On Fri, Apr 09, 2021 at 01:22:49PM -0500, Saripalli, RK wrote:
> > And I think you don't need this one either if we do a "light" controls
> > thing but lemme look at the rest first.
Ok, and what I mean with "lite" version is something like this below
which needs finishing and testing.
Initially, it could support the cmdline params:
predict_store_fwd={on,off,auto}
to give people the opportunity to experiment with the feature.
If it turns out that prctl and seccomp per-task toggling is needed then
sure, we can extend but I don't see the reason for a whole separate set
of options yet. Especially is ssbd already controls this.
AFAICT, of course and if I'm not missing some other aspect here.
Thx.
---
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 2d11384dc9ab..226b73700f88 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -1165,3 +1165,22 @@ void set_dr_addr_mask(unsigned long mask, int dr)
break;
}
}
+
+static int __init psf_cmdline(char *str)
+{
+ if (!boot_cpu_has(X86_FEATURE_PSFD))
+ return 0;
+
+ if (!str)
+ return -EINVAL;
+
+ if (!strcmp(str, "off")) {
+ x86_spec_ctrl_base |= SPEC_CTRL_PSFD;
+ setup_clear_cpu_cap(X86_FEATURE_PSFD);
+ }
+
+ return 0;
+}
+early_param("predict_store_fwd", psf_cmdline);
+
+
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
