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x86/bugs: Remove x86_spec_ctrl_set() 

x86_spec_ctrl_set() is only used in bugs.c and the extra mask checks there
provide no real value as both call sites can just write x86_spec_ctrl_base
to MSR_SPEC_CTRL. x86_spec_ctrl_base is valid and does not need any extra
masking or checking.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
This commit is contained in:
Thomas Gleixner 2018-05-12 20:53:14 +02:00
parent fa8ac49882
commit 4b59bdb569
2 changed files with 2 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/x86/include/asm/nospec-branch.h
View File

@ -217,8 +217,6 @@ enum spectre_v2_mitigation {
SPECTRE_V2_IBRS,
};
extern void x86_spec_ctrl_set(u64);
/* The Speculative Store Bypass disable variants */
enum ssb_mitigation {
SPEC_STORE_BYPASS_NONE,

13
arch/x86/kernel/cpu/bugs.c
View File

@ -133,15 +133,6 @@ static const char *spectre_v2_strings[] = {
static enum spectre_v2_mitigation spectre_v2_enabled __ro_after_init =
SPECTRE_V2_NONE;
void x86_spec_ctrl_set(u64 val)
{
if (val & x86_spec_ctrl_mask)
WARN_ONCE(1, "SPEC_CTRL MSR value 0x%16llx is unknown.\n", val);
else
wrmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base | val);
}
EXPORT_SYMBOL_GPL(x86_spec_ctrl_set);
void
x86_virt_spec_ctrl(u64 guest_spec_ctrl, u64 guest_virt_spec_ctrl, bool setguest)
{
@ -503,7 +494,7 @@ static enum ssb_mitigation __init __ssb_select_mitigation(void)
case X86_VENDOR_INTEL:
x86_spec_ctrl_base |= SPEC_CTRL_SSBD;
x86_spec_ctrl_mask &= ~SPEC_CTRL_SSBD;
x86_spec_ctrl_set(SPEC_CTRL_SSBD);
wrmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base);
break;
case X86_VENDOR_AMD:
x86_amd_ssb_disable();
@ -615,7 +606,7 @@ int arch_prctl_spec_ctrl_get(struct task_struct *task, unsigned long which)
void x86_spec_ctrl_setup_ap(void)
{
if (boot_cpu_has(X86_FEATURE_MSR_SPEC_CTRL))
x86_spec_ctrl_set(x86_spec_ctrl_base & ~x86_spec_ctrl_mask);
wrmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base);
if (ssb_mode == SPEC_STORE_BYPASS_DISABLE)
x86_amd_ssb_disable();