#include <linux/module.h>
#include <linux/hrtimer.h>
#include <linux/kmemleak.h>
+#include <linux/dma-mapping.h>
+#include <xen/xen.h>
#ifdef DEBUG
/* For development, we want to crash whenever the ring is screwed. */
#define END_USE(vq)
#endif
+struct vring_desc_state {
+ void *data; /* Data for callback. */
+ struct vring_desc *indir_desc; /* Indirect descriptor, if any. */
+};
+
struct vring_virtqueue {
struct virtqueue vq;
/* How to notify other side. FIXME: commonalize hcalls! */
bool (*notify)(struct virtqueue *vq);
+ /* DMA, allocation, and size information */
+ bool we_own_ring;
+ size_t queue_size_in_bytes;
+ dma_addr_t queue_dma_addr;
+
#ifdef DEBUG
/* They're supposed to lock for us. */
unsigned int in_use;
ktime_t last_add_time;
#endif
- /* Tokens for callbacks. */
- void *data[];
+ /* Per-descriptor state. */
+ struct vring_desc_state desc_state[];
};
#define to_vvq(_vq) container_of(_vq, struct vring_virtqueue, vq)
+/*
+ * The interaction between virtio and a possible IOMMU is a mess.
+ *
+ * On most systems with virtio, physical addresses match bus addresses,
+ * and it doesn't particularly matter whether we use the DMA API.
+ *
+ * On some systems, including Xen and any system with a physical device
+ * that speaks virtio behind a physical IOMMU, we must use the DMA API
+ * for virtio DMA to work at all.
+ *
+ * On other systems, including SPARC and PPC64, virtio-pci devices are
+ * enumerated as though they are behind an IOMMU, but the virtio host
+ * ignores the IOMMU, so we must either pretend that the IOMMU isn't
+ * there or somehow map everything as the identity.
+ *
+ * For the time being, we preserve historic behavior and bypass the DMA
+ * API.
+ */
+
+static bool vring_use_dma_api(struct virtio_device *vdev)
+{
+ /*
+ * In theory, it's possible to have a buggy QEMU-supposed
+ * emulated Q35 IOMMU and Xen enabled at the same time. On
+ * such a configuration, virtio has never worked and will
+ * not work without an even larger kludge. Instead, enable
+ * the DMA API if we're a Xen guest, which at least allows
+ * all of the sensible Xen configurations to work correctly.
+ */
+ if (xen_domain())
+ return true;
+
+ return false;
+}
+
+/*
+ * The DMA ops on various arches are rather gnarly right now, and
+ * making all of the arch DMA ops work on the vring device itself
+ * is a mess. For now, we use the parent device for DMA ops.
+ */
+struct device *vring_dma_dev(const struct vring_virtqueue *vq)
+{
+ return vq->vq.vdev->dev.parent;
+}
+
+/* Map one sg entry. */
+static dma_addr_t vring_map_one_sg(const struct vring_virtqueue *vq,
+ struct scatterlist *sg,
+ enum dma_data_direction direction)
+{
+ if (!vring_use_dma_api(vq->vq.vdev))
+ return (dma_addr_t)sg_phys(sg);
+
+ /*
+ * We can't use dma_map_sg, because we don't use scatterlists in
+ * the way it expects (we don't guarantee that the scatterlist
+ * will exist for the lifetime of the mapping).
+ */
+ return dma_map_page(vring_dma_dev(vq),
+ sg_page(sg), sg->offset, sg->length,
+ direction);
+}
+
+static dma_addr_t vring_map_single(const struct vring_virtqueue *vq,
+ void *cpu_addr, size_t size,
+ enum dma_data_direction direction)
+{
+ if (!vring_use_dma_api(vq->vq.vdev))
+ return (dma_addr_t)virt_to_phys(cpu_addr);
+
+ return dma_map_single(vring_dma_dev(vq),
+ cpu_addr, size, direction);
+}
+
+static void vring_unmap_one(const struct vring_virtqueue *vq,
+ struct vring_desc *desc)
+{
+ u16 flags;
+
+ if (!vring_use_dma_api(vq->vq.vdev))
+ return;
+
+ flags = virtio16_to_cpu(vq->vq.vdev, desc->flags);
+
+ if (flags & VRING_DESC_F_INDIRECT) {
+ dma_unmap_single(vring_dma_dev(vq),
+ virtio64_to_cpu(vq->vq.vdev, desc->addr),
+ virtio32_to_cpu(vq->vq.vdev, desc->len),
+ (flags & VRING_DESC_F_WRITE) ?
