[ipxe-devel] [PATCH v2 3/4] [virtio] Add virtio 1.0 PCI support

Ladi Prosek lprosek at redhat.com
Tue Apr 5 10:44:52 UTC 2016


On Sun, Apr 3, 2016 at 1:51 PM, Michael S. Tsirkin <mst at redhat.com> wrote:
> On Mon, Mar 14, 2016 at 03:48:24PM +0100, Ladi Prosek wrote:
>> This commit adds support for driving virtio 1.0 PCI devices.
>> In addition to various helpers, a number of vpm_ functions are
>> introduced to be used instead of their legacy vp_ counterparts
>> when accessing virtio 1.0 (aka modern) devices.
>>
>> Signed-off-by: Ladi Prosek <lprosek at redhat.com>
>> ---
>>  src/drivers/bus/virtio-pci.c   | 324 ++++++++++++++++++++++++++++++++++++++++-
>>  src/drivers/bus/virtio-ring.c  |  15 +-
>>  src/drivers/net/virtio-net.c   |   4 +-
>>  src/include/ipxe/errfile.h     |   1 +
>>  src/include/ipxe/virtio-pci.h  | 147 +++++++++++++++++++
>>  src/include/ipxe/virtio-ring.h |   4 +-
>>  6 files changed, 483 insertions(+), 12 deletions(-)
>>
>> diff --git a/src/drivers/bus/virtio-pci.c b/src/drivers/bus/virtio-pci.c
>> index fbef067..d4eb7c0 100644
>> --- a/src/drivers/bus/virtio-pci.c
>> +++ b/src/drivers/bus/virtio-pci.c
>> @@ -11,10 +11,14 @@
>>   *
>>   */
>>
>> +#include "errno.h"
>> +#include "byteswap.h"
>>  #include "etherboot.h"
>>  #include "ipxe/io.h"
>> -#include "ipxe/virtio-ring.h"
>> +#include "ipxe/iomap.h"
>> +#include "ipxe/pci.h"
>>  #include "ipxe/virtio-pci.h"
>> +#include "ipxe/virtio-ring.h"
>>
>>  int vp_find_vq(unsigned int ioaddr, int queue_index,
>>                 struct vring_virtqueue *vq)
>> @@ -30,19 +34,19 @@ int vp_find_vq(unsigned int ioaddr, int queue_index,
>>
>>     num = inw(ioaddr + VIRTIO_PCI_QUEUE_NUM);
>>     if (!num) {
>> -           printf("ERROR: queue size is 0\n");
>> +           DBG("VIRTIO-PCI ERROR: queue size is 0\n");
>>             return -1;
>>     }
>>
>>     if (num > MAX_QUEUE_NUM) {
>> -           printf("ERROR: queue size %d > %d\n", num, MAX_QUEUE_NUM);
>> +           DBG("VIRTIO-PCI ERROR: queue size %d > %d\n", num, MAX_QUEUE_NUM);
>>             return -1;
>>     }
>>
>>     /* check if the queue is already active */
>>
>>     if (inl(ioaddr + VIRTIO_PCI_QUEUE_PFN)) {
>> -           printf("ERROR: queue already active\n");
>> +           DBG("VIRTIO-PCI ERROR: queue already active\n");
>>             return -1;
>>     }
>>
>> @@ -62,3 +66,315 @@ int vp_find_vq(unsigned int ioaddr, int queue_index,
>>
>>     return num;
>>  }
>> +
>> +#define CFG_POS(vdev, field) \
>> +    (vdev->cfg_cap_pos + offsetof(struct virtio_pci_cfg_cap, field))
>> +
>> +static void prep_pci_cfg_cap(struct virtio_pci_modern_device *vdev,
>> +                             struct virtio_pci_region *region,
>> +                             size_t offset, u32 length)
>> +{
>> +    pci_write_config_byte(vdev->pci, CFG_POS(vdev, cap.bar), region->bar);
>> +    pci_write_config_dword(vdev->pci, CFG_POS(vdev, cap.length), length);
>> +    pci_write_config_dword(vdev->pci, CFG_POS(vdev, cap.offset),
>> +        (uint32_t)(region->base + offset));
>> +}
>> +
>> +void vpm_iowrite8(struct virtio_pci_modern_device *vdev,
>> +                  struct virtio_pci_region *region, u8 data, size_t offset)
>> +{
>> +    switch (region->flags & VIRTIO_PCI_REGION_TYPE_MASK) {
>> +    case VIRTIO_PCI_REGION_MEMORY:
>> +        writeb(data, region->base + offset);
>> +        break;
>> +    case VIRTIO_PCI_REGION_PORT:
