to find_vqs().
 * @name: virtqueue description. Used mainly for debugging, NULL for
 *        a virtqueue unused by the driver.
 * @callback: A callback to invoke on a used buffer notification.
 *            NULL for a virtqueue that does not need a callback.
 * @ctx: A flag to indicate to maintain an extra context per virtqueue.
 */
struct virtqueue_info {
	const char *name;
	vq_callback_t *callback;
	bool ctx;
};

/**
 * struct virtio_config_ops - operations for configuring a virtio device
 * Note: Do not assume that a transport implements all of the operations
 *       getting/setting a value as a simple read/write! Generally speaking,
 *       any of @get/@set, @get_status/@set_status, or @get_features/
 *       @finalize_features are NOT safe to be called from an atomic
 *       context.
 * @get: read the value of a configuration field
 *	vdev: the virtio_device
 *	offset: the offset of the configuration field
 *	buf: the buffer to write the field value into.
 *	len: the length of the buffer
 * @set: write the value of a configuration field
 *	vdev: the virtio_device
 *	offset: the offset of the configuration field
 *	buf: the buffer to read the field value from.
 *	len: the length of the buffer
 * @generation: config generation counter (optional)
 *	vdev: the virtio_device
 *	Returns the config generation counter
 * @get_status: read the status byte
 *	vdev: the virtio_device
 *	Returns the status byte
 * @set_status: write the status byte
 *	vdev: the virtio_device
 *	status: the new status byte
 * @reset: reset the device
 *	vdev: the virtio device
 *	After this, status and feature negotiation must be done again
 *	Device must not be reset from its vq/config callbacks, or in
 *	parallel with being added/removed.
 * @find_vqs: find virtqueues and instantiate them.
 *	vdev: the virtio_device
 *	nvqs: the number of virtqueues to find
 *	vqs: on success, includes new virtqueues
 *	vqs_info: array of virtqueue info structures
 *	Returns 0 on success or error status
 * @del_vqs: free virtqueues found by find_vqs().
 * @synchronize_cbs: synchronize with the virtqueue callbacks (optional)
 *      The function guarantees that all memory operations on the
 *      queue before it are visible to the vring_interrupt() that is
 *      called after it.
 *      vdev: the virtio_device
 * @get_features: get the array of feature bits for this device.
 *	vdev: the virtio_device
 *	Returns the first 64 feature bits (all we currently need).
 * @finalize_features: confirm what device features we'll be using.
 *	vdev: the virtio_device
 *	This sends the driver feature bits to the device: it can change
 *	the dev->feature bits if it wants.
 *	Note that despite the name this	can be called any number of
 *	times.
 *	Returns 0 on success or error status
 * @bus_name: return the bus name associated with the device (optional)
 *	vdev: the virtio_device
 *      This returns a pointer to the bus name a la pci_name from which
 *      the caller can then copy.
 * @set_vq_affinity: set the affinity for a virtqueue (optional).
 * @get_vq_affinity: get the affinity for a virtqueue (optional).
 * @get_shm_region: get a shared memory region based on the index.
 * @disable_vq_and_reset: reset a queue individually (optional).
 *	vq: the virtqueue
 *	Returns 0 on success or error status
 *	disable_vq_and_reset will guarantee that the callbacks are disabled and
 *	synchronized.
 *	Except for the callback, the caller should guarantee that the vring is
 *	not accessed by any functions of virtqueue.
 * @enable_vq_after_reset: enable a reset queue
 *	vq: the virtqueue
 *	Returns 0 on success or error status
 *	If disable_vq_and_reset is set, then enable_vq_after_reset must also be
 *	set.
 */
struct virtio_config_ops {
	void (*get)(struct virtio_device *vdev, unsigned offset,
		    void *buf, unsigned len);
	void (*set)(struct virtio_device *vdev, unsigned offset,
		    const void *buf, unsigned len);
	u32 (*generation)(struct virtio_device *vdev);
	u8 (*get_status)(struct virtio_device *vdev);
	void (*set_status)(struct virtio_device *vdev, u8 status);
	void (*reset)(struct virtio_device *vdev);
	int (*find_vqs)(struct virtio_device *vdev, unsigned int nvqs,
			struct virtqueue *vqs[],
			struct virtqueue_info vqs_info[],
			struct irq_affinity *desc);
	void (*del_vqs)(struct virtio_device *);
	void (*synchronize_cbs)(struct virtio_device *);
	u64 (*get_features)(struct virtio_device *vdev);
	int (*finalize_features)(struct virtio_device *vdev);
	const char *(*bus_name)(struct virtio_device *vdev);
	int (*set_vq_affinity)(struct virtqueue *vq,
			       const struct cpumask *cpu_mask);
	const struct cpumask *(*get_vq_affinity)(struct virtio_device *vdev,
						 int index);
	bool (*get_shm_region)(struct virtio_device *vdev,
			       struct virtio_shm_region *region, u8 id);
	int (*disable_vq_and_reset)(struct virtqueue *vq);
	int (*enable_vq_after_reset)(struct virtqueue *vq);
};

