[tpmdd-devel,RFC,v2,3/5] tpm: infrastructure for TPM spaces
diff mbox

Message ID 20170112174612.9314-4-jarkko.sakkinen@linux.intel.com
State New
Headers show

Commit Message

Jarkko Sakkinen Jan. 12, 2017, 5:46 p.m. UTC
Added ability to tpm_transmit() to supply a TPM space that contains
mapping from virtual handles to physical handles and backing storage for
swapping transient objects. TPM space is isolated from other users of
the TPM.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
---
 drivers/char/tpm/Makefile        |   2 +-
 drivers/char/tpm/tpm-chip.c      |   7 +
 drivers/char/tpm/tpm-dev.c       |   2 +-
 drivers/char/tpm/tpm-interface.c |  61 ++++----
 drivers/char/tpm/tpm-sysfs.c     |   2 +-
 drivers/char/tpm/tpm.h           |  22 ++-
 drivers/char/tpm/tpm2-cmd.c      |  34 +++--
 drivers/char/tpm/tpm2-space.c    | 298 +++++++++++++++++++++++++++++++++++++++
 8 files changed, 382 insertions(+), 46 deletions(-)
 create mode 100644 drivers/char/tpm/tpm2-space.c

Comments

James Bottomley Jan. 12, 2017, 6:38 p.m. UTC | #1
On Thu, 2017-01-12 at 19:46 +0200, Jarkko Sakkinen wrote:
> @@ -435,17 +440,23 @@ ssize_t tpm_transmit(struct tpm_chip *chip,
> const u8 *buf, size_t bufsiz,
>         goto out;
> 
>  out_recv:
> -       rc = chip->ops->recv(chip, (u8 *) buf, bufsiz);
> -       if (rc < 0)
> +       len = chip->ops->recv(chip, (u8 *) buf, bufsiz);
> +       if (len < 0) {
>                 dev_err(&chip->dev,
> -                       "tpm_transmit: tpm_recv: error %zd\n", rc);
> +                       "tpm_transmit: tpm_recv: error %d\n", rc);
> +               rc = len;
> +               goto out;
> +       }
> +
> +       rc = tpm2_commit_space(chip, space, ordinal, buf, bufsiz);

I think this should be

rc = tpm2_commit_space(chip, space, ordinal, buf, len)

because tpm2_commit_space wants to know the length of the response, not
the length of the original command.

James



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Jarkko Sakkinen Jan. 12, 2017, 8:31 p.m. UTC | #2
On Thu, Jan 12, 2017 at 10:38:30AM -0800, James Bottomley wrote:
> On Thu, 2017-01-12 at 19:46 +0200, Jarkko Sakkinen wrote:
> > @@ -435,17 +440,23 @@ ssize_t tpm_transmit(struct tpm_chip *chip,
> > const u8 *buf, size_t bufsiz,
> >         goto out;
> > 
> >  out_recv:
> > -       rc = chip->ops->recv(chip, (u8 *) buf, bufsiz);
> > -       if (rc < 0)
> > +       len = chip->ops->recv(chip, (u8 *) buf, bufsiz);
> > +       if (len < 0) {
> >                 dev_err(&chip->dev,
> > -                       "tpm_transmit: tpm_recv: error %zd\n", rc);
> > +                       "tpm_transmit: tpm_recv: error %d\n", rc);
> > +               rc = len;
> > +               goto out;
> > +       }
> > +
> > +       rc = tpm2_commit_space(chip, space, ordinal, buf, bufsiz);
> 
> I think this should be
> 
> rc = tpm2_commit_space(chip, space, ordinal, buf, len)
> 
> because tpm2_commit_space wants to know the length of the response, not
> the length of the original command.

Yeah, would make sense.

