Re: [PATCH v2 1/5] powerpc/rtas: Handle special return format for RTAS_FN_IBM_OPEN_ERRINJCT
From: Sourabh Jain <hidden>
Date: 2026-06-07 11:20:26
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On 27/05/26 12:54, Narayana Murty N wrote:
RTAS_FN_IBM_OPEN_ERRINJCT returns results in special format: rets[0] = session token (output) rets[1] = status code rets[2..] = additional outputs (if any) Unlike standard RTAS calls where: rets[0] = status code rets[1..] = outputs This patch adds special handling for OPEN_ERRINJCT to: 1. Check correct status position (rets[1]) for __fetch_rtas_last_error()
You can consider fixing the same for the RTAS syscall.
quoted hunk ↗ jump to hunk
2. Copy all rets[0..nret-1] to outputs[] (including token at rets[0]) 3. Return status from rets[1] instead of rets[0] Reference: OpenPOWER PAPR documentation https://files.openpower.foundation/s/XFgfMaqLMD5Bcm8 Signed-off-by: Narayana Murty N <redacted> --- arch/powerpc/kernel/rtas.c | 47 ++++++++++++++++++++++++++++++++------ 1 file changed, 40 insertions(+), 7 deletions(-)diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c index 8d81c1e7a8db..a2dd94eed9d0 100644 --- a/arch/powerpc/kernel/rtas.c +++ b/arch/powerpc/kernel/rtas.c@@ -1183,7 +1183,7 @@ int rtas_call(int token, int nargs, int nret, int *outputs, ...) unsigned long flags; struct rtas_args *args; char *buff_copy = NULL; - int ret; + int ret = 0; if (!rtas.entry || token == RTAS_UNKNOWN_SERVICE) return -1;@@ -1213,15 +1213,48 @@ int rtas_call(int token, int nargs, int nret, int *outputs, ...) va_rtas_call_unlocked(args, token, nargs, nret, list); va_end(list); + /* + * Special handling for RTAS_FN_IBM_OPEN_ERRINJCT: + * Per PAPR, ibm,open-errinjct has a unique return format: + * rets[0] = injection session token (output parameter) + * rets[1] = status code + * + * This differs from standard RTAS calls which return: + * rets[0] = status code + * rets[1..] = output parameters + * + * We must extract status from rets[1] (not rets[0]) to correctly + * detect errors and trigger __fetch_rtas_last_error() when status == -1. + */ /* A -1 return code indicates that the last command couldn't - be completed due to a hardware error. */
The above comment should be moved to next if block, if (ret == -1).
- if (be32_to_cpu(args->rets[0]) == -1)
+ * be completed due to a hardware error.
+ */
+ if (token == rtas_function_token(RTAS_FN_IBM_OPEN_ERRINJCT) && nret > 1)
+ ret = be32_to_cpu(args->rets[1]);
+ else if (nret > 0)
+ ret = be32_to_cpu(args->rets[0]);
+
+ if (ret == -1)
buff_copy = __fetch_rtas_last_error(NULL);
- if (nret > 1 && outputs != NULL)
- for (i = 0; i < nret-1; ++i)
- outputs[i] = be32_to_cpu(args->rets[i + 1]);
- ret = (nret > 0) ? be32_to_cpu(args->rets[0]) : 0;
+ /* Copy all return values to caller's outputs buffer if provided */
+ if (nret > 1 && outputs != NULL) {
+ if (token == rtas_function_token(RTAS_FN_IBM_OPEN_ERRINJCT)) {
+ /* Special case: rets[0]=token, rets[1]=status, rets[2..]=outputs */
+ for (i = 0; i < nret; ++i)
+ outputs[i] = be32_to_cpu(args->rets[i]);
+ } else {
+ /* Normal case: rets[0]=status, rets[1..]=outputs */
+ for (i = 0; i < nret - 1; ++i)
+ outputs[i] = be32_to_cpu(args->rets[i + 1]);I am surprised that status is never copied to the output buffer even though it is part of the output as per PAPR. But status is copied for ibm,open-errinjct, which is okay.
+ }
+ } else {
+ /* Either no outputs to copy (nret <= 1) or caller
+ * didn't provide output buffer ensure ret contains
+ * the status code for standard RTAS calls.
+ */
+ ret = (nret > 0) ? be32_to_cpu(args->rets[0]) : 0;What is the need to find ret again? Isn't it already done above?
+ } lockdep_unpin_lock(&rtas_lock, cookie); raw_spin_unlock_irqrestore(&rtas_lock, flags);