+ DMA_FROM_DEVICE : DMA_TO_DEVICE);
+ } else {
+ dma_unmap_page(vring_dma_dev(vq),
+ virtio64_to_cpu(vq->vq.vdev, desc->addr),
+ virtio32_to_cpu(vq->vq.vdev, desc->len),
+ (flags & VRING_DESC_F_WRITE) ?
+ DMA_FROM_DEVICE : DMA_TO_DEVICE);
+ }
+}
+
+static int vring_mapping_error(const struct vring_virtqueue *vq,
+ dma_addr_t addr)
+{
+ if (!vring_use_dma_api(vq->vq.vdev))
+ return 0;
+
+ return dma_mapping_error(vring_dma_dev(vq), addr);
+}
+
static struct vring_desc *alloc_indirect(struct virtqueue *_vq,
unsigned int total_sg, gfp_t gfp)
{
struct vring_virtqueue *vq = to_vvq(_vq);
struct scatterlist *sg;
struct vring_desc *desc;
- unsigned int i, n, avail, descs_used, uninitialized_var(prev);
+ unsigned int i, n, avail, descs_used, uninitialized_var(prev), err_idx;
int head;
bool indirect;
if (desc) {
/* Use a single buffer which doesn't continue */
- vq->vring.desc[head].flags = cpu_to_virtio16(_vq->vdev, VRING_DESC_F_INDIRECT);
- vq->vring.desc[head].addr = cpu_to_virtio64(_vq->vdev, virt_to_phys(desc));
- /* avoid kmemleak false positive (hidden by virt_to_phys) */
- kmemleak_ignore(desc);
- vq->vring.desc[head].len = cpu_to_virtio32(_vq->vdev, total_sg * sizeof(struct vring_desc));
-
+ indirect = true;
/* Set up rest to use this indirect table. */
i = 0;
descs_used = 1;
- indirect = true;
} else {
+ indirect = false;
desc = vq->vring.desc;
i = head;
descs_used = total_sg;
- indirect = false;
}
if (vq->vq.num_free < descs_used) {
return -ENOSPC;
}
- /* We're about to use some buffers from the free list. */
- vq->vq.num_free -= descs_used;
-
for (n = 0; n < out_sgs; n++) {
for (sg = sgs[n]; sg; sg = sg_next(sg)) {
+ dma_addr_t addr = vring_map_one_sg(vq, sg, DMA_TO_DEVICE);
+ if (vring_mapping_error(vq, addr))
+ goto unmap_release;
+
desc[i].flags = cpu_to_virtio16(_vq->vdev, VRING_DESC_F_NEXT);
- desc[i].addr = cpu_to_virtio64(_vq->vdev, sg_phys(sg));
+ desc[i].addr = cpu_to_virtio64(_vq->vdev, addr);
desc[i].len = cpu_to_virtio32(_vq->vdev, sg->length);
prev = i;
i = virtio16_to_cpu(_vq->vdev, desc[i].next);
}
for (; n < (out_sgs + in_sgs); n++) {
for (sg = sgs[n]; sg; sg = sg_next(sg)) {
+ dma_addr_t addr = vring_map_one_sg(vq, sg, DMA_FROM_DEVICE);
+ if (vring_mapping_error(vq, addr))
+ goto unmap_release;
+
desc[i].flags = cpu_to_virtio16(_vq->vdev, VRING_DESC_F_NEXT | VRING_DESC_F_WRITE);
- desc[i].addr = cpu_to_virtio64(_vq->vdev, sg_phys(sg));
+ desc[i].addr = cpu_to_virtio64(_vq->vdev, addr);
desc[i].len = cpu_to_virtio32(_vq->vdev, sg->length);
prev = i;
i = virtio16_to_cpu(_vq->vdev, desc[i].next);
/* Last one doesn't continue. */
desc[prev].flags &= cpu_to_virtio16(_vq->vdev, ~VRING_DESC_F_NEXT);
+ if (indirect) {
+ /* Now that the indirect table is filled in, map it. */
+ dma_addr_t addr = vring_map_single(
+ vq, desc, total_sg * sizeof(struct vring_desc),
+ DMA_TO_DEVICE);
+ if (vring_mapping_error(vq, addr))
+ goto unmap_release;
+
+ vq->vring.desc[head].flags = cpu_to_virtio16(_vq->vdev, VRING_DESC_F_INDIRECT);
+ vq->vring.desc[head].addr = cpu_to_virtio64(_vq->vdev, addr);
+
+ vq->vring.desc[head].len = cpu_to_virtio32(_vq->vdev, total_sg * sizeof(struct vring_desc));
+ }
+
+ /* We're using some buffers from the free list. */
