diff options
author | Michael S. Tsirkin <mst@redhat.com> | 2014-12-11 13:59:51 +0200 |
---|---|---|
committer | Rusty Russell <rusty@rustcorp.com.au> | 2015-01-21 16:28:53 +1030 |
commit | 1fcf0512c9c870e78e1c9898ecb9458593403466 (patch) | |
tree | 002fa2a03688453e491f2224c31a96c1b3a47be6 | |
parent | 71d70c266c84c4e708bb36b20d0c0a29af42821c (diff) | |
download | linux-stable-1fcf0512c9c870e78e1c9898ecb9458593403466.tar.gz linux-stable-1fcf0512c9c870e78e1c9898ecb9458593403466.tar.bz2 linux-stable-1fcf0512c9c870e78e1c9898ecb9458593403466.zip |
virtio_pci: modern driver
Lightly tested against qemu.
One thing *not* implemented here is separate mappings
for descriptor/avail/used rings. That's nice to have,
will be done later after we have core support.
This also exposes the PCI layout to userspace, and
adds macros for PCI layout offsets:
QEMU wants it, so why not? Trust, but verify.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
-rw-r--r-- | drivers/virtio/Makefile | 2 | ||||
-rw-r--r-- | drivers/virtio/virtio_pci_common.c | 14 | ||||
-rw-r--r-- | drivers/virtio/virtio_pci_common.h | 25 | ||||
-rw-r--r-- | drivers/virtio/virtio_pci_modern.c | 587 | ||||
-rw-r--r-- | include/uapi/linux/virtio_pci.h | 7 |
5 files changed, 625 insertions, 10 deletions
diff --git a/drivers/virtio/Makefile b/drivers/virtio/Makefile index bf5104b56894..bd230d1c0533 100644 --- a/drivers/virtio/Makefile +++ b/drivers/virtio/Makefile @@ -1,5 +1,5 @@ obj-$(CONFIG_VIRTIO) += virtio.o virtio_ring.o obj-$(CONFIG_VIRTIO_MMIO) += virtio_mmio.o obj-$(CONFIG_VIRTIO_PCI) += virtio_pci.o -virtio_pci-y := virtio_pci_legacy.o virtio_pci_common.o +virtio_pci-y := virtio_pci_modern.o virtio_pci_legacy.o virtio_pci_common.o obj-$(CONFIG_VIRTIO_BALLOON) += virtio_balloon.o diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c index 457cbe29c8c4..8ae34a34f3af 100644 --- a/drivers/virtio/virtio_pci_common.c +++ b/drivers/virtio/virtio_pci_common.c @@ -505,7 +505,9 @@ static int virtio_pci_probe(struct pci_dev *pci_dev, if (rc) goto err_request_regions; - rc = virtio_pci_legacy_probe(vp_dev); + rc = virtio_pci_modern_probe(vp_dev); + if (rc == -ENODEV) + rc = virtio_pci_legacy_probe(vp_dev); if (rc) goto err_probe; @@ -518,7 +520,10 @@ static int virtio_pci_probe(struct pci_dev *pci_dev, return 0; err_register: - virtio_pci_legacy_remove(vp_dev); + if (vp_dev->ioaddr) + virtio_pci_legacy_remove(vp_dev); + else + virtio_pci_modern_remove(vp_dev); err_probe: pci_release_regions(pci_dev); err_request_regions: @@ -534,7 +539,10 @@ static void virtio_pci_remove(struct pci_dev *pci_dev) unregister_virtio_device(&vp_dev->vdev); - virtio_pci_legacy_remove(pci_dev); + if (vp_dev->ioaddr) + virtio_pci_legacy_remove(vp_dev); + else + virtio_pci_modern_remove(vp_dev); pci_release_regions(pci_dev); pci_disable_device(pci_dev); diff --git a/drivers/virtio/virtio_pci_common.h b/drivers/virtio/virtio_pci_common.h index 2b1e70db44a0..610c43f19230 100644 --- a/drivers/virtio/virtio_pci_common.h +++ b/drivers/virtio/virtio_pci_common.h @@ -53,12 +53,29 @@ struct virtio_pci_device { struct virtio_device vdev; struct pci_dev *pci_dev; + /* In legacy mode, these two point to within ->legacy. */ + /* Where to read and clear interrupt */ + u8 __iomem *isr; + + /* Modern only fields */ + /* The IO mapping for the PCI config space (non-legacy mode) */ + struct virtio_pci_common_cfg __iomem *common; + /* Device-specific data (non-legacy mode) */ + void __iomem *device; + + /* So we can sanity-check