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Peter Anvin" , Andy Lutomirski , Peter Zijlstra , Arnaldo Carvalho de Melo , Josh Poimboeuf , Paolo Bonzini , Arnd Bergmann , Frederic Weisbecker , "Paul E. McKenney" , Jason Baron , Steven Rostedt , Ard Biesheuvel , Sami Tolvanen , "David S. Miller" , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , Boqun Feng , Uladzislau Rezki , Mathieu Desnoyers , Mel Gorman , Andrew Morton , Masahiro Yamada , Han Shen , Rik van Riel , Jann Horn , Dan Carpenter , Oleg Nesterov , Juri Lelli , Clark Williams , Yair Podemsky , Marcelo Tosatti , Daniel Wagner , Petr Tesarik Subject: [PATCH v6 17/29] x86/speculation/mds: Mark cpu_buf_idle_clear key as allowed in .noinstr Date: Fri, 10 Oct 2025 17:38:27 +0200 Message-ID: <20251010153839.151763-18-vschneid@redhat.com> In-Reply-To: <20251010153839.151763-1-vschneid@redhat.com> References: <20251010153839.151763-1-vschneid@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 X-Stat-Signature: puntb3dohs9n8frnrkgq988idi7g78i1 X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 07FBE180006 X-HE-Tag: 1760111120-371584 X-HE-Meta: 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 +LqWzIS0 93MQ5UilCPbD0Ibcmk7bXwWiRoFBeNOPf/wlD20Abhbf66o7rHH5cqCsqVSIbh5+c+m3pVSzfsTadqHSYzZQcyGFRGSxw0f0DwVLrNKkLmFPIT7d8fY0EX6LzjfVn0vuDNHl8smOz0mw0JiQH5EIhBVIWeYEDkYYsmKZmTYeRA5UuPOiXEcv1QRiJYLldXPrx9ZMtfYRsXfXYwN5xAJAFKGiQ6Vy14XnqFOPqQlKp8+No23JVbD4pjTEHjg4xttwSUABkakwF/GBFvuYkwSuWfeKc291YJInuBqRS6v/3/K98jDcSI+paf1qyXEFRh86MduOjITFbmQyIkXSLZOkhkrESc+YNsDVARnGHy+WWHHhXCjG7RPNeOMp8tWmsF0Uk206w7pp5D5IOAZWwZWwQZCjeUeKDpcldCf10hMls0ImtrjiTYe/IIbjl7PEDAkzVvSpC0yz8ukQinZn+gDwQdjc4ltUhm7tQIQ/1 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Later commits will cause objtool to warn about static keys being used in .noinstr sections in order to safely defer instruction patching IPIs targeted at NOHZ_FULL CPUs. cpu_buf_idle_clear is used in .noinstr code, and can be modified at runtime (SMT hotplug). Suppressing the text_poke_sync() IPI has little benefits for this key, as hotplug implies eventually going through takedown_cpu() -> stop_machine_cpuslocked() which is going to cause interference on all online CPUs anyway. Mark it to let objtool know not to warn about it. Signed-off-by: Valentin Schneider --- arch/x86/kernel/cpu/bugs.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 36dcfc5105be9..3aca329a853b5 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -182,7 +182,7 @@ DEFINE_STATIC_KEY_FALSE(switch_vcpu_ibpb); EXPORT_SYMBOL_GPL(switch_vcpu_ibpb); /* Control CPU buffer clear before idling (halt, mwait) */ -DEFINE_STATIC_KEY_FALSE(cpu_buf_idle_clear); +DEFINE_STATIC_KEY_FALSE_NOINSTR(cpu_buf_idle_clear); EXPORT_SYMBOL_GPL(cpu_buf_idle_clear); /* -- 2.51.0