> James

/Jarkko

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Jarkko Sakkinen Jan. 12, 2017, 8:50 p.m. UTC | #3
On Thu, Jan 12, 2017 at 07:46:06PM +0200, Jarkko Sakkinen wrote:
> Added ability to tpm_transmit() to supply a TPM space that contains
> mapping from virtual handles to physical handles and backing storage for
> swapping transient objects. TPM space is isolated from other users of
> the TPM.
> 
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> ---
>  drivers/char/tpm/Makefile        |   2 +-
>  drivers/char/tpm/tpm-chip.c      |   7 +
>  drivers/char/tpm/tpm-dev.c       |   2 +-
>  drivers/char/tpm/tpm-interface.c |  61 ++++----
>  drivers/char/tpm/tpm-sysfs.c     |   2 +-
>  drivers/char/tpm/tpm.h           |  22 ++-
>  drivers/char/tpm/tpm2-cmd.c      |  34 +++--
>  drivers/char/tpm/tpm2-space.c    | 298 +++++++++++++++++++++++++++++++++++++++
>  8 files changed, 382 insertions(+), 46 deletions(-)
>  create mode 100644 drivers/char/tpm/tpm2-space.c
> 
> diff --git a/drivers/char/tpm/Makefile b/drivers/char/tpm/Makefile
> index a05b1eb..251d0ed 100644
> --- a/drivers/char/tpm/Makefile
> +++ b/drivers/char/tpm/Makefile
> @@ -3,7 +3,7 @@
>  #
>  obj-$(CONFIG_TCG_TPM) += tpm.o
>  tpm-y := tpm-interface.o tpm-dev.o tpm-sysfs.o tpm-chip.o tpm2-cmd.o \
> -		tpm_eventlog.o
> +	 tpm_eventlog.o tpm2-space.o
>  tpm-$(CONFIG_ACPI) += tpm_ppi.o tpm_acpi.o
>  tpm-$(CONFIG_OF) += tpm_of.o
>  obj-$(CONFIG_TCG_TIS_CORE) += tpm_tis_core.o
> diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
> index c406343..993b9ae 100644
> --- a/drivers/char/tpm/tpm-chip.c
> +++ b/drivers/char/tpm/tpm-chip.c
> @@ -128,6 +128,7 @@ static void tpm_dev_release(struct device *dev)
>  	mutex_unlock(&idr_lock);
>  
>  	kfree(chip->log.bios_event_log);
> +	kfree(chip->work_space.context_buf);
>  	kfree(chip);
>  }
>  
> @@ -189,6 +190,12 @@ struct tpm_chip *tpm_chip_alloc(struct device *pdev,
>  	chip->cdev.owner = THIS_MODULE;
>  	chip->cdev.kobj.parent = &chip->dev.kobj;
>  
> +	chip->work_space.context_buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
> +	if (!chip->work_space.context_buf) {
> +		rc = -ENOMEM;
> +		goto out;
> +	}
> +
>  	return chip;
>  
>  out:
> diff --git a/drivers/char/tpm/tpm-dev.c b/drivers/char/tpm/tpm-dev.c
> index 912ad30..249eeb0 100644
> --- a/drivers/char/tpm/tpm-dev.c
> +++ b/drivers/char/tpm/tpm-dev.c
> @@ -144,7 +144,7 @@ static ssize_t tpm_write(struct file *file, const char __user *buf,
>  		mutex_unlock(&priv->buffer_mutex);
>  		return -EPIPE;
>  	}
> -	out_size = tpm_transmit(priv->chip, priv->data_buffer,
> +	out_size = tpm_transmit(priv->chip, NULL, priv->data_buffer,
>  				sizeof(priv->data_buffer), 0);
>  
>  	tpm_put_ops(priv->chip);
> diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
> index 0c5aba1..65fcd04c 100644
> --- a/drivers/char/tpm/tpm-interface.c
> +++ b/drivers/char/tpm/tpm-interface.c
> @@ -370,10 +370,11 @@ static bool tpm_validate_command(struct tpm_chip *chip, const u8 *cmd,
>   *     0 when the operation is successful.
>   *     A negative number for system errors (errno).
>   */
> -ssize_t tpm_transmit(struct tpm_chip *chip, const u8 *buf, size_t bufsiz,
> -		     unsigned int flags)
> +ssize_t tpm_transmit(struct tpm_chip *chip, struct tpm_space *space,
> +		     u8 *buf, size_t bufsiz, unsigned int flags)
>  {
> -	ssize_t rc;
> +	int rc;
> +	ssize_t len = 0;
>  	u32 count, ordinal;
>  	unsigned long stop;
>  
> @@ -399,10 +400,14 @@ ssize_t tpm_transmit(struct tpm_chip *chip, const u8 *buf, size_t bufsiz,
>  	if (chip->dev.parent)
>  		pm_runtime_get_sync(chip->dev.parent);
>  
> +	rc = tpm2_prepare_space(chip, space, ordinal, buf, bufsiz);
> +	if (rc)
> +		goto out;
> +
>  	rc = chip->ops->send(chip, (u8 *) buf, count);
>  	if (rc < 0) {
>  		dev_err(&chip->dev,
> -			"tpm_transmit: tpm_send: error %zd\n", rc);
> +			"tpm_transmit: tpm_send: error %d\n", rc);
>  		goto out;
>  	}
>  
> @@ -435,17 +440,23 @@ ssize_t tpm_transmit(struct tpm_chip *chip, const u8 *buf, size_t bufsiz,
>  	goto out;
>  
>  out_recv:
> -	rc = chip->ops->recv(chip, (u8 *) buf, bufsiz);
> -	if (rc < 0)
> +	len = chip->ops->recv(chip, (u8 *) buf, bufsiz);
> +	if (len < 0) {
>  		dev_err(&chip->dev,
> -			"tpm_transmit: tpm_recv: error %zd\n", rc);
> +			"tpm_transmit: tpm_recv: error %d\n", rc);
> +		rc = len;
> +		goto out;
> +	}
> +
> +	rc = tpm2_commit_space(chip, space, ordinal, buf, bufsiz);
> +
>  out:
>  	if (chip->dev.parent)
>  		pm_runtime_put_sync(chip->dev.parent);
>  
>  	if (!(flags & TPM_TRANSMIT_UNLOCKED))
>  		mutex_unlock(&chip->tpm_mutex);
> -	return rc;
> +	return rc ? rc : len;
>  }
>  
>  /**
> @@ -463,13 +474,14 @@ ssize_t tpm_transmit(struct tpm_chip *chip, const u8 *buf, size_t bufsiz,
>   *     A negative number for system errors (errno).
>   *     A positive number for a TPM error.
>   */
> -ssize_t tpm_transmit_cmd(struct tpm_chip *chip, const void *cmd,
> -			 int len, unsigned int flags, const char *desc)
> +ssize_t tpm_transmit_cmd(struct tpm_chip *chip, struct tpm_space *space,
> +			 void *cmd, int len, unsigned int flags,
> +			 const char *desc)
>  {
>  	const struct tpm_output_header *header;
>  	int err;
>  
> -	len = tpm_transmit(chip, (const u8 *)cmd, len, flags);
> +	len = tpm_transmit(chip, space, cmd, len, flags);
