Shunsuke Mie
2022-Dec-27 02:25 UTC
[RFC PATCH 4/9] vringh: unify the APIs for all accessors
Each vringh memory accessors that are for user, kern and iotlb has own
interfaces that calls common code. But some codes are duplicated and that
becomes loss extendability.
Introduce a struct vringh_ops and provide a common APIs for all accessors.
It can bee easily extended vringh code for new memory accessor and
simplified a caller code.
Signed-off-by: Shunsuke Mie <mie at igel.co.jp>
---
drivers/vhost/vringh.c | 667 +++++++++++------------------------------
include/linux/vringh.h | 100 +++---
2 files changed, 225 insertions(+), 542 deletions(-)
diff --git a/drivers/vhost/vringh.c b/drivers/vhost/vringh.c
index aa3cd27d2384..ebfd3644a1a3 100644
--- a/drivers/vhost/vringh.c
+++ b/drivers/vhost/vringh.c
@@ -35,15 +35,12 @@ static __printf(1,2) __cold void vringh_bad(const char *fmt,
...)
}
/* Returns vring->num if empty, -ve on error. */
-static inline int __vringh_get_head(const struct vringh *vrh,
- int (*getu16)(const struct vringh *vrh,
- u16 *val, const __virtio16 *p),
- u16 *last_avail_idx)
+static inline int __vringh_get_head(const struct vringh *vrh, u16
*last_avail_idx)
{
u16 avail_idx, i, head;
int err;
- err = getu16(vrh, &avail_idx, &vrh->vring.avail->idx);
+ err = vrh->ops.getu16(vrh, &avail_idx,
&vrh->vring.avail->idx);
if (err) {
vringh_bad("Failed to access avail idx at %p",
&vrh->vring.avail->idx);
@@ -58,7 +55,7 @@ static inline int __vringh_get_head(const struct vringh *vrh,
i = *last_avail_idx & (vrh->vring.num - 1);
- err = getu16(vrh, &head, &vrh->vring.avail->ring[i]);
+ err = vrh->ops.getu16(vrh, &head,
&vrh->vring.avail->ring[i]);
if (err) {
vringh_bad("Failed to read head: idx %d address %p",
*last_avail_idx, &vrh->vring.avail->ring[i]);
@@ -131,12 +128,10 @@ static inline ssize_t vringh_iov_xfer(struct vringh *vrh,
/* May reduce *len if range is shorter. */
static inline bool range_check(struct vringh *vrh, u64 addr, size_t *len,
- struct vringh_range *range,
- bool (*getrange)(struct vringh *,
- u64, struct vringh_range *))
+ struct vringh_range *range)
{
if (addr < range->start || addr > range->end_incl) {
- if (!getrange(vrh, addr, range))
+ if (!vrh->ops.getrange(vrh, addr, range))
return false;
}
BUG_ON(addr < range->start || addr > range->end_incl);
@@ -165,9 +160,7 @@ static inline bool range_check(struct vringh *vrh, u64 addr,
size_t *len,
}
static inline bool no_range_check(struct vringh *vrh, u64 addr, size_t *len,
- struct vringh_range *range,
- bool (*getrange)(struct vringh *,
- u64, struct vringh_range *))
+ struct vringh_range *range)
{
return true;
}
@@ -244,17 +237,7 @@ static u16 __cold return_from_indirect(const struct vringh
*vrh, int *up_next,
}
static int slow_copy(struct vringh *vrh, void *dst, const void *src,
- bool (*rcheck)(struct vringh *vrh, u64 addr, size_t *len,
- struct vringh_range *range,
- bool (*getrange)(struct vringh *vrh,
- u64,
- struct vringh_range *)),
- bool (*getrange)(struct vringh *vrh,
- u64 addr,
- struct vringh_range *r),
- struct vringh_range *range,
- int (*copy)(const struct vringh *vrh,
- void *dst, const void *src, size_t len))
+ struct vringh_range *range)
{
size_t part, len = sizeof(struct vring_desc);
@@ -265,10 +248,10 @@ static int slow_copy(struct vringh *vrh, void *dst, const
void *src,
part = len;
addr = (u64)(unsigned long)src - range->offset;
- if (!rcheck(vrh, addr, &part, range, getrange))
+ if (!vrh->ops.range_check(vrh, addr, &part, range))
return -EINVAL;
- err = copy(vrh, dst, src, part);
+ err = vrh->ops.copydesc(vrh, dst, src, part);
if (err)
return err;
@@ -279,18 +262,35 @@ static int slow_copy(struct vringh *vrh, void *dst, const
void *src,
return 0;
}
+static int __vringh_init(struct vringh *vrh, u64 features, unsigned int num,
+ bool weak_barriers, gfp_t gfp, struct vring_desc *desc,
+ struct vring_avail *avail, struct vring_used *used)
+{
+ /* Sane power of 2 please! */
+ if (!num || num > 0xffff || (num & (num - 1))) {
+ vringh_bad("Bad ring size %u", num);
+ return -EINVAL;
+ }
+
+ vrh->little_endian = (features & (1ULL << VIRTIO_F_VERSION_1));
+ vrh->event_indices = (features & (1 << VIRTIO_RING_F_EVENT_IDX));
+ vrh->weak_barriers = weak_barriers;
+ vrh->completed = 0;
+ vrh->last_avail_idx = 0;
+ vrh->last_used_idx = 0;
+ vrh->vring.num = num;
+ vrh->vring.desc = desc;
+ vrh->vring.avail = avail;
+ vrh->vring.used = used;
+ vrh->desc_gfp = gfp;
+
+ return 0;
+}
+
static inline int
__vringh_iov(struct vringh *vrh, u16 i,
struct vringh_kiov *riov,
- struct vringh_kiov *wiov,
- bool (*rcheck)(struct vringh *vrh, u64 addr, size_t *len,
- struct vringh_range *range,
- bool (*getrange)(struct vringh *, u64,
- struct vringh_range *)),
- bool (*getrange)(struct vringh *, u64, struct vringh_range *),
- gfp_t gfp,
- int (*copy)(const struct vringh *vrh,
- void *dst, const void *src, size_t len))
+ struct vringh_kiov *wiov, gfp_t gfp)
{
int err, count = 0, indirect_count = 0, up_next, desc_max;
struct vring_desc desc, *descs;
@@ -317,10 +317,9 @@ __vringh_iov(struct vringh *vrh, u16 i,
size_t len;
if (unlikely(slow))
- err = slow_copy(vrh, &desc, &descs[i], rcheck, getrange,
- &slowrange, copy);
+ err = slow_copy(vrh, &desc, &descs[i], &slowrange);
else
- err = copy(vrh, &desc, &descs[i], sizeof(desc));
+ err = vrh->ops.copydesc(vrh, &desc, &descs[i], sizeof(desc));