accesses. */ + size_t device_len; + + /* Capability for when we need to map notifications per-vq. */ + int notify_map_cap; + + /* Multiply queue_notify_off by this value. (non-legacy mode). */ + u32 notify_offset_multiplier; + + /* Legacy only field */ /* the IO mapping for the PCI config space */ void __iomem *ioaddr; - /* the IO mapping for ISR operation */ - void __iomem *isr; - /* a list of queues so we can dispatch IRQs */ spinlock_t lock; struct list_head virtqueues; @@ -129,5 +146,7 @@ int vp_set_vq_affinity(struct virtqueue *vq, int cpu); int virtio_pci_legacy_probe(struct virtio_pci_device *); void virtio_pci_legacy_remove(struct virtio_pci_device *); +int virtio_pci_modern_probe(struct virtio_pci_device *); +void virtio_pci_modern_remove(struct virtio_pci_device *); #endif diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c new file mode 100644 index 000000000000..a3d81013e0c2 --- /dev/null +++ b/drivers/virtio/virtio_pci_modern.c @@ -0,0 +1,587 @@ +/* + * Virtio PCI driver - modern (virtio 1.0) device support + * + * This module allows virtio devices to be used over a virtual PCI device. + * This can be used with QEMU based VMMs like KVM or Xen. + * + * Copyright IBM Corp. 2007 + * Copyright Red Hat, Inc. 2014 + * + * Authors: + * Anthony Liguori <aliguori@us.ibm.com> + * Rusty Russell <rusty@rustcorp.com.au> + * Michael S. Tsirkin <mst@redhat.com> + * + * This work is licensed under the terms of the GNU GPL, version 2 or later. + * See the COPYING file in the top-level directory. + * + */ + +#define VIRTIO_PCI_NO_LEGACY +#include "virtio_pci_common.h" + +static void __iomem *map_capability(struct pci_dev *dev, int off, + size_t minlen, + u32 align, + u32 start, u32 size, + size_t *len) +{ + u8 bar; + u32 offset, length; + void __iomem *p; + + pci_read_config_byte(dev, off + offsetof(struct virtio_pci_cap, + bar), + &bar); + pci_read_config_dword(dev, off + offsetof(struct virtio_pci_cap, offset), + &offset); + pci_read_config_dword(dev, off + offsetof(struct virtio_pci_cap, length), + &length); + + if (length <= start) { + dev_err(&dev->dev, + "virtio_pci: bad capability len %u (>%u expected)\n", + length, start); + return NULL; + } + + if (length - start < minlen) { + dev_err(&dev->dev, + "virtio_pci: bad capability len %u (>=%zu expected)\n", + length, minlen); + return NULL; + } + + length -= start; + + if (start + offset < offset) { + dev_err(&dev->dev, + "virtio_pci: map wrap-around %u+%u\n", + start, offset); + return NULL; + } + + offset += start; + + if (offset & (align - 1)) { + dev_err(&dev->dev, + "virtio_pci: offset %u not aligned to %u\n", + offset, align); + return NULL; + } + + if (length > size) + length = size; + + if (len) + *len = length; + + if (minlen + offset < minlen || + minlen + offset > pci_resource_len(dev, bar)) { + dev_err(&dev->dev, + "virtio_pci: map virtio %zu@%u " + "out of range on bar %i length %lu\n", + minlen, offset, + bar, (unsigned long)pci_resource_len(dev, bar)); + return NULL; + } + + p = pci_iomap_range(dev, bar, offset, length); + if (!p) + dev_err(&dev->dev, + "virtio_pci: unable to map virtio %u@%u on bar %i\n", + length, offset, bar); + return p; +} + +static void iowrite64_twopart(u64 val, __le32 __iomem *lo, __le32 __iomem *hi) +{ + iowrite32((u32)val, lo); + iowrite32(val >> 32, hi); +} + +/* virtio config->get_features() implementation */ +static u64 vp_get_features(struct virtio_device *vdev) +{ + struct virtio_pci_device *vp_dev = to_vp_device(vdev); + u64 