Add virtio.c and virtio.h that define the functions needed
to manage virtqueues.
Signed-off-by: Laurent Vivier <lvivier(a)redhat.com>
---
Makefile | 4 +-
util.h | 11 ++
virtio.c | 446 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
virtio.h | 123 +++++++++++++++
4 files changed, 582 insertions(+), 2 deletions(-)
create mode 100644 virtio.c
create mode 100644 virtio.h
diff --git a/Makefile b/Makefile
index 09fc461d087e..39613a7cf1f2 100644
--- a/Makefile
+++ b/Makefile
@@ -47,7 +47,7 @@ FLAGS += -DDUAL_STACK_SOCKETS=$(DUAL_STACK_SOCKETS)
PASST_SRCS = arch.c arp.c checksum.c conf.c dhcp.c dhcpv6.c flow.c fwd.c \
icmp.c igmp.c inany.c iov.c ip.c isolation.c lineread.c log.c mld.c \
ndp.c netlink.c packet.c passt.c pasta.c pcap.c pif.c tap.c tcp.c \
- tcp_buf.c tcp_splice.c udp.c util.c
+ tcp_buf.c tcp_splice.c udp.c util.c virtio.c
QRAP_SRCS = qrap.c
SRCS = $(PASST_SRCS) $(QRAP_SRCS)
@@ -57,7 +57,7 @@ PASST_HEADERS = arch.h arp.h checksum.h conf.h dhcp.h dhcpv6.h flow.h
fwd.h \
flow_table.h icmp.h icmp_flow.h inany.h iov.h ip.h isolation.h \
lineread.h log.h ndp.h netlink.h packet.h passt.h pasta.h pcap.h pif.h \
siphash.h tap.h tcp.h tcp_buf.h tcp_conn.h tcp_internal.h tcp_splice.h \
- udp.h util.h
+ udp.h util.h virtio.h
HEADERS = $(PASST_HEADERS) seccomp.h
C := \#include <linux/tcp.h>\nstruct tcp_info x = { .tcpi_snd_wnd = 0 };
diff --git a/util.h b/util.h
index eebb027be487..56c4e2e7b4fe 100644
--- a/util.h
+++ b/util.h
@@ -48,6 +48,9 @@
#define ROUND_DOWN(x, y) ((x) & ~((y) - 1))
#define ROUND_UP(x, y) (((x) + (y) - 1) & ~((y) - 1))
+#define ALIGN_DOWN(n, m) ((n) / (m) * (m))
+#define ALIGN_UP(n, m) ALIGN_DOWN((n) + (m) - 1, (m))
+
#define MAX_FROM_BITS(n) (((1U << (n)) - 1))
#define BIT(n) (1UL << (n))
@@ -116,6 +119,14 @@
#define htonl_constant(x) (__bswap_constant_32(x))
#endif
+static inline void barrier(void) { __asm__ __volatile__("" :::
"memory"); }
+#define smp_mb() do { barrier(); __atomic_thread_fence(__ATOMIC_SEQ_CST); } while (0)
+#define smp_mb_release() do { barrier(); __atomic_thread_fence(__ATOMIC_RELEASE); } while
(0)
+#define smp_mb_acquire() do { barrier(); __atomic_thread_fence(__ATOMIC_ACQUIRE); } while
(0)
+
+#define smp_wmb() smp_mb_release()
+#define smp_rmb() smp_mb_acquire()
+
#define NS_FN_STACK_SIZE (RLIMIT_STACK_VAL * 1024 / 8)
int do_clone(int (*fn)(void *), char *stack_area, size_t stack_size, int flags,
void *arg);
diff --git a/virtio.c b/virtio.c
new file mode 100644
index 000000000000..50ec8b5119ed
--- /dev/null
+++ b/virtio.c
@@ -0,0 +1,446 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+/* some parts copied from QEMU subprojects/libvhost-user/libvhost-user.c */
+
+#include <stddef.h>
+#include <endian.h>
+#include <string.h>
+#include <errno.h>
+#include <sys/eventfd.h>
+#include <sys/socket.h>
+
+#include "util.h"
+#include "virtio.h"
+
+#define VIRTQUEUE_MAX_SIZE 1024
+
+/* Translate guest physical address to our virtual address. */
+static void *vu_gpa_to_va(VuDev *dev, uint64_t *plen, uint64_t guest_addr)
+{
+ unsigned int i;
+
+ if (*plen == 0)
+ return NULL;
+
+ /* Find matching memory region. */
+ for (i = 0; i < dev->nregions; i++) {
+ const VuDevRegion *r = &dev->regions[i];
+
+ if ((guest_addr >= r->gpa) && (guest_addr < (r->gpa + r->size)))
{
+ if ((guest_addr + *plen) > (r->gpa + r->size))
+ *plen = r->gpa + r->size - guest_addr;
+ /* NOLINTNEXTLINE(performance-no-int-to-ptr) */
+ return (void *)(guest_addr - r->gpa + r->mmap_addr + r->mmap_offset);