if (unlikely(err))
goto fail;
@@ -330,7 +329,7 @@ __vringh_iov(struct vringh *vrh, u16 i,
/* Make sure it's OK, and get offset. */
len = vringh32_to_cpu(vrh, desc.len);
- if (!rcheck(vrh, a, &len, &range, getrange)) {
+ if (!vrh->ops.range_check(vrh, a, &len, &range)) {
err = -EINVAL;
goto fail;
}
@@ -382,8 +381,7 @@ __vringh_iov(struct vringh *vrh, u16 i,
again:
/* Make sure it's OK, and get offset. */
len = vringh32_to_cpu(vrh, desc.len);
- if (!rcheck(vrh, vringh64_to_cpu(vrh, desc.addr), &len, &range,
- getrange)) {
+ if (!vrh->ops.range_check(vrh, vringh64_to_cpu(vrh, desc.addr), &len,
&range)) {
err = -EINVAL;
goto fail;
}
@@ -436,13 +434,7 @@ __vringh_iov(struct vringh *vrh, u16 i,
static inline int __vringh_complete(struct vringh *vrh,
const struct vring_used_elem *used,
- unsigned int num_used,
- int (*putu16)(const struct vringh *vrh,
- __virtio16 *p, u16 val),
- int (*putused)(const struct vringh *vrh,
- struct vring_used_elem *dst,
- const struct vring_used_elem
- *src, unsigned num))
+ unsigned int num_used)
{
struct vring_used *used_ring;
int err;
@@ -456,12 +448,12 @@ static inline int __vringh_complete(struct vringh *vrh,
/* Compiler knows num_used == 1 sometimes, hence extra check */
if (num_used > 1 && unlikely(off + num_used >=
vrh->vring.num)) {
u16 part = vrh->vring.num - off;
- err = putused(vrh, &used_ring->ring[off], used, part);
+ err = vrh->ops.putused(vrh, &used_ring->ring[off], used, part);
if (!err)
- err = putused(vrh, &used_ring->ring[0], used + part,
+ err = vrh->ops.putused(vrh, &used_ring->ring[0], used + part,
num_used - part);
} else
- err = putused(vrh, &used_ring->ring[off], used, num_used);
+ err = vrh->ops.putused(vrh, &used_ring->ring[off], used, num_used);
if (err) {
vringh_bad("Failed to write %u used entries %u at %p",
@@ -472,7 +464,7 @@ static inline int __vringh_complete(struct vringh *vrh,
/* Make sure buffer is written before we update index. */
virtio_wmb(vrh->weak_barriers);
- err = putu16(vrh, &vrh->vring.used->idx, used_idx + num_used);
+ err = vrh->ops.putu16(vrh, &vrh->vring.used->idx, used_idx +
num_used);
if (err) {
vringh_bad("Failed to update used index at %p",
&vrh->vring.used->idx);
@@ -483,11 +475,13 @@ static inline int __vringh_complete(struct vringh *vrh,
return 0;
}
-
-static inline int __vringh_need_notify(struct vringh *vrh,
- int (*getu16)(const struct vringh *vrh,
- u16 *val,
- const __virtio16 *p))
+/**
+ * vringh_need_notify - must we tell the other side about used buffers?
+ * @vrh: the vring we've called vringh_complete() on.
+ *
+ * Returns -errno or 0 if we don't need to tell the other side, 1 if we do.
+ */
+int vringh_need_notify(struct vringh *vrh)
{
bool notify;
u16 used_event;
@@ -501,7 +495,7 @@ static inline int __vringh_need_notify(struct vringh *vrh,
/* Old-style, without event indices. */
if (!vrh->event_indices) {
u16 flags;
- err = getu16(vrh, &flags, &vrh->vring.avail->flags);
+ err = vrh->ops.getu16(vrh, &flags,
&vrh->vring.avail->flags);
if (err) {
vringh_bad("Failed to get flags at %p",
&vrh->vring.avail->flags);
@@ -511,7 +505,7 @@ static inline int __vringh_need_notify(struct vringh *vrh,
}
/* Modern: we know when other side wants to know. */
- err = getu16(vrh, &used_event, &vring_used_event(&vrh->vring));
+ err = vrh->ops.getu16(vrh, &used_event,
&vring_used_event(&vrh->vring));
if (err) {
vringh_bad("Failed to get used event idx at %p",
&vring_used_event(&vrh->vring));
@@ -530,24 +524,28 @@ static inline int __vringh_need_notify(struct vringh *vrh,
vrh->completed = 0;
return notify;
}
+EXPORT_SYMBOL(vringh_need_notify);
-static inline bool __vringh_notify_enable(struct vringh *vrh,
- int (*getu16)(const struct vringh *vrh,
- u16 *val, const __virtio16 *p),
- int (*putu16)(const struct vringh *vrh,
- __virtio16 *p, u16 val))
+/**
+ * vringh_notify_enable - we want to know if something changes.
+ * @vrh: the vring.
+ *
+ * This always enables notifications, but returns false if there are
+ * now more buffers available in the vring.
+ */
+bool vringh_notify_enable(struct vringh *vrh)
{
u16 avail;
if (!vrh->event_indices) {
/* Old-school; update flags. */
- if (putu16(vrh, &vrh->vring.used->flags, 0) != 0) {
+ if (vrh->ops.putu16(vrh, &vrh->vring.used->flags, 0) != 0) {
vringh_bad("Clearing used flags %p",
&vrh->vring.used->flags);
return true;
}
} else {
- if (putu16(vrh, &vring_avail_event(&vrh->vring),
+ if (vrh->ops.putu16(vrh, &vring_avail_event(&vrh->vring),
vrh->last_avail_idx) != 0) {
vringh_bad("Updating avail event index %p",
&vring_avail_event(&vrh->vring));
@@ -559,7 +557,7 @@ static inline bool __vringh_notify_enable(struct vringh
*vrh,
* sure it's written, then check again. */
virtio_mb(vrh->weak_barriers);
- if (getu16(vrh, &avail, &vrh->vring.avail->idx) != 0) {
+ if (vrh->ops.getu16(vrh, &avail, &vrh->vring.avail->idx) !=
0) {
vringh_bad("Failed to check avail idx at %p",
&vrh->vring.avail->idx);
return true;
@@ -570,20 +568,27 @@ static inline bool __vringh_notify_enable(struct vringh
*vrh,
* notification anyway). */
return avail == vrh->last_avail_idx;
}
+EXPORT_SYMBOL(vringh_notify_enable);
-static inline void __vringh_notify_disable(struct vringh *vrh,
- int (*putu16)(const struct vringh *vrh,
- __virtio16 *p, u16 val))
+/**
+ * vringh_notify_disable - don't tell us if something changes.