/* If driver didn't advertise the feature, it will never appear. */
void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
					 unsigned int fbit);

/**
 * __virtio_test_bit - helper to test feature bits. For use by transports.
 *                     Devices should normally use virtio_has_feature,
 *                     which includes more checks.
 * @vdev: the device
 * @fbit: the feature bit
 */
static inline bool __virtio_test_bit(const struct virtio_device *vdev,
				     unsigned int fbit)
{
	/* Did you forget to fix assumptions on max features? */
	if (__builtin_constant_p(fbit))
		BUILD_BUG_ON(fbit >= 64);
	else
		BUG_ON(fbit >= 64);

	return vdev->features & BIT_ULL(fbit);
}

/**
 * __virtio_set_bit - helper to set feature bits. For use by transports.
 * @vdev: the device
 * @fbit: the feature bit
 */
static inline void __virtio_set_bit(struct virtio_device *vdev,
				    unsigned int fbit)
{
	/* Did you forget to fix assumptions on max features? */
	if (__builtin_constant_p(fbit))
		BUILD_BUG_ON(fbit >= 64);
	else
		BUG_ON(fbit >= 64);

	vdev->features |= BIT_ULL(fbit);
}

/**
 * __virtio_clear_bit - helper to clear feature bits. For use by transports.
 * @vdev: the device
 * @fbit: the feature bit
 */
static inline void __virtio_clear_bit(struct virtio_device *vdev,
				      unsigned int fbit)
{
	/* Did you forget to fix assumptions on max features? */
	if (__builtin_constant_p(fbit))
		BUILD_BUG_ON(fbit >= 64);
	else
		BUG_ON(fbit >= 64);

	vdev->features &= ~BIT_ULL(fbit);
}

/**
 * virtio_has_feature - helper to determine if this device has this feature.
 * @vdev: the device
 * @fbit: the feature bit
 */
static inline bool virtio_has_feature(const struct virtio_device *vdev,
				      unsigned int fbit)
{
	if (fbit < VIRTIO_TRANSPORT_F_START)
		virtio_check_driver_offered_feature(vdev, fbit);

	return __virtio_test_bit(vdev, fbit);
}

/**
 * virtio_has_dma_quirk - determine whether this device has the DMA quirk
 * @vdev: the device
 */
static inline bool virtio_has_dma_quirk(const struct virtio_device *vdev)
{
	/*
	 * Note the reverse polarity of the quirk feature (compared to most
	 * other features), this is for compatibility with legacy systems.
	 */
	return !virtio_has_feature(vdev, VIRTIO_F_ACCESS_PLATFORM);
}

static inline
int virtio_find_vqs(struct virtio_device *vdev, unsigned int nvqs,
		    struct virtqueue *vqs[],
		    struct virtqueue_info vqs_info[],
		    struct irq_affinity *desc)
{
	return vdev->config->find_vqs(vdev, nvqs, vqs, vqs_info, desc);
}

static inline
struct virtqueue *virtio_find_single_vq(struct virtio_device *vdev,
					vq_callback_t *c, const char *n)
{
	struct virtqueue_info vqs_info[] = {
		{ n, c },
	};
	struct virtqueue *vq;
	int err = virtio_find_vqs(vdev, 1, &vq, vqs_info, NULL);

	if (err < 0)
		return ERR_PTR(err);
	return vq;
}

/**
 * virtio_synchronize_cbs - synchronize with virtqueue callbacks
 * @dev: the virtio device
 */
static inline
void virtio_synchronize_cbs(struct virtio_device *dev)
{
	if (dev->config->synchronize_cbs) {
		dev->config->synchronize_cbs(dev);
	} else {
		/*
		 * A best effort fallback to synchronize with
		 * interrupts, preemption and softirq disabled
		 * regions. See comment above synchronize_rcu().
		 */
		synchronize_rcu();
	}
}

