This is a bit hard to track down, but I think I've found a relevant bit of the PTP spec (section 3.8): https://www.trustedcomputinggroup.org/wp-content/uploads/PC-Client-Specific-Platform-TPM-Profile-for-TPM-2-0-v43-150126.pdf
> The TPM2_Shutdown > (STATE) command allows a Static OS to indicate to the TPM that the platform > may > enter a low power state where the TPM will be required to enter into the D3 > power > state. The use of the term "may" is significant in that there is no > requirement for the > platform to actually enter the low power state after sending the TPM2_Shutdown > (STATE) command. The software may, in fact, send subsequent commands after > sending the TPM2_Shutdown (STATE) commands. The TPM2_Shutdown (STATE) > command simply tells the TPM to save the required volatile contents because > power to > the TPM may be removed at any time. The TPM is responsible for tracking its > internal > state so that, if a command that alters the TPM’s saved state is sent to the > TPM after a > TPM2_Shutdown (STATE) command, the TPM voids the saved internal state so a > subsequent TPM2_Startup(STATE) will fail. In this case, it is the > responsibility of > platform software to send a subsequent TPM2_Shutdown (STATE) command to > preserve the new internal state of the TPM. From Part 1 (architecture), https://trustedcomputinggroup.org/wp-content/uploads/TPM-Rev-2.0-Part-1-Architecture-01.38.pdf: > A TPM implementation may invalidate a preserved context on any command except > TPM2_GetCapability(). I haven't found anything in the spec that explicitly addresses being able to immediately follow a TPM2_Shutdown(STATE) with a TPM2_Shutdown(CLEAR), but my understanding based on the first quote is that a TPM2_Shutdown(CLEAR) may clear the previous shutdown state, and as long as the Shutdown(CLEAR) is the final command, the shutdown will be orderly. Josh On Thu, May 18, 2017 at 2:13 PM, Stefan Berger <stef...@us.ibm.com> wrote: > Does it work when doing suspend (to RAM) and tpm_pm_suspend sent a > tpm2_shutdown(chip, TPM2_SU_STATE) presumably before that? > > Stefan > > > ----- Original message ----- > From: Josh Zimmerman <jo...@google.com> > To: Peter Huewe <peterhu...@gmx.de>, Marcel Selhorst <tp...@selhorst.net>, > Jarkko Sakkinen <jarkko.sakki...@linux.intel.com>, Jason Gunthorpe > <jguntho...@obsidianresearch.com>, tpmdd-devel@lists.sourceforge.net > Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org> > Subject: Re: [tpmdd-devel] [PATCH v3] tpm: Issue a TPM2_Shutdown for TPM2 > devices. > Date: Thu, May 18, 2017 11:22 AM > > Are there any other changes I should make to this patch, or is it good > to go once the patch it depends on is in? > > Thanks! > Josh > > > On Mon, May 15, 2017 at 5:08 PM, Josh Zimmerman <jo...@google.com> wrote: >> If a TPM2 loses power without a TPM2_Shutdown command being issued (a >> "disorderly reboot"), it may lose some state that has yet to be >> persisted to NVRam, and will increment the DA counter (eventually, this >> will cause the TPM to lock the user out.) >> >> NOTE: This only changes behavior on TPM2 devices. Since TPM1 uses sysfs, >> and sysfs relies on implicit locking on chip->ops, it is not safe to >> allow this code to run in TPM1, or to add sysfs support to TPM2, until >> that locking is made explicit. >> >> This patch is dependent on '[PATCH] Add "shutdown" to "struct class".' >> http://marc.info/?l=linux-kernel&m=149463235025420&w=2 >> >> Signed-off-by: Josh Zimmerman <jo...@google.com> >> >> ---- >> v2: >> - Properly split changes between this and another commit >> - Use proper locking primitive. >> - Fix commenting style >> v3: >> - Re-fix commenting style >> --- >> drivers/char/tpm/tpm-chip.c | 20 ++++++++++++++++++++ >> drivers/char/tpm/tpm-sysfs.c | 3 +++ >> 2 files changed, 23 insertions(+) >> >> diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c >> index 9dec9f551b83..272a42e77574 100644 >> --- a/drivers/char/tpm/tpm-chip.c >> +++ b/drivers/char/tpm/tpm-chip.c >> @@ -142,6 +142,25 @@ static void tpm_devs_release(struct device *dev) >> put_device(&chip->dev); >> } >> >> +static void tpm_shutdown(struct device *dev) >> +{ >> + struct tpm_chip *chip = container_of(dev, struct tpm_chip, dev); >> + /* TPM 2.0 requires that the TPM2_Shutdown() command be issued >> prior to >> + * loss of power. If it is not, the DA counter will be incremented >> and, >> + * eventually, the user will be locked out of their TPM. >> + * XXX: This codepath relies on the fact that sysfs is not enabled >> for >> + * TPM2: sysfs uses an implicit lock on chip->ops, so this use >> could >> + * race if TPM2 has sysfs support enabled before TPM sysfs's >> implicit >> + * locking is fixed. >> + */ >> + if (chip->flags & TPM_CHIP_FLAG_TPM2) { >> + down_write(&chip->ops_sem); >> + tpm2_shutdown(chip, TPM_SU_CLEAR); >> + chip->ops = NULL; >> + up_write(&chip->ops_sem); >> + } >> +} >> + >> /** >> * tpm_chip_alloc() - allocate a new struct tpm_chip instance >> * @pdev: device to which the chip is associated >> @@ -181,6 +200,7 @@ struct tpm_chip *tpm_chip_alloc(struct device *pdev, >> device_initialize(&chip->devs); >> >> chip->dev.class = tpm_class; >> + chip->dev.class.shutdown = tpm_shutdown; >> chip->dev.release = tpm_dev_release; >> chip->dev.parent = pdev; >> chip->dev.groups = chip->groups; >> diff --git a/drivers/char/tpm/tpm-sysfs.c b/drivers/char/tpm/tpm-sysfs.c >> index 55405dbe43fa..5e5ff7eb6f7e 100644 >> --- a/drivers/char/tpm/tpm-sysfs.c >> +++ b/drivers/char/tpm/tpm-sysfs.c >> @@ -294,6 +294,9 @@ static const struct attribute_group tpm_dev_group = { >> >> void tpm_sysfs_add_device(struct tpm_chip *chip) >> { >> + /* XXX: Before this restriction is removed, tpm_sysfs must be >> updated >> + * to explicitly lock chip->ops. >> + */ >> if (chip->flags & TPM_CHIP_FLAG_TPM2) >> return; >> >> -- >> 2.13.0.303.g4ebf302169-goog >> > > ------------------------------------------------------------------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > _______________________________________________ > tpmdd-devel mailing list > tpmdd-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/tpmdd-devel > > > > ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ tpmdd-devel mailing list tpmdd-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/tpmdd-devel