+ * @vrh: the vring.
+ *
+ * This is our normal running state: we disable and then only enable when
+ * we're going to sleep.
+ */
+void vringh_notify_disable(struct vringh *vrh)
{
if (!vrh->event_indices) {
/* Old-school; update flags. */
- if (putu16(vrh, &vrh->vring.used->flags,
+ if (vrh->ops.putu16(vrh, &vrh->vring.used->flags,
VRING_USED_F_NO_NOTIFY)) {
vringh_bad("Setting used flags %p",
&vrh->vring.used->flags);
}
}
}
+EXPORT_SYMBOL(vringh_notify_disable);
/* Userspace access helpers: in this case, addresses are really userspace. */
static inline int getu16_user(const struct vringh *vrh, u16 *val, const
__virtio16 *p)
@@ -630,6 +635,16 @@ static inline int xfer_to_user(const struct vringh *vrh,
-EFAULT : 0;
}
+static struct vringh_ops user_vringh_ops = {
+ .getu16 = getu16_user,
+ .putu16 = putu16_user,
+ .xfer_from = xfer_from_user,
+ .xfer_to = xfer_to_user,
+ .putused = putused_user,
+ .copydesc = copydesc_user,
+ .range_check = range_check,
+};
+
/**
* vringh_init_user - initialize a vringh for a userspace vring.
* @vrh: the vringh to initialize.
@@ -639,6 +654,7 @@ static inline int xfer_to_user(const struct vringh *vrh,
* @desc: the userpace descriptor pointer.
* @avail: the userpace avail pointer.
* @used: the userpace used pointer.
+ * @getrange: a function that return a range that vring can access.
*
* Returns an error if num is invalid: you should check pointers
* yourself!
@@ -647,36 +663,32 @@ int vringh_init_user(struct vringh *vrh, u64 features,
unsigned int num, bool weak_barriers,
vring_desc_t __user *desc,
vring_avail_t __user *avail,
- vring_used_t __user *used)
+ vring_used_t __user *used,
+ bool (*getrange)(struct vringh *vrh, u64 addr, struct vringh_range *r))
{
- /* Sane power of 2 please! */
- if (!num || num > 0xffff || (num & (num - 1))) {
- vringh_bad("Bad ring size %u", num);
- return -EINVAL;
- }
+ int err;
+
+ err = __vringh_init(vrh, features, num, weak_barriers, GFP_KERNEL,
+ (__force struct vring_desc *)desc,
+ (__force struct vring_avail *)avail,
+ (__force struct vring_used *)used);
+ if (err)
+ return err;
+
+ memcpy(&vrh->ops, &user_vringh_ops, sizeof(user_vringh_ops));
+ vrh->ops.getrange = getrange;
- vrh->little_endian = (features & (1ULL << VIRTIO_F_VERSION_1));
- vrh->event_indices = (features & (1 << VIRTIO_RING_F_EVENT_IDX));
- vrh->weak_barriers = weak_barriers;
- vrh->completed = 0;
- vrh->last_avail_idx = 0;
- vrh->last_used_idx = 0;
- vrh->vring.num = num;
- /* vring expects kernel addresses, but only used via accessors. */
- vrh->vring.desc = (__force struct vring_desc *)desc;
- vrh->vring.avail = (__force struct vring_avail *)avail;
- vrh->vring.used = (__force struct vring_used *)used;
return 0;
}
EXPORT_SYMBOL(vringh_init_user);
/**
- * vringh_getdesc_user - get next available descriptor from userspace ring.
- * @vrh: the userspace vring.
+ * vringh_getdesc - get next available descriptor from ring.
+ * @vrh: the vringh to get desc.
* @riov: where to put the readable descriptors (or NULL)
* @wiov: where to put the writable descriptors (or NULL)
* @getrange: function to call to check ranges.
- * @head: head index we received, for passing to vringh_complete_user().
+ * @head: head index we received, for passing to vringh_complete().
*
* Returns 0 if there was no descriptor, 1 if there was, or -errno.
*
@@ -690,17 +702,15 @@ EXPORT_SYMBOL(vringh_init_user);
* When you don't have to use riov and wiov anymore, you should clean up
them
* calling vringh_iov_cleanup() to release the memory, even on error!
*/
-int vringh_getdesc_user(struct vringh *vrh,
+int vringh_getdesc(struct vringh *vrh,
struct vringh_kiov *riov,
struct vringh_kiov *wiov,
- bool (*getrange)(struct vringh *vrh,
- u64 addr, struct vringh_range *r),
u16 *head)
{
int err;
*head = vrh->vring.num;
- err = __vringh_get_head(vrh, getu16_user, &vrh->last_avail_idx);
+ err = __vringh_get_head(vrh, &vrh->last_avail_idx);
if (err < 0)
return err;
@@ -709,137 +719,100 @@ int vringh_getdesc_user(struct vringh *vrh,
return 0;
*head = err;
- err = __vringh_iov(vrh, *head, (struct vringh_kiov *)riov,
- (struct vringh_kiov *)wiov,
- range_check, getrange, GFP_KERNEL, copydesc_user);
+ err = __vringh_iov(vrh, *head, riov, wiov, GFP_KERNEL);
if (err)
return err;
return 1;
}
-EXPORT_SYMBOL(vringh_getdesc_user);
+EXPORT_SYMBOL(vringh_getdesc);
/**
- * vringh_iov_pull_user - copy bytes from vring_kiov.
- * @riov: the riov as passed to vringh_getdesc_user() (updated as we consume)
+ * vringh_iov_pull - copy bytes from vring_kiov.
+ * @vrh: the vringh to load data.
+ * @riov: the riov as passed to vringh_getdesc() (updated as we consume)
* @dst: the place to copy.
* @len: the maximum length to copy.
*
* Returns the bytes copied <= len or a negative errno.