+ }
+ }
+
+ return NULL;
+}
+
+static inline uint16_t vring_avail_flags(const VuVirtq *vq)
+{
+ return le16toh(vq->vring.avail->flags);
+}
+
+static inline uint16_t vring_avail_idx(VuVirtq *vq)
+{
+ vq->shadow_avail_idx = le16toh(vq->vring.avail->idx);
+
+ return vq->shadow_avail_idx;
+}
+
+static inline uint16_t vring_avail_ring(const VuVirtq *vq, int i)
+{
+ return le16toh(vq->vring.avail->ring[i]);
+}
+
+static inline uint16_t vring_get_used_event(const VuVirtq *vq)
+{
+ return vring_avail_ring(vq, vq->vring.num);
+}
+
+static bool virtqueue_get_head(VuDev *dev, const VuVirtq *vq,
+ unsigned int idx, unsigned int *head)
+{
+ /* Grab the next descriptor number they're advertising, and increment
+ * the index we've seen.
+ */
+ *head = vring_avail_ring(vq, idx % vq->vring.num);
+
+ /* If their number is silly, that's a fatal mistake. */
+ if (*head >= vq->vring.num) {
+ vu_panic(dev, "Guest says index %u is available", *head);
+ return false;
+ }
+
+ return true;
+}
+
+static int
+virtqueue_read_indirect_desc(VuDev *dev, struct vring_desc *desc,
+ uint64_t addr, size_t len)
+{
+ uint64_t read_len;
+
+ if (len > (VIRTQUEUE_MAX_SIZE * sizeof(struct vring_desc)))
+ return -1;
+
+ if (len == 0)
+ return -1;
+
+ while (len) {
+ const struct vring_desc *ori_desc;
+
+ read_len = len;
+ ori_desc = vu_gpa_to_va(dev, &read_len, addr);
+ if (!ori_desc)
+ return -1;
+
+ memcpy(desc, ori_desc, read_len);
+ len -= read_len;
+ addr += read_len;
+ desc += read_len;
+ }
+
+ return 0;
+}
+
+enum {
+ VIRTQUEUE_READ_DESC_ERROR = -1,
+ VIRTQUEUE_READ_DESC_DONE = 0, /* end of chain */
+ VIRTQUEUE_READ_DESC_MORE = 1, /* more buffers in chain */
+};
+
+static int
+virtqueue_read_next_desc(VuDev *dev, const struct vring_desc *desc,
+ int i, unsigned int max, unsigned int *next)
+{
+ /* If this descriptor says it doesn't chain, we're done. */
+ if (!(le16toh(desc[i].flags) & VRING_DESC_F_NEXT))
+ return VIRTQUEUE_READ_DESC_DONE;
+
+ /* Check they're not leading us off end of descriptors. */
+ *next = le16toh(desc[i].next);
+ /* Make sure compiler knows to grab that: we don't want it changing! */
+ smp_wmb();
+
+ if (*next >= max) {
+ vu_panic(dev, "Desc next is %u", *next);
+ return VIRTQUEUE_READ_DESC_ERROR;
+ }
+
+ return VIRTQUEUE_READ_DESC_MORE;
+}
+
+bool vu_queue_empty(const VuDev *dev, VuVirtq *vq)
+{
+ if (dev->broken ||
+ !vq->vring.avail) {
+ return true;
+ }
+
+ if (vq->shadow_avail_idx != vq->last_avail_idx)
+ return false;
+
+ return vring_avail_idx(vq) == vq->last_avail_idx;
+}
+
+static bool vring_notify(const VuDev *dev, VuVirtq *vq)
+{
+ uint16_t old, new;
+ bool v;
+
+ /* We need to expose used array entries before checking used event. */
+ smp_mb();
+
+ /* Always notify when queue is empty (when feature acknowledge) */
+ if (vu_has_feature(dev, VIRTIO_F_NOTIFY_ON_EMPTY) &&
+ !vq->inuse && vu_queue_empty(dev, vq)) {
+ return true;
+ }
+
+ if (!vu_has_feature(dev, VIRTIO_RING_F_EVENT_IDX))
+ return !(vring_avail_flags(vq) & VRING_AVAIL_F_NO_INTERRUPT);
+
+ v = vq->signalled_used_valid;
+ vq->signalled_used_valid = true;
+ old = vq->signalled_used;
+ new = vq->signalled_used = vq->used_idx;
+ return !v || vring_need_event(vring_get_used_event(vq), new, old);
+}
+
+/* cppcheck-suppress unusedFunction */
+void vu_queue_notify(VuDev *dev, VuVirtq *vq)
+{
+ if (dev->broken || !vq->vring.avail)
+ return;
+
+ if (!vring_notify(dev, vq)) {
+ debug("skipped notify...");
+ return;
+ }
+
+ if (eventfd_write(vq->call_fd, 1) < 0)
+ vu_panic(dev, "Error writing eventfd: %s", strerror(errno));
+}
+
+static inline void vring_set_avail_event(VuVirtq *vq, uint16_t val)
+{
+ uint16_t val_le = htole16(val);
+
+ if (!vq->notification)
+ return;
+
+ memcpy(&vq->vring.used->ring[vq->vring.num], &val_le,
sizeof(uint16_t));
+}
+
+static bool virtqueue_map_desc(VuDev *dev,
+ unsigned int *p_num_sg, struct iovec *iov,
+ unsigned int max_num_sg,
+ uint64_t pa, size_t sz)
+{
+ unsigned int num_sg = *p_num_sg;
+
+ ASSERT(num_sg <= max_num_sg);
+
+ if (!sz) {
+ vu_panic(dev, "virtio: zero sized buffers are not allowed");
+ return false;
+ }
+
+ while (sz) {
+ uint64_t len = sz;
+
+ if (num_sg == max_num_sg) {
+ vu_panic(dev, "virtio: too many descriptors in indirect table");
+ return false;
+ }
+
+ iov[num_sg].iov_base = vu_gpa_to_va(dev, &len, pa);
+ if (iov[num_sg].iov_base == NULL) {
+ vu_panic(dev, "virtio: invalid address for buffers");
+ return false;
+ }
+ iov[num_sg].iov_len = len;
+ num_sg++;
+ sz -= len;
+ pa += len;
+ }
+
+ *p_num_sg = num_sg;
+ return true;
+}
+
+static int
+vu_queue_map_desc(VuDev *dev, VuVirtq *vq, unsigned int idx,
+ VuVirtqElement *elem)
+{
+ const struct vring_desc *desc = vq->vring.desc;
+ struct vring_desc desc_buf[VIRTQUEUE_MAX_SIZE];
+ unsigned int out_num = 0, in_num = 0;
+ unsigned int max = vq->vring.num;
+ unsigned int i = idx;
+ uint64_t read_len;
+ int rc;
+
+ if (le16toh(desc[i].flags) & VRING_DESC_F_INDIRECT) {
+ unsigned int desc_len;
+ uint64_t desc_addr;
+
+ if (le32toh(desc[i].len) % sizeof(struct vring_desc)) {
+ vu_panic(dev, "Invalid size for indirect buffer table");
+ return -1;
+ }
+
+ /* loop over the indirect descriptor table */
+ desc_addr = le64toh(desc[i].addr);
+ desc_len = le32toh(desc[i].len);
+ max = desc_len / sizeof(struct vring_desc);
+ read_len = desc_len;
+ desc = vu_gpa_to_va(dev, &read_len, desc_addr);
+ if (desc && read_len != desc_len) {
+ /* Failed to use zero copy */
+ desc = NULL;
+ if (!virtqueue_read_indirect_desc(dev, desc_buf, desc_addr, desc_len))
+ desc = desc_buf;
+ }
+ if (!desc) {
+ vu_panic(dev, "Invalid indirect buffer table");
+ return -1;
+ }
+ i = 0;
+ }
+
+ /* Collect all the descriptors */
+ do {
+ if (le16toh(desc[i].flags) & VRING_DESC_F_WRITE) {
+ if (!virtqueue_map_desc(dev, &in_num, elem->in_sg,
+ elem->in_num,
+ le64toh(desc[i].addr),
+ le32toh(desc[i].len))) {
+ return -1;
+ }
+ } else {
+ if (in_num) {
+ vu_panic(dev, "Incorrect order for descriptors");
+ return -1;
+ }
+ if (!virtqueue_map_desc(dev, &out_num, elem->out_sg,
+ elem->out_num,
+ le64toh(desc[i].addr),
+ le32toh(desc[i].len))) {
+ return -1;
+ }
+ }
+
+ /* If we've got too many, that implies a descriptor loop. */
+ if ((in_num + out_num) > max) {
+ vu_panic(dev, "Looped descriptor");
+ return -1;
+ }
+ rc = virtqueue_read_next_desc(dev, desc, i, max, &i);
+ } while (rc == VIRTQUEUE_READ_DESC_MORE);
+
+ if (rc == VIRTQUEUE_READ_DESC_ERROR) {
+ vu_panic(dev, "read descriptor error");
+ return -1;
+ }
+
+ elem->index = idx;
+ elem->in_num = in_num;
+ elem->out_num = out_num;
+
+ return 0;
+}
+
+/* cppcheck-suppress unusedFunction */
+int vu_queue_pop(VuDev *dev, VuVirtq *vq, VuVirtqElement *elem)
+{
+ unsigned int head;
+ int ret;
+
+ if (dev->broken || !vq->vring.avail)
+ return -1;
+
+ if (vu_queue_empty(dev, vq))
+ return -1;
+
+ /*
+ * Needed after virtio_queue_empty(), see comment in
+ * virtqueue_num_heads().
+ */
+ smp_rmb();
+
+ if (vq->inuse >= vq->vring.num) {
+ vu_panic(dev, "Virtqueue size exceeded");
+ return -1;
+ }
+
+ if (!virtqueue_get_head(dev, vq, vq->last_avail_idx++, &head))
+ return -1;
+
+ if (vu_has_feature(dev, VIRTIO_RING_F_EVENT_IDX))
+ vring_set_avail_event(vq, vq->last_avail_idx);
+
+ ret = vu_queue_map_desc(dev, vq, head, elem);
+
+ if (ret < 0)
+ return ret;
+
+ vq->inuse++;
+
+ return 0;
+}
+
+void vu_queue_detach_element(VuDev *dev, VuVirtq *vq,
+ unsigned int index, size_t len)
+{
+ (void)dev;
+ (void)index;
+ (void)len;
+
+ vq->inuse--;
+ /* unmap, when DMA support is added */
+}
+
+/* cppcheck-suppress unusedFunction */
+void vu_queue_unpop(VuDev *dev, VuVirtq *vq, unsigned int index, size_t len)
+{
+ vq->last_avail_idx--;
+ vu_queue_detach_element(dev, vq, index, len);
+}
+
+/* cppcheck-suppress unusedFunction */
+bool vu_queue_rewind(VuDev *dev, VuVirtq *vq, unsigned int num)
+{
+ (void)dev;
+ if (num > vq->inuse)
+ return false;
+
+ vq->last_avail_idx -= num;
+ vq->inuse -= num;
+ return true;
+}
+
+static inline void vring_used_write(VuVirtq *vq,
+ const struct vring_used_elem *uelem, int i)
+{
+ struct vring_used *used = vq->vring.used;
+
+ used->ring[i] = *uelem;
+}
+
+void vu_queue_fill_by_index(const VuDev *dev, VuVirtq *vq, unsigned int index,
+ unsigned int len, unsigned int idx)
+{
+ struct vring_used_elem uelem;
+
+ if (dev->broken || !vq->vring.avail)
+ return;
+
+ idx = (idx + vq->used_idx) % vq->vring.num;
+
+ uelem.id = htole32(index);
+ uelem.len = htole32(len);
+ vring_used_write(vq, &uelem, idx);
+}
+
+void vu_queue_fill(const VuDev *dev, VuVirtq *vq, const VuVirtqElement *elem,
+ unsigned int len, unsigned int idx)
+{
+ vu_queue_fill_by_index(dev, vq, elem->index, len, idx);
+}
+
+static inline void vring_used_idx_set(VuVirtq *vq, uint16_t val)
+{
+ vq->vring.used->idx = htole16(val);
+
+ vq->used_idx = val;
+}
+
+void vu_queue_flush(const VuDev *dev, VuVirtq *vq, unsigned int count)
+{
+ uint16_t old, new;
+
+ if (dev->broken || !vq->vring.avail)
+ return;
+
+ /* Make sure buffer is written before we update index. */
+ smp_wmb();
+
+ old = vq->used_idx;
+ new = old + count;
+ vring_used_idx_set(vq, new);
+ vq->inuse -= count;
+ if ((int16_t)(new - vq->signalled_used) < (uint16_t)(new - old))
+ vq->signalled_used_valid = false;
+}
+
+/* cppcheck-suppress unusedFunction */
+void vu_queue_push(const VuDev *dev, VuVirtq *vq,
+ const VuVirtqElement *elem, unsigned int len)
+{
+ vu_queue_fill(dev, vq, elem, len, 0);
+ vu_queue_flush(dev, vq, 1);
+}
+
diff --git a/virtio.h b/virtio.h
new file mode 100644
index 000000000000..61398bb432bc
--- /dev/null
+++ b/virtio.h
@@ -0,0 +1,123 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+//
+/* come parts copied from QEMU subprojects/libvhost-user/libvhost-user.h */
+
+#ifndef VIRTIO_H
+#define VIRTIO_H
+
+#include <stdbool.h>
+#include <linux/vhost_types.h>