>  	if (len <  0)
>  		return len;
>  	else if (len < TPM_HEADER_SIZE)
> @@ -521,7 +533,7 @@ ssize_t tpm_getcap(struct tpm_chip *chip, u32 subcap_id, cap_t *cap,
>  		tpm_cmd.params.getcap_in.subcap_size = cpu_to_be32(4);
>  		tpm_cmd.params.getcap_in.subcap = cpu_to_be32(subcap_id);
>  	}
> -	rc = tpm_transmit_cmd(chip, &tpm_cmd, TPM_INTERNAL_RESULT_SIZE, 0,
> +	rc = tpm_transmit_cmd(chip, NULL, &tpm_cmd, TPM_INTERNAL_RESULT_SIZE, 0,
>  			      desc);
>  	if (!rc)
>  		*cap = tpm_cmd.params.getcap_out.cap;
> @@ -545,8 +557,9 @@ static int tpm_startup(struct tpm_chip *chip, __be16 startup_type)
>  	start_cmd.header.in = tpm_startup_header;
>  
>  	start_cmd.params.startup_in.startup_type = startup_type;
> -	return tpm_transmit_cmd(chip, &start_cmd, TPM_INTERNAL_RESULT_SIZE, 0,
> -				"attempting to start the TPM");
> +	return tpm_transmit_cmd(chip, NULL, &start_cmd,
> +				TPM_INTERNAL_RESULT_SIZE,
> +				0, "attempting to start the TPM");
>  }
>  
>  int tpm_get_timeouts(struct tpm_chip *chip)
> @@ -687,8 +700,8 @@ static int tpm_continue_selftest(struct tpm_chip *chip)
>  	struct tpm_cmd_t cmd;
>  
>  	cmd.header.in = continue_selftest_header;
> -	rc = tpm_transmit_cmd(chip, &cmd, CONTINUE_SELFTEST_RESULT_SIZE, 0,
> -			      "continue selftest");
> +	rc = tpm_transmit_cmd(chip, NULL, &cmd, CONTINUE_SELFTEST_RESULT_SIZE,
> +			      0, "continue selftest");
>  	return rc;
>  }
>  
> @@ -707,7 +720,7 @@ int tpm_pcr_read_dev(struct tpm_chip *chip, int pcr_idx, u8 *res_buf)
>  
>  	cmd.header.in = pcrread_header;
>  	cmd.params.pcrread_in.pcr_idx = cpu_to_be32(pcr_idx);
> -	rc = tpm_transmit_cmd(chip, &cmd, READ_PCR_RESULT_SIZE, 0,
> +	rc = tpm_transmit_cmd(chip, NULL, &cmd, READ_PCR_RESULT_SIZE, 0,
>  			      "attempting to read a pcr value");
>  
>  	if (rc == 0)
> @@ -805,7 +818,7 @@ int tpm_pcr_extend(u32 chip_num, int pcr_idx, const u8 *hash)
>  	cmd.header.in = pcrextend_header;
>  	cmd.params.pcrextend_in.pcr_idx = cpu_to_be32(pcr_idx);
>  	memcpy(cmd.params.pcrextend_in.hash, hash, TPM_DIGEST_SIZE);
> -	rc = tpm_transmit_cmd(chip, &cmd, EXTEND_PCR_RESULT_SIZE, 0,
> +	rc = tpm_transmit_cmd(chip, NULL, &cmd, EXTEND_PCR_RESULT_SIZE, 0,
>  			      "attempting extend a PCR value");
>  
>  	tpm_put_ops(chip);
> @@ -909,7 +922,7 @@ int tpm_send(u32 chip_num, void *cmd, size_t buflen)
>  	if (chip == NULL)
>  		return -ENODEV;
>  
> -	rc = tpm_transmit_cmd(chip, cmd, buflen, 0, "attempting tpm_cmd");
> +	rc = tpm_transmit_cmd(chip, NULL, cmd, buflen, 0, "attempting tpm_cmd");
>  
>  	tpm_put_ops(chip);
>  	return rc;
> @@ -1011,15 +1024,15 @@ int tpm_pm_suspend(struct device *dev)
>  		cmd.params.pcrextend_in.pcr_idx = cpu_to_be32(tpm_suspend_pcr);
>  		memcpy(cmd.params.pcrextend_in.hash, dummy_hash,
>  		       TPM_DIGEST_SIZE);
> -		rc = tpm_transmit_cmd(chip, &cmd, EXTEND_PCR_RESULT_SIZE, 0,
> -				      "extending dummy pcr before suspend");
> +		rc = tpm_transmit_cmd(chip, NULL, &cmd, EXTEND_PCR_RESULT_SIZE,
> +				      0, "extending dummy pcr before suspend");
>  	}
>  
>  	/* now do the actual savestate */
>  	for (try = 0; try < TPM_RETRY; try++) {
>  		cmd.header.in = savestate_header;
> -		rc = tpm_transmit_cmd(chip, &cmd, SAVESTATE_RESULT_SIZE, 0,
> -				      NULL);
> +		rc = tpm_transmit_cmd(chip, NULL, &cmd, SAVESTATE_RESULT_SIZE,
> +				      0, NULL);
>  
>  		/*
>  		 * If the TPM indicates that it is too busy to respond to
> @@ -1102,7 +1115,7 @@ int tpm_get_random(u32 chip_num, u8 *out, size_t max)
>  		tpm_cmd.header.in = tpm_getrandom_header;
>  		tpm_cmd.params.getrandom_in.num_bytes = cpu_to_be32(num_bytes);
>  
> -		err = tpm_transmit_cmd(chip, &tpm_cmd,
> +		err = tpm_transmit_cmd(chip, NULL, &tpm_cmd,
>  				       TPM_GETRANDOM_RESULT_SIZE + num_bytes,
>  				       0, "attempting get random");
>  		if (err)
> diff --git a/drivers/char/tpm/tpm-sysfs.c b/drivers/char/tpm/tpm-sysfs.c
> index 848ad65..dd31a00 100644
> --- a/drivers/char/tpm/tpm-sysfs.c
> +++ b/drivers/char/tpm/tpm-sysfs.c
> @@ -39,7 +39,7 @@ static ssize_t pubek_show(struct device *dev, struct device_attribute *attr,
>  	struct tpm_chip *chip = to_tpm_chip(dev);
>  
>  	tpm_cmd.header.in = tpm_readpubek_header;
> -	err = tpm_transmit_cmd(chip, &tpm_cmd, READ_PUBEK_RESULT_SIZE, 0,
> +	err = tpm_transmit_cmd(chip, NULL, &tpm_cmd, READ_PUBEK_RESULT_SIZE, 0,
>  			       "attempting to read the PUBEK");
>  	if (err)
>  		goto out;
> diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
> index c87c221..0e93b93 100644
> --- a/drivers/char/tpm/tpm.h
> +++ b/drivers/char/tpm/tpm.h
> @@ -91,6 +91,7 @@ enum tpm2_structures {
>  
>  enum tpm2_return_codes {
>  	TPM2_RC_HASH		= 0x0083, /* RC_FMT1 */
> +	TPM2_RC_HANDLE		= 0x008B,
>  	TPM2_RC_INITIALIZE	= 0x0100, /* RC_VER1 */
>  	TPM2_RC_DISABLED	= 0x0120,
>  	TPM2_RC_TESTING		= 0x090A, /* RC_WARN */
> @@ -114,6 +115,8 @@ enum tpm2_command_codes {
>  	TPM2_CC_CREATE		= 0x0153,
>  	TPM2_CC_LOAD		= 0x0157,
>  	TPM2_CC_UNSEAL		= 0x015E,
> +	TPM2_CC_CONTEXT_LOAD	= 0x0161,
> +	TPM2_CC_CONTEXT_SAVE	= 0x0162,
>  	TPM2_CC_FLUSH_CONTEXT	= 0x0165,
>  	TPM2_CC_GET_CAPABILITY	= 0x017A,
>  	TPM2_CC_GET_RANDOM	= 0x017B,
> @@ -151,6 +154,11 @@ enum tpm2_cc_attrs {
>  
>  #define TPM_PPI_VERSION_LEN		3
>  
> +struct tpm_space {
> +	u32 context_tbl[14];
> +	u8 *context_buf;
> +};

