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    SubjectRe: [Virtio-fs] [PATCH 04/19] virtio: Implement get_shm_region for PCI transport
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    On 2019/8/22 1:57, Vivek Goyal wrote:
    > From: Sebastien Boeuf <sebastien.boeuf@intel.com>
    >
    > On PCI the shm regions are found using capability entries;
    > find a region by searching for the capability.
    >
    > Cc: kvm@vger.kernel.org
    > Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
    > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
    > Signed-off-by: kbuild test robot <lkp@intel.com>
    > ---
    > drivers/virtio/virtio_pci_modern.c | 108 +++++++++++++++++++++++++++++
    > include/uapi/linux/virtio_pci.h | 11 ++-
    > 2 files changed, 118 insertions(+), 1 deletion(-)
    >
    > diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c
    > index 7abcc50838b8..1cdedd93f42a 100644
    > --- a/drivers/virtio/virtio_pci_modern.c
    > +++ b/drivers/virtio/virtio_pci_modern.c
    > @@ -443,6 +443,112 @@ static void del_vq(struct virtio_pci_vq_info *info)
    > vring_del_virtqueue(vq);
    > }
    >
    > +static int virtio_pci_find_shm_cap(struct pci_dev *dev,
    > + u8 required_id,
    > + u8 *bar, u64 *offset, u64 *len)
    > +{
    > + 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, cap_len, id;
    > + u32 tmp32;
    > + u64 res_offset, res_length;
    > +
    > + pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
    > + cfg_type),
    > + &type);
    > + if (type != VIRTIO_PCI_CAP_SHARED_MEMORY_CFG)
    > + continue;
    > +
    > + pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
    > + cap_len),
    > + &cap_len);
    > + if (cap_len != sizeof(struct virtio_pci_cap64)) {
    > + printk(KERN_ERR "%s: shm cap with bad size offset: %d size: %d\n",
    > + __func__, pos, cap_len);
    > + continue;
    > + }
    > +
    > + pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
    > + id),
    > + &id);
    > + if (id != required_id)
    > + continue;
    > +
    > + /* Type, and ID match, looks good */
    > + pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
    > + bar),
    > + bar);
    > +
    > + /* Read the lower 32bit of length and offset */
    > + pci_read_config_dword(dev, pos + offsetof(struct virtio_pci_cap, offset),
    > + &tmp32);
    > + res_offset = tmp32;
    > + pci_read_config_dword(dev, pos + offsetof(struct virtio_pci_cap, length),
    > + &tmp32);
    > + res_length = tmp32;
    > +
    > + /* and now the top half */
    > + pci_read_config_dword(dev,
    > + pos + offsetof(struct virtio_pci_cap64,
    > + offset_hi),
    > + &tmp32);
    > + res_offset |= ((u64)tmp32) << 32;
    > + pci_read_config_dword(dev,
    > + pos + offsetof(struct virtio_pci_cap64,
    > + length_hi),
    > + &tmp32);
    > + res_length |= ((u64)tmp32) << 32;
    > +
    > + *offset = res_offset;
    > + *len = res_length;
    > +
    > + return pos;
    > + }
    > + return 0;
    > +}
    > +
    > +static bool vp_get_shm_region(struct virtio_device *vdev,
    > + struct virtio_shm_region *region, u8 id)
    > +{
    > + struct virtio_pci_device *vp_dev = to_vp_device(vdev);
    > + struct pci_dev *pci_dev = vp_dev->pci_dev;
    > + u8 bar;
    > + u64 offset, len;
    > + phys_addr_t phys_addr;
    > + size_t bar_len;
    > + char *bar_name;

    'char *bar_name' should be cleaned up to avoid compiling warning. And I
    wonder if you mix tab and blankspace for code indent? Or it's just my
    email display problem?

    Thanks,
    Jun

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