>> +        outb(data, region->base + offset);
>> +        break;
>> +    default: /* VIRTIO_PCI_REGION_PCI_CONFIG */
>> +        prep_pci_cfg_cap(vdev, region, offset, 1);
>> +        pci_write_config_byte(vdev->pci, CFG_POS(vdev, pci_cfg_data), data);
>> +        break;
>> +    }
>> +}
>> +
>> +void vpm_iowrite16(struct virtio_pci_modern_device *vdev,
>> +                   struct virtio_pci_region *region, u16 data, size_t offset)
>> +{
>> +    data = cpu_to_le16(data);
>> +    switch (region->flags & VIRTIO_PCI_REGION_TYPE_MASK) {
>> +    case VIRTIO_PCI_REGION_MEMORY:
>> +        writew(data, region->base + offset);
>> +        break;
>> +    case VIRTIO_PCI_REGION_PORT:
>> +        outw(data, region->base + offset);
>> +        break;
>> +    default: /* VIRTIO_PCI_REGION_PCI_CONFIG */
>> +        prep_pci_cfg_cap(vdev, region, offset, 2);
>> +        pci_write_config_word(vdev->pci, CFG_POS(vdev, pci_cfg_data), data);
>> +        break;
>> +    }
>> +}
>> +
>> +void vpm_iowrite32(struct virtio_pci_modern_device *vdev,
>> +                   struct virtio_pci_region *region, u32 data, size_t offset)
>> +{
>> +    data = cpu_to_le32(data);
>> +    switch (region->flags & VIRTIO_PCI_REGION_TYPE_MASK) {
>> +    case VIRTIO_PCI_REGION_MEMORY:
>> +        writel(data, region->base + offset);
>> +        break;
>> +    case VIRTIO_PCI_REGION_PORT:
>> +        outl(data, region->base + offset);
>> +        break;
>> +    default: /* VIRTIO_PCI_REGION_PCI_CONFIG */
>> +        prep_pci_cfg_cap(vdev, region, offset, 4);
>> +        pci_write_config_dword(vdev->pci, CFG_POS(vdev, pci_cfg_data), data);
>> +        break;
>> +    }
>> +}
>> +
>> +u8 vpm_ioread8(struct virtio_pci_modern_device *vdev,
>> +               struct virtio_pci_region *region, size_t offset)
>> +{
>> +    uint8_t data;
>> +    switch (region->flags & VIRTIO_PCI_REGION_TYPE_MASK) {
>> +    case VIRTIO_PCI_REGION_MEMORY:
>> +        data = readb(region->base + offset);
>> +        break;
>> +    case VIRTIO_PCI_REGION_PORT:
>> +        data = inb(region->base + offset);
>> +        break;
>> +    default: /* VIRTIO_PCI_REGION_PCI_CONFIG */
>> +        prep_pci_cfg_cap(vdev, region, offset, 1);
>> +        pci_read_config_byte(vdev->pci, CFG_POS(vdev, pci_cfg_data), &data);
>> +        break;
>> +    }
>> +    return data;
>> +}
>> +
>> +u16 vpm_ioread16(struct virtio_pci_modern_device *vdev,
>> +                 struct virtio_pci_region *region, size_t offset)
>> +{
>> +    uint16_t data;
>> +    switch (region->flags & VIRTIO_PCI_REGION_TYPE_MASK) {
>> +    case VIRTIO_PCI_REGION_MEMORY:
>> +        data = readw(region->base + offset);
>> +        break;
>> +    case VIRTIO_PCI_REGION_PORT:
>> +        data = inw(region->base + offset);
>> +        break;
>> +    default: /* VIRTIO_PCI_REGION_PCI_CONFIG */
>> +        prep_pci_cfg_cap(vdev, region, offset, 2);
>> +        pci_read_config_word(vdev->pci, CFG_POS(vdev, pci_cfg_data), &data);
>> +        break;
>> +    }
>> +    return le16_to_cpu(data);
>> +}
>> +
>> +u32 vpm_ioread32(struct virtio_pci_modern_device *vdev,
>> +                 struct virtio_pci_region *region, size_t offset)
>> +{
>> +    uint32_t data;
>> +    switch (region->flags & VIRTIO_PCI_REGION_TYPE_MASK) {
>> +    case VIRTIO_PCI_REGION_MEMORY:
>> +        data = readw(region->base + offset);
>> +        break;
>> +    case VIRTIO_PCI_REGION_PORT:
