Re: [Xen-devel] vTPM Manager shuts down

[Ross Philipson <Ross.Philipson@xxxxxxxxxx>]

> -----Original Message-----
> From: Konrad Rzeszutek Wilk [mailto:konrad.wilk@xxxxxxxxxx]
> Sent: Wednesday, May 22, 2013 4:54 PM
> To: Ross Philipson
> Cc: Daniel De Graaf; Jordi Cucurull Juan; xen-devel@xxxxxxxxxxxxx
> Subject: Re: [Xen-devel] vTPM Manager shuts down
> 
> On Wed, May 22, 2013 at 07:14:04PM +0000, Ross Philipson wrote:
> > > -----Original Message-----
> > > From: xen-devel-bounces@xxxxxxxxxxxxx [mailto:xen-devel-
> > > bounces@xxxxxxxxxxxxx] On Behalf Of Ross Philipson
> > > Sent: Wednesday, May 22, 2013 3:06 PM
> > > To: Konrad Rzeszutek Wilk; Daniel De Graaf
> > > Cc: Jordi Cucurull Juan; xen-devel@xxxxxxxxxxxxx
> > > Subject: Re: [Xen-devel] vTPM Manager shuts down
> > >
> > > > -----Original Message-----
> > > > From: xen-devel-bounces@xxxxxxxxxxxxx [mailto:xen-devel-
> > > > bounces@xxxxxxxxxxxxx] On Behalf Of Konrad Rzeszutek Wilk
> > > > Sent: Wednesday, May 22, 2013 2:00 PM
> > > > To: Daniel De Graaf
> > > > Cc: Jordi Cucurull Juan; xen-devel@xxxxxxxxxxxxx
> > > > Subject: Re: [Xen-devel] vTPM Manager shuts down
> > > >
> > > > > (XEN) General information for domain 5:
> > > > > (XEN)     refcnt=3 dying=0 pause_count=0
> > > > > (XEN)     nr_pages=7168 xenheap_pages=5 shared_pages=0
> paged_pages=0
> > > > dirty_cpus={} max_pages=7424
> > > > > (XEN)     handle=3097d8b9-8d80-4bde-94b6-978c98c37296
> > > > vm_assist=00000000
> > > > > (XEN) Rangesets belonging to domain 5:
> > > > > (XEN)     I/O Ports  { }
> > > > > (XEN)     Interrupts { }
> > > > > (XEN)     I/O Memory { fed40 }
> > > > >
> > > > > Note: my config contains "iomem=['fed40,1']" not
> "iomem=['fed40,5']"
> > > > so your
> > > > > output will differ there.
> > > >
> > > > Is that address (fed40) standard? Are there other TPM devices at
> other
> > > > locations?
> > >
> > > Yes that is defined in the TCG's TPM spec. That is the beginning of
> the
> > > PCRs
> > > for locality 0 and they range up to locality 4: FED4_0xxxh -
> FED4_4xxxh
> > >
> > > If you search for something like TCG_PCClientTPMSpecification_1-
> 21_1-
> > > 00_FINAL.pdf
> > > you can find that information (chapter 9 is on locality).
> > >
> > > > How does one find them? lspci?
> > >
> > > The TPM lives on the LPC bus. Some of its features are exported in
> > > sysfs:
> > >
> > > /sys/class/misc/tpm0
> >
> > Oh and sorry I sent it before I finished what I was going to say. You
> can
> > find information about it in ACPI. E.g. this Dell I have has a
> Broadcom
> > 1.2 TPM:
> >
> >     Device (\_SB.PCI0.LPCB.TPM)
> >     {
> >         Name (_HID, EisaId ("BCM0102"))
> >         Name (_CID, 0x310CD041)
> >         Name (_STR, Unicode ("TPM 1.2 Device"))
> >         Name (_CRS, ResourceTemplate ()
> >         {
> >             Memory32Fixed (ReadOnly,
> >                 0xFED40000,         // Address Base
> >                 0x00005000,         // Address Length
> >                 )
> >         })
> >         ...
> >     }
> 
> Would it make sense to have libxl when creating one of the TPM manager
> domains to automatically get that info from /sys/class/misc/tpm0?

Do you mean to get that address? It is pretty well fixed (at least on PC
platforms). In fact the tpm_tis Linux driver has it hard coded in its
defaults:

enum tis_defaults {
        TIS_MEM_BASE = 0xFED40000,
        TIS_MEM_LEN = 0x5000,
        TIS_SHORT_TIMEOUT = 750,        /* ms */
        TIS_LONG_TIMEOUT = 2000,        /* 2 sec */
};

Though the pnp code in tpm_tis can take external values for
the memory base. I guess the best place to find the actual value(s)
would be in ACPI firmware (reading the _CRS).

As to your other question, I guess I never thought about whether there
could or would be more than one actual TPM on a platform. I am not sure
what that would be used for and it seems like the answer is "no" on the
surface but I could be wrong.

> 
> Hm, I guess it wouldn't really work unless you added some new
> config option called 'vtpm_manager=1' to do this.

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel