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Re: [Qemu-devel] [virtio-dev] Re: [PATCH v4 07/13] virtio-crypto: set ca
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [virtio-dev] Re: [PATCH v4 07/13] virtio-crypto: set capacity of algorithms supported |
Date: |
Wed, 5 Oct 2016 13:55:22 +0100 |
User-agent: |
Mutt/1.7.0 (2016-08-17) |
On Wed, Oct 05, 2016 at 03:30:42AM +0000, Gonglei (Arei) wrote:
>
> > -----Original Message-----
> > From: address@hidden [mailto:address@hidden
> > On Behalf Of Stefan Hajnoczi
> > Sent: Tuesday, October 04, 2016 5:46 PM
> > Subject: [virtio-dev] Re: [PATCH v4 07/13] virtio-crypto: set capacity of
> > algorithms supported
> >
> > On Wed, Sep 28, 2016 at 04:25:46PM +0800, Gonglei wrote:
> > > static void virtio_crypto_get_config(VirtIODevice *vdev, uint8_t *config)
> > > {
> > > -
> > > + VirtIOCrypto *c = VIRTIO_CRYPTO(vdev);
> > > + struct virtio_crypto_config crypto_cfg;
> > > +
> > > + crypto_cfg.status = c->status;
> > > + crypto_cfg.max_dataqueues = c->max_queues;
> > > + crypto_cfg.crypto_services = c->conf.crypto_services;
> > > + crypto_cfg.cipher_algo_l = c->conf.cipher_algo_l;
> > > + crypto_cfg.cipher_algo_h = c->conf.cipher_algo_h;
> > > + crypto_cfg.hash_algo = c->conf.hash_algo;
> > > + crypto_cfg.mac_algo_l = c->conf.mac_algo_l;
> > > + crypto_cfg.mac_algo_h = c->conf.mac_algo_h;
> > > + crypto_cfg.aead_algo = c->conf.aead_algo;
> > > +
> > > + memcpy(config, &crypto_cfg, c->config_size);
> > > }
> >
> > What about endianness? For example, if the host is big-endian then this
> > VIRTIO 1.0 device needs to byteswap multi-byte fields. There is a
> > family of functions to help with this: virtio_stl_p().
>
> I did that in v1. Michael told me that Virtio-1.0 devices are always
> little-endian, so
> I removed those helper functions in the following functions. But after this
> version,
> the virtio-crypto device isn't virtio-1.0 device by default, so I should use
> them again.
Endian awareness is still necessary for VIRTIO 1.0-only devices. The
uint8_t *config data is just a blob. Therefore nothing automatically
handles little-endian conversion for us. We *must* read little-endian
from config[].
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