>> +        data = inw(region->base + offset);
>> +        break;
>> +    default: /* VIRTIO_PCI_REGION_PCI_CONFIG */
>> +        prep_pci_cfg_cap(vdev, region, offset, 4);
>> +        pci_read_config_dword(vdev->pci, CFG_POS(vdev, pci_cfg_data), &data);
>> +        break;
>> +    }
>> +    return le32_to_cpu(data);
>> +}
>> +
>> +int virtio_pci_find_capability(struct pci_device *pci, uint8_t cfg_type)
>> +{
>> +    int pos;
>> +    uint8_t type, bar;
>> +
>> +    for (pos = pci_find_capability(pci, PCI_CAP_ID_VNDR);
>> +         pos > 0;
>> +         pos = pci_find_next_capability(pci, pos, PCI_CAP_ID_VNDR)) {
>> +
>> +        pci_read_config_byte(pci, pos + offsetof(struct virtio_pci_cap,
>> +            cfg_type), &type);
>> +        pci_read_config_byte(pci, pos + offsetof(struct virtio_pci_cap,
>> +            bar), &bar);
>> +
>> +        /* Ignore structures with reserved BAR values */
>> +        if (bar > 0x5) {
>> +            continue;
>> +        }
>> +
>> +        if (type == cfg_type) {
>> +            return pos;
>> +        }
>> +    }
>> +    return 0;
>> +}
>> +
>> +int virtio_pci_map_capability(struct pci_device *pci, int cap, size_t minlen,
>> +                              u32 align, u32 start, u32 size,
>> +                              struct virtio_pci_region *region)
>> +{
>> +    u8 bar;
>> +    u32 offset, length, base_raw;
>> +    unsigned long base;
>> +
>> +    pci_read_config_byte(pci, cap + offsetof(struct virtio_pci_cap, bar), &bar);
>> +    pci_read_config_dword(pci, cap + offsetof(struct virtio_pci_cap, offset),
>> +                          &offset);
>> +    pci_read_config_dword(pci, cap + offsetof(struct virtio_pci_cap, length),
>> +                          &length);
>> +
>> +    if (length <= start) {
>> +        DBG("VIRTIO-PCI bad capability len %u (>%u expected)\n", length, start);
>> +        return -EINVAL;
>> +    }
>> +    if (length - start < minlen) {
>> +        DBG("VIRTIO-PCI bad capability len %u (>=%zu expected)\n", length, minlen);
>> +        return -EINVAL;
>> +    }
>> +    length -= start;
>> +    if (start + offset < offset) {
>> +        DBG("VIRTIO-PCI map wrap-around %u+%u\n", start, offset);
>> +        return -EINVAL;
>> +    }
>> +    offset += start;
>> +    if (offset & (align - 1)) {
>> +        DBG("VIRTIO-PCI offset %u not aligned to %u\n", offset, align);
>> +        return -EINVAL;
>> +    }
>> +    if (length > size) {
>> +        length = size;
>> +    }
>> +
>> +    if (minlen + offset < minlen ||
>> +        minlen + offset > pci_bar_size(pci, PCI_BASE_ADDRESS(bar))) {
>> +        DBG("VIRTIO-PCI map virtio %zu@%u out of range on bar %i length %lu\n",
>> +            minlen, offset,
>> +            bar, (unsigned long)pci_bar_size(pci, PCI_BASE_ADDRESS(bar)));
>> +        return -EINVAL;
>> +    }
>> +
>> +    region->base = NULL;
>> +    region->length = length;
>> +    region->bar = bar;
>> +
>> +    base = pci_bar_start(pci, PCI_BASE_ADDRESS(bar));
>> +    if (base) {
>> +        pci_read_config_dword(pci, PCI_BASE_ADDRESS(bar), &base_raw);
>> +
>> +        if (base_raw & PCI_BASE_ADDRESS_SPACE_IO) {
>> +            /* Region accessed using port I/O */
>> +            region->base = (void *)(base + offset);
>> +            region->flags = VIRTIO_PCI_REGION_PORT;
>> +        } else {
>> +            /* Region mapped into memory space */
