Re: Trying to make VHOST-BLK to work - Vasile Catalin-B50542

From: Vasile Catalin-B50542 <catalin.vasile@freescale.com>
To: Sudheer K <sudheer.kurichiyath@gmail.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>,
	virtualization@lists.linux-foundation.org
Subject: Re: Trying to make VHOST-BLK to work
Date: Wed, 20 May 2015 13:01:58 +0300	[thread overview]
Message-ID: <555C5B96.2010407@freescale.com> (raw)
In-Reply-To: <CADM6D_oUqgwvngrY-mNm_HQrfY_qoz-zJY5RMzGaKnCRYB4J7g@mail.gmail.com>

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There is no code in >>QEMU<< that actually triggers notifications to the 
guest when using vhost.
When you are using vhost, interrupts are triggered directly to the guest.
The interrupt lines are mapped as a shared memory, that don't pass 
through QEMU, if they don't have to.
Indeed, there is an initial setup in QEMU that makes this configuration.

Note:
The things that I am saying are somewhat deductions from what I've 
studied from the code myself and some answers
from qemu-devel (so I cannot assure you on the correctness of this 
answer), as the kvm and virtualization community themselves
aren't very active.

On 19.05.2015 14:13, Sudheer K wrote:
> Hi Kernel KVM folks and Michael,
>
> I am trying to make VHOST-BLK to work by myself since I did not hear 
> from Asias on my personal mail to him. I will be grateful to you for 
> your time and response.
>
> The problem I am seeing is there is no response seen by the VM through 
> the HOST has executed the IO successfully and issued 
> vhost_add_used_and_signal.  Here is my question. Which code in QEMU 
> issues virtio_notify() when the VHOST completes the IO in kernel?
>
> I have some related questions. Could I connect a iscsi LUN to a VM via 
> vhost-scsi? Could you please point me to some documents if there are any?
>
> Thanks and Regards
>
> Sudheer
>
>
> _______________________________________________
> Virtualization mailing list
> Virtualization@lists.linux-foundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/virtualization

-- 

CatalinVasile

Intern, DN-Software

FreescaleSemiconductor, Inc.

www.freescale.com

phone: 073-021-1938

e-mail: catalin.vasile@freescale.com <mailto:your.name@freescale.com>

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