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

Stefan Berger
2024-03-06T15:55:34Z

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.

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