*/
-ssize_t vringh_iov_pull_user(struct vringh_kiov *riov, void *dst, size_t len)
+ssize_t vringh_iov_pull(struct vringh *vrh, struct vringh_kiov *riov, void
*dst, size_t len)
{
return vringh_iov_xfer(NULL, (struct vringh_kiov *)riov,
- dst, len, xfer_from_user);
+ dst, len, vrh->ops.xfer_from);
}
-EXPORT_SYMBOL(vringh_iov_pull_user);
+EXPORT_SYMBOL(vringh_iov_pull);
/**
- * vringh_iov_push_user - copy bytes into vring_kiov.
- * @wiov: the wiov as passed to vringh_getdesc_user() (updated as we consume)
+ * vringh_iov_push - copy bytes into vring_kiov.
+ * @vrh: the vringh to store data.
+ * @wiov: the wiov as passed to vringh_getdesc() (updated as we consume)
* @src: the place to copy from.
* @len: the maximum length to copy.
*
* Returns the bytes copied <= len or a negative errno.
*/
-ssize_t vringh_iov_push_user(struct vringh_kiov *wiov,
+ssize_t vringh_iov_push(struct vringh *vrh, struct vringh_kiov *wiov,
const void *src, size_t len)
{
return vringh_iov_xfer(NULL, (struct vringh_kiov *)wiov,
- (void *)src, len, xfer_to_user);
+ (void *)src, len, vrh->ops.xfer_to);
}
-EXPORT_SYMBOL(vringh_iov_push_user);
+EXPORT_SYMBOL(vringh_iov_push);
/**
- * vringh_abandon_user - we've decided not to handle the descriptor(s).
+ * vringh_abandon - we've decided not to handle the descriptor(s).
* @vrh: the vring.
* @num: the number of descriptors to put back (ie. num
* vringh_get_user() to undo).
*
* The next vringh_get_user() will return the old descriptor(s) again.
*/
-void vringh_abandon_user(struct vringh *vrh, unsigned int num)
+void vringh_abandon(struct vringh *vrh, unsigned int num)
{
/* We only update vring_avail_event(vr) when we want to be notified,
* so we haven't changed that yet. */
vrh->last_avail_idx -= num;
}
-EXPORT_SYMBOL(vringh_abandon_user);
+EXPORT_SYMBOL(vringh_abandon);
/**
- * vringh_complete_user - we've finished with descriptor, publish it.
+ * vringh_complete - we've finished with descriptor, publish it.
* @vrh: the vring.
- * @head: the head as filled in by vringh_getdesc_user.
+ * @head: the head as filled in by vringh_getdesc.
* @len: the length of data we have written.
*
- * You should check vringh_need_notify_user() after one or more calls
+ * You should check vringh_need_notify() after one or more calls
* to this function.
*/
-int vringh_complete_user(struct vringh *vrh, u16 head, u32 len)
+int vringh_complete(struct vringh *vrh, u16 head, u32 len)
{
struct vring_used_elem used;
used.id = cpu_to_vringh32(vrh, head);
used.len = cpu_to_vringh32(vrh, len);
- return __vringh_complete(vrh, &used, 1, putu16_user, putused_user);
+ return __vringh_complete(vrh, &used, 1);
}
-EXPORT_SYMBOL(vringh_complete_user);
+EXPORT_SYMBOL(vringh_complete);
/**
- * vringh_complete_multi_user - we've finished with many descriptors.
+ * vringh_complete_multi - we've finished with many descriptors.
* @vrh: the vring.
* @used: the head, length pairs.
* @num_used: the number of used elements.
*
- * You should check vringh_need_notify_user() after one or more calls
+ * You should check vringh_need_notify() after one or more calls
* to this function.
*/
-int vringh_complete_multi_user(struct vringh *vrh,
+int vringh_complete_multi(struct vringh *vrh,
const struct vring_used_elem used[],
unsigned num_used)
{
- return __vringh_complete(vrh, used, num_used,
- putu16_user, putused_user);
-}
-EXPORT_SYMBOL(vringh_complete_multi_user);
-
-/**
- * vringh_notify_enable_user - we want to know if something changes.
- * @vrh: the vring.
- *
- * This always enables notifications, but returns false if there are
- * now more buffers available in the vring.
- */
-bool vringh_notify_enable_user(struct vringh *vrh)
-{
- return __vringh_notify_enable(vrh, getu16_user, putu16_user);
+ return __vringh_complete(vrh, used, num_used);
}
-EXPORT_SYMBOL(vringh_notify_enable_user);
+EXPORT_SYMBOL(vringh_complete_multi);
-/**
- * vringh_notify_disable_user - don't tell us if something changes.
- * @vrh: the vring.
- *
- * This is our normal running state: we disable and then only enable when
- * we're going to sleep.
- */
-void vringh_notify_disable_user(struct vringh *vrh)
-{
- __vringh_notify_disable(vrh, putu16_user);
-}
-EXPORT_SYMBOL(vringh_notify_disable_user);
-/**
- * vringh_need_notify_user - must we tell the other side about used buffers?
- * @vrh: the vring we've called vringh_complete_user() on.
- *
- * Returns -errno or 0 if we don't need to tell the other side, 1 if we do.
- */
-int vringh_need_notify_user(struct vringh *vrh)
-{
- return __vringh_need_notify(vrh, getu16_user);
-}
-EXPORT_SYMBOL(vringh_need_notify_user);
/* Kernelspace access helpers. */
static inline int getu16_kern(const struct vringh *vrh,
@@ -885,6 +858,17 @@ static inline int kern_xfer(const struct vringh *vrh, void
*dst,
return 0;
}
+static const struct vringh_ops kern_vringh_ops = {
+ .getu16 = getu16_kern,
+ .putu16 = putu16_kern,
+ .xfer_from = xfer_kern,
+ .xfer_to = xfer_kern,
+ .putused = putused_kern,
+ .copydesc = copydesc_kern,
+ .range_check = no_range_check,
+ .getrange = NULL,
+};
+
/**
* vringh_init_kern - initialize a vringh for a kernelspace vring.
* @vrh: the vringh to initialize.
@@ -898,179 +882,22 @@ static inline int kern_xfer(const struct vringh *vrh,
void *dst,
* Returns an error if num is invalid.
