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(parent: 62b4db5) | patch
x86/bugs: Optimize SPEC_CTRL MSR writes
authorPeter Zijlstra <peterz@infradead.org>
Tue, 14 Jun 2022 21:15:54 +0000 (23:15 +0200)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Sat, 23 Jul 2022 10:54:03 +0000 (12:54 +0200)
commite03415eeba781f0b7568d359e5f161a7b3a5c7c7
tree988ea173fe0a0e1e987758364f39fa11d6e51b91tree | snapshot
parent62b4db57eefec6ab544749a4f0178c4f68bad835commit | diff
x86/bugs: Optimize SPEC_CTRL MSR writes

commit c779bc1a9002fa474175b80e72b85c9bf628abb0 upstream.

When changing SPEC_CTRL for user control, the WRMSR can be delayed
until return-to-user when KERNEL_IBRS has been enabled.

This avoids an MSR write during context switch.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
arch/x86/include/asm/nospec-branch.h diff | blob | history
arch/x86/kernel/cpu/bugs.c diff | blob | history
arch/x86/kernel/process.c diff | blob | history
Domain: System / Kernel;