[PATCH 4.14 248/284] x86/speculation: Restore speculation related MSRs during S3 resume

Greg Kroah-Hartman
2022-04-18T14:02:04Z

From: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>

commit e2a1256b17b16f9b9adf1b6fea56819e7b68e463 upstream.

After resuming from suspend-to-RAM, the MSRs that control CPU's
speculative execution behavior are not being restored on the boot CPU.

These MSRs are used to mitigate speculative execution vulnerabilities.
Not restoring them correctly may leave the CPU vulnerable. Secondary
CPU's MSRs are correctly being restored at S3 resume by
identify_secondary_cpu().

During S3 resume, restore these MSRs for boot CPU when restoring its
processor state.

Fixes: 772439717dbf ("x86/bugs/intel: Set proper CPU features and setup RDS")
Reported-by: Neelima Krishnan <neelima.krishnan@intel.com>
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Tested-by: Neelima Krishnan <neelima.krishnan@intel.com>
Acked-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/power/cpu.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)

--- a/arch/x86/power/cpu.c
+++ b/arch/x86/power/cpu.c
@@ -517,10 +517,24 @@ static int pm_cpu_check(const struct x86
return ret;
}

+static void pm_save_spec_msr(void)
+{
+ u32 spec_msr_id[] = {
+ MSR_IA32_SPEC_CTRL,
+ MSR_IA32_TSX_CTRL,
+ MSR_TSX_FORCE_ABORT,
+ MSR_IA32_MCU_OPT_CTRL,
+ MSR_AMD64_LS_CFG,
+ };
+
+ msr_build_context(spec_msr_id, ARRAY_SIZE(spec_msr_id));
+}
+
static int pm_check_save_msr(void)
{
dmi_check_system(msr_save_dmi_table);
pm_cpu_check(msr_save_cpu_table);
+ pm_save_spec_msr();

return 0;
}