On Mon, Mar 11, 2024 at 09:20:28AM -0400, Stefan Berger wrote:
> linux,sml-base holds the address of a buffer with the TPM log. This
> buffer may become invalid after a kexec. To avoid accessing an invalid
> address or corrupted buffer, embed the whole TPM log in the device tree
> property linux,sml-log. This helps to protect the log since it is
> properly carried across a kexec soft reboot with both of the kexec
> syscalls.
>
> Avoid having the firmware ingest the whole TPM log when calling
> prom_setprop but only create the linux,sml-log property as a place holder.
> Insert the actual TPM log during the tree flattening phase.
>
> Fixes: 4a727429abec ("PPC64: Add support for instantiating SML from Open Firmware")
> Suggested-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
> Signed-off-by: Stefan Berger <stefanb@xxxxxxxxxxxxx>
> ---
> arch/powerpc/kernel/prom_init.c | 27 +++++++++++++++++++--------
> 1 file changed, 19 insertions(+), 8 deletions(-)
>
> diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c
> index e67effdba85c..6f7ca72013c2 100644
> --- a/arch/powerpc/kernel/prom_init.c
> +++ b/arch/powerpc/kernel/prom_init.c
> @@ -211,6 +211,8 @@ static cell_t __prombss regbuf[1024];
>
> static bool __prombss rtas_has_query_cpu_stopped;
>
> +static u64 __prombss sml_base;
> +static u32 __prombss sml_size;
Should inside an #ifdef CONFIG_PPC64 since prom_instantiate_sml() is?
>
> /*
> * Error results ... some OF calls will return "-1" on error, some
> @@ -1954,17 +1956,15 @@ static void __init prom_instantiate_sml(void)
> }
> prom_printf(" done\n");
>
> - reserve_mem(base, size);
> -
> - prom_setprop(ibmvtpm_node, "/vdevice/vtpm", "linux,sml-base",
> - &base, sizeof(base));
> - prom_setprop(ibmvtpm_node, "/vdevice/vtpm", "linux,sml-size",
> - &size, sizeof(size));
> -
> - prom_debug("sml base = 0x%llx\n", base);
> + /* Add property now, defer adding log to tree flattening phase */
> + prom_setprop(ibmvtpm_node, "/vdevice/vtpm", "linux,sml-log",
> + NULL, 0);
> prom_debug("sml size = 0x%x\n", size);
>
> prom_debug("prom_instantiate_sml: end...\n");
> +
> + sml_base = base;
> + sml_size = size;
> }
>
> /*
> @@ -2645,6 +2645,17 @@ static void __init scan_dt_build_struct(phandle node, unsigned long *mem_start,
> }
> prev_name = sstart + soff;
>
> + if (!prom_strcmp("linux,sml-log", pname)) {
> + /* push property head */
> + dt_push_token(OF_DT_PROP, mem_start, mem_end);
> + dt_push_token(sml_size, mem_start, mem_end);
> + dt_push_token(soff, mem_start, mem_end);
> + /* push property content */
> + valp = make_room(mem_start, mem_end, sml_size, 1);
> + memcpy(valp, (void *)sml_base, sml_size);
> + *mem_start = ALIGN(*mem_start, 4);
> + continue;
> + }
Same question as above.
Regards,
Jerry
> /* get length */
> l = call_prom("getproplen", 2, 1, node, pname);
>
> --
> 2.43.0
>