+
+#define VIRTQUEUE_MAX_SIZE 1024
+
+#define vu_panic(vdev, ...) \
+ do { \
+ (vdev)->broken = true; \
+ err( __VA_ARGS__ ); \
+ } while (0)
+
+typedef struct VuRing {
+ unsigned int num;
+ struct vring_desc *desc;
+ struct vring_avail *avail;
+ struct vring_used *used;
+ uint64_t log_guest_addr;
+ uint32_t flags;
+} VuRing;
+
+typedef struct VuVirtq {
+ VuRing vring;
+
+ /* Next head to pop */
+ uint16_t last_avail_idx;
+
+ /* Last avail_idx read from VQ. */
+ uint16_t shadow_avail_idx;
+
+ uint16_t used_idx;
+
+ /* Last used index value we have signalled on */
+ uint16_t signalled_used;
+
+ /* Last used index value we have signalled on */
+ bool signalled_used_valid;
+
+ bool notification;
+
+ unsigned int inuse;
+
+ int call_fd;
+ int kick_fd;
+ int err_fd;
+ unsigned int enable;
+ bool started;
+
+ /* Guest addresses of our ring */
+ struct vhost_vring_addr vra;
+} VuVirtq;
+
+typedef struct VuDevRegion {
+ uint64_t gpa;
+ uint64_t size;
+ uint64_t qva;
+ uint64_t mmap_offset;
+ uint64_t mmap_addr;
+} VuDevRegion;
+
+#define VHOST_USER_MAX_QUEUES 2
+
+/*
+ * Set a reasonable maximum number of ram slots, which will be supported by
+ * any architecture.
+ */
+#define VHOST_USER_MAX_RAM_SLOTS 32
+
+typedef struct VuDev {
+ uint32_t nregions;
+ VuDevRegion regions[VHOST_USER_MAX_RAM_SLOTS];
+ VuVirtq vq[VHOST_USER_MAX_QUEUES];
+ uint64_t features;
+ uint64_t protocol_features;
+ bool broken;
+ int hdrlen;
+} VuDev;
+
+typedef struct VuVirtqElement {
+ unsigned int index;
+ unsigned int out_num;
+ unsigned int in_num;
+ struct iovec *in_sg;
+ struct iovec *out_sg;
+} VuVirtqElement;
+
+static inline bool has_feature(uint64_t features, unsigned int fbit)
+{
+ return !!(features & (1ULL << fbit));
+}
+
+static inline bool vu_has_feature(const VuDev *vdev, unsigned int fbit)
+{
+ return has_feature(vdev->features, fbit);
+}
+
+/* cppcheck-suppress unusedFunction */
+static inline bool vu_has_protocol_feature(const VuDev *vdev, unsigned int fbit)
+{
+ return has_feature(vdev->protocol_features, fbit);
+}
+
+bool vu_queue_empty(const VuDev *dev, VuVirtq *vq);
+void vu_queue_notify(VuDev *dev, VuVirtq *vq);
+int vu_queue_pop(VuDev *dev, VuVirtq *vq, VuVirtqElement *elem);
+void vu_queue_detach_element(VuDev *dev, VuVirtq *vq, unsigned int index, size_t len);
+void vu_queue_unpop(VuDev *dev, VuVirtq *vq, unsigned int index, size_t len);
+bool vu_queue_rewind(VuDev *dev, VuVirtq *vq, unsigned int num);
+
+void vu_queue_fill_by_index(const VuDev *dev, VuVirtq *vq, unsigned int index,
+ unsigned int len, unsigned int idx);
+void vu_queue_fill(const VuDev *dev, VuVirtq *vq, const VuVirtqElement *elem,
+ unsigned int len, unsigned int idx);
+void vu_queue_flush(const VuDev *dev, VuVirtq *vq, unsigned int count);
+void vu_queue_push(const VuDev *dev, VuVirtq *vq, const VuVirtqElement *elem,
+ unsigned int len);
+#endif /* VIRTIO_H */
--
2.45.2