I'll add a cc whitelist here in the next version. I also
decrease the size of the context_tbl to three.

It could be something like

DECLARE_BITMAP(cc_map, TPM2_CC_LAST - TPM2_CC_FIRST + 1);

Or

u32 *cc_tbl;
unsigned int cc_tbl_cnt;

The first alternative takes less space and is quicker to look up.
The second alternative is more dynamic (in terms of range).

/Jarkko

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Patch
diff mbox

diff --git a/drivers/char/tpm/Makefile b/drivers/char/tpm/Makefile
index a05b1eb..251d0ed 100644
--- a/drivers/char/tpm/Makefile
+++ b/drivers/char/tpm/Makefile
@@ -3,7 +3,7 @@ 
 #
 obj-$(CONFIG_TCG_TPM) += tpm.o
 tpm-y := tpm-interface.o tpm-dev.o tpm-sysfs.o tpm-chip.o tpm2-cmd.o \
-		tpm_eventlog.o
+	 tpm_eventlog.o tpm2-space.o
 tpm-$(CONFIG_ACPI) += tpm_ppi.o tpm_acpi.o
 tpm-$(CONFIG_OF) += tpm_of.o
 obj-$(CONFIG_TCG_TIS_CORE) += tpm_tis_core.o
diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
index c406343..993b9ae 100644
--- a/drivers/char/tpm/tpm-chip.c
+++ b/drivers/char/tpm/tpm-chip.c
@@ -128,6 +128,7 @@  static void tpm_dev_release(struct device *dev)
 	mutex_unlock(&idr_lock);
 
 	kfree(chip->log.bios_event_log);
+	kfree(chip->work_space.context_buf);
 	kfree(chip);
 }
 
@@ -189,6 +190,12 @@  struct tpm_chip *tpm_chip_alloc(struct device *pdev,
 	chip->cdev.owner = THIS_MODULE;
 	chip->cdev.kobj.parent = &chip->dev.kobj;
 
+	chip->work_space.context_buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!chip->work_space.context_buf) {
+		rc = -ENOMEM;
+		goto out;
+	}
+
 	return chip;
 
 out:
diff --git a/drivers/char/tpm/tpm-dev.c b/drivers/char/tpm/tpm-dev.c
index 912ad30..249eeb0 100644
--- a/drivers/char/tpm/tpm-dev.c
+++ b/drivers/char/tpm/tpm-dev.c
@@ -144,7 +144,7 @@  static ssize_t tpm_write(struct file *file, const char __user *buf,
 		mutex_unlock(&priv->buffer_mutex);
 		return -EPIPE;
 	}
-	out_size = tpm_transmit(priv->chip, priv->data_buffer,
+	out_size = tpm_transmit(priv->chip, NULL, priv->data_buffer,
 				sizeof(priv->data_buffer), 0);
 
 	tpm_put_ops(priv->chip);
diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 0c5aba1..65fcd04c 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -370,10 +370,11 @@  static bool tpm_validate_command(struct tpm_chip *chip, const u8 *cmd,
  *     0 when the operation is successful.
  *     A negative number for system errors (errno).
  */
-ssize_t tpm_transmit(struct tpm_chip *chip, const u8 *buf, size_t bufsiz,
-		     unsigned int flags)
+ssize_t tpm_transmit(struct tpm_chip *chip, struct tpm_space *space,
+		     u8 *buf, size_t bufsiz, unsigned int flags)
 {
-	ssize_t rc;
+	int rc;
+	ssize_t len = 0;
 	u32 count, ordinal;
 	unsigned long stop;
 
@@ -399,10 +400,14 @@  ssize_t tpm_transmit(struct tpm_chip *chip, const u8 *buf, size_t bufsiz,
 	if (chip->dev.parent)
 		pm_runtime_get_sync(chip->dev.parent);
 
+	rc = tpm2_prepare_space(chip, space, ordinal, buf, bufsiz);
+	if (rc)
+		goto out;
+
 	rc = chip->ops->send(chip, (u8 *) buf, count);
 	if (rc < 0) {
 		dev_err(&chip->dev,
-			"tpm_transmit: tpm_send: error %zd\n", rc);
+			"tpm_transmit: tpm_send: error %d\n", rc);
 		goto out;
 	}
 
@@ -435,17 +440,23 @@  ssize_t tpm_transmit(struct tpm_chip *chip, const u8 *buf, size_t bufsiz,
 	goto out;
 
 out_recv:
-	rc = chip->ops->recv(chip, (u8 *) buf, bufsiz);
-	if (rc < 0)
+	len = chip->ops->recv(chip, (u8 *) buf, bufsiz);
+	if (len < 0) {
 		dev_err(&chip->dev,
-			"tpm_transmit: tpm_recv: error %zd\n", rc);
+			"tpm_transmit: tpm_recv: error %d\n", rc);
+		rc = len;
+		goto out;
+	}
+
+	rc = tpm2_commit_space(chip, space, ordinal, buf, bufsiz);
+
 out:
 	if (chip->dev.parent)
 		pm_runtime_put_sync(chip->dev.parent);
 
 	if (!(flags & TPM_TRANSMIT_UNLOCKED))
 		mutex_unlock(&chip->tpm_mutex);
-	return rc;
+	return rc ? rc : len;
 }
 
 /**
@@ -463,13 +474,14 @@  ssize_t tpm_transmit(struct tpm_chip *chip, const u8 *buf, size_t bufsiz,
  *     A negative number for system errors (errno).
  *     A positive number for a TPM error.
  */
-ssize_t tpm_transmit_cmd(struct tpm_chip *chip, const void *cmd,
-			 int len, unsigned int flags, const char *desc)
+ssize_t tpm_transmit_cmd(struct tpm_chip *chip, struct tpm_space *space,
+			 void *cmd, int len, unsigned int flags,
+			 const char *desc)
 {
 	const struct tpm_output_header *header;
 	int err;
 
-	len = tpm_transmit(chip, (const u8 *)cmd, len, flags);
+	len = tpm_transmit(chip, space, cmd, len, flags);
 	if (len <  0)
 		return len;
 	else if (len < TPM_HEADER_SIZE)
@@ -521,7 +533,7 @@  ssize_t tpm_getcap(struct tpm_chip *chip, u32 subcap_id, cap_t *cap,
 		tpm_cmd.params.getcap_in.subcap_size = cpu_to_be32(4);
 		tpm_cmd.params.getcap_in.subcap = cpu_to_be32(subcap_id);
 	}
-	rc = tpm_transmit_cmd(chip, &tpm_cmd, TPM_INTERNAL_RESULT_SIZE, 0,
+	rc = tpm_transmit_cmd(chip, NULL, &tpm_cmd, TPM_INTERNAL_RESULT_SIZE, 0,
 			      desc);
 	if (!rc)
 		*cap = tpm_cmd.params.getcap_out.cap;
@@ -545,8 +557,9 @@  static int tpm_startup(struct tpm_chip *chip, __be16 startup_type)
 	start_cmd.header.in = tpm_startup_header;
 
 	start_cmd.params.startup_in.startup_type = startup_type;
-	return tpm_transmit_cmd(chip, &start_cmd, TPM_INTERNAL_RESULT_SIZE, 0,
-				"attempting to start the TPM");
+	return tpm_transmit_cmd(chip, NULL, &start_cmd,
+				TPM_INTERNAL_RESULT_SIZE,
+				0, "attempting to start the TPM");
 }
 
 int tpm_get_timeouts(struct tpm_chip *chip)
@@ -687,8 +700,8 @@  static int tpm_continue_selftest(struct tpm_chip *chip)
 	struct tpm_cmd_t cmd;
 
 	cmd.header.in = continue_selftest_header;
-	rc = tpm_transmit_cmd(chip, &cmd, CONTINUE_SELFTEST_RESULT_SIZE, 0,
-			      "continue selftest");
+	rc = tpm_transmit_cmd(chip, NULL, &cmd, CONTINUE_SELFTEST_RESULT_SIZE,
+			      0, "continue selftest");
 	return rc;
 }
 
