From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jarkko Sakkinen Subject: Re: [PATCH v7 08/10] tpm: Proxy driver for supporting multiple emulated TPMs Date: Sun, 13 Mar 2016 22:06:52 +0200 Message-ID: <20160313200652.GA3087@intel.com> References: <1457751065-11507-1-git-send-email-stefanb@linux.vnet.ibm.com> <1457751065-11507-9-git-send-email-stefanb@linux.vnet.ibm.com> <20160312185154.GA12412@intel.com> <201603122327.u2CNRI56031122@d01av04.pok.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <201603122327.u2CNRI56031122-YREtIfBy6dDImUpY6SP3GEEOCMrvLtNR@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: tpmdd-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org To: Stefan Berger Cc: linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-security-module-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, tpmdd-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: tpmdd-devel@lists.sourceforge.net On Sat, Mar 12, 2016 at 06:27:13PM -0500, Stefan Berger wrote: > Jarkko Sakkinen wrote on 03/12/2016 > 01:51:54 PM: > > > > > On Fri, Mar 11, 2016 at 09:51:03PM -0500, Stefan Berger wrote: > > > This patch implements a proxy driver for supporting multiple emulated > TPMs > > > in a system. > > > > > > The driver implements a device /dev/vtpmx that is used to created > > > a client device pair /dev/tpmX (e.g., /dev/tpm10) and a server side > that > > > is accessed using a file descriptor returned by an ioctl. > > > The device /dev/tpmX is the usual TPM device created by the core TPM > > > driver. Applications or kernel subsystems can send TPM commands to it > > > and the corresponding server-side file descriptor receives these > > > commands and delivers them to an emulated TPM. > > > > With my test script [1] running on QEMU and TPM 2.0 simulator running on > the > > host side I get this: > > > > $ python tpm2-simulator-vtpm --host=10.0.2.2 > > cmd > > 80 01 00 00 00 0c 00 00 01 44 00 00 > > rsp > > 80 01 00 00 00 0a 00 00 00 00 > > Traceback (most recent call last): > > File "tpm2-simulator-vtpm", line 85, in > > main() > > File "tpm2-simulator-vtpm", line 80, in main > > resp = client.send_cmd(stream) > > File "/home/tpmdd/tpm2-scripts/tpm2.py", line 454, in send_cmd > > rsp = self.simulator.send_cmd(cmd) > > File "/home/tpmdd/tpm2-scripts/tpm2.py", line 436, in send_cmd > > raise SimulatorError("Empty response") > > tpm2.SimulatorError: Empty response > > > > However, the process does not exit before the read call expires: > > > > $ python tpm2-list-handles > > Traceback (most recent call last): > > File "tpm2-list-handles", line 61, in > > main() > > File "tpm2-list-handles", line 51, in main > > handles += client.get_cap(tpm2.TPM2_CAP_HANDLES, > tpm2.HR_LOADED_SESSION) > > File "/home/tpmdd/tpm2-scripts/tpm2.py", line 782, in get_cap > > next_handles, more_data = self.__get_cap_cnt(cap, pt, 1) > > File "/home/tpmdd/tpm2-scripts/tpm2.py", line 766, in __get_cap_cnt > > rsp = self.send_cmd(cmd)[10:] > > File "/home/tpmdd/tpm2-scripts/tpm2.py", line 458, in send_cmd > > rsp = f.read() > > IOError: [Errno 62] Timer expired > > > > The server side stays stuck unti this happens. > > This fix should solve the problem: > > diff --git a/drivers/char/tpm/tpm_vtpm_proxy.c > b/drivers/char/tpm/tpm_vtpm_proxy.c > index d73944e..01e5070 100644 > --- a/drivers/char/tpm/tpm_vtpm_proxy.c > +++ b/drivers/char/tpm/tpm_vtpm_proxy.c > @@ -456,10 +456,10 @@ err_delete_proxy_dev: > */ > static void vtpm_proxy_delete_device(struct proxy_dev *proxy_dev) > { > - tpm_chip_unregister(proxy_dev->chip); > - > vtpm_proxy_fops_undo_open(proxy_dev); > > + tpm_chip_unregister(proxy_dev->chip); > + > vtpm_proxy_delete_proxy_dev(proxy_dev); > } > > Can you let me know whether this gets it working for you? I'd prepare a > v9. So is the deadlock such that: * tpm_chip_unregister() tries to write lock ops_sem. * tpm_transmit() holds read lock to ops_sem. This takes two minutes if no timeouts are calculated. And is the effect of moving vtpm_proxy_fops_undo_open() upwards such that vtpm_proxy_tpm_req_canceled() starts returning true, which in effect breaks the loop in tpm_transmit()? Yeah, the fix as a code change is very simple but I had to use perf probe to verify this so maybe a comment there would be in place to tell why tpm_chip_unregister() must be called last (write lock). > Stefan /Jarkko ------------------------------------------------------------------------------ Transform Data into Opportunity. Accelerate data analysis in your applications with Intel Data Analytics Acceleration Library. Click to learn more. http://pubads.g.doubleclick.net/gampad/clk?id=278785111&iu=/4140