linux-kernel - RE: [PATCH] add tpm_xenu.ko: Xen Virtual TPM frontend driver

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Date:	Thu, 8 Nov 2012 10:40:34 -0500
From:	"Fioravante, Matthew E." <Matthew.Fioravante@...apl.edu>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
CC:	"key@...ux.vnet.ibm.com" <key@...ux.vnet.ibm.com>,
	"mail@...jiv.net" <mail@...jiv.net>,
	"jeremy@...p.org" <jeremy@...p.org>,
	"tpmdd-devel@...ts.sourceforge.net" 
	<tpmdd-devel@...ts.sourceforge.net>,
	"xen-devel@...ts.xensource.com" <xen-devel@...ts.xensource.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] add tpm_xenu.ko: Xen Virtual TPM frontend driver



-----Original Message-----
From: Konrad Rzeszutek Wilk [mailto:konrad.wilk@...cle.com] 
Sent: Wednesday, November 07, 2012 11:07 AM
To: Fioravante, Matthew E.
Cc: key@...ux.vnet.ibm.com; mail@...jiv.net; jeremy@...p.org; tpmdd-devel@...ts.sourceforge.net; xen-devel@...ts.xensource.com; linux-kernel@...r.kernel.org
Subject: Re: [PATCH] add tpm_xenu.ko: Xen Virtual TPM frontend driver

On Wed, Nov 07, 2012 at 09:05:26AM -0500, Matthew Fioravante wrote:
> On 11/06/2012 02:39 PM, Konrad Rzeszutek Wilk wrote:
> >On Mon, Nov 05, 2012 at 10:09:57AM -0500, Matthew Fioravante wrote:
> >>This patch ports the xen vtpm frontend driver for linux from the 
> >>linux-2.6.18-xen.hg tree to linux-stable.
> >So how does on test it ? Set it up? Use it? Is there some 
> >documentation about it - if so it should be in the patch description.
> Thats actually a question I had. To use this driver now you have to 
> use my vtpm mini-os domains which are currently being evaluated in the 
> xen-devel mailing list. Once they are accepted I will submit a 
> documentation update to the Xen tree.
> 
> Whats the best practice for documentation in this case? All in xen?
> Some linux/some xen? If the latter, how much goes in linux and where?

As much as possible. I would say stick both of them in Xen and in Linux.
And you can designate one of them as primary (say the Xen one) and say in the Linux:

"For up-to-date information, please refer to XXYYZZ"

I grepped through the linux source code and didn't see any documentation for the other xen drivers. I could put a "please refer to XXX in xen" line in the Kconfig or as a comment in the source code or both. Am I missing something or is there some standard way the xen devs handle this documentation issue for linux drivers?

> >
> >I did a very very cursory look at it, see some of the comments.
> >
> >>
> >>+
> >>+
> >>+static inline struct transmission *transmission_alloc(void) {
> >>+     return kzalloc(sizeof(struct transmission), GFP_ATOMIC); }
> >>+
> >>+     static unsigned char *
> >
> >That is very weird tabbing? Did you run this patch through 
> >scripts/checkpatch.pl ?
> Wow thats ugly. I ran the check script and it looks like it didn't 
> pick this up. For some reason my editor wants to autoindent like that.
> Fixed.
> >
> >>+
> >>+static const struct file_operations vtpm_ops = {
> >>+     .owner = THIS_MODULE,
> >>+     .llseek = no_llseek,
> >>+     .open = tpm_open,
> >>+     .read = tpm_read,
> >>+     .write = tpm_write,
> >>+     .release = tpm_release,
> >>+};
> >>+
> >>+static DEVICE_ATTR(pubek, S_IRUGO, tpm_show_pubek, NULL); static 
> >>+DEVICE_ATTR(pcrs, S_IRUGO, tpm_show_pcrs, NULL); static 
> >>+DEVICE_ATTR(enabled, S_IRUGO, tpm_show_enabled, NULL); static 
> >>+DEVICE_ATTR(active, S_IRUGO, tpm_show_active, NULL); static 
> >>+DEVICE_ATTR(owned, S_IRUGO, tpm_show_owned, NULL); static 
> >>+DEVICE_ATTR(temp_deactivated, S_IRUGO, tpm_show_temp_deactivated,
> >>+             NULL);
> >>+static DEVICE_ATTR(caps, S_IRUGO, tpm_show_caps, NULL); static 
> >>+DEVICE_ATTR(cancel, S_IWUSR | S_IWGRP, NULL, tpm_store_cancel);
> >>+
> >>+static struct attribute *vtpm_attrs[] = {
> >>+     &dev_attr_pubek.attr,
> >>+     &dev_attr_pcrs.attr,
> >>+     &dev_attr_enabled.attr,
> >>+     &dev_attr_active.attr,
> >>+     &dev_attr_owned.attr,
> >>+     &dev_attr_temp_deactivated.attr,
> >>+     &dev_attr_caps.attr,
> >>+     &dev_attr_cancel.attr,
> >>+     NULL,
> >So are these going to show up in SysFS? If so, there should also be a 
> >corresponding file in Documentation/.../sysfs/something.
> These are similar to the entries made by the other tpm drivers. I 
> don't see any documentation about those either. TPM maintainers, any 
> guidance there?
> >
> >>+#include "tpm.h"
> >>+#include "tpm_vtpm.h"
> >>+
> >>+#undef DEBUG
> >>+
> >>+#define GRANT_INVALID_REF 0
> >Interesting. The 0 grant value is actually a valid one. I think you 
> >want (-1ULL).
> Is it?
> drivers/block/xen-blkfront.c and
> drivers/net/xen-netfront.c
> 
> do the exact same thing

You are right. Just leave it as that then.

> >>+
> >>+     init_tpm_xenbus();
> >>+     return 0;
> >>+}
> >>+
> >>+
> >>+module_init(tpmif_init);
> >no module_exit?
> Will fix
> 
> 


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