From f88aabad33ea22be2ce1c60d8901942e4e2a9edb Mon Sep 17 00:00:00 2001 From: Nathan Lynch Date: Wed, 7 Sep 2022 17:01:11 -0500 Subject: Revert "powerpc/rtas: Implement reentrant rtas call" At the time this was submitted by Leonardo, I confirmed -- or thought I had confirmed -- with PowerVM partition firmware development that the following RTAS functions: - ibm,get-xive - ibm,int-off - ibm,int-on - ibm,set-xive were safe to call on multiple CPUs simultaneously, not only with respect to themselves as indicated by PAPR, but with arbitrary other RTAS calls: https://lore.kernel.org/linuxppc-dev/875zcy2v8o.fsf@linux.ibm.com/ Recent discussion with firmware development makes it clear that this is not true, and that the code in commit b664db8e3f97 ("powerpc/rtas: Implement reentrant rtas call") is unsafe, likely explaining several strange bugs we've seen in internal testing involving DLPAR and LPM. These scenarios use ibm,configure-connector, whose internal state can be corrupted by the concurrent use of the "reentrant" functions, leading to symptoms like endless busy statuses from RTAS. Fixes: b664db8e3f97 ("powerpc/rtas: Implement reentrant rtas call") Cc: stable@vger.kernel.org # v5.8+ Signed-off-by: Nathan Lynch Reviewed-by: Laurent Dufour Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220907220111.223267-1-nathanl@linux.ibm.com --- arch/powerpc/include/asm/rtas.h | 1 - 1 file changed, 1 deletion(-) (limited to 'arch/powerpc/include/asm/rtas.h') diff --git a/arch/powerpc/include/asm/rtas.h b/arch/powerpc/include/asm/rtas.h index 00531af17ce0..56319aea646e 100644 --- a/arch/powerpc/include/asm/rtas.h +++ b/arch/powerpc/include/asm/rtas.h @@ -240,7 +240,6 @@ extern struct rtas_t rtas; extern int rtas_token(const char *service); extern int rtas_service_present(const char *service); extern int rtas_call(int token, int, int, int *, ...); -int rtas_call_reentrant(int token, int nargs, int nret, int *outputs, ...); void rtas_call_unlocked(struct rtas_args *args, int token, int nargs, int nret, ...); extern void __noreturn rtas_restart(char *cmd); -- cgit