*/
int vringh_init_kern(struct vringh *vrh, u64 features,
- unsigned int num, bool weak_barriers,
+ unsigned int num, bool weak_barriers, gfp_t gfp,
struct vring_desc *desc,
struct vring_avail *avail,
struct vring_used *used)
-{
- /* Sane power of 2 please! */
- if (!num || num > 0xffff || (num & (num - 1))) {
- vringh_bad("Bad ring size %u", num);
- return -EINVAL;
- }
-
- vrh->little_endian = (features & (1ULL << VIRTIO_F_VERSION_1));
- vrh->event_indices = (features & (1 << VIRTIO_RING_F_EVENT_IDX));
- vrh->weak_barriers = weak_barriers;
- vrh->completed = 0;
- vrh->last_avail_idx = 0;
- vrh->last_used_idx = 0;
- vrh->vring.num = num;
- vrh->vring.desc = desc;
- vrh->vring.avail = avail;
- vrh->vring.used = used;
- return 0;
-}
-EXPORT_SYMBOL(vringh_init_kern);
-
-/**
- * vringh_getdesc_kern - get next available descriptor from kernelspace ring.
- * @vrh: the kernelspace vring.
- * @riov: where to put the readable descriptors (or NULL)
- * @wiov: where to put the writable descriptors (or NULL)
- * @head: head index we received, for passing to vringh_complete_kern().
- * @gfp: flags for allocating larger riov/wiov.
- *
- * Returns 0 if there was no descriptor, 1 if there was, or -errno.
- *
- * Note that on error return, you can tell the difference between an
- * invalid ring and a single invalid descriptor: in the former case,
- * *head will be vrh->vring.num. You may be able to ignore an invalid
- * descriptor, but there's not much you can do with an invalid ring.
- *
- * Note that you can reuse riov and wiov with subsequent calls. Content is
- * overwritten and memory reallocated if more space is needed.
- * When you don't have to use riov and wiov anymore, you should clean up
them
- * calling vringh_kiov_cleanup() to release the memory, even on error!
- */
-int vringh_getdesc_kern(struct vringh *vrh,
- struct vringh_kiov *riov,
- struct vringh_kiov *wiov,
- u16 *head,
- gfp_t gfp)
{
int err;
- err = __vringh_get_head(vrh, getu16_kern, &vrh->last_avail_idx);
- if (err < 0)
- return err;
-
- /* Empty... */
- if (err == vrh->vring.num)
- return 0;
-
- *head = err;
- err = __vringh_iov(vrh, *head, riov, wiov, no_range_check, NULL,
- gfp, copydesc_kern);
+ err = __vringh_init(vrh, features, num, weak_barriers, gfp, desc, avail,
used);
if (err)
return err;
- return 1;
-}
-EXPORT_SYMBOL(vringh_getdesc_kern);
-
-/**
- * vringh_iov_pull_kern - copy bytes from vring_iov.
- * @riov: the riov as passed to vringh_getdesc_kern() (updated as we consume)
- * @dst: the place to copy.
- * @len: the maximum length to copy.
- *
- * Returns the bytes copied <= len or a negative errno.
- */
-ssize_t vringh_iov_pull_kern(struct vringh_kiov *riov, void *dst, size_t len)
-{
- return vringh_iov_xfer(NULL, riov, dst, len, xfer_kern);
-}
-EXPORT_SYMBOL(vringh_iov_pull_kern);
-
-/**
- * vringh_iov_push_kern - copy bytes into vring_iov.
- * @wiov: the wiov as passed to vringh_getdesc_kern() (updated as we consume)
- * @src: the place to copy from.
- * @len: the maximum length to copy.
- *
- * Returns the bytes copied <= len or a negative errno.
- */
-ssize_t vringh_iov_push_kern(struct vringh_kiov *wiov,
- const void *src, size_t len)
-{
- return vringh_iov_xfer(NULL, wiov, (void *)src, len, kern_xfer);
-}
-EXPORT_SYMBOL(vringh_iov_push_kern);
+ memcpy(&vrh->ops, &kern_vringh_ops, sizeof(kern_vringh_ops));
-/**
- * vringh_abandon_kern - we've decided not to handle the descriptor(s).
- * @vrh: the vring.
- * @num: the number of descriptors to put back (ie. num
- * vringh_get_kern() to undo).
- *
- * The next vringh_get_kern() will return the old descriptor(s) again.
- */
-void vringh_abandon_kern(struct vringh *vrh, unsigned int num)
-{
- /* We only update vring_avail_event(vr) when we want to be notified,
- * so we haven't changed that yet. */
- vrh->last_avail_idx -= num;
-}
-EXPORT_SYMBOL(vringh_abandon_kern);
-
-/**
- * vringh_complete_kern - we've finished with descriptor, publish it.
- * @vrh: the vring.
- * @head: the head as filled in by vringh_getdesc_kern.
- * @len: the length of data we have written.
- *
- * You should check vringh_need_notify_kern() after one or more calls
- * to this function.
- */
-int vringh_complete_kern(struct vringh *vrh, u16 head, u32 len)
-{
- struct vring_used_elem used;
-
- used.id = cpu_to_vringh32(vrh, head);
- used.len = cpu_to_vringh32(vrh, len);
-
- return __vringh_complete(vrh, &used, 1, putu16_kern, putused_kern);
-}
-EXPORT_SYMBOL(vringh_complete_kern);
-
-/**
- * vringh_notify_enable_kern - we want to know if something changes.
- * @vrh: the vring.
- *
- * This always enables notifications, but returns false if there are
- * now more buffers available in the vring.
- */
-bool vringh_notify_enable_kern(struct vringh *vrh)
-{
- return __vringh_notify_enable(vrh, getu16_kern, putu16_kern);
-}
-EXPORT_SYMBOL(vringh_notify_enable_kern);
-
-/**
- * vringh_notify_disable_kern - don't tell us if something changes.
- * @vrh: the vring.
- *
- * This is our normal running state: we disable and then only enable when
- * we're going to sleep.
- */
-void vringh_notify_disable_kern(struct vringh *vrh)
-{
- __vringh_notify_disable(vrh, putu16_kern);
-}
-EXPORT_SYMBOL(vringh_notify_disable_kern);
-
-/**
- * vringh_need_notify_kern - must we tell the other side about used buffers?
- * @vrh: the vring we've called vringh_complete_kern() on.
- *
- * Returns -errno or 0 if we don't need to tell the other side, 1 if we do.
