Re: [PATCH 1/2] kvm tools: Bring VIRTIO_BLK_F_SEG_MAX feature back to virtio blk

[Pekka Enberg <penberg@cs.helsinki.fi>]

On 5/13/11 5:40 AM, Asias He wrote:
> commit b764422bb0b46b00b896f6d4538ac3d3dde9e56b
> (kvm tools: Add support for multiple virtio-blk)
> removed the VIRTIO_BLK_F_SEG_MAX publishment to guest.
>
> There is no reason we should not support it. Just bring it back.
>
> Signed-off-by: Asias He<asias.hejun@gmail.com>

Sasha?

> ---
>   tools/kvm/virtio/blk.c |   19 +++++++++++++++----
>   1 files changed, 15 insertions(+), 4 deletions(-)
>
> diff --git a/tools/kvm/virtio/blk.c b/tools/kvm/virtio/blk.c
> index 5085f1b..8740bc4 100644
> --- a/tools/kvm/virtio/blk.c
> +++ b/tools/kvm/virtio/blk.c
> @@ -21,6 +21,10 @@
>   #define NUM_VIRT_QUEUES			1
>
>   #define VIRTIO_BLK_QUEUE_SIZE		128
> +/*
> + * the header and status consume too entries
> + */
> +#define DISK_SEG_MAX			(VIRTIO_BLK_QUEUE_SIZE - 2)
>
>   struct blk_dev_job {
>   	struct virt_queue		*vq;
> @@ -278,11 +282,12 @@ void virtio_blk__init(struct kvm *kvm, struct disk_image *disk)
>   	blk_dev_base_addr	= IOPORT_VIRTIO_BLK + new_dev_idx * IOPORT_VIRTIO_BLK_SIZE;
>
>   	*bdev			= (struct blk_dev) {
> -		.mutex			= PTHREAD_MUTEX_INITIALIZER,
> -		.disk			= disk,
> -		.idx			= new_dev_idx,
> -		.blk_config		= (struct virtio_blk_config) {
> +		.mutex				= PTHREAD_MUTEX_INITIALIZER,
> +		.disk				= disk,
> +		.idx				= new_dev_idx,
> +		.blk_config			= (struct virtio_blk_config) {
>   			.capacity		= disk->size / SECTOR_SIZE,
> +			.seg_max		= DISK_SEG_MAX,
>   		},
>   		.pci_hdr = (struct pci_device_header) {
>   			.vendor_id		= PCI_VENDOR_ID_REDHAT_QUMRANET,
> @@ -294,6 +299,12 @@ void virtio_blk__init(struct kvm *kvm, struct disk_image *disk)
>   			.subsys_id		= PCI_SUBSYSTEM_ID_VIRTIO_BLK,
>   			.bar[0]			= blk_dev_base_addr | PCI_BASE_ADDRESS_SPACE_IO,
>   		},
> +		/*
> +		 * Note we don't set VIRTIO_BLK_F_GEOMETRY here so the
> +		 * guest kernel will compute disk geometry by own, the
> +		 * same applies to VIRTIO_BLK_F_BLK_SIZE
> +		 */
> +		.host_features			= (1UL<<  VIRTIO_BLK_F_SEG_MAX),
>   	};
>
>   	if (irq__register_device(PCI_DEVICE_ID_VIRTIO_BLK,&dev,&pin,&line)<  0)