Re: [PATCH v7 1/2] tpm: enhance read_log_of() to support Physical TPM event log

[Nayna]

On 12/12/2016 08:10 PM, Jarkko Sakkinen wrote:
On Sun, Dec 11, 2016 at 12:35:32AM -0500, Nayna Jain wrote:
Physical TPMs use Open Firmware Device Tree bindings that are similar
to the IBM Power virtual TPM to support event log. However, these
properties store the values in different endianness for Physical
and Virtual TPM.

This patch fixes the endianness issue by doing appropriate conversion
based on Physical or Virtual TPM.

Will other device tree using firmwares than OF use the same bindings?

Yes, that is what expected that all other device tree using firmware 
will also use same bindings.

Thanks & Regards,
    - Nayna


Signed-off-by: Nayna Jain <na...@linux.vnet.ibm.com>
---
  drivers/char/tpm/tpm_of.c | 27 +++++++++++++++++++++++----
  1 file changed, 23 insertions(+), 4 deletions(-)

diff --git a/drivers/char/tpm/tpm_of.c b/drivers/char/tpm/tpm_of.c
index 7dee42d7..de57d4a 100644
--- a/drivers/char/tpm/tpm_of.c
+++ b/drivers/char/tpm/tpm_of.c
@@ -27,6 +27,8 @@ int tpm_read_log_of(struct tpm_chip *chip)
        const u32 *sizep;
        const u64 *basep;
        struct tpm_bios_log *log;
+       u32 size;
+       u64 base;

        log = &chip->log;
        if (chip->dev.parent && chip->dev.parent->of_node)
@@ -41,18 +43,35 @@ int tpm_read_log_of(struct tpm_chip *chip)
        if (sizep == NULL || basep == NULL)
                return -EIO;

-       if (*sizep == 0) {
+       /*
+        * For both vtpm/tpm, firmware has log addr and log size in big
+        * endian format. But in case of vtpm, there is a method called
+        * sml-handover which is run during kernel init even before
+        * device tree is setup. This sml-handover function takes care
+        * of endianness and writes to sml-base and sml-size in little
+        * endian format. For this reason, vtpm doesn't need conversion
+        * but physical tpm needs the conversion.
+        */
+       if (of_property_match_string(np, "compatible", "IBM,vtpm") < 0) {
+               size = be32_to_cpup(sizep);
+               base = be64_to_cpup(basep);
+       } else {
+               size = *sizep;
+               base = *basep;
+       }
+
+       if (size == 0) {
                dev_warn(&chip->dev, "%s: Event log area empty\n", __func__);
                return -EIO;
        }

-       log->bios_event_log = kmalloc(*sizep, GFP_KERNEL);
+       log->bios_event_log = kmalloc(size, GFP_KERNEL);
        if (!log->bios_event_log)
                return -ENOMEM;

-       log->bios_event_log_end = log->bios_event_log + *sizep;
+       log->bios_event_log_end = log->bios_event_log + size;

-       memcpy(log->bios_event_log, __va(*basep), *sizep);
+       memcpy(log->bios_event_log, __va(base), size);

        return 0;
  }
--
2.5.0


Reviewed-by: Jarkko Sakkinen <jarkko.sakki...@linux.intel.com>

/Jarkko