x86/speculation: Restore speculation related MSRs during S3 resume

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: 7724397 ("x86/bugs/intel: Set proper CPU features and setup RDS")
Reported-by: Neelima Krishnan <[email protected]>
Signed-off-by: Pawan Gupta <[email protected]>
Tested-by: Neelima Krishnan <[email protected]>
Acked-by: Borislav Petkov <[email protected]>
Reviewed-by: Dave Hansen <[email protected]>
Cc: [email protected]
Signed-off-by: Linus Torvalds <[email protected]>

Author: pa1gupta

arch/x86/power/cpu.c

@@ -503,10 +503,24 @@ static int pm_cpu_check(const struct x86_cpu_id *c)
 	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;
 }