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Commit d7a8d5ed authored by Alex Williamson's avatar Alex Williamson
Browse files

vfio: Add capability chain helpers 



Allow sub-modules to easily reallocate a buffer for managing
capability chains for info ioctls.

Signed-off-by: default avatarAlex Williamson <alex.williamson@redhat.com>
parent c84982ad

drivers/vfio/vfio.c

+54 −0
Original line number Diff line number Diff line
@@ -1728,6 +1728,60 @@ long vfio_external_check_extension(struct vfio_group *group, unsigned long arg) 
}

EXPORT_SYMBOL_GPL(vfio_external_check_extension);



/**

 * Sub-module support

 */

/*

 * Helper for managing a buffer of info chain capabilities, allocate or

 * reallocate a buffer with additional @size, filling in @id and @version

 * of the capability.  A pointer to the new capability is returned.

 *

 * NB. The chain is based at the head of the buffer, so new entries are

 * added to the tail, vfio_info_cap_shift() should be called to fixup the

 * next offsets prior to copying to the user buffer.

 */

struct vfio_info_cap_header *vfio_info_cap_add(struct vfio_info_cap *caps,

					       size_t size, u16 id, u16 version)

{

	void *buf;

	struct vfio_info_cap_header *header, *tmp;



	buf = krealloc(caps->buf, caps->size + size, GFP_KERNEL);

	if (!buf) {

		kfree(caps->buf);

		caps->size = 0;

		return ERR_PTR(-ENOMEM);

	}



	caps->buf = buf;

	header = buf + caps->size;



	/* Eventually copied to user buffer, zero */

	memset(header, 0, size);



	header->id = id;

	header->version = version;



	/* Add to the end of the capability chain */

	for (tmp = caps->buf; tmp->next; tmp = (void *)tmp + tmp->next)

		; /* nothing */



	tmp->next = caps->size;

	caps->size += size;



	return header;

}

EXPORT_SYMBOL_GPL(vfio_info_cap_add);



void vfio_info_cap_shift(struct vfio_info_cap *caps, size_t offset)

{

	struct vfio_info_cap_header *tmp;



	for (tmp = caps->buf; tmp->next; tmp = (void *)tmp + tmp->next - offset)

		tmp->next += offset;

}

EXPORT_SYMBOL_GPL(vfio_info_cap_shift);



/**

 * Module/class support

 */

include/linux/vfio.h

+11 −0
Original line number Diff line number Diff line
@@ -92,6 +92,17 @@ extern int vfio_external_user_iommu_id(struct vfio_group *group); 
extern long vfio_external_check_extension(struct vfio_group *group,

					  unsigned long arg);



/*

 * Sub-module helpers

 */

struct vfio_info_cap {

	struct vfio_info_cap_header *buf;

	size_t size;

};

extern struct vfio_info_cap_header *vfio_info_cap_add(

		struct vfio_info_cap *caps, size_t size, u16 id, u16 version);

extern void vfio_info_cap_shift(struct vfio_info_cap *caps, size_t offset);



struct pci_dev;

#ifdef CONFIG_EEH

extern void vfio_spapr_pci_eeh_open(struct pci_dev *pdev);