- */
-int vringh_need_notify_kern(struct vringh *vrh)
-{
- return __vringh_need_notify(vrh, getu16_kern);
+ return 0;
}
-EXPORT_SYMBOL(vringh_need_notify_kern);
+EXPORT_SYMBOL(vringh_init_kern);
#if IS_REACHABLE(CONFIG_VHOST_IOTLB)
@@ -1122,7 +949,7 @@ static int iotlb_translate(const struct vringh *vrh,
return ret;
}
-static inline int copy_from_iotlb(const struct vringh *vrh, void *dst,
+static int copy_from_iotlb(const struct vringh *vrh, void *dst,
void *src, size_t len)
{
u64 total_translated = 0;
@@ -1155,7 +982,7 @@ static inline int copy_from_iotlb(const struct vringh *vrh,
void *dst,
return total_translated;
}
-static inline int copy_to_iotlb(const struct vringh *vrh, void *dst,
+static int copy_to_iotlb(const struct vringh *vrh, void *dst,
void *src, size_t len)
{
u64 total_translated = 0;
@@ -1188,7 +1015,7 @@ static inline int copy_to_iotlb(const struct vringh *vrh,
void *dst,
return total_translated;
}
-static inline int getu16_iotlb(const struct vringh *vrh,
+static int getu16_iotlb(const struct vringh *vrh,
u16 *val, const __virtio16 *p)
{
struct bio_vec iov;
@@ -1209,7 +1036,7 @@ static inline int getu16_iotlb(const struct vringh *vrh,
return 0;
}
-static inline int putu16_iotlb(const struct vringh *vrh,
+static int putu16_iotlb(const struct vringh *vrh,
__virtio16 *p, u16 val)
{
struct bio_vec iov;
@@ -1230,7 +1057,7 @@ static inline int putu16_iotlb(const struct vringh *vrh,
return 0;
}
-static inline int copydesc_iotlb(const struct vringh *vrh,
+static int copydesc_iotlb(const struct vringh *vrh,
void *dst, const void *src, size_t len)
{
int ret;
@@ -1242,7 +1069,7 @@ static inline int copydesc_iotlb(const struct vringh *vrh,
return 0;
}
-static inline int xfer_from_iotlb(const struct vringh *vrh, void *src,
+static int xfer_from_iotlb(const struct vringh *vrh, void *src,
void *dst, size_t len)
{
int ret;
@@ -1254,7 +1081,7 @@ static inline int xfer_from_iotlb(const struct vringh
*vrh, void *src,
return 0;
}
-static inline int xfer_to_iotlb(const struct vringh *vrh,
+static int xfer_to_iotlb(const struct vringh *vrh,
void *dst, void *src, size_t len)
{
int ret;
@@ -1266,7 +1093,7 @@ static inline int xfer_to_iotlb(const struct vringh *vrh,
return 0;
}
-static inline int putused_iotlb(const struct vringh *vrh,
+static int putused_iotlb(const struct vringh *vrh,
struct vring_used_elem *dst,
const struct vring_used_elem *src,
unsigned int num)
@@ -1281,6 +1108,17 @@ static inline int putused_iotlb(const struct vringh *vrh,
return 0;
}
+static const struct vringh_ops iotlb_vringh_ops = {
+ .getu16 = getu16_iotlb,
+ .putu16 = putu16_iotlb,
+ .xfer_from = xfer_from_iotlb,
+ .xfer_to = xfer_to_iotlb,
+ .putused = putused_iotlb,
+ .copydesc = copydesc_iotlb,
+ .range_check = no_range_check,
+ .getrange = NULL,
+};
+
/**
* vringh_init_iotlb - initialize a vringh for a ring with IOTLB.
* @vrh: the vringh to initialize.
@@ -1294,13 +1132,20 @@ static inline int putused_iotlb(const struct vringh
*vrh,
* Returns an error if num is invalid.
*/
int vringh_init_iotlb(struct vringh *vrh, u64 features,
- unsigned int num, bool weak_barriers,
+ unsigned int num, bool weak_barriers, gfp_t gfp,
struct vring_desc *desc,
struct vring_avail *avail,
struct vring_used *used)
{
- return vringh_init_kern(vrh, features, num, weak_barriers,
- desc, avail, used);
+ int err;
+
+ err = __vringh_init(vrh, features, num, weak_barriers, gfp, desc, avail,
used);
+ if (err)
+ return err;
+
+ memcpy(&vrh->ops, &iotlb_vringh_ops, sizeof(iotlb_vringh_ops));
+
+ return 0;
}
EXPORT_SYMBOL(vringh_init_iotlb);
@@ -1318,162 +1163,6 @@ void vringh_set_iotlb(struct vringh *vrh, struct
vhost_iotlb *iotlb,
}
EXPORT_SYMBOL(vringh_set_iotlb);
-/**
- * vringh_getdesc_iotlb - get next available descriptor from ring with
- * IOTLB.
- * @vrh: the kernelspace vring.
- * @riov: where to put the readable descriptors (or NULL)
- * @wiov: where to put the writable descriptors (or NULL)
- * @head: head index we received, for passing to vringh_complete_iotlb().
- * @gfp: flags for allocating larger riov/wiov.
- *
- * Returns 0 if there was no descriptor, 1 if there was, or -errno.
- *
- * Note that on error return, you can tell the difference between an
- * invalid ring and a single invalid descriptor: in the former case,
- * *head will be vrh->vring.num. You may be able to ignore an invalid
- * descriptor, but there's not much you can do with an invalid ring.
- *
- * Note that you can reuse riov and wiov with subsequent calls. Content is
- * overwritten and memory reallocated if more space is needed.
- * When you don't have to use riov and wiov anymore, you should clean up
them
- * calling vringh_kiov_cleanup() to release the memory, even on error!
- */
-int vringh_getdesc_iotlb(struct vringh *vrh,
- struct vringh_kiov *riov,
- struct vringh_kiov *wiov,
- u16 *head,
- gfp_t gfp)
-{
- int err;
-
- err = __vringh_get_head(vrh, getu16_iotlb, &vrh->last_avail_idx);
- if (err < 0)
- return err;
-
- /* Empty... */
- if (err == vrh->vring.num)
- return 0;
-
- *head = err;
- err = __vringh_iov(vrh, *head, riov, wiov, no_range_check, NULL,
- gfp, copydesc_iotlb);
- if (err)
- return err;
-
- return 1;
-}
-EXPORT_SYMBOL(vringh_getdesc_iotlb);
-
-/**
- * vringh_iov_pull_iotlb - copy bytes from vring_iov.
- * @vrh: the vring.
- * @riov: the riov as passed to vringh_getdesc_iotlb() (updated as we consume)
- * @dst: the place to copy.
- * @len: the maximum length to copy.
- *
- * Returns the bytes copied <= len or a negative errno.
- */
-ssize_t vringh_iov_pull_iotlb(struct vringh *vrh,
- struct vringh_kiov *riov,
- void *dst, size_t len)
-{
- return vringh_iov_xfer(vrh, riov, dst, len, xfer_from_iotlb);
-}
-EXPORT_SYMBOL(vringh_iov_pull_iotlb);
-
-/**
- * vringh_iov_push_iotlb - copy bytes into vring_iov.