>> +            region->base = ioremap(base + offset, length);
>> +            region->flags = VIRTIO_PCI_REGION_MEMORY;
>> +        }
>> +    }
>> +    if (!region->base) {
>> +        /* Region accessed via PCI config space window */
>> +        region->base = (void *)offset;
>> +        region->flags = VIRTIO_PCI_REGION_PCI_CONFIG;
>> +    }
>> +    return 0;
>> +}
>> +
>> +void virtio_pci_unmap_capability(struct virtio_pci_region *region)
>> +{
>> +    unsigned region_type = region->flags & VIRTIO_PCI_REGION_TYPE_MASK;
>> +    if (region_type == VIRTIO_PCI_REGION_MEMORY) {
>> +        iounmap(region->base);
>> +    }
>> +}
>> +
>> +void vpm_notify(struct virtio_pci_modern_device *vdev,
>> +                struct vring_virtqueue *vq)
>> +{
>> +    vpm_iowrite16(vdev, &vq->notification, (u16)vq->queue_index, 0);
>> +}
>> +
>> +int vpm_find_vqs(struct virtio_pci_modern_device *vdev,
>> +                 unsigned nvqs, struct vring_virtqueue *vqs)
>> +{
>> +    unsigned i;
>> +    struct vring_virtqueue *vq;
>> +    u16 size, off;
>> +    int err;
>> +
>> +    if (nvqs > vpm_ioread16(vdev, &vdev->common, COMMON_OFFSET(num_queues))) {
>> +        return -ENOENT;
>> +    }
>> +
>> +    for (i = 0; i < nvqs; i++) {
>> +        /* Select the queue we're interested in */
>> +        vpm_iowrite16(vdev, &vdev->common, (u16)i, COMMON_OFFSET(queue_select));
>> +
>> +        /* Check if queue is either not available or already active. */
>> +        size = vpm_ioread16(vdev, &vdev->common, COMMON_OFFSET(queue_size));
>> +        /* QEMU has a bug where queues don't revert to inactive on device
>> +         * reset. Skip checking the queue_enable field until it is fixed.
>> +         */
>> +        if (!size /*|| vpm_ioread16(vdev, &vdev->common.queue_enable)*/)
>> +            return -ENOENT;
>> +
>> +        if (size & (size - 1)) {
>> +            DBG("VIRTIO-PCI %p: bad queue size %u", vdev, size);
>> +            return -EINVAL;
>> +        }
>> +
>> +        vq = &vqs[i];
>> +        vq->queue_index = i;
>> +
>> +        /* get offset of notification word for this vq */
>> +        off = vpm_ioread16(vdev, &vdev->common, COMMON_OFFSET(queue_notify_off));
>> +        vq->vring.num = size;
>> +
>> +        vring_init(&vq->vring, size, (unsigned char *)vq->queue);
>> +
>> +        /* activate the queue */
>> +        vpm_iowrite16(vdev, &vdev->common, size, COMMON_OFFSET(queue_size));
>> +
>> +        vpm_iowrite64(vdev, &vdev->common, virt_to_phys(vq->vring.desc),
>> +                      COMMON_OFFSET(queue_desc_lo),
>> +                      COMMON_OFFSET(queue_desc_hi));
>> +        vpm_iowrite64(vdev, &vdev->common, virt_to_phys(vq->vring.avail),
>> +                      COMMON_OFFSET(queue_avail_lo),
>> +                      COMMON_OFFSET(queue_avail_hi));
>> +        vpm_iowrite64(vdev, &vdev->common, virt_to_phys(vq->vring.used),
>> +                      COMMON_OFFSET(queue_used_lo),
>> +                      COMMON_OFFSET(queue_used_hi));
>> +
>> +        err = virtio_pci_map_capability(vdev->pci,
>> +            vdev->notify_cap_pos, 2, 2,
>> +            off * vdev->notify_offset_multiplier, 2,
>> +            &vq->notification);
>> +        if (err) {
>> +            goto err_map_notify;
>> +        }
>> +    }
>> +
>> +    /* Select and activate all queues. Has to be done last: once we do
>> +     * this, there's no way to go back except reset.
