Re: [PATCH 1/3] tpm_crb: map locality registers

From: Jarkko Sakkinen
Date: Tue Oct 11 2016 - 14:21:17 EST


On Tue, Oct 11, 2016 at 11:01:43AM -0600, Jason Gunthorpe wrote:
> On Tue, Oct 11, 2016 at 12:23:04PM +0300, Jarkko Sakkinen wrote:
> > In order to provide access to locality registers, this commits adds
> > mapping of the head of the CRB registers, which are located right
> > before the control area.
>
> I think you should squash this into the prior patch, no sense in
> changing all these lines twice
>
> But looks better to me.

So... do you suggest to squash with request/reliquish locality stuff?
Just checking because this is 1/3 :)

> > - priv->cca = crb_map_res(dev, priv, &io_res, buf->control_address,
> > - sizeof(struct crb_control_area));
> > - if (IS_ERR(priv->cca))
> > - return PTR_ERR(priv->cca);
> > + if (priv->flags & CRB_FL_CRB_START) {
> > + priv->regs_h = crb_map_res(dev, priv, &io_res, io_res.start,
> > + sizeof(struct crb_regs_head));
> > + if (IS_ERR(priv->regs_h))
> > + return PTR_ERR(priv->regs_h);
> > + }
> > +
> > + priv->regs_t = crb_map_res(dev, priv, &io_res, buf->control_address,
> > + sizeof(struct crb_regs_tail));
> > + if (IS_ERR(priv->regs_t))
> > + return PTR_ERR(priv->regs_t);
>
> So.. The ACPI IO region starts at the head area and continues to
> include the control area, as one nice sane region - except for some
> older stuff that puts the control area outside the ACPI IO region?

Yes. The old hardware triggered SMM to do a DMA transfer (those that
so called ACPI start). As a workaround for some of the hardware the
driver always sets the CRB start flag also in the control area.

That's why I also propose that we replace them with a single flag.

> That makes a lot more sense..
>
> Maybe chuck in a
>
> if (priv->flags & CRB_FL_CRB_START) {
> if (buf->control_address != io_res.start + sizeof(struct
> crb_regs_head))
> dev_warn(dev, FIRMWARE_BUG "Bad ACPI memory layout")
>
> Jason

As a sanity check this would probably make sense.


/Jarkko