/**
 * virtio_device_ready - enable vq use in probe function
 * @dev: the virtio device
 *
 * Driver must call this to use vqs in the probe function.
 *
 * Note: vqs are enabled automatically after probe returns.
 */
static inline
void virtio_device_ready(struct virtio_device *dev)
{
	unsigned status = dev->config->get_status(dev);

	WARN_ON(status & VIRTIO_CONFIG_S_DRIVER_OK);

#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION
	/*
	 * The virtio_synchronize_cbs() makes sure vring_interrupt()
	 * will see the driver specific setup if it sees vq->broken
	 * as false (even if the notifications come before DRIVER_OK).
	 */
	virtio_synchronize_cbs(dev);
	__virtio_unbreak_device(dev);
#endif
	/*
	 * The transport should ensure the visibility of vq->broken
	 * before setting DRIVER_OK. See the comments for the transport
	 * specific set_status() method.
	 *
	 * A well behaved device will only notify a virtqueue after
	 * DRIVER_OK, this means the device should "see" the coherenct
	 * memory write that set vq->broken as false which is done by
	 * the driver when it sees DRIVER_OK, then the following
	 * driver's vring_interrupt() will see vq->broken as false so
	 * we won't lose any notification.
	 */
	dev->config->set_status(dev, status | VIRTIO_CONFIG_S_DRIVER_OK);
}

static inline
const char *virtio_bus_name(struct virtio_device *vdev)
{
	if (!vdev->config->bus_name)
		return "virtio";
	return vdev->config->bus_name(vdev);
}

/**
 * virtqueue_set_affinity - setting affinity for a virtqueue
 * @vq: the virtqueue
 * @cpu_mask: the cpu mask
 *
 * Pay attention the function are best-effort: the affinity hint may not be set
 * due to config support, irq type and sharing.
 *
 */
static inline
int virtqueue_set_affinity(struct virtqueue *vq, const struct cpumask *cpu_mask)
{
	struct virtio_device *vdev = vq->vdev;
	if (vdev->config->set_vq_affinity)
		return vdev->config->set_vq_affinity(vq, cpu_mask);
	return 0;
}

static inline
bool virtio_get_shm_region(struct virtio_device *vdev,
			   struct virtio_shm_region *region, u8 id)
{
	if (!vdev->config->get_shm_region)
		return false;
	return vdev->config->get_shm_region(vdev, region, id);
}

static inline bool virtio_is_little_endian(struct virtio_device *vdev)
{
	return virtio_has_feature(vdev, VIRTIO_F_VERSION_1) ||
		virtio_legacy_is_little_endian();
}

/* Memory accessors */
static inline u16 virtio16_to_cpu(struct virtio_device *vdev, __virtio16 val)
{
	return __virtio16_to_cpu(virtio_is_little_endian(vdev), val);
}

static inline __virtio16 cpu_to_virtio16(struct virtio_device *vdev, u16 val)
{
	return __cpu_to_virtio16(virtio_is_little_endian(vdev), val);
}

static inline u32 virtio32_to_cpu(struct virtio_device *vdev, __virtio32 val)
{
	return __virtio32_to_cpu(virtio_is_little_endian(vdev), val);
}

static inline __virtio32 cpu_to_virtio32(struct virtio_device *vdev, u32 val)
{
	return __cpu_to_virtio32(virtio_is_little_endian(vdev), val);
}

static inline u64 virtio64_to_cpu(struct virtio_device *vdev, __virtio64 val)
{
	return __virtio64_to_cpu(virtio_is_little_endian(vdev), val);
}

static inline __virtio64 cpu_to_virtio64(struct virtio_device *vdev, u64 val)
{
	return __cpu_to_virtio64(virtio_is_little_endian(vdev), val);
}