>> +     */
>> +    for (i = 0; i < nvqs; i++) {
>> +        vq = &vqs[i];
>> +        vpm_iowrite16(vdev, &vdev->common, (u16)vq->queue_index,
>> +                      COMMON_OFFSET(queue_select));
>> +        vpm_iowrite16(vdev, &vdev->common, 1, COMMON_OFFSET(queue_enable));
>> +    }
>> +    return 0;
>> +
>> +err_map_notify:
>> +    /* Undo the virtio_pci_map_capability calls. */
>> +    while (i-- > 0) {
>> +        virtio_pci_unmap_capability(&vqs[i].notification);
>> +    }
>> +    return err;
>> +}
>> diff --git a/src/drivers/bus/virtio-ring.c b/src/drivers/bus/virtio-ring.c
>> index e55b6d0..649cde3 100644
>> --- a/src/drivers/bus/virtio-ring.c
>> +++ b/src/drivers/bus/virtio-ring.c
>> @@ -18,8 +18,8 @@ FILE_LICENCE ( GPL2_OR_LATER );
>>
>>  #include "etherboot.h"
>>  #include "ipxe/io.h"
>> -#include "ipxe/virtio-ring.h"
>>  #include "ipxe/virtio-pci.h"
>> +#include "ipxe/virtio-ring.h"
>>
>>  #define BUG() do { \
>>     printf("BUG: failure at %s:%d/%s()!\n", \
>> @@ -122,7 +122,8 @@ void vring_add_buf(struct vring_virtqueue *vq,
>>     wmb();
>>  }
>>
>> -void vring_kick(unsigned int ioaddr, struct vring_virtqueue *vq, int num_added)
>> +void vring_kick(struct virtio_pci_modern_device *vdev, unsigned int ioaddr,
>> +                struct vring_virtqueue *vq, int num_added)
>>  {
>>     struct vring *vr = &vq->vring;
>>
>> @@ -130,7 +131,11 @@ void vring_kick(unsigned int ioaddr, struct vring_virtqueue *vq, int num_added)
>>     vr->avail->idx += num_added;
>>
>>     mb();
>> -   if (!(vr->used->flags & VRING_USED_F_NO_NOTIFY))
>> -           vp_notify(ioaddr, vq->queue_index);
>> +   if (!(vr->used->flags & VRING_USED_F_NO_NOTIFY)) {
>> +           if (ioaddr) {
>> +                   vp_notify(ioaddr, vq->queue_index);
>> +           } else {
>> +                   vpm_notify(vdev, vq);
>> +           }
>> +   }
>>  }
>> -
>> diff --git a/src/drivers/net/virtio-net.c b/src/drivers/net/virtio-net.c
>> index 533ccb0..1c535f7 100644
>> --- a/src/drivers/net/virtio-net.c
>> +++ b/src/drivers/net/virtio-net.c
>> @@ -30,8 +30,8 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
>>  #include <ipxe/pci.h>
>>  #include <ipxe/if_ether.h>
>>  #include <ipxe/ethernet.h>
>> -#include <ipxe/virtio-ring.h>
>>  #include <ipxe/virtio-pci.h>
>> +#include <ipxe/virtio-ring.h>
>>  #include "virtio-net.h"
>>
>>  /*
>> @@ -135,7 +135,7 @@ static void virtnet_enqueue_iob ( struct net_device *netdev,
>>               virtnet, iobuf, vq_idx );
>>
>>       vring_add_buf ( vq, list, out, in, iobuf, 0 );
>> -     vring_kick ( virtnet->ioaddr, vq, 1 );
>> +     vring_kick ( NULL, virtnet->ioaddr, vq, 1 );
>>  }
>>
>>  /** Try to keep rx virtqueue filled with iobufs
>> diff --git a/src/include/ipxe/errfile.h b/src/include/ipxe/errfile.h
>> index 65b4d9c..2fb4898 100644
>> --- a/src/include/ipxe/errfile.h
>> +++ b/src/include/ipxe/errfile.h
>> @@ -345,6 +345,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
>>  #define ERRFILE_efi_pxe                    ( ERRFILE_OTHER | 0x004a0000 )
>>  #define ERRFILE_efi_usb                    ( ERRFILE_OTHER | 0x004b0000 )
>>  #define ERRFILE_efi_fbcon          ( ERRFILE_OTHER | 0x004c0000 )
>> +#define ERRFILE_virtio_pci         ( ERRFILE_OTHER | 0x004d0000 )
>>
>>  /** @} */
>>
>> diff --git a/src/include/ipxe/virtio-pci.h b/src/include/ipxe/virtio-pci.h
>> index 8076f20..d1596f6 100644
>> --- a/src/include/ipxe/virtio-pci.h
>> +++ b/src/include/ipxe/virtio-pci.h
>> @@ -97,6 +97,45 @@ struct virtio_pci_common_cfg {
>>      __le32 queue_used_hi;         /* read-write */
>>  };
>>
>> +/* Virtio 1.0 PCI region descriptor. We support memory mapped I/O, port I/O,