- * @vrh: the vring.
- * @wiov: the wiov as passed to vringh_getdesc_iotlb() (updated as we consume)
- * @src: the place to copy from.
- * @len: the maximum length to copy.
- *
- * Returns the bytes copied <= len or a negative errno.
- */
-ssize_t vringh_iov_push_iotlb(struct vringh *vrh,
- struct vringh_kiov *wiov,
- const void *src, size_t len)
-{
- return vringh_iov_xfer(vrh, wiov, (void *)src, len, xfer_to_iotlb);
-}
-EXPORT_SYMBOL(vringh_iov_push_iotlb);
-
-/**
- * vringh_abandon_iotlb - we've decided not to handle the descriptor(s).
- * @vrh: the vring.
- * @num: the number of descriptors to put back (ie. num
- * vringh_get_iotlb() to undo).
- *
- * The next vringh_get_iotlb() will return the old descriptor(s) again.
- */
-void vringh_abandon_iotlb(struct vringh *vrh, unsigned int num)
-{
- /* We only update vring_avail_event(vr) when we want to be notified,
- * so we haven't changed that yet.
- */
- vrh->last_avail_idx -= num;
-}
-EXPORT_SYMBOL(vringh_abandon_iotlb);
-
-/**
- * vringh_complete_iotlb - we've finished with descriptor, publish it.
- * @vrh: the vring.
- * @head: the head as filled in by vringh_getdesc_iotlb.
- * @len: the length of data we have written.
- *
- * You should check vringh_need_notify_iotlb() after one or more calls
- * to this function.
- */
-int vringh_complete_iotlb(struct vringh *vrh, u16 head, u32 len)
-{
- struct vring_used_elem used;
-
- used.id = cpu_to_vringh32(vrh, head);
- used.len = cpu_to_vringh32(vrh, len);
-
- return __vringh_complete(vrh, &used, 1, putu16_iotlb, putused_iotlb);
-}
-EXPORT_SYMBOL(vringh_complete_iotlb);
-
-/**
- * vringh_notify_enable_iotlb - we want to know if something changes.
- * @vrh: the vring.
- *
- * This always enables notifications, but returns false if there are
- * now more buffers available in the vring.
- */
-bool vringh_notify_enable_iotlb(struct vringh *vrh)
-{
- return __vringh_notify_enable(vrh, getu16_iotlb, putu16_iotlb);
-}
-EXPORT_SYMBOL(vringh_notify_enable_iotlb);
-
-/**
- * vringh_notify_disable_iotlb - don't tell us if something changes.
- * @vrh: the vring.
- *
- * This is our normal running state: we disable and then only enable when
- * we're going to sleep.
- */
-void vringh_notify_disable_iotlb(struct vringh *vrh)
-{
- __vringh_notify_disable(vrh, putu16_iotlb);
-}
-EXPORT_SYMBOL(vringh_notify_disable_iotlb);
-
-/**
- * vringh_need_notify_iotlb - must we tell the other side about used buffers?
- * @vrh: the vring we've called vringh_complete_iotlb() on.
- *
- * Returns -errno or 0 if we don't need to tell the other side, 1 if we do.
- */
-int vringh_need_notify_iotlb(struct vringh *vrh)
-{
- return __vringh_need_notify(vrh, getu16_iotlb);
-}
-EXPORT_SYMBOL(vringh_need_notify_iotlb);
-
#endif
MODULE_LICENSE("GPL");
diff --git a/include/linux/vringh.h b/include/linux/vringh.h
index 733d948e8123..89c73605c85f 100644
--- a/include/linux/vringh.h
+++ b/include/linux/vringh.h
@@ -21,6 +21,36 @@
#endif
#include <asm/barrier.h>
+struct vringh;
+struct vringh_range;
+
+/**
+ * struct vringh_ops - ops for accessing a vring and checking to access range.
+ * @getu16: read u16 value from pointer
+ * @putu16: write u16 value to pointer
+ * @xfer_from: copy memory range from specified address to local virtual
address
+ * @xfer_tio: copy memory range from local virtual address to specified address
+ * @putused: update vring used descriptor
+ * @copydesc: copy desiptor from target to local virtual address
+ * @range_check: check if the region is accessible
+ * @getrange: return a range that vring can access
+ */
+struct vringh_ops {
+ int (*getu16)(const struct vringh *vrh, u16 *val, const __virtio16 *p);
+ int (*putu16)(const struct vringh *vrh, __virtio16 *p, u16 val);
+ int (*xfer_from)(const struct vringh *vrh, void *src, void *dst,
+ size_t len);
+ int (*xfer_to)(const struct vringh *vrh, void *dst, void *src,
+ size_t len);
+ int (*putused)(const struct vringh *vrh, struct vring_used_elem *dst,
+ const struct vring_used_elem *src, unsigned int num);
+ int (*copydesc)(const struct vringh *vrh, void *dst, const void *src,
+ size_t len);
+ bool (*range_check)(struct vringh *vrh, u64 addr, size_t *len,
+ struct vringh_range *range);
+ bool (*getrange)(struct vringh *vrh, u64 addr, struct vringh_range *r);
+};
+
/* virtio_ring with information needed for host access. */
struct vringh {
/* Everything is little endian */
@@ -52,6 +82,10 @@ struct vringh {
/* The function to call to notify the guest about added buffers */
void (*notify)(struct vringh *);
+
+ struct vringh_ops ops;
+
+ gfp_t desc_gfp;
};
/**
@@ -99,41 +133,40 @@ int vringh_init_user(struct vringh *vrh, u64 features,
unsigned int num, bool weak_barriers,
vring_desc_t __user *desc,
vring_avail_t __user *avail,
- vring_used_t __user *used);
+ vring_used_t __user *used,
+ bool (*getrange)(struct vringh *vrh, u64 addr, struct vringh_range *r));
/* Convert a descriptor into iovecs. */
-int vringh_getdesc_user(struct vringh *vrh,
+int vringh_getdesc(struct vringh *vrh,
struct vringh_kiov *riov,
struct vringh_kiov *wiov,
- bool (*getrange)(struct vringh *vrh,
- u64 addr, struct vringh_range *r),
u16 *head);
/* Copy bytes from readable vsg, consuming it (and incrementing wiov->i). */
-ssize_t vringh_iov_pull_user(struct vringh_kiov *riov, void *dst, size_t len);
+ssize_t vringh_iov_pull(struct vringh *vrh, struct vringh_kiov *riov, void
*dst, size_t len);
