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x86/speculation: Add __update_spec_ctrl() helper

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Add a new __update_spec_ctrl() helper which is a variant of
update_spec_ctrl() that can be used in a noinstr function.

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20230727184600.26768-2-longman@redhat.com
This commit is contained in:
Waiman Long 2023-07-27 14:45:57 -04:00 committed by Ingo Molnar
parent ea41bb514f
commit e3e3bab184
1 changed files with 11 additions and 0 deletions
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11
arch/x86/include/asm/spec-ctrl.h
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@ -4,6 +4,7 @@
#include <linux/thread_info.h>
#include <asm/nospec-branch.h>
#include <asm/msr.h>
/*
* On VMENTER we must preserve whatever view of the SPEC_CTRL MSR
@ -76,6 +77,16 @@ static inline u64 ssbd_tif_to_amd_ls_cfg(u64 tifn)
return (tifn & _TIF_SSBD) ? x86_amd_ls_cfg_ssbd_mask : 0ULL;
}
/*
* This can be used in noinstr functions & should only be called in bare
* metal context.
*/
static __always_inline void __update_spec_ctrl(u64 val)
{
__this_cpu_write(x86_spec_ctrl_current, val);
native_wrmsrl(MSR_IA32_SPEC_CTRL, val);
}
#ifdef CONFIG_SMP
extern void speculative_store_bypass_ht_init(void);
#else