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[v3,rcu,05/11] arch/x86: Add ARCH_HAS_NMI_SAFE_THIS_CPU_OPS Kconfig option

Message ID 20221019225846.2501109-5-paulmck@kernel.org
State New
Headers
Series NMI-safe SRCU readers for v6.2 |

Commit Message

Paul E. McKenney Oct. 19, 2022, 10:58 p.m. UTC 
  The x86 architecture uses an add-to-memory instruction to implement
this_cpu_add(), which is NMI safe.  This means that the old and
more-efficient srcu_read_lock() may be used in NMI context, without
the need for srcu_read_lock_nmisafe().  Therefore, add the new Kconfig
option ARCH_HAS_NMI_SAFE_THIS_CPU_OPS to arch/x86/Kconfig, which will
cause NEED_SRCU_NMI_SAFE to be deselected, thus preserving the current
srcu_read_lock() behavior.

Link: https://lore.kernel.org/all/20220910221947.171557773@linutronix.de/

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Petr Mladek <pmladek@suse.com>
Cc: <x86@kernel.org>
---
 arch/x86/Kconfig | 1 +
 1 file changed, 1 insertion(+)
diff mbox series

Patch

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 6d1879ef933a2..bcb3190eaa266 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -81,6 +81,7 @@  config X86
 	select ARCH_HAS_KCOV			if X86_64
 	select ARCH_HAS_MEM_ENCRYPT
 	select ARCH_HAS_MEMBARRIER_SYNC_CORE
+	select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
 	select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
 	select ARCH_HAS_PMEM_API		if X86_64
 	select ARCH_HAS_PTE_DEVMAP		if X86_64