Re: [PATCH 2/3 V2] kvm tools: Add support for multiple virtio-blk

[Ingo Molnar <mingo@elte.hu>]

* Sasha Levin <levinsasha928@gmail.com> wrote:

> Add support for multiple blk_devices by un-globalizing
> the current blk_device and allow multiple blk_devices.

Very nice!

One nit:

> +	mpc_intsrc		= last_addr;
> +	mpc_intsrc->type	= MP_INTSRC;
> +	mpc_intsrc->irqtype	= mp_INT;
> +	mpc_intsrc->irqflag	= MP_IRQDIR_DEFAULT;
> +	mpc_intsrc->srcbus	= pcibusid;
> +	mpc_intsrc->srcbusirq	= 1; /* virtio block irq pin */
> +	mpc_intsrc->dstapic	= ioapicid;
> +	mpc_intsrc->dstirq	= 10; /* VIRTIO_BLK_IRQ */
> +
> +	last_addr = (void *)&mpc_intsrc[1];
> +	nentries++;
> +
> +	mpc_intsrc		= last_addr;
> +	mpc_intsrc->type	= MP_INTSRC;
> +	mpc_intsrc->irqtype	= mp_INT;
> +	mpc_intsrc->irqflag	= MP_IRQDIR_DEFAULT;
> +	mpc_intsrc->srcbus	= pcibusid;
> +	mpc_intsrc->srcbusirq	= 1; /* virtio block irq pin */
> +	mpc_intsrc->dstapic	= ioapicid;
> +	mpc_intsrc->dstirq	= 11; /* VIRTIO_BLK_IRQ */
> +
> +	last_addr = (void *)&mpc_intsrc[1];
> +	nentries++;
> +
> +	mpc_intsrc		= last_addr;
> +	mpc_intsrc->type	= MP_INTSRC;
> +	mpc_intsrc->irqtype	= mp_INT;
> +	mpc_intsrc->irqflag	= MP_IRQDIR_DEFAULT;
> +	mpc_intsrc->srcbus	= pcibusid;
> +	mpc_intsrc->srcbusirq	= 1; /* virtio block irq pin */
> +	mpc_intsrc->dstapic	= ioapicid;
> +	mpc_intsrc->dstirq	= 12; /* VIRTIO_BLK_IRQ */

There should really be a helper function for these initializations - and a loop 
that creates VIRTIO_BLK_MAX_DEV of them, right?

Also, the IRQs used by kvm should be enumerated in an include file in a single 
place, with ranges allocated for specific purposes, otherwise we'll quickly 
lose track of them.

And a pet peeve of mine:

> +struct blk_device_job {
> +	struct virt_queue	*vq;
> +	struct blk_device	*blk_device;
> +	void			*job_id;
> +};
> +
>  struct blk_device {
>  	pthread_mutex_t			mutex;
>  
>  	struct virtio_blk_config	blk_config;
> -	struct disk_image			*disk;
> +	struct disk_image		*disk;
>  	uint32_t			host_features;
>  	uint32_t			guest_features;
>  	uint16_t			config_vector;
>  	uint8_t				status;
> +	u8				idx;

The vertical spacing of those two structures (blk_device_job and blk_device) is 
inconsistent.

>  static bool virtio_blk_pci_io_in(struct kvm *self, uint16_t port, void *data, int size, uint32_t count)
>  {
> -	unsigned long offset;
> +	u16 offset, dev_idx;
>  	bool ret = true;
> +	struct blk_device *blk_device;

Suggestion: please standardize on shorter but still obvious variable names. For 
blk_device a good one could be 'bdev'.

Given how frequently it's used you might even abbreviate 'struct blk_device' to 
'struct blk_dev' - even in that shortr form it's still very obvious what it 
means.

The new, standardized and streamlined naming convention should be propagated to 
all 'struct blk_device' using functions. (in separate patches)

Thanks,

	Ingo