On Thu, Jul 14, 2022 at 04:15:35PM -0700, Pawan Gupta wrote:
IBRS mitigation for spectre_v2 forces write to MSR_IA32_SPEC_CTRL at every kernel entry/exit. On Enhanced IBRS parts setting MSR_IA32_SPEC_CTRL[IBRS] only once at boot is sufficient. MSR writes at every kernel entry/exit incur unnecessary performance loss.
When Enhanced IBRS feature is present, print a warning about this unnecessary performance loss.
Signed-off-by: Pawan Gupta pawan.kumar.gupta@linux.intel.com
v1->v2: Instead of changing the mitigation, print a warning about the perf loss.
v1: https://lore.kernel.org/lkml/0456b35fb9ef957d9a9138e0913fb1a3fd445dff.165774...
arch/x86/kernel/cpu/bugs.c | 3 +++ 1 file changed, 3 insertions(+)
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This is not the correct way to submit patches for inclusion in the stable kernel tree. Please read: https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html for how to do this properly.
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