+ vq->vq.num_free -= descs_used;
+
/* Update free pointer */
if (indirect)
vq->free_head = virtio16_to_cpu(_vq->vdev, vq->vring.desc[head].next);
else
vq->free_head = i;
- /* Set token. */
- vq->data[head] = data;
+ /* Store token and indirect buffer state. */
+ vq->desc_state[head].data = data;
+ if (indirect)
+ vq->desc_state[head].indir_desc = desc;
/* Put entry in available array (but don't update avail->idx until they
* do sync). */
virtqueue_kick(_vq);
return 0;
+
+unmap_release:
+ err_idx = i;
+ i = head;
+
+ for (n = 0; n < total_sg; n++) {
+ if (i == err_idx)
+ break;
+ vring_unmap_one(vq, &desc[i]);
+ i = vq->vring.desc[i].next;
+ }
+
+ vq->vq.num_free += total_sg;
+
+ if (indirect)
+ kfree(desc);
+
+ return -EIO;
}
/**
static void detach_buf(struct vring_virtqueue *vq, unsigned int head)
{
- unsigned int i;
+ unsigned int i, j;
+ u16 nextflag = cpu_to_virtio16(vq->vq.vdev, VRING_DESC_F_NEXT);
/* Clear data ptr. */
- vq->data[head] = NULL;
+ vq->desc_state[head].data = NULL;
- /* Put back on free list: find end */
+ /* Put back on free list: unmap first-level descriptors and find end */
i = head;
- /* Free the indirect table */
- if (vq->vring.desc[i].flags & cpu_to_virtio16(vq->vq.vdev, VRING_DESC_F_INDIRECT))
- kfree(phys_to_virt(virtio64_to_cpu(vq->vq.vdev, vq->vring.desc[i].addr)));
-
- while (vq->vring.desc[i].flags & cpu_to_virtio16(vq->vq.vdev, VRING_DESC_F_NEXT)) {
+ while (vq->vring.desc[i].flags & nextflag) {
+ vring_unmap_one(vq, &vq->vring.desc[i]);
i = virtio16_to_cpu(vq->vq.vdev, vq->vring.desc[i].next);
vq->vq.num_free++;
}
+ vring_unmap_one(vq, &vq->vring.desc[i]);
vq->vring.desc[i].next = cpu_to_virtio16(vq->vq.vdev, vq->free_head);
vq->free_head = head;
+
/* Plus final descriptor */
vq->vq.num_free++;
+
+ /* Free the indirect table, if any, now that it's unmapped. */
+ if (vq->desc_state[head].indir_desc) {
+ struct vring_desc *indir_desc = vq->desc_state[head].indir_desc;
+ u32 len = virtio32_to_cpu(vq->vq.vdev, vq->vring.desc[head].len);
+
+ BUG_ON(!(vq->vring.desc[head].flags &
+ cpu_to_virtio16(vq->vq.vdev, VRING_DESC_F_INDIRECT)));
+ BUG_ON(len == 0 || len % sizeof(struct vring_desc));
+
+ for (j = 0; j < len / sizeof(struct vring_desc); j++)
+ vring_unmap_one(vq, &indir_desc[j]);
+
+ kfree(vq->desc_state[head].indir_desc);
+ vq->desc_state[head].indir_desc = NULL;
+ }
}
static inline bool more_used(const struct vring_virtqueue *vq)
BAD_RING(vq, "id %u out of range\n", i);
return NULL;
}
- if (unlikely(!vq->data[i])) {
+ if (unlikely(!vq->desc_state[i].data)) {
BAD_RING(vq, "id %u is not a head!\n", i);
return NULL;
}
/* detach_buf clears data, so grab it now. */
- ret = vq->data[i];
+ ret = vq->desc_state[i].data;
detach_buf(vq, i);
vq->last_used_idx++;
/* If we expect an interrupt for the next entry, tell host
START_USE(vq);
for (i = 0; i < vq->vring.num; i++) {
- if (!vq->data[i])
+ if (!vq->desc_state[i].data)
continue;
/* detach_buf clears data, so grab it now. */
- buf = vq->data[i];
+ buf = vq->desc_state[i].data;
detach_buf(vq, i);
vq->avail_idx_shadow--;
vq->vring.avail->idx = cpu_to_virtio16(_vq->vdev, vq->avail_idx_shadow);
}
EXPORT_SYMBOL_GPL(vring_interrupt);
-struct virtqueue *vring_new_virtqueue(unsigned int index,
