Re: [PATCH 2/2] tpm: of: If available Use linux,sml-log to get the log and its size

Michael Ellerman
2024-03-07T10:43:00Z

Stefan Berger <stefanb@linux.ibm.com> writes:
> If linux,sml-log is available use it to get the TPM log rather than the
> pointer found in linux,sml-base. This resolves an issue on PowerVM and KVM
> on Power where after a kexec the memory pointed to by linux,sml-base may
> have been corrupted. Also, linux,sml-log has replaced linux,sml-base and
> linux,sml-size on these two platforms.

It would be good to mention that powernv platforms (sometimes called
Open Power or bare metal) still use linux,sml-base/size, via skiboot.

cheers

> Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
> ---
> drivers/char/tpm/eventlog/of.c | 36 +++++++++++-----------------------
> 1 file changed, 11 insertions(+), 25 deletions(-)
>
> diff --git a/drivers/char/tpm/eventlog/of.c b/drivers/char/tpm/eventlog/of.c
> index 930fe43d5daf..e37196e64ef1 100644
> --- a/drivers/char/tpm/eventlog/of.c
> +++ b/drivers/char/tpm/eventlog/of.c
> @@ -54,8 +54,8 @@ int tpm_read_log_of(struct tpm_chip *chip)
> const u32 *sizep;
> const u64 *basep;
> struct tpm_bios_log *log;
> + const void *logp;
> u32 size;
> - u64 base;
>
> log = &chip->log;
> if (chip->dev.parent && chip->dev.parent->of_node)
> @@ -66,37 +66,23 @@ int tpm_read_log_of(struct tpm_chip *chip)
> if (of_property_read_bool(np, "powered-while-suspended"))
> chip->flags |= TPM_CHIP_FLAG_ALWAYS_POWERED;
>
> - sizep = of_get_property(np, "linux,sml-size", NULL);
> - basep = of_get_property(np, "linux,sml-base", NULL);
> - if (sizep == NULL && basep == NULL)
> - return tpm_read_log_memory_region(chip);
> - if (sizep == NULL || basep == NULL)
> - return -EIO;
> -
> - /*
> - * 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 &&
> - of_property_match_string(np, "compatible", "IBM,vtpm20") < 0) {
> + logp = of_get_property(np, "linux,sml-log", &size);
> + if (logp == NULL) {
> + sizep = of_get_property(np, "linux,sml-size", NULL);
> + basep = of_get_property(np, "linux,sml-base", NULL);
> + if (sizep == NULL && basep == NULL)
> + return tpm_read_log_memory_region(chip);
> + if (sizep == NULL || basep == NULL)
> + return -EIO;
> + logp = __va(be64_to_cpup((__force __be64 *)basep));
> size = be32_to_cpup((__force __be32 *)sizep);
> - base = be64_to_cpup((__force __be64 *)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 = devm_kmemdup(&chip->dev, __va(base), size, GFP_KERNEL);
> + log->bios_event_log = devm_kmemdup(&chip->dev, logp, size, GFP_KERNEL);
> if (!log->bios_event_log)
> return -ENOMEM;
>
> --
> 2.43.0