@@ -707,7 +720,7 @@  int tpm_pcr_read_dev(struct tpm_chip *chip, int pcr_idx, u8 *res_buf)
 
 	cmd.header.in = pcrread_header;
 	cmd.params.pcrread_in.pcr_idx = cpu_to_be32(pcr_idx);
-	rc = tpm_transmit_cmd(chip, &cmd, READ_PCR_RESULT_SIZE, 0,
+	rc = tpm_transmit_cmd(chip, NULL, &cmd, READ_PCR_RESULT_SIZE, 0,
 			      "attempting to read a pcr value");
 
 	if (rc == 0)
@@ -805,7 +818,7 @@  int tpm_pcr_extend(u32 chip_num, int pcr_idx, const u8 *hash)
 	cmd.header.in = pcrextend_header;
 	cmd.params.pcrextend_in.pcr_idx = cpu_to_be32(pcr_idx);
 	memcpy(cmd.params.pcrextend_in.hash, hash, TPM_DIGEST_SIZE);
-	rc = tpm_transmit_cmd(chip, &cmd, EXTEND_PCR_RESULT_SIZE, 0,
+	rc = tpm_transmit_cmd(chip, NULL, &cmd, EXTEND_PCR_RESULT_SIZE, 0,
 			      "attempting extend a PCR value");
 
 	tpm_put_ops(chip);
@@ -909,7 +922,7 @@  int tpm_send(u32 chip_num, void *cmd, size_t buflen)
 	if (chip == NULL)
 		return -ENODEV;
 
-	rc = tpm_transmit_cmd(chip, cmd, buflen, 0, "attempting tpm_cmd");
+	rc = tpm_transmit_cmd(chip, NULL, cmd, buflen, 0, "attempting tpm_cmd");
 
 	tpm_put_ops(chip);
 	return rc;
@@ -1011,15 +1024,15 @@  int tpm_pm_suspend(struct device *dev)
 		cmd.params.pcrextend_in.pcr_idx = cpu_to_be32(tpm_suspend_pcr);
 		memcpy(cmd.params.pcrextend_in.hash, dummy_hash,
 		       TPM_DIGEST_SIZE);
-		rc = tpm_transmit_cmd(chip, &cmd, EXTEND_PCR_RESULT_SIZE, 0,
-				      "extending dummy pcr before suspend");
+		rc = tpm_transmit_cmd(chip, NULL, &cmd, EXTEND_PCR_RESULT_SIZE,
+				      0, "extending dummy pcr before suspend");
 	}
 
 	/* now do the actual savestate */
 	for (try = 0; try < TPM_RETRY; try++) {
 		cmd.header.in = savestate_header;
-		rc = tpm_transmit_cmd(chip, &cmd, SAVESTATE_RESULT_SIZE, 0,
-				      NULL);
+		rc = tpm_transmit_cmd(chip, NULL, &cmd, SAVESTATE_RESULT_SIZE,
+				      0, NULL);
 
 		/*
 		 * If the TPM indicates that it is too busy to respond to
@@ -1102,7 +1115,7 @@  int tpm_get_random(u32 chip_num, u8 *out, size_t max)
 		tpm_cmd.header.in = tpm_getrandom_header;
 		tpm_cmd.params.getrandom_in.num_bytes = cpu_to_be32(num_bytes);
 
-		err = tpm_transmit_cmd(chip, &tpm_cmd,
+		err = tpm_transmit_cmd(chip, NULL, &tpm_cmd,
 				       TPM_GETRANDOM_RESULT_SIZE + num_bytes,
 				       0, "attempting get random");
 		if (err)
diff --git a/drivers/char/tpm/tpm-sysfs.c b/drivers/char/tpm/tpm-sysfs.c
index 848ad65..dd31a00 100644
--- a/drivers/char/tpm/tpm-sysfs.c
+++ b/drivers/char/tpm/tpm-sysfs.c
@@ -39,7 +39,7 @@  static ssize_t pubek_show(struct device *dev, struct device_attribute *attr,
 	struct tpm_chip *chip = to_tpm_chip(dev);
 
 	tpm_cmd.header.in = tpm_readpubek_header;
-	err = tpm_transmit_cmd(chip, &tpm_cmd, READ_PUBEK_RESULT_SIZE, 0,
+	err = tpm_transmit_cmd(chip, NULL, &tpm_cmd, READ_PUBEK_RESULT_SIZE, 0,
 			       "attempting to read the PUBEK");
 	if (err)
 		goto out;
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index c87c221..0e93b93 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -91,6 +91,7 @@  enum tpm2_structures {
 
 enum tpm2_return_codes {
 	TPM2_RC_HASH		= 0x0083, /* RC_FMT1 */
+	TPM2_RC_HANDLE		= 0x008B,
 	TPM2_RC_INITIALIZE	= 0x0100, /* RC_VER1 */
 	TPM2_RC_DISABLED	= 0x0120,
 	TPM2_RC_TESTING		= 0x090A, /* RC_WARN */
@@ -114,6 +115,8 @@  enum tpm2_command_codes {
 	TPM2_CC_CREATE		= 0x0153,
 	TPM2_CC_LOAD		= 0x0157,
 	TPM2_CC_UNSEAL		= 0x015E,
+	TPM2_CC_CONTEXT_LOAD	= 0x0161,
+	TPM2_CC_CONTEXT_SAVE	= 0x0162,
 	TPM2_CC_FLUSH_CONTEXT	= 0x0165,
 	TPM2_CC_GET_CAPABILITY	= 0x017A,
 	TPM2_CC_GET_RANDOM	= 0x017B,
@@ -151,6 +154,11 @@  enum tpm2_cc_attrs {
 
 #define TPM_PPI_VERSION_LEN		3
 
+struct tpm_space {
+	u32 context_tbl[14];
+	u8 *context_buf;
+};
+
 enum tpm_chip_flags {
 	TPM_CHIP_FLAG_TPM2		= BIT(1),
 	TPM_CHIP_FLAG_IRQ		= BIT(2),
@@ -202,6 +210,7 @@  struct tpm_chip {
 	char ppi_version[TPM_PPI_VERSION_LEN + 1];
 #endif /* CONFIG_ACPI */
 