- unsigned int num,
- unsigned int vring_align,
- struct virtio_device *vdev,
- bool weak_barriers,
- void *pages,
- bool (*notify)(struct virtqueue *),
- void (*callback)(struct virtqueue *),
- const char *name)
+struct virtqueue *__vring_new_virtqueue(unsigned int index,
+ struct vring vring,
+ struct virtio_device *vdev,
+ bool weak_barriers,
+ bool (*notify)(struct virtqueue *),
+ void (*callback)(struct virtqueue *),
+ const char *name)
{
- struct vring_virtqueue *vq;
unsigned int i;
+ struct vring_virtqueue *vq;
- /* We assume num is a power of 2. */
- if (num & (num - 1)) {
- dev_warn(&vdev->dev, "Bad virtqueue length %u\n", num);
- return NULL;
- }
-
- vq = kmalloc(sizeof(*vq) + sizeof(void *)*num, GFP_KERNEL);
+ vq = kmalloc(sizeof(*vq) + vring.num * sizeof(struct vring_desc_state),
+ GFP_KERNEL);
if (!vq)
return NULL;
- vring_init(&vq->vring, num, pages, vring_align);
+ vq->vring = vring;
vq->vq.callback = callback;
vq->vq.vdev = vdev;
vq->vq.name = name;
- vq->vq.num_free = num;
+ vq->vq.num_free = vring.num;
vq->vq.index = index;
+ vq->we_own_ring = false;
+ vq->queue_dma_addr = 0;
+ vq->queue_size_in_bytes = 0;
vq->notify = notify;
vq->weak_barriers = weak_barriers;
vq->broken = false;
/* Put everything in free lists. */
vq->free_head = 0;
- for (i = 0; i < num-1; i++) {
+ for (i = 0; i < vring.num-1; i++)
vq->vring.desc[i].next = cpu_to_virtio16(vdev, i + 1);
- vq->data[i] = NULL;
- }
- vq->data[i] = NULL;
+ memset(vq->desc_state, 0, vring.num * sizeof(struct vring_desc_state));
return &vq->vq;
}
+EXPORT_SYMBOL_GPL(__vring_new_virtqueue);
+
+static void *vring_alloc_queue(struct virtio_device *vdev, size_t size,
+ dma_addr_t *dma_handle, gfp_t flag)
+{
+ if (vring_use_dma_api(vdev)) {
+ return dma_alloc_coherent(vdev->dev.parent, size,
+ dma_handle, flag);
+ } else {
+ void *queue = alloc_pages_exact(PAGE_ALIGN(size), flag);
+ if (queue) {
+ phys_addr_t phys_addr = virt_to_phys(queue);
+ *dma_handle = (dma_addr_t)phys_addr;
+
+ /*
+ * Sanity check: make sure we dind't truncate
+ * the address. The only arches I can find that
+ * have 64-bit phys_addr_t but 32-bit dma_addr_t
+ * are certain non-highmem MIPS and x86
+ * configurations, but these configurations
+ * should never allocate physical pages above 32
+ * bits, so this is fine. Just in case, throw a
+ * warning and abort if we end up with an
+ * unrepresentable address.
+ */
+ if (WARN_ON_ONCE(*dma_handle != phys_addr)) {
+ free_pages_exact(queue, PAGE_ALIGN(size));
+ return NULL;
+ }
+ }
+ return queue;
+ }
+}
+
+static void vring_free_queue(struct virtio_device *vdev, size_t size,
+ void *queue, dma_addr_t dma_handle)
+{
+ if (vring_use_dma_api(vdev)) {
+ dma_free_coherent(vdev->dev.parent, size, queue, dma_handle);
+ } else {
+ free_pages_exact(queue, PAGE_ALIGN(size));
+ }
+}
+
+struct virtqueue *vring_create_virtqueue(
+ unsigned int index,
+ unsigned int num,
+ unsigned int vring_align,
+ struct virtio_device *vdev,
+ bool weak_barriers,
+ bool may_reduce_num,
+ bool (*notify)(struct virtqueue *),
+ void (*callback)(struct virtqueue *),
+ const char *name)
+{
+ struct virtqueue *vq;
+ void *queue;
+ dma_addr_t dma_addr;
+ size_t queue_size_in_bytes;
+ struct vring vring;
+
+ /* We assume num is a power of 2. */
