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SubjectRe: [RFC 09/10] x86/enter: Create macros to restrict/unrestrict Indirect Branch Speculation
On Fri, Jan 26, 2018 at 09:19:09AM -0800, Linus Torvalds wrote:
> But did we do that "disable stuffing with SMEP"? I'm not seeing it. In
> my tree, it's only conditional on X86_FEATURE_RETPOLINE.

Or rather, enable stuffing on !SMEP:

+ if ((!boot_cpu_has(X86_FEATURE_PTI) &&
+ !boot_cpu_has(X86_FEATURE_SMEP)) || is_skylake_era()) {
+ setup_force_cpu_cap(X86_FEATURE_RSB_CTXSW);
+ pr_info("Filling RSB on context switch\n");
+ }

Should be

c995efd5a740 ("x86/retpoline: Fill RSB on context switch for affected CPUs")

in your tree.


SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)

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