#define virtio_to_cpu(vdev, x) \
	_Generic((x), \
		__u8: (x), \
		__virtio16: virtio16_to_cpu((vdev), (x)), \
		__virtio32: virtio32_to_cpu((vdev), (x)), \
		__virtio64: virtio64_to_cpu((vdev), (x)) \
		)

#define cpu_to_virtio(vdev, x, m) \
	_Generic((m), \
		__u8: (x), \
		__virtio16: cpu_to_virtio16((vdev), (x)), \
		__virtio32: cpu_to_virtio32((vdev), (x)), \
		__virtio64: cpu_to_virtio64((vdev), (x)) \
		)

#define __virtio_native_type(structname, member) \
	typeof(virtio_to_cpu(NULL, ((structname*)0)->member))

/* Config space accessors. */
#define virtio_cread(vdev, structname, member, ptr)			\
	do {								\
		typeof(((structname*)0)->member) virtio_cread_v;	\
									\
		might_sleep();						\
		/* Sanity check: must match the member's type */	\
		typecheck(typeof(virtio_to_cpu((vdev), virtio_cread_v)), *(ptr)); \
									\
		switch (sizeof(virtio_cread_v)) {			\
		case 1:							\
		case 2:							\
		case 4:							\
			vdev->config->get((vdev), 			\
					  offsetof(structname, member), \
					  &virtio_cread_v,		\
					  sizeof(virtio_cread_v));	\
			break;						\
		default:						\
			__virtio_cread_many((vdev), 			\
					  offsetof(structname, member), \
					  &virtio_cread_v,		\
					  1,				\
					  sizeof(virtio_cread_v));	\
			break;						\
		}							\
		*(ptr) = virtio_to_cpu(vdev, virtio_cread_v);		\
	} while(0)

/* Config space accessors. */
#define virtio_cwrite(vdev, structname, member, ptr)			\
	do {								\
		typeof(((structname*)0)->member) virtio_cwrite_v =	\
			cpu_to_virtio(vdev, *(ptr), ((structname*)0)->member); \
									\
		might_sleep();						\
		/* Sanity check: must match the member's type */	\
		typecheck(typeof(virtio_to_cpu((vdev), virtio_cwrite_v)), *(ptr)); \
									\
		vdev->config->set((vdev), offsetof(structname, member),	\
				  &virtio_cwrite_v,			\
				  sizeof(virtio_cwrite_v));		\
	} while(0)

/*
 * Nothing virtio-specific about these, but let's worry about generalizing
 * these later.
 */
#define virtio_le_to_cpu(x) \
	_Generic((x), \
		__u8: (u8)(x), \
		 __le16: (u16)le16_to_cpu(x), \
		 __le32: (u32)le32_to_cpu(x), \
		 __le64: (u64)le64_to_cpu(x) \
		)

#define virtio_cpu_to_le(x, m) \
	_Generic((m), \
		 __u8: (x), \
		 __le16: cpu_to_le16(x), \
		 __le32: cpu_to_le32(x), \
		 __le64: cpu_to_le64(x) \
		)

/* LE (e.g. modern) Config space accessors. */
#define virtio_cread_le(vdev, structname, member, ptr)			\
	do {								\
		typeof(((structname*)0)->member) virtio_cread_v;	\
									\
		might_sleep();						\
		/* Sanity check: must match the member's type */	\
		typecheck(typeof(virtio_le_to_cpu(virtio_cread_v)), *(ptr)); \
									\
		switch (sizeof(virtio_cread_v)) {			\
		case 1:							\
		case 2:							\
		case 4:							\
			vdev->config->get((vdev), 			\
					  offsetof(structname, member), \
					  &virtio_cread_v,		\
					  sizeof(virtio_cread_v));	\
			break;						\
		default:						\
			__virtio_cread_many((vdev), 			\
					  offsetof(structname, member), \
					  &virtio_cread_v,		\
					  1,				\
					  sizeof(virtio_cread_v));	\
			break;						\
		}							\
		*(ptr) = virtio_le_to_cpu(virtio_cread_v);		\
	} while(0)