features; + + iowrite32(0, &vp_dev->common->device_feature_select); + features = ioread32(&vp_dev->common->device_feature); + iowrite32(1, &vp_dev->common->device_feature_select); + features |= ((u64)ioread32(&vp_dev->common->device_feature) << 32); + + return features; +} + +/* virtio config->finalize_features() implementation */ +static int vp_finalize_features(struct virtio_device *vdev) +{ + struct virtio_pci_device *vp_dev = to_vp_device(vdev); + + /* Give virtio_ring a chance to accept features. */ + vring_transport_features(vdev); + + if (!__virtio_test_bit(vdev, VIRTIO_F_VERSION_1)) { + dev_err(&vdev->dev, "virtio: device uses modern interface " + "but does not have VIRTIO_F_VERSION_1\n"); + return -EINVAL; + } + + iowrite32(0, &vp_dev->common->guest_feature_select); + iowrite32((u32)vdev->features, &vp_dev->common->guest_feature); + iowrite32(1, &vp_dev->common->guest_feature_select); + iowrite32(vdev->features >> 32, &vp_dev->common->guest_feature); + + return 0; +} + +/* virtio config->get() implementation */ +static void vp_get(struct virtio_device *vdev, unsigned offset, + void *buf, unsigned len) +{ + struct virtio_pci_device *vp_dev = to_vp_device(vdev); + u8 b; + __le16 w; + __le32 l; + + BUG_ON(offset + len > vp_dev->device_len); + + switch (len) { + case 1: + b = ioread8(vp_dev->device + offset); + memcpy(buf, &b, sizeof b); + break; + case 2: + w = cpu_to_le16(ioread16(vp_dev->device + offset)); + memcpy(buf, &w, sizeof w); + break; + case 4: + l = cpu_to_le32(ioread32(vp_dev->device + offset)); + memcpy(buf, &l, sizeof l); + break; + case 8: + l = cpu_to_le32(ioread32(vp_dev->device + offset)); + memcpy(buf, &l, sizeof l); + l = cpu_to_le32(ioread32(vp_dev->device + offset + sizeof l)); + memcpy(buf + sizeof l, &l, sizeof l); + break; + default: + BUG(); + } +} + +/* the config->set() implementation. it's symmetric to the config->get() + * implementation */ +static void vp_set(struct virtio_device *vdev, unsigned offset, + const void *buf, unsigned len) +{ + struct virtio_pci_device *vp_dev = to_vp_device(vdev); + u8 b; + __le16 w; + __le32 l; + + BUG_ON(offset + len > vp_dev->device_len); + + switch (len) { + case 1: + memcpy(&b, buf, sizeof b); + iowrite8(b, vp_dev->device + offset); + break; + case 2: + memcpy(&w, buf, sizeof w); + iowrite16(le16_to_cpu(w), vp_dev->device + offset); + break; + case 4: + memcpy(&l, buf, sizeof l); + iowrite32(le32_to_cpu(l), vp_dev->device + offset); + break; + case 8: + memcpy(&l, buf, sizeof l); + iowrite32(le32_to_cpu(l), vp_dev->device + offset); + memcpy(&l, buf + sizeof l, sizeof l); + iowrite32(le32_to_cpu(l), vp_dev->device + offset + sizeof l); + break; + default: + BUG(); + } +} + +static u32 vp_generation(struct virtio_device *vdev) +{ + struct virtio_pci_device *vp_dev = to_vp_device(vdev); + return ioread8(&vp_dev->common->config_generation); +} + +/* config->{get,set}_status() implementations */ +static u8 vp_get_status(struct virtio_device *vdev) +{ + struct virtio_pci_device *vp_dev = to_vp_device(vdev); + return ioread8(&vp_dev->common->device_status); +} + +static void vp_set_status(struct virtio_device *vdev, u8 status) +{ + struct virtio_pci_device *vp_dev = to_vp_device(vdev); + /* We should never be setting status to 0. */ + BUG_ON(status == 0); + iowrite8(status, &vp_dev->common->device_status); +} + +static void vp_reset(struct virtio_device *vdev) +{ + struct virtio_pci_device *vp_dev = to_vp_device(vdev); + /* 0 status means a reset. */ + iowrite8(0, &vp_dev->common->device_status); + /* Flush out the status write, and flush in device writes, + * including MSI-X interrupts, if any. */ + ioread8(&vp_dev->common->device_status); + /* Flush pending VQ/configuration callbacks. */ + vp_synchronize_vectors(vdev); +} + +static u16 vp_config_vector(struct virtio_pci_device *vp_dev, u16 vector) +{ + /* Setup the vector used for configuration events */ + iowrite16(vector, &vp_dev->common->msix_config); + /* Verify we had enough resources to assign the vector */ + /* Will also flush the write out to device */ + return ioread16(&vp_dev->common->msix_config); +} + +static size_t vring_pci_size(u16 num) +{ + /* We only need a cacheline separation. */ + return PAGE_ALIGN(vring_size(num, SMP_CACHE_BYTES)); +} + +static void *alloc_virtqueue_pages(int *num) +{ + void *pages; + + /* TODO: allocate each queue chunk individually */ + for (; *num && vring_pci_size(*num) > PAGE_SIZE; *num /= 2) { + pages = alloc_pages_exact(vring_pci_size(*num), + GFP_KERNEL|__GFP_ZERO|__GFP_NOWARN); + if (pages) + return pages; + } + + if (!*num) + return NULL; + + /* Try to get a single page. You are my only hope! */ + return alloc_pages_exact(vring_pci_size(*num), GFP_KERNEL|__GFP_ZERO); +} + +static struct virtqueue *setup_vq(struct virtio_pci_device *vp_dev, + struct virtio_pci_vq_info *info, + unsigned index, + void (*callback)(struct virtqueue *vq), + const char *name, + u16 msix_vec) +{ + struct virtio_pci_common_cfg __iomem *cfg = vp_dev->common; + struct virtqueue *vq; + u16 num, off; + int err; + + if (index >= ioread16(&cfg->num_queues)) + return ERR_PTR(-ENOENT); + + /* Select the queue we're interested in */ + iowrite16(index, &cfg->queue_select); + + /* Check if queue is either not available or already active. */ + num = ioread16(&cfg->queue_size); + if (!num || ioread8(&cfg->queue_enable)) + return ERR_PTR(-ENOENT); + + if (num & (num - 1)) { + dev_warn(&vp_dev->pci_dev->dev, "bad queue size %u", num); + return ERR_PTR(-EINVAL); + } + + /* get offset of notification word for this vq */ + off = ioread16(&cfg->queue_notify_off); + + info->num = num; + info->msix_vector = msix_vec; + + info->queue = alloc_virtqueue_pages(&info->num); + if (info->queue == NULL) + return ERR_PTR(-ENOMEM); + + /* create the vring */ + vq = vring_new_virtqueue(index, info->num, + SMP_CACHE_BYTES, &vp_dev->vdev, + true, info->queue, vp_notify, callback, name); + if (!vq) { + err = -ENOMEM; + goto err_new_queue; + } + + /* activate the queue */ + iowrite16(num, &cfg->queue_size); + iowrite64_twopart(virt_to_phys(info->queue), + &cfg->queue_desc_lo, &cfg->queue_desc_hi); + iowrite64_twopart(virt_to_phys(virtqueue_get_avail(vq)), + &cfg->queue_avail_lo, &cfg->queue_avail_hi); + iowrite64_twopart(virt_to_phys(virtqueue_get_used(vq)), + &cfg->queue_used_lo, &cfg->queue_used_hi); + + vq->priv = (void __force *)map_capability(vp_dev->pci_dev, + vp_dev->notify_map_cap, 2, 2, + off * vp_dev->notify_offset_multiplier, 2, + NULL); + + if (!vq->priv) { + err = -ENOMEM; + goto err_map_notify; + } + + if (msix_vec != VIRTIO_MSI_NO_VECTOR) { + iowrite16(msix_vec, &cfg->queue_msix_vector); + msix_vec = ioread16(&cfg->queue_msix_vector); + if (msix_vec == VIRTIO_MSI_NO_VECTOR) { + err = -EBUSY; + goto err_assign_vector; + } + } + + return vq; + +err_assign_vector: + pci_iounmap(vp_dev->pci_dev, (void __iomem __force *)vq->priv); +err_map_notify: + vring_del_virtqueue(vq); +err_new_queue: + free_pages_exact(info->queue, vring_pci_size(info->num)); + return