/* Copy bytes into writable vsg, consuming it (and incrementing wiov->i). */
-ssize_t vringh_iov_push_user(struct vringh_kiov *wiov,
+ssize_t vringh_iov_push(struct vringh *vrh, struct vringh_kiov *wiov,
const void *src, size_t len);
/* Mark a descriptor as used. */
-int vringh_complete_user(struct vringh *vrh, u16 head, u32 len);
-int vringh_complete_multi_user(struct vringh *vrh,
+int vringh_complete(struct vringh *vrh, u16 head, u32 len);
+int vringh_complete_multi(struct vringh *vrh,
const struct vring_used_elem used[],
unsigned num_used);
/* Pretend we've never seen descriptor (for easy error handling). */
-void vringh_abandon_user(struct vringh *vrh, unsigned int num);
+void vringh_abandon(struct vringh *vrh, unsigned int num);
/* Do we need to fire the eventfd to notify the other side? */
-int vringh_need_notify_user(struct vringh *vrh);
+int vringh_need_notify(struct vringh *vrh);
-bool vringh_notify_enable_user(struct vringh *vrh);
-void vringh_notify_disable_user(struct vringh *vrh);
+bool vringh_notify_enable(struct vringh *vrh);
+void vringh_notify_disable(struct vringh *vrh);
/* Helpers for kernelspace vrings. */
int vringh_init_kern(struct vringh *vrh, u64 features,
- unsigned int num, bool weak_barriers,
+ unsigned int num, bool weak_barriers, gfp_t gfp,
struct vring_desc *desc,
struct vring_avail *avail,
struct vring_used *used);
@@ -176,23 +209,6 @@ static inline size_t vringh_kiov_length(struct vringh_kiov
*kiov)
void vringh_kiov_advance(struct vringh_kiov *kiov, size_t len);
-int vringh_getdesc_kern(struct vringh *vrh,
- struct vringh_kiov *riov,
- struct vringh_kiov *wiov,
- u16 *head,
- gfp_t gfp);
-
-ssize_t vringh_iov_pull_kern(struct vringh_kiov *riov, void *dst, size_t len);
-ssize_t vringh_iov_push_kern(struct vringh_kiov *wiov,
- const void *src, size_t len);
-void vringh_abandon_kern(struct vringh *vrh, unsigned int num);
-int vringh_complete_kern(struct vringh *vrh, u16 head, u32 len);
-
-bool vringh_notify_enable_kern(struct vringh *vrh);
-void vringh_notify_disable_kern(struct vringh *vrh);
-
-int vringh_need_notify_kern(struct vringh *vrh);
-
/* Notify the guest about buffers added to the used ring */
static inline void vringh_notify(struct vringh *vrh)
{
@@ -242,33 +258,11 @@ void vringh_set_iotlb(struct vringh *vrh, struct
vhost_iotlb *iotlb,
spinlock_t *iotlb_lock);
int vringh_init_iotlb(struct vringh *vrh, u64 features,
- unsigned int num, bool weak_barriers,
+ unsigned int num, bool weak_barriers, gfp_t gfp,
struct vring_desc *desc,
struct vring_avail *avail,
struct vring_used *used);
-int vringh_getdesc_iotlb(struct vringh *vrh,
- struct vringh_kiov *riov,
- struct vringh_kiov *wiov,
- u16 *head,
- gfp_t gfp);
-
-ssize_t vringh_iov_pull_iotlb(struct vringh *vrh,
- struct vringh_kiov *riov,
- void *dst, size_t len);
-ssize_t vringh_iov_push_iotlb(struct vringh *vrh,
- struct vringh_kiov *wiov,
- const void *src, size_t len);
-
-void vringh_abandon_iotlb(struct vringh *vrh, unsigned int num);
-
-int vringh_complete_iotlb(struct vringh *vrh, u16 head, u32 len);
-
-bool vringh_notify_enable_iotlb(struct vringh *vrh);
-void vringh_notify_disable_iotlb(struct vringh *vrh);
-
-int vringh_need_notify_iotlb(struct vringh *vrh);
-
#endif /* CONFIG_VHOST_IOTLB */
#endif /* _LINUX_VRINGH_H */
--
2.25.1
Michael S. Tsirkin
2022-Dec-27 07:04 UTC
[RFC PATCH 4/9] vringh: unify the APIs for all accessors
On Tue, Dec 27, 2022 at 11:25:26AM +0900, Shunsuke Mie wrote:> Each vringh memory accessors that are for user, kern and iotlb has own > interfaces that calls common code. But some codes are duplicated and that > becomes loss extendability. > > Introduce a struct vringh_ops and provide a common APIs for all accessors. > It can bee easily extended vringh code for new memory accessor and > simplified a caller code. > > Signed-off-by: Shunsuke Mie <mie at igel.co.jp> > --- > drivers/vhost/vringh.c | 667 +++++++++++------------------------------ > include/linux/vringh.h | 100 +++--- > 2 files changed, 225 insertions(+), 542 deletions(-) > > diff --git a/drivers/vhost/vringh.c b/drivers/vhost/vringh.c > index aa3cd27d2384..ebfd3644a1a3 100644 > --- a/drivers/vhost/vringh.c > +++ b/drivers/vhost/vringh.c > @@ -35,15 +35,12 @@ static __printf(1,2) __cold void vringh_bad(const char *fmt, ...) > } > > /* Returns vring->num if empty, -ve on error. */ > -static inline int __vringh_get_head(const struct vringh *vrh, > - int (*getu16)(const struct vringh *vrh, > - u16 *val, const __virtio16 *p), > - u16 *last_avail_idx) > +static inline int __vringh_get_head(const struct vringh *vrh, u16 *last_avail_idx) > { > u16 avail_idx, i, head; > int err; > > - err = getu16(vrh, &avail_idx, &vrh->vring.avail->idx); > + err = vrh->ops.getu16(vrh, &avail_idx, &vrh->vring.avail->idx); > if (err) { > vringh_bad("Failed to access avail idx at %p", > &vrh->vring.avail->idx);I like that this patch removes more lines of code than it adds. However one of the design points of vringh abstractions is that they were carefully written to be very low overhead. This is why we are passing function pointers to inline functions - compiler can optimize that out. I think that introducing ops indirect functions calls here is going to break these assumptions and hurt performance. Unless compiler can somehow figure it out and optimize? I don't see how it's possible with ops pointer in memory but maybe I'm wrong. Was any effort taken to test effect of these patches on performance? Thanks!