linux-kernel - RE: [tpmdd-devel] [PATCH v3 1/3] tpm

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Date:   Mon, 12 Dec 2016 15:57:54 +0000
From:   "Winkler, Tomas" <tomas.winkler@...el.com>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
CC:     Peter Huewe <peterhuewe@....de>,
        open list <linux-kernel@...r.kernel.org>,
        "linux-security-module@...r.kernel.org" 
        <linux-security-module@...r.kernel.org>,
        "moderated list:TPM DEVICE DRIVER" 
        <tpmdd-devel@...ts.sourceforge.net>
Subject: RE: [tpmdd-devel] [PATCH v3 1/3] tpm_crb: map locality registers

> > On Mon, Dec 12, 2016 at 02:25:32PM +0000, Winkler, Tomas 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.
> > > >
> > > > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
> > > > ---
> > > >  drivers/char/tpm/tpm_crb.c | 89
> > > > +++++++++++++++++++++++++++++------------
> > > > -----
> > > >  1 file changed, 57 insertions(+), 32 deletions(-)
> > > >
> > > > diff --git a/drivers/char/tpm/tpm_crb.c
> > > > b/drivers/char/tpm/tpm_crb.c index
> > > > 717b6b4..80b9759 100644
> > > > --- a/drivers/char/tpm/tpm_crb.c
> > > > +++ b/drivers/char/tpm/tpm_crb.c
> > > > @@ -52,18 +52,28 @@ enum crb_cancel {
> > > >  	CRB_CANCEL_INVOKE	= BIT(0),
> > > >  };
> > > >
> > > > -struct crb_control_area {
> > > > -	u32 req;
> > > > -	u32 sts;
> > > > -	u32 cancel;
> > > > -	u32 start;
> > > > -	u32 int_enable;
> > > > -	u32 int_sts;
> > > > -	u32 cmd_size;
> > > > -	u32 cmd_pa_low;
> > > > -	u32 cmd_pa_high;
> > > > -	u32 rsp_size;
> > > > -	u64 rsp_pa;
> > > > +struct crb_regs_head {
> > > > +	u32 loc_state;
> > > > +	u32 reserved1;
> > > > +	u32 loc_ctrl;
> > > > +	u32 loc_sts;
> > > > +	u8 reserved2[32];
> > > > +	u64 intf_id;
> > > > +	u64 ctrl_ext;
> > > > +} __packed;
> > > > +
> > >
> > > > +struct crb_regs_tail {
> > > Why to change the name this is still control_area
> 
> And how would you name struct crb_regs_h then?

Just crb_regs
 
> In my opinion PC it makes a lot of sense to speak about registers here rather
> than control area now that it is extended to the full range. The PC Client
> Specification also speaks about registers.

Right so crb_regs is to be and the nonstandard implementation of the legacy platforms should be even factored out.

> 
> > > > +	u32 ctrl_req;
> > > > +	u32 ctrl_sts;
> > > > +	u32 ctrl_cancel;
> > > > +	u32 ctrl_start;
> > > > +	u32 ctrl_int_enable;
> > > > +	u32 ctrl_int_sts;
> > > > +	u32 ctrl_cmd_size;
> > > > +	u32 ctrl_cmd_pa_low;
> > > > +	u32 ctrl_cmd_pa_high;
> > > > +	u32 ctrl_rsp_size;
> > > > +	u64 ctrl_rsp_pa;
> > > >  } __packed;
> > > >
> > > >  enum crb_status {
> > > > @@ -78,7 +88,8 @@ enum crb_flags {  struct crb_priv {
> > > >  	unsigned int flags;
> > > >  	void __iomem *iobase;
> > > > -	struct crb_control_area __iomem *cca;
> > > > +	struct crb_regs_head __iomem *regs_h;
> > > > +	struct crb_regs_tail __iomem *regs_t;
> > >
> > > Same here, why to change the name, let's keep it cca it will reduce
> > > the size of patch and make it more back portable.
> 
> Backportability is a always a secondary priority for new features albeit
> something that can be considered if it doesn't get in the way.

I think of it as a staged steps. First do the minimal fix then do the overhaul. 
Anyway you are kind of counterproductive to yourself as you already know this need a back port.

Thanks
Tomas