Re: [Qemu-devel] [virtio-dev] Re: [PATCH v15 0/2] virtio-crypto: virtio crypto device specification

[Gonglei (Arei)]

> 
> On Fri, Jan 13, 2017 at 02:54:29AM +0000, Gonglei (Arei) wrote:
> >
> > >
> > > On Thu, Jan 12, 2017 at 12:26:24PM +0000, Gonglei (Arei) wrote:
> > > > Hi,
> > > >
> > > >
> > > > >
> > > > > On 01/04/2017 11:10 AM, Gonglei (Arei) wrote:
> > > > > > Hi all,
> > > > > >
> > > > > > I attach the diff files between v14 and v15 for better review.
> > > > > >
> > > > > Hi,
> > > > >
> > > > > only had a quick look. Will try to come back to this later.
> > > > >
> > > > That's cool.
> > > >
> > > > > > diff --git a/virtio-crypto.tex b/virtio-crypto.tex
> > > > > > index 9f7faf0..884ee95 100644
> > > > > > --- a/virtio-crypto.tex
> > > > > > +++ b/virtio-crypto.tex
> > > > > > @@ -2,8 +2,8 @@
> > > > > >
> > > > > >  The virtio crypto device is a virtual cryptography device as well 
> > > > > > as a
> kind
> > > of
> > > > > >  virtual hardware accelerator for virtual machines. The encryption
> and
> > > > > > -decryption requests are placed in the data queue and are ultimately
> > > handled
> > > > > by the
> > > > > > -backend crypto accelerators. The second queue is the control queue
> used
> > > to
> > > > > create
> > > > > > +decryption requests are placed in any of the data active queues and
> are
> > > > > ultimately handled by the
> > > > > s/data active/active data/
> > > > > > +backend crypto accelerators. The second kind of queue is the 
> > > > > > control
> > > queue
> > > > > used to create
> > > > > >  or destroy sessions for symmetric algorithms and will control some
> > > > > advanced
> > > > > >  features in the future. The virtio crypto device provides the 
> > > > > > following
> > > crypto
> > > > > >  services: CIPHER, MAC, HASH, and AEAD.
> > > > >
> > > > > [..]
> > > > >
> > > > > > ===============The below diff shows the changes of add
> non-session
> > > mode
> > > > > support:
> > > > > >
> > > > > > diff --git a/virtio-crypto.tex b/virtio-crypto.tex
> > > > > > index 884ee95..44819f9 100644
> > > > > > --- a/virtio-crypto.tex
> > > > > > +++ b/virtio-crypto.tex
> > > > > > @@ -26,7 +26,10 @@ N is set by \field{max_dataqueues}.
> > > > > >
> > > > > >  \subsection{Feature bits}\label{sec:Device Types / Crypto Device /
> > > Feature
> > > > > bits}
> > > > > >
> > > > > > -None currently defined.
> > > > > > +VIRTIO_CRYPTO_F_CIPHER_SESSION_MODE (1) Session mode is
> > > available
> > > > > for CIPHER service.
> > > > > > +VIRTIO_CRYPTO_F_HASH_SESSION_MODE (2) Session mode is
> available
> > > for
> > > > > HASH service.
> > > > > > +VIRTIO_CRYPTO_F_MAC_SESSION_MODE (3) Session mode is
> available
> > > for
> > > > > MAC service.
> > > > > > +VIRTIO_CRYPTO_F_AEAD_SESSION_MODE (4) Session mode is
> available
> > > for
> > > > > AEAD service.
> > > > > >
> > > > > >  \subsection{Device configuration layout}\label{sec:Device Types /
> > > Crypto
> > > > > Device / Device configuration layout}
> > > > > >
> > > > > > @@ -208,6 +211,9 @@ Operation parameters are algorithm-specific
> > > > > parameters, output data is the
> > > > > >  data that should be utilized in operations, and input data is 
> > > > > > equal to
> > > > > >  "operation result + result data".
> > > > > >
> > > > > > +The device can support both session mode (See \ref{sec:Device Types
> /
> > > > > Crypto Device / Device Operation / Control Virtqueue / Session
> operation})
> > > and
> > > > > non-session mode, for example,
> > > > > > +As VIRTIO_CRYPTO_F_CIPHER_SESSION feature bit is negotiated,
> the
> > > driver
> > > > > can use session mode for CIPHER service, otherwise it can only use
> > > non-session
> > > > > mode.
> > > > > > +
> > > > >
> > > > > As far as I understand you are adding non-session mode to the mix but
> > > > > providing feature bits for session mode. Would this render the the
> current
> > > > > implementation non-compliant?
> > > > >
> > > > You are right, shall we use feature bits for non-session mode for
> compliancy?
> > > > Or because the spec is on the fly, and some structures in the
> virtio_crypto.h
> > > need to
> > > > be modified, can we keep the compliancy completely?
> > > >
> > > > Thanks,
> > > > -Gonglei
> > >
> > > Since there's a linux driver upstream you must at least
> > > keep compatibility with that.
> > >
> > Sure. We use feature bits for non-session mode then.
> > For structures modification, do we need to do some specific
> > actions for compatibility?  Take CIPHER service as an example:
> >
> > The present structure:
> >
> > struct virtio_crypto_cipher_para {
> >     /*
> >      * Byte Length of valid IV/Counter data pointed to by the below iv data.
> >      *
> >      * For block ciphers in CBC or F8 mode, or for Kasumi in F8 mode, or for
> >      *   SNOW3G in UEA2 mode, this is the length of the IV (which
> >      *   must be the same as the block length of the cipher).
> >      * For block ciphers in CTR mode, this is the length of the counter
> >      *   (which must be the same as the block length of the cipher).
> >      */
> >     le32 iv_len;
> >     /* length of source data */
> >     le32 src_data_len;
> >     /* length of destination data */
> >     le32 dst_data_len;
> > };
> >
> > The future structure if supporting non-session based operations:
> >
> > struct virtio_crypto_cipher_para {
> >     struct {
> >         /* See VIRTIO_CRYPTO_CIPHER* above */
> >         le32 algo;
> >         /* length of key */
> >         le32 keylen;
> >
> >         /* See VIRTIO_CRYPTO_OP_* above */
> >         le32 op;
> >     } sess_para;
> >
> >     /*
> >      * Byte Length of valid IV/Counter data pointed to by the below iv data.
> >      *
> >      * For block ciphers in CBC or F8 mode, or for Kasumi in F8 mode, or for
> >      *   SNOW3G in UEA2 mode, this is the length of the IV (which
> >      *   must be the same as the block length of the cipher).
> >      * For block ciphers in CTR mode, this is the length of the counter
> >      *   (which must be the same as the block length of the cipher).
> >      */
> >     le32 iv_len;
> >     /* length of source data */
> >     le32 src_data_len;
> >     /* length of destination data */
> >     le32 dst_data_len;
> > };
> >
> > Thanks,
> > -Gonglei
> 
> So you will have to maintain both structures for when non-session based
> feature is and aren't present. You will have to give them different
> names, too.
> 
OK, I get your point. :)

Thanks,
-Gonglei