+	struct tpm_space work_space;
 	u32 nr_commands;
 	u32 *cc_attrs_tbl;
 };
@@ -509,10 +518,11 @@  enum tpm_transmit_flags {
 	TPM_TRANSMIT_UNLOCKED	= BIT(0),
 };
 
-ssize_t tpm_transmit(struct tpm_chip *chip, const u8 *buf, size_t bufsiz,
-		     unsigned int flags);
-ssize_t tpm_transmit_cmd(struct tpm_chip *chip, const void *cmd, int len,
-			 unsigned int flags, const char *desc);
+ssize_t tpm_transmit(struct tpm_chip *chip, struct tpm_space *space,
+		     u8 *buf, size_t bufsiz, unsigned int flags);
+ssize_t tpm_transmit_cmd(struct tpm_chip *chip, struct tpm_space *space,
+			 void *cmd, int len, unsigned int flags,
+			 const char *desc);
 ssize_t tpm_getcap(struct tpm_chip *chip, u32 subcap_id, cap_t *cap,
 		   const char *desc);
 int tpm_get_timeouts(struct tpm_chip *);
@@ -566,4 +576,8 @@  void tpm2_shutdown(struct tpm_chip *chip, u16 shutdown_type);
 unsigned long tpm2_calc_ordinal_duration(struct tpm_chip *chip, u32 ordinal);
 int tpm2_probe(struct tpm_chip *chip);
 bool tpm2_find_cc_attrs(struct tpm_chip *chip, u32 cc, u32 *attrs);
+int tpm2_prepare_space(struct tpm_chip *chip, struct tpm_space *space,
+		       u32 cc, u8 *buf, size_t bufsiz);
+int tpm2_commit_space(struct tpm_chip *chip, struct tpm_space *space,
+		      u32 cc, u8 *buf, size_t bufsiz);
 #endif
diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index e2b4c75..6842555 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -280,7 +280,7 @@  int tpm2_pcr_read(struct tpm_chip *chip, int pcr_idx, u8 *res_buf)
 	       sizeof(cmd.params.pcrread_in.pcr_select));
 	cmd.params.pcrread_in.pcr_select[pcr_idx >> 3] = 1 << (pcr_idx & 0x7);
 
-	rc = tpm_transmit_cmd(chip, &cmd, sizeof(cmd), 0,
+	rc = tpm_transmit_cmd(chip, NULL, &cmd, sizeof(cmd), 0,
 			      "attempting to read a pcr value");
 	if (rc == 0) {
 		buf = cmd.params.pcrread_out.digest;
@@ -327,7 +327,7 @@  int tpm2_pcr_extend(struct tpm_chip *chip, int pcr_idx, const u8 *hash)
 	cmd.params.pcrextend_in.hash_alg = cpu_to_be16(TPM2_ALG_SHA1);
 	memcpy(cmd.params.pcrextend_in.digest, hash, TPM_DIGEST_SIZE);
 
-	rc = tpm_transmit_cmd(chip, &cmd, sizeof(cmd), 0,
+	rc = tpm_transmit_cmd(chip, NULL, &cmd, sizeof(cmd), 0,
 			      "attempting extend a PCR value");
 
 	return rc;
@@ -373,7 +373,7 @@  int tpm2_get_random(struct tpm_chip *chip, u8 *out, size_t max)
 		cmd.header.in = tpm2_getrandom_header;
 		cmd.params.getrandom_in.size = cpu_to_be16(num_bytes);
 
-		err = tpm_transmit_cmd(chip, &cmd, sizeof(cmd), 0,
+		err = tpm_transmit_cmd(chip, NULL, &cmd, sizeof(cmd), 0,
 				       "attempting get random");
 		if (err)
 			break;
@@ -423,8 +423,8 @@  void tpm2_flush_context_cmd(struct tpm_chip *chip, u32 handle,
 
 	tpm_buf_append_u32(&buf, handle);
 
-	rc = tpm_transmit_cmd(chip, buf.data, PAGE_SIZE, flags,
-			     "flushing context");
+	rc = tpm_transmit_cmd(chip, NULL, buf.data, TPM_BUFSIZE, flags,
+			      "flushing context");
 	if (rc)
 		dev_warn(&chip->dev, "0x%08x was not flushed, rc=%d\n", handle,
 			 rc);
@@ -542,7 +542,8 @@  int tpm2_seal_trusted(struct tpm_chip *chip,
 		goto out;
 	}
 
-	rc = tpm_transmit_cmd(chip, buf.data, PAGE_SIZE, 0, "sealing data");
+	rc = tpm_transmit_cmd(chip, NULL, buf.data, TPM_BUFSIZE, 0,
+			      "sealing data");
 	if (rc)
 		goto out;
 
@@ -620,7 +621,8 @@  static int tpm2_load_cmd(struct tpm_chip *chip,
 		goto out;
 	}
 
-	rc = tpm_transmit_cmd(chip, buf.data, PAGE_SIZE, flags, "loading blob");
+	rc = tpm_transmit_cmd(chip, NULL, buf.data, TPM_BUFSIZE, flags,
+			      "loading blob");
 	if (!rc)
 		*blob_handle = be32_to_cpup(
 			(__be32 *) &buf.data[TPM_HEADER_SIZE]);
@@ -670,7 +672,8 @@  static int tpm2_unseal_cmd(struct tpm_chip *chip,
 			     options->blobauth /* hmac */,
 			     TPM_DIGEST_SIZE);
 
-	rc = tpm_transmit_cmd(chip, buf.data, PAGE_SIZE, flags, "unsealing");
+	rc = tpm_transmit_cmd(chip, NULL, buf.data, TPM_BUFSIZE, flags,
+			      "unsealing");
 	if (rc > 0)
 		rc = -EPERM;
 
@@ -738,7 +741,7 @@  ssize_t tpm2_get_tpm_pt(struct tpm_chip *chip, u32 property_id,  u32 *value,
 	cmd.params.get_tpm_pt_in.property_id = cpu_to_be32(property_id);
 	cmd.params.get_tpm_pt_in.property_cnt = cpu_to_be32(1);
 
-	rc = tpm_transmit_cmd(chip, &cmd, sizeof(cmd), 0, desc);
+	rc = tpm_transmit_cmd(chip, NULL, &cmd, sizeof(cmd), 0, desc);
 	if (!rc)
 		*value = be32_to_cpu(cmd.params.get_tpm_pt_out.value);
 
