Re: [PATCH] tpm: Add reserved memory event log

Jarkko Sakkinen
2023-01-16T06:53:31Z

On Tue, Jan 03, 2023 at 10:20:10AM -0600, Eddie James wrote:
> Some platforms may desire to pass the event log up to linux in the
> form of a reserved memory region. Add support for this in the TPM
> core to find the reserved memory region and map it.
>
> Signed-off-by: Eddie James <eajames@linux.ibm.com>

Which platforms?

I do not see information of

+ void (*release)(void *ptr);

in the commit message. The description of the implemenation approach is
missing.

> ---
> drivers/char/tpm/eventlog/of.c | 38 +++++++++++++++++++++++++++++++++-
> drivers/char/tpm/tpm-chip.c | 3 ++-
> include/linux/tpm.h | 1 +
> 3 files changed, 40 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/char/tpm/eventlog/of.c b/drivers/char/tpm/eventlog/of.c
> index a9ce66d09a75..0455d7f61c10 100644
> --- a/drivers/char/tpm/eventlog/of.c
> +++ b/drivers/char/tpm/eventlog/of.c
> @@ -11,12 +11,48 @@
> */
>
> #include <linux/slab.h>
> +#include <linux/io.h>
> +#include <linux/ioport.h>
> #include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/of_reserved_mem.h>
> #include <linux/tpm_eventlog.h>
>
> #include "../tpm.h"
> #include "common.h"
>
> +static int tpm_read_log_memory_region(struct tpm_chip *chip)
> +{
> + struct device_node *node;
> + struct resource res;
> + int rc;
> +
> + node = of_parse_phandle(chip->dev.parent->of_node, "memory-region", 0);
> + if (!node) {
> + dev_info(&chip->dev, "no phandle\n");
> + return -ENODEV;
> + }
> +
> + rc = of_address_to_resource(node, 0, &res);
> + of_node_put(node);
> + if (rc) {
> + dev_info(&chip->dev, "no mem\n");
> + return rc;
> + }
> +
> + chip->log.bios_event_log = memremap(res.start, resource_size(&res), MEMREMAP_WB);
> + if (!chip->log.bios_event_log) {
> + dev_info(&chip->dev, "err memremap\n");
> + return -ENOMEM;
> + }
> +
> + chip->log.release = memunmap;
> + chip->log.bios_event_log_end = chip->log.bios_event_log + resource_size(&res);
> +
> + return chip->flags & TPM_CHIP_FLAG_TPM2 ? EFI_TCG2_EVENT_LOG_FORMAT_TCG_2 :
> + EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2;
> +}

We do not want to support TPM 1.2 for new features.

> +
> int tpm_read_log_of(struct tpm_chip *chip)
> {
> struct device_node *np;
> @@ -38,7 +74,7 @@ int tpm_read_log_of(struct tpm_chip *chip)
> sizep = of_get_property(np, "linux,sml-size", NULL);
> basep = of_get_property(np, "linux,sml-base", NULL);
> if (sizep == NULL && basep == NULL)
> - return -ENODEV;
> + return tpm_read_log_memory_region(chip);
> if (sizep == NULL || basep == NULL)
> return -EIO;
>
> diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
> index 741d8f3e8fb3..09ea8145d7c6 100644
> --- a/drivers/char/tpm/tpm-chip.c
> +++ b/drivers/char/tpm/tpm-chip.c
> @@ -267,7 +267,7 @@ static void tpm_dev_release(struct device *dev)
> idr_remove(&dev_nums_idr, chip->dev_num);
> mutex_unlock(&idr_lock);
>
> - kfree(chip->log.bios_event_log);
> + chip->log.release(chip->log.bios_event_log);
> kfree(chip->work_space.context_buf);
> kfree(chip->work_space.session_buf);
> kfree(chip->allocated_banks);
> @@ -324,6 +324,7 @@ struct tpm_chip *tpm_chip_alloc(struct device *pdev,
> init_rwsem(&chip->ops_sem);
>
> chip->ops = ops;
> + chip->log.release = (void(*)(void *))kfree;

Why do you need this cast?

>
> mutex_lock(&idr_lock);
> rc = idr_alloc(&dev_nums_idr, NULL, 0, TPM_NUM_DEVICES, GFP_KERNEL);
> diff --git a/include/linux/tpm.h b/include/linux/tpm.h
> index dfeb25a0362d..f1c0b0eb20a5 100644
> --- a/include/linux/tpm.h
> +++ b/include/linux/tpm.h
> @@ -109,6 +109,7 @@ struct tpm_space {
> struct tpm_bios_log {
> void *bios_event_log;
> void *bios_event_log_end;
> + void (*release)(void *ptr);
> };
>
> struct tpm_chip_seqops {
> --
> 2.31.1
>

BR, Jarkko