#define virtio_cwrite_le(vdev, structname, member, ptr)			\
	do {								\
		typeof(((structname*)0)->member) virtio_cwrite_v =	\
			virtio_cpu_to_le(*(ptr), ((structname*)0)->member); \
									\
		might_sleep();						\
		/* Sanity check: must match the member's type */	\
		typecheck(typeof(virtio_le_to_cpu(virtio_cwrite_v)), *(ptr)); \
									\
		vdev->config->set((vdev), offsetof(structname, member),	\
				  &virtio_cwrite_v,			\
				  sizeof(virtio_cwrite_v));		\
	} while(0)


/* Read @count fields, @bytes each. */
static inline void __virtio_cread_many(struct virtio_device *vdev,
				       unsigned int offset,
				       void *buf, size_t count, size_t bytes)
{
	u32 old, gen = vdev->config->generation ?
		vdev->config->generation(vdev) : 0;
	int i;

	might_sleep();
	do {
		old = gen;

		for (i = 0; i < count; i++)
			vdev->config->get(vdev, offset + bytes * i,
					  buf + i * bytes, bytes);

		gen = vdev->config->generation ?
			vdev->config->generation(vdev) : 0;
	} while (gen != old);
}

static inline void virtio_cread_bytes(struct virtio_device *vdev,
				      unsigned int offset,
				      void *buf, size_t len)
{
	__virtio_cread_many(vdev, offset, buf, len, 1);
}

static inline u8 virtio_cread8(struct virtio_device *vdev, unsigned int offset)
{
	u8 ret;

	might_sleep();
	vdev->config->get(vdev, offset, &ret, sizeof(ret));
	return ret;
}

static inline void virtio_cwrite8(struct virtio_device *vdev,
				  unsigned int offset, u8 val)
{
	might_sleep();
	vdev->config->set(vdev, offset, &val, sizeof(val));
}

static inline u16 virtio_cread16(struct virtio_device *vdev,
				 unsigned int offset)
{
	__virtio16 ret;

	might_sleep();
	vdev->config->get(vdev, offset, &ret, sizeof(ret));
	return virtio16_to_cpu(vdev, ret);
}

static inline void virtio_cwrite16(struct virtio_device *vdev,
				   unsigned int offset, u16 val)
{
	__virtio16 v;

	might_sleep();
	v = cpu_to_virtio16(vdev, val);
	vdev->config->set(vdev, offset, &v, sizeof(v));
}

static inline u32 virtio_cread32(struct virtio_device *vdev,
				 unsigned int offset)
{
	__virtio32 ret;

	might_sleep();
	vdev->config->get(vdev, offset, &ret, sizeof(ret));
	return virtio32_to_cpu(vdev, ret);
}

static inline void virtio_cwrite32(struct virtio_device *vdev,
				   unsigned int offset, u32 val)
{
	__virtio32 v;

	might_sleep();
	v = cpu_to_virtio32(vdev, val);
	vdev->config->set(vdev, offset, &v, sizeof(v));
}

static inline u64 virtio_cread64(struct virtio_device *vdev,
				 unsigned int offset)
{
	__virtio64 ret;

	__virtio_cread_many(vdev, offset, &ret, 1, sizeof(ret));
	return virtio64_to_cpu(vdev, ret);
}

static inline void virtio_cwrite64(struct virtio_device *vdev,
				   unsigned int offset, u64 val)
{
	__virtio64 v;

	might_sleep();
	v = cpu_to_virtio64(vdev, val);
	vdev->config->set(vdev, offset, &v, sizeof(v));
}

/* Conditional config space accessors. */
#define virtio_cread_feature(vdev, fbit, structname, member, ptr)	\
	({								\
		int _r = 0;						\
		if (!virtio_has_feature(vdev, fbit))			\
			_r = -ENOENT;					\
		else							\
			virtio_cread((vdev), structname, member, ptr);	\
		_r;							\
	})

/* Conditional config space accessors. */
#define virtio_cread_le_feature(vdev, fbit, structname, member, ptr)	\
	({								\
		int _r = 0;						\
		if (!virtio_has_feature(vdev, fbit))			\
			_r = -ENOENT;					\
		else							\
			virtio_cread_le((vdev), structname, member, ptr); \
		_r;							\
	})

#endif /* _LINUX_VIRTIO_CONFIG_H */