@@ -772,7 +775,7 @@  static int tpm2_startup(struct tpm_chip *chip, u16 startup_type)
 	cmd.header.in = tpm2_startup_header;
 
 	cmd.params.startup_in.startup_type = cpu_to_be16(startup_type);
-	return tpm_transmit_cmd(chip, &cmd, sizeof(cmd), 0,
+	return tpm_transmit_cmd(chip, NULL, &cmd, sizeof(cmd), 0,
 				"attempting to start the TPM");
 }
 
@@ -801,7 +804,8 @@  void tpm2_shutdown(struct tpm_chip *chip, u16 shutdown_type)
 	cmd.header.in = tpm2_shutdown_header;
 	cmd.params.startup_in.startup_type = cpu_to_be16(shutdown_type);
 
-	rc = tpm_transmit_cmd(chip, &cmd, sizeof(cmd), 0, "stopping the TPM");
+	rc = tpm_transmit_cmd(chip, NULL, &cmd, sizeof(cmd), 0,
+			      "stopping the TPM");
 
 	/* In places where shutdown command is sent there's no much we can do
 	 * except print the error code on a system failure.
@@ -864,7 +868,7 @@  static int tpm2_start_selftest(struct tpm_chip *chip, bool full)
 	cmd.header.in = tpm2_selftest_header;
 	cmd.params.selftest_in.full_test = full;
 
-	rc = tpm_transmit_cmd(chip, &cmd, TPM2_SELF_TEST_IN_SIZE, 0,
+	rc = tpm_transmit_cmd(chip, NULL, &cmd, TPM2_SELF_TEST_IN_SIZE, 0,
 			      "continue selftest");
 
 	/* At least some prototype chips seem to give RC_TESTING error
@@ -915,7 +919,7 @@  static int tpm2_do_selftest(struct tpm_chip *chip)
 		cmd.params.pcrread_in.pcr_select[1] = 0x00;
 		cmd.params.pcrread_in.pcr_select[2] = 0x00;
 
-		rc = tpm_transmit_cmd(chip, &cmd, sizeof(cmd), 0, NULL);
+		rc = tpm_transmit_cmd(chip, NULL, &cmd, sizeof(cmd), 0, NULL);
 		if (rc < 0)
 			break;
 
@@ -948,7 +952,7 @@  int tpm2_probe(struct tpm_chip *chip)
 	cmd.params.get_tpm_pt_in.property_id = cpu_to_be32(0x100);
 	cmd.params.get_tpm_pt_in.property_cnt = cpu_to_be32(1);
 
-	rc = tpm_transmit_cmd(chip, &cmd, sizeof(cmd),  0, NULL);
+	rc = tpm_transmit_cmd(chip, NULL, &cmd, sizeof(cmd),  0, NULL);
 	if (rc <  0)
 		return rc;
 
@@ -1010,7 +1014,7 @@  int tpm2_auto_startup(struct tpm_chip *chip)
 	tpm_buf_append_u32(&buf, TPM2_CC_FIRST);
 	tpm_buf_append_u32(&buf, nr_commands);
 
