Re: [virtio-comment] RE: [virtio-dev] Re: [virtio-comment] [PATCH] Add virtio rpmb device specification

["Michael S. Tsirkin" <mst@redhat.com>]

On Sun, Aug 04, 2019 at 02:07:49AM +0000, Huang, Yang wrote:
> 
> 
> > -----Original Message-----
> > From: virtio-dev@lists.oasis-open.org [mailto:virtio-dev@lists.oasis-open.org]
> > On Behalf Of Michael S. Tsirkin
> > Sent: Sunday, August 4, 2019 5:00
> > To: Huang, Yang <yang.huang@intel.com>
> > Cc: Paolo Bonzini <pbonzini@redhat.com>; virtio-dev@lists.oasis-open.org;
> > virtio-comment@lists.oasis-open.org; Zhu, Bing <bing.zhu@intel.com>; Winkler,
> > Tomas <tomas.winkler@intel.com>
> > Subject: [virtio-dev] Re: [virtio-comment] [PATCH] Add virtio rpmb device
> > specification
> > 
> > On Tue, Jul 30, 2019 at 12:33:17AM +0000, Huang, Yang wrote:
> > >
> > >
> > > > -----Original Message-----
> > > > From: virtio-comment@lists.oasis-open.org
> > > > [mailto:virtio-comment@lists.oasis-
> > > > open.org] On Behalf Of Paolo Bonzini
> > > > Sent: Monday, July 29, 2019 17:19
> > > > To: Huang, Yang <yang.huang@intel.com>;
> > > > virtio-dev@lists.oasis-open.org
> > > > Cc: virtio-comment@lists.oasis-open.org; mst@redhat.com; Zhu, Bing
> > > > <bing.zhu@intel.com>; Winkler, Tomas <tomas.winkler@intel.com>
> > > > Subject: Re: [virtio-comment] [PATCH] Add virtio rpmb device
> > > > specification
> > > >
> > > > On 29/07/19 09:48, Huang Yang wrote:
> > > > >
> > > > > But virtualization software like Qemu doesn't provide
> > > > > eMMC/UFS/NVMe RPMB emulation. It blocks the OS like Trusty or
> > > > > OP-TEE running in a virtualization environment. For instance,
> > > > > Google right now uses another way to work around RPMB emulation
> > > > > issue when running Trusty in
> > > > ARM Qemu:
> > > > > https://android.googlesource.com/trusty/external/trusty/+/refs/hea
> > > > > ds/m
> > > > > aster/test-runner/
> > > > >
> > > > > Virtio RPMB standardization will definitely benefit OP-TEE, Google
> > > > > Trusty TEE, Qemu, OVMF or other modules to develop the RPMB based
> > > > > secure storage in virtualization.
> > > > >
> > > >
> > > > Is there any reason to use a new virtio-blk device, and not add this
> > > > functionality to virtio-blk?
> > > >
> > > > Paolo
> > >
> > > RPMB does not behave as a blk device. It doesn't have block device APIs.
> > > Current virtio blk features or definitions in spec are mostly useless or
> > inapplicable to virtio rpmb.
> > > It performs a different behaviors from the operations on a blk device.
> > > Key, writer counter or nonce are required to read/write on it.
> > > If add it to blk device, it will not only cause to a higher complexity, but also
> > cause to two different behaviors on a same device.
> > >
> > 
> > 
> > Well it seems that current RPMB implementations are all tied to a storage device,
> > like MMC or NVMe. Why is that and why doesn't the same logic apply here?
> > 
> > --
> > MST
> > 
> 
> RPMB is a mandatory hardware partition of eMMC, UFS and optional for NVMe.
> It is standardized by JEDEC and NVMe. 
> This partition is different from the user data partition that blk device emulates.
> It provides a signed access in an authenticated and replay protected manner that
> blk device does not perform. Only RPMB key owner can write to it while anybody
> can access to a user data partition.

Sorry if I'm being dense, so how is this different from e.g. NVMe?

-- 
MST