+ if (num & (num - 1)) {
+ dev_warn(&vdev->dev, "Bad virtqueue length %u\n", num);
+ return NULL;
+ }
+
+ /* TODO: allocate each queue chunk individually */
+ for (; num && vring_size(num, vring_align) > PAGE_SIZE; num /= 2) {
+ queue = vring_alloc_queue(vdev, vring_size(num, vring_align),
+ &dma_addr,
+ GFP_KERNEL|__GFP_NOWARN|__GFP_ZERO);
+ if (queue)
+ break;
+ }
+
+ if (!num)
+ return NULL;
+
+ if (!queue) {
+ /* Try to get a single page. You are my only hope! */
+ queue = vring_alloc_queue(vdev, vring_size(num, vring_align),
+ &dma_addr, GFP_KERNEL|__GFP_ZERO);
+ }
+ if (!queue)
+ return NULL;
+
+ queue_size_in_bytes = vring_size(num, vring_align);
+ vring_init(&vring, num, queue, vring_align);
+
+ vq = __vring_new_virtqueue(index, vring, vdev, weak_barriers,
+ notify, callback, name);
+ if (!vq) {
+ vring_free_queue(vdev, queue_size_in_bytes, queue,
+ dma_addr);
+ return NULL;
+ }
+
+ to_vvq(vq)->queue_dma_addr = dma_addr;
+ to_vvq(vq)->queue_size_in_bytes = queue_size_in_bytes;
+ to_vvq(vq)->we_own_ring = true;
+
+ return vq;
+}
+EXPORT_SYMBOL_GPL(vring_create_virtqueue);
+
+struct virtqueue *vring_new_virtqueue(unsigned int index,
+ unsigned int num,
+ unsigned int vring_align,
+ struct virtio_device *vdev,
+ bool weak_barriers,
+ void *pages,
+ bool (*notify)(struct virtqueue *vq),
+ void (*callback)(struct virtqueue *vq),
+ const char *name)
+{
+ struct vring vring;
+ vring_init(&vring, num, pages, vring_align);
+ return __vring_new_virtqueue(index, vring, vdev, weak_barriers,
+ notify, callback, name);
+}
EXPORT_SYMBOL_GPL(vring_new_virtqueue);
-void vring_del_virtqueue(struct virtqueue *vq)
+void vring_del_virtqueue(struct virtqueue *_vq)
{
- list_del(&vq->list);
- kfree(to_vvq(vq));
+ struct vring_virtqueue *vq = to_vvq(_vq);
+
+ if (vq->we_own_ring) {
+ vring_free_queue(vq->vq.vdev, vq->queue_size_in_bytes,
+ vq->vring.desc, vq->queue_dma_addr);
+ }
+ list_del(&_vq->list);
+ kfree(vq);
}
EXPORT_SYMBOL_GPL(vring_del_virtqueue);
}
EXPORT_SYMBOL_GPL(virtio_break_device);
-void *virtqueue_get_avail(struct virtqueue *_vq)
+dma_addr_t virtqueue_get_desc_addr(struct virtqueue *_vq)
{
struct vring_virtqueue *vq = to_vvq(_vq);
- return vq->vring.avail;
+ BUG_ON(!vq->we_own_ring);
+
+ return vq->queue_dma_addr;
}
-EXPORT_SYMBOL_GPL(virtqueue_get_avail);
+EXPORT_SYMBOL_GPL(virtqueue_get_desc_addr);
-void *virtqueue_get_used(struct virtqueue *_vq)
+dma_addr_t virtqueue_get_avail_addr(struct virtqueue *_vq)
{
struct vring_virtqueue *vq = to_vvq(_vq);
- return vq->vring.used;
+ BUG_ON(!vq->we_own_ring);
+
+ return vq->queue_dma_addr +
+ ((char *)vq->vring.avail - (char *)vq->vring.desc);
+}
+EXPORT_SYMBOL_GPL(virtqueue_get_avail_addr);
+
+dma_addr_t virtqueue_get_used_addr(struct virtqueue *_vq)
+{
+ struct vring_virtqueue *vq = to_vvq(_vq);
+
+ BUG_ON(!vq->we_own_ring);
+
+ return vq->queue_dma_addr +
+ ((char *)vq->vring.used - (char *)vq->vring.desc);
+}
+EXPORT_SYMBOL_GPL(virtqueue_get_used_addr);
+
+const struct vring *virtqueue_get_vring(struct virtqueue *vq)
+{
+ return &to_vvq(vq)->vring;
}
-EXPORT_SYMBOL_GPL(virtqueue_get_used);
+EXPORT_SYMBOL_GPL(virtqueue_get_vring);
MODULE_LICENSE("GPL");
projects / linux-2.6-block.git / blobdiff