>> + * and PCI config space access via the cfg PCI capability as a fallback. */
>> +struct virtio_pci_region {
>> +    void *base;
>> +    size_t length;
>> +    u8 bar;
>> +
>> +/* How to interpret the base field */
>> +#define VIRTIO_PCI_REGION_TYPE_MASK  0x00000003
>> +/* The base field is a memory address */
>> +#define VIRTIO_PCI_REGION_MEMORY     0x00000000
>> +/* The base field is a port address */
>> +#define VIRTIO_PCI_REGION_PORT       0x00000001
>> +/* The base field is an offset within the PCI bar */
>> +#define VIRTIO_PCI_REGION_PCI_CONFIG 0x00000002
>> +    unsigned flags;
>> +};
>> +
>> +/* Virtio 1.0 device state */
>> +struct virtio_pci_modern_device {
>> +    struct pci_device *pci;
>> +
>> +    /* VIRTIO_PCI_CAP_PCI_CFG position */
>> +    int cfg_cap_pos;
>> +
>> +    /* VIRTIO_PCI_CAP_COMMON_CFG data */
>> +    struct virtio_pci_region common;
>> +
>> +    /* VIRTIO_PCI_CAP_DEVICE_CFG data */
>> +    struct virtio_pci_region device;
>> +
>> +    /* VIRTIO_PCI_CAP_ISR_CFG data */
>> +    struct virtio_pci_region isr;
>> +
>> +    /* VIRTIO_PCI_CAP_NOTIFY_CFG data */
>> +    int notify_cap_pos;
>> +    u32 notify_offset_multiplier;
>> +};
>> +
>>  static inline u32 vp_get_features(unsigned int ioaddr)
>>  {
>>     return inl(ioaddr + VIRTIO_PCI_HOST_FEATURES);
>> @@ -156,6 +195,114 @@ static inline void vp_del_vq(unsigned int ioaddr, int queue_index)
>>     outl(0, ioaddr + VIRTIO_PCI_QUEUE_PFN);
>>  }
>>
>> +struct vring_virtqueue;
>> +
>>  int vp_find_vq(unsigned int ioaddr, int queue_index,
>>                 struct vring_virtqueue *vq);
>> +
>> +/* Virtio 1.0 I/O routines abstract away the three possible HW access
>> + * mechanisms - memory, port I/O, and PCI cfg space access. Also built-in
>> + * are endianness conversions - to LE on write and from LE on read. */
>> +
>> +void vpm_iowrite8(struct virtio_pci_modern_device *vdev,
>> +                  struct virtio_pci_region *region, u8 data, size_t offset);
>> +
>> +void vpm_iowrite16(struct virtio_pci_modern_device *vdev,
>> +                   struct virtio_pci_region *region, u16 data, size_t offset);
>> +
>> +void vpm_iowrite32(struct virtio_pci_modern_device *vdev,
>> +                   struct virtio_pci_region *region, u32 data, size_t offset);
>> +
>> +static inline void vpm_iowrite64(struct virtio_pci_modern_device *vdev,
>> +                                 struct virtio_pci_region *region,
>> +                                 u64 data, size_t offset_lo, size_t offset_hi)
>> +{
>> +    vpm_iowrite32(vdev, region, (u32)data, offset_lo);
>> +    vpm_iowrite32(vdev, region, data >> 32, offset_hi);
>> +}
>> +
>> +u8 vpm_ioread8(struct virtio_pci_modern_device *vdev,
>> +               struct virtio_pci_region *region, size_t offset);
>> +
>> +u16 vpm_ioread16(struct virtio_pci_modern_device *vdev,
>> +                 struct virtio_pci_region *region, size_t offset);
>> +
>> +u32 vpm_ioread32(struct virtio_pci_modern_device *vdev,
>> +                 struct virtio_pci_region *region, size_t offset);
>> +
>> +/* Virtio 1.0 device manipulation routines */
>> +
>> +#define COMMON_OFFSET(field) offsetof(struct virtio_pci_common_cfg, field)
>> +
>> +static inline void vpm_reset(struct virtio_pci_modern_device *vdev)
>> +{
>> +    vpm_iowrite8(vdev, &vdev->common, 0, COMMON_OFFSET(device_status));
>> +    (void)vpm_ioread8(vdev, &vdev->common, COMMON_OFFSET(device_status));
>
> In fact this is a bug in linux code.
> We should wait until status is read as 0.
> I'll fix Linux, pls fix ipxe.

Will do, thanks.

>> +}



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