ERR_PTR(err); +} + +static int vp_modern_find_vqs(struct virtio_device *vdev, unsigned nvqs, + struct virtqueue *vqs[], + vq_callback_t *callbacks[], + const char *names[]) +{ + struct virtio_pci_device *vp_dev = to_vp_device(vdev); + struct virtqueue *vq; + int rc = vp_find_vqs(vdev, nvqs, vqs, callbacks, names); + + if (rc) + return rc; + + /* Select and activate all queues. Has to be done last: once we do + * this, there's no way to go back except reset. + */ + list_for_each_entry(vq, &vdev->vqs, list) { + iowrite16(vq->index, &vp_dev->common->queue_select); + iowrite8(1, &vp_dev->common->queue_enable); + } + + return 0; +} + +static void del_vq(struct virtio_pci_vq_info *info) +{ + struct virtqueue *vq = info->vq; + struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev); + + iowrite16(vq->index, &vp_dev->common->queue_select); + + if (vp_dev->msix_enabled) { + iowrite16(VIRTIO_MSI_NO_VECTOR, + &vp_dev->common->queue_msix_vector); + /* Flush the write out to device */ + ioread16(&vp_dev->common->queue_msix_vector); + } + + pci_iounmap(vp_dev->pci_dev, (void __force __iomem *)vq->priv); + + vring_del_virtqueue(vq); + + free_pages_exact(info->queue, vring_pci_size(info->num)); +} + +static const struct virtio_config_ops virtio_pci_config_ops = { + .get = vp_get, + .set = vp_set, + .generation = vp_generation, + .get_status = vp_get_status, + .set_status = vp_set_status, + .reset = vp_reset, + .find_vqs = vp_modern_find_vqs, + .del_vqs = vp_del_vqs, + .get_features = vp_get_features, + .finalize_features = vp_finalize_features, + .bus_name = vp_bus_name, + .set_vq_affinity = vp_set_vq_affinity, +}; + +/** + * virtio_pci_find_capability - walk capabilities to find device info. + * @dev: the pci device + * @cfg_type: the VIRTIO_PCI_CAP_* value we seek + * @ioresource_types: IORESOURCE_MEM and/or IORESOURCE_IO. + * + * Returns offset of the capability, or 0. + */ +static inline int virtio_pci_find_capability(struct pci_dev *dev, u8 cfg_type, + u32 ioresource_types) +{ + int pos; + + for (pos = pci_find_capability(dev, PCI_CAP_ID_VNDR); + pos > 0; + pos = pci_find_next_capability(dev, pos, PCI_CAP_ID_VNDR)) { + u8 type, bar; + pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap, + cfg_type), + &type); + pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap, + bar), + &bar); + + /* Ignore structures with reserved BAR values */ + if (bar > 0x5) + continue; + + if (type == cfg_type) { + if (pci_resource_len(dev, bar) && + pci_resource_flags(dev, bar) & ioresource_types) + return pos; + } + } + return 0; +} + +static void virtio_pci_release_dev(struct device *_d) +{ + struct virtio_device *vdev = dev_to_virtio(_d); + struct virtio_pci_device *vp_dev = to_vp_device(vdev); + + kfree(vp_dev); +} + +/* TODO: validate the ABI statically. */ +static inline void check_offsets(void) +{ +} + +/* the PCI probing function */ +int virtio_pci_modern_probe(struct virtio_pci_device *vp_dev) +{ + struct pci_dev *pci_dev = vp_dev->pci_dev; + int err, common, isr, notify, device; + u32 notify_length; + + check_offsets(); + + /* We only own devices >= 0x1000 and <= 0x107f: leave the rest. */ + if (pci_dev->device < 0x1000 || pci_dev->device > 0x107f) + return -ENODEV; + + if (pci_dev->device < 0x1040) { + /* Transitional devices: use the PCI subsystem device id as + * virtio device id, same as legacy driver always did. + */ + vp_dev->vdev.id.device = pci_dev->subsystem_device; + } else { + /* Modern devices: simply use PCI device