Jason Gunthorpe <[email protected]> wrote on 02/09/2016
11:52:28 AM:
>
> On Tue, Feb 09, 2016 at 11:19:15AM -0500, Stefan Berger wrote:
> > Jason Gunthorpe <[email protected]> wrote on 02/09/
> 2016 12:33:23
> > AM:
> >
> >
> > >
> > > On Mon, Feb 08, 2016 at 02:27:07PM -0500, Stefan Berger wrote:
> > > > Add the retrieval of TPM 1.2 durations and timeouts. Since this
requires
> > > > the startup of the TPM, do this for TPM 1.2 and TPM 2.
> > > >
> > > > To not allow to interleave with commands from user space, so send
the
> > > > TPM_Startup as the first command. The timeouts can then be gotten
at any
> > > > later time, even interleaved with commands from user space.
> > >
> > > Do not call tpm_register until get_timeouts has completed and this
> > > will naturally be avoided the same way every other TPM driver does.
> >
> > Getting the timeouts cannot complete before the TPM emulator has
> started, which
> > in turn cannot start before the ioctl returns. We don't know
> whether user space
> > starts a client first on /dev/tpm1 or the TPM emulator starts
> first on the file
> > descriptor. We can control which command gets *queued* for the TPM
> emulator and
> > that's what I am doing by having the kernel queue the startup command
first.
>
> I keep saying this same solution - start a work queue just before the
> ioctl returns and do the get_timeouts and registration in there.
And how do we unroll if tpm_chip_register fails? We just close the fd that
we gave to user space?
I also don't see why it is a better solution than what I have here now:
https://github.com/stefanberger/linux/commit/954c7dece4a5c44525ca07a9569dc2f3b2b3d174
Stefan
>
> Jason
>
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