-	rc = tpm_transmit_cmd(chip, buf.data, PAGE_SIZE, 0, NULL);
+	rc = tpm_transmit_cmd(chip, NULL, buf.data, PAGE_SIZE, 0, NULL);
 	if (rc < 0) {
 		tpm_buf_destroy(&buf);
 		goto out;
diff --git a/drivers/char/tpm/tpm2-space.c b/drivers/char/tpm/tpm2-space.c
new file mode 100644
index 0000000..ca55feb
--- /dev/null
+++ b/drivers/char/tpm/tpm2-space.c
@@ -0,0 +1,298 @@ 
+/*
+ * Copyright (C) 2016 Intel Corporation
+ *
+ * Authors:
+ * Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
+ *
+ * Maintained by: <tpmdd-devel@lists.sourceforge.net>
+ *
+ * This file contains TPM2 protocol implementations of the commands
+ * used by the kernel internally.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; version 2
+ * of the License.
+ */
+
+#include <linux/gfp.h>
+#include "tpm.h"
+
+enum tpm2_handle_types {
+	TPM2_HT_HMAC_SESSION	= 0x02000000,
+	TPM2_HT_POLICY_SESSION	= 0x03000000,
+	TPM2_HT_TRANSIENT	= 0x80000000,
+};
+
+static void tpm2_flush_space(struct tpm_chip *chip)
+{
+	struct tpm_space *space = &chip->work_space;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(space->context_tbl); i++)
+		if (space->context_tbl[i] && ~space->context_tbl[i])
+			tpm2_flush_context_cmd(chip, space->context_tbl[i],
+					       TPM_TRANSMIT_UNLOCKED);
+}
+
+struct tpm2_context {
+	__be64 sequence;
+	__be32 saved_handle;
+	__be32 hierarchy;
+	__be16 blob_size;
+} __packed;
+
+static int tpm2_load_space(struct tpm_chip *chip)
+{
+	struct tpm_space *space = &chip->work_space;
+	struct tpm2_context *ctx;
+	struct tpm_buf buf;
+	int i;
+	int j;
+	int rc;
+	u32 s;
+
+	for (i = 0, j = 0; i < ARRAY_SIZE(space->context_tbl); i++) {
+		if (!space->context_tbl[i])
+			continue;
+
+		/* sanity check, should never happen */
+		if (~space->context_tbl[i]) {
+			dev_err(&chip->dev, "context table is inconsistent");
+			return -EFAULT;
+		}
+
+		rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS,
+				 TPM2_CC_CONTEXT_LOAD);
+		if (rc)
+			return rc;
+
+		ctx = (struct tpm2_context *)&space->context_buf[j];
+		s = sizeof(*ctx) + be16_to_cpu(ctx->blob_size);
+		tpm_buf_append(&buf, &space->context_buf[j], s);
+
+		rc = tpm_transmit_cmd(chip, NULL, buf.data, PAGE_SIZE,
+				      TPM_TRANSMIT_UNLOCKED, NULL);
+		if (rc) {
+			dev_warn(&chip->dev, "%s: loading failed with %d\n",
+				 __func__, rc);
+			rc = -EFAULT;
+			goto out_err;
+		}
+
+		space->context_tbl[i] =
+			be32_to_cpup((__be32 *)&buf.data[TPM_HEADER_SIZE]);
+
+		j += s;
+
+		tpm_buf_destroy(&buf);
+	}
+
+	return 0;
+
+out_err:
+	tpm_buf_destroy(&buf);
+	tpm2_flush_space(chip);
+	return rc;
+}
+
+static int tpm2_map_command(struct tpm_chip *chip, u32 cc, u8 *cmd, size_t len)
+{
+	struct tpm_space *space = &chip->work_space;
+	unsigned int nr_handles;
+	u32 vhandle;
+	u32 phandle;
+	u32 attrs;
+	int i;
+	int j;
+	int rc;
+
+	if (!tpm2_find_cc_attrs(chip, cc, &attrs)) {
+		rc = -EINVAL;
+		goto out_err;
+	}
+
+	nr_handles = (attrs >> TPM2_CC_ATTR_CHANDLES) & GENMASK(2, 0);
+
+	for (i = 0; i < nr_handles; i++) {
+		vhandle = be32_to_cpup((__be32 *)&cmd[TPM_HEADER_SIZE + 4 * i]);
+		if ((vhandle & 0xFF000000) != TPM2_HT_TRANSIENT)
+			continue;
+
+		j = 0xFFFFFF - (vhandle & 0xFFFFFF);
+		if (j > ARRAY_SIZE(space->context_tbl) ||
+		    !space->context_tbl[j]) {
+			rc = -EINVAL;
+			goto out_err;
+		}
+
+		phandle = space->context_tbl[j];
+		*((__be32 *)&cmd[TPM_HEADER_SIZE + 4 * i]) =
+			cpu_to_be32(phandle);
+	}
+
+	return 0;
+
+out_err:
+	tpm2_flush_space(chip);
+	return rc;
+}
+
+int tpm2_prepare_space(struct tpm_chip *chip, struct tpm_space *space,
+		       u32 cc, u8 *buf, size_t bufsiz)
+{
+	int rc;
+
+	if (!space)
+		return 0;
+
+	memcpy(&chip->work_space.context_tbl, &space->context_tbl,
+	       sizeof(space->context_tbl));
+	memcpy(chip->work_space.context_buf, space->context_buf, PAGE_SIZE);
+
+	rc = tpm2_load_space(chip);
+	if (rc)
+		return rc;
+
+	rc = tpm2_map_command(chip, cc, buf, bufsiz);
+	if (rc)
+		return rc;
+
+	return 0;
+}
+
+static int tpm2_map_response(struct tpm_chip *chip, u32 cc, u8 *rsp, size_t len)
+{
+	struct tpm_space *space = &chip->work_space;
+	u32 phandle;
+	u32 vhandle;
+	u32 attrs;
+	int i;
+	int rc;
+
+	if (!tpm2_find_cc_attrs(chip, cc, &attrs)) {
+		/* should never happen */
+		dev_err(&chip->dev, "TPM returned a different CC: 0x%04x\n",
+			cc);
+		rc = -EFAULT;
+		goto out_err;
+	}
+
+	if (!((attrs >> TPM2_CC_ATTR_RHANDLE) & 1))
+		return 0;
+
+	phandle = be32_to_cpup((__be32 *)&rsp[TPM_HEADER_SIZE]);
+	if ((phandle & 0xFF000000) != TPM2_HT_TRANSIENT)
+		return 0;
+
+	/* Garbage collect a dead context. */
+	for (i = 0; i < ARRAY_SIZE(space->context_tbl); i++) {
+		if (space->context_tbl[i] == phandle) {
+			space->context_tbl[i] = 0;
+			break;
+		}
+	}
+
+	for (i = 0; i < ARRAY_SIZE(space->context_tbl); i++)
+		if (!space->context_tbl[i])
+			break;
+
+	if (i == ARRAY_SIZE(space->context_tbl)) {
+		dev_warn(&chip->dev, "%s: out of context slots\n", __func__);
+		tpm2_flush_context_cmd(chip, phandle, TPM_TRANSMIT_UNLOCKED);
+		rc = -ENOMEM;
+		goto out_err;
+	}
+
+	space->context_tbl[i] = phandle;
+	vhandle = TPM2_HT_TRANSIENT | (0xFFFFFF - i);
+	*(__be32 *)&rsp[TPM_HEADER_SIZE] = cpu_to_be32(vhandle);
+
+	return 0;
+
+out_err:
+	tpm2_flush_space(chip);
+	return rc;
+}
+
+static int tpm2_save_space(struct tpm_chip *chip)
+{
+	struct tpm_space *space = &chip->work_space;
+	struct tpm_buf buf;
+	int i;
+	int j;
+	int rc;
+	u32 s;
+
+	for (i = 0, j = 0; i < ARRAY_SIZE(space->context_tbl); i++) {
+		if (!(space->context_tbl[i] && ~space->context_tbl[i]))
+			continue;
+
+		rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS,
+				  TPM2_CC_CONTEXT_SAVE);
+		if (rc)
+			return rc;
+
+		tpm_buf_append_u32(&buf, space->context_tbl[i]);
+
+		rc = tpm_transmit_cmd(chip, NULL, buf.data, PAGE_SIZE,
+				      TPM_TRANSMIT_UNLOCKED, NULL);
+		if ((rc & TPM2_RC_HANDLE) == TPM2_RC_HANDLE) {
+			space->context_tbl[i] = 0;
+			continue;
+		} else if (rc) {
+			dev_warn(&chip->dev, "%s: saving failed with %d\n",
+				 __func__, rc);
+			rc = -EFAULT;
+			goto out_err;
+		}
+
+		s = tpm_buf_length(&buf) - TPM_HEADER_SIZE;
+		if ((j + s) > PAGE_SIZE) {
+			dev_warn(&chip->dev, "%s: out of backing storage\n",
+				 __func__);
+			rc = -ENOMEM;
+			goto out_err;
+		}
+
+		memcpy(&space->context_buf[j], &buf.data[TPM_HEADER_SIZE], s);
+
+		tpm2_flush_context_cmd(chip, space->context_tbl[i],
+				       TPM_TRANSMIT_UNLOCKED);
+
+		space->context_tbl[i] = ~0;
+
+		j += s;
+
+		tpm_buf_destroy(&buf);
+	}
+
+	return 0;
+out_err:
+	tpm_buf_destroy(&buf);
+	tpm2_flush_space(chip);
+	return rc;
+}
+
+int tpm2_commit_space(struct tpm_chip *chip, struct tpm_space *space,
+		      u32 cc, u8 *buf, size_t bufsiz)
+{
+	int rc;
+
+	if (!space)
+		return 0;
+
+	rc = tpm2_map_response(chip, cc, buf, bufsiz);
+	if (rc)
+		return rc;
+
+	rc = tpm2_save_space(chip);
+	if (rc)
+		return rc;
+
+	memcpy(&space->context_tbl, &chip->work_space.context_tbl,
+	       sizeof(space->context_tbl));
+	memcpy(space->context_buf, chip->work_space.context_buf, PAGE_SIZE);
+
+	return 0;
+}