id, but start from 0x1040. */ + vp_dev->vdev.id.device = pci_dev->device - 0x1040; + } + vp_dev->vdev.id.vendor = pci_dev->subsystem_vendor; + + if (virtio_device_is_legacy_only(vp_dev->vdev.id)) + return -ENODEV; + + /* check for a common config: if not, use legacy mode (bar 0). */ + common = virtio_pci_find_capability(pci_dev, VIRTIO_PCI_CAP_COMMON_CFG, + IORESOURCE_IO | IORESOURCE_MEM); + if (!common) { + dev_info(&pci_dev->dev, + "virtio_pci: leaving for legacy driver\n"); + return -ENODEV; + } + + /* If common is there, these should be too... */ + isr = virtio_pci_find_capability(pci_dev, VIRTIO_PCI_CAP_ISR_CFG, + IORESOURCE_IO | IORESOURCE_MEM); + notify = virtio_pci_find_capability(pci_dev, VIRTIO_PCI_CAP_NOTIFY_CFG, + IORESOURCE_IO | IORESOURCE_MEM); + if (!isr || !notify) { + dev_err(&pci_dev->dev, + "virtio_pci: missing capabilities %i/%i/%i\n", + common, isr, notify); + return -EINVAL; + } + + /* Device capability is only mandatory for devices that have + * device-specific configuration. + */ + device = virtio_pci_find_capability(pci_dev, VIRTIO_PCI_CAP_DEVICE_CFG, + IORESOURCE_IO | IORESOURCE_MEM); + + err = -EINVAL; + vp_dev->common = map_capability(pci_dev, common, + sizeof(struct virtio_pci_common_cfg), 4, + 0, sizeof(struct virtio_pci_common_cfg), + NULL); + if (!vp_dev->common) + goto err_map_common; + vp_dev->isr = map_capability(pci_dev, isr, sizeof(u8), 1, + 0, 1, + NULL); + if (!vp_dev->isr) + goto err_map_isr; + + /* Read notify_off_multiplier from config space. */ + pci_read_config_dword(pci_dev, + notify + offsetof(struct virtio_pci_notify_cap, + notify_off_multiplier), + &vp_dev->notify_offset_multiplier); + /* Read notify length from config space. */ + pci_read_config_dword(pci_dev, + notify + offsetof(struct virtio_pci_notify_cap, + cap.length), + ¬ify_length); + + vp_dev->notify_map_cap = notify; + + /* Again, we don't know how much we should map, but PAGE_SIZE + * is more than enough for all existing devices. + */ + if (device) { + vp_dev->device = map_capability(pci_dev, device, 0, 4, + 0, PAGE_SIZE, + &vp_dev->device_len); + if (!vp_dev->device) + goto err_map_device; + } + + vp_dev->vdev.config = &virtio_pci_config_ops; + + vp_dev->config_vector = vp_config_vector; + vp_dev->setup_vq = setup_vq; + vp_dev->del_vq = del_vq; + + return 0; + +err_map_device: + pci_iounmap(pci_dev, vp_dev->isr); +err_map_isr: + pci_iounmap(pci_dev, vp_dev->common); +err_map_common: + return err; +} + +void virtio_pci_modern_remove(struct virtio_pci_device *vp_dev) +{ + struct pci_dev *pci_dev = vp_dev->pci_dev; + + if (vp_dev->device) + pci_iounmap(pci_dev, vp_dev->device); + pci_iounmap(pci_dev, vp_dev->isr); + pci_iounmap(pci_dev, vp_dev->common); +} diff --git a/include/uapi/linux/virtio_pci.h b/include/uapi/linux/virtio_pci.h index 4e054235358f..a2b2e1353e30 100644 --- a/include/uapi/linux/virtio_pci.h +++ b/include/uapi/linux/virtio_pci.h @@ -117,10 +117,11 @@ struct virtio_pci_cap { __u8 cap_vndr; /* Generic PCI field: PCI_CAP_ID_VNDR */ __u8 cap_next; /* Generic PCI field: next ptr. */ __u8 cap_len; /* Generic PCI field: capability length */ - __u8 type_and_bar; /* Upper 3 bits: bar. - * Lower 3 is VIRTIO_PCI_CAP_*_CFG. */ + __u8 cfg_type; /* Identifies the structure. */ + __u8 bar; /* Where to find it. */ + __u8 padding[3]; /* Pad to full dword. */ __le32 offset; /* Offset within bar. */ - __le32 length; /* Length. */ + __le32 length; /* Length of the structure, in bytes. */ }; #define VIRTIO_PCI_CAP_BAR_SHIFT 5 |