On 3/7/24 16:52, Rob Herring wrote:
On Thu, Mar 07, 2024 at 09:41:31PM +1100, Michael Ellerman wrote:
Stefan Berger <stefanb@xxxxxxxxxxxxx> writes:
linux,sml-base holds the address of a buffer with the TPM log. This
buffer may become invalid after a kexec and therefore embed the whole TPM
log in linux,sml-log. This helps to protect the log since it is properly
carried across a kexec with both of the kexec syscalls.
Signed-off-by: Stefan Berger <stefanb@xxxxxxxxxxxxx>
---
arch/powerpc/kernel/prom_init.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)
Also adding the new linux,sml-log property should be accompanied by a
change to the device tree binding.
The syntax is not very obvious to me, but possibly something like?
diff --git a/Documentation/devicetree/bindings/tpm/ibm,vtpm.yaml b/Documentation/devicetree/bindings/tpm/ibm,vtpm.yaml
index 50a3fd31241c..cd75037948bc 100644
--- a/Documentation/devicetree/bindings/tpm/ibm,vtpm.yaml
+++ b/Documentation/devicetree/bindings/tpm/ibm,vtpm.yaml
@@ -74,8 +74,6 @@ required:
- ibm,my-dma-window
- ibm,my-drc-index
- ibm,loc-code
- - linux,sml-base
- - linux,sml-size
Dropping required properties is an ABI break. If you drop them, an older
OS version won't work.
1) On PowerVM and KVM on Power these two properties were added in the
Linux code. I replaced the creation of these properties with creation of
linux,sml-log (1/2 in this series). I also replaced the handling of
these two (2/2 in this series) for these two platforms but leaving it
for powernv systems where the firmware creates these.
https://elixir.bootlin.com/linux/latest/source/arch/powerpc/kernel/prom_init.c#L1959
2) There is an example in the ibm,vtpm.yaml file that has both of these
and the test case still passes the check when the two entries above are
removed. I will post v2 with the changes to the DT bindings for
linux,sml-log including an example for linux,sml-log. [The test cases
fail, as expected, when an additional property is added, such as when
linux,sml-base is added when linux,sml-log is there or linux,sml-log is
added when linux,sml-base is there.]
allOf:
- $ref: tpm-common.yaml#
diff --git a/Documentation/devicetree/bindings/tpm/tpm-common.yaml b/Documentation/devicetree/bindings/tpm/tpm-common.yaml
index 3c1241b2a43f..616604707c95 100644
--- a/Documentation/devicetree/bindings/tpm/tpm-common.yaml
+++ b/Documentation/devicetree/bindings/tpm/tpm-common.yaml
@@ -25,6 +25,11 @@ properties:
base address of reserved memory allocated for firmware event log
$ref: /schemas/types.yaml#/definitions/uint64
+ linux,sml-log:
Why is this Linux specific?
I am not sure about the criteria when to prefix with 'linux,' and when
not to. In this case I did it because it is created by Linux and because
of existing linux,sml-base and linux,sml-size.
