3.16.59-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Konrad Rzeszutek Wilk konrad.wilk@oracle.com
commit 1115a859f33276fe8afb31c60cf9d8e657872558 upstream.
Intel and AMD SPEC_CTRL (0x48) MSR semantics may differ in the future (or in fact use different MSRs for the same functionality).
As such a run-time mechanism is required to whitelist the appropriate MSR values.
[ tglx: Made the variable __ro_after_init ]
Signed-off-by: Konrad Rzeszutek Wilk konrad.wilk@oracle.com Signed-off-by: Thomas Gleixner tglx@linutronix.de Reviewed-by: Ingo Molnar mingo@kernel.org [bwh: Backported to 3.16: - We don't have __ro_after_init - Adjust context] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- arch/x86/kernel/cpu/bugs.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)
--- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -34,6 +34,12 @@ static void __init ssb_select_mitigation */ static u64 x86_spec_ctrl_base;
+/* + * The vendor and possibly platform specific bits which can be modified in + * x86_spec_ctrl_base. + */ +static u64 x86_spec_ctrl_mask = ~SPEC_CTRL_IBRS; + #ifdef CONFIG_X86_32
static double __initdata x = 4195835.0; @@ -179,7 +185,7 @@ static enum spectre_v2_mitigation spectr
void x86_spec_ctrl_set(u64 val) { - if (val & ~(SPEC_CTRL_IBRS | SPEC_CTRL_RDS)) + 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); @@ -497,6 +503,7 @@ static enum ssb_mitigation_cmd __init __ switch (boot_cpu_data.x86_vendor) { case X86_VENDOR_INTEL: x86_spec_ctrl_base |= SPEC_CTRL_RDS; + x86_spec_ctrl_mask &= ~SPEC_CTRL_RDS; x86_spec_ctrl_set(SPEC_CTRL_RDS); break; case X86_VENDOR_AMD: @@ -520,7 +527,7 @@ static void ssb_select_mitigation() void x86_spec_ctrl_setup_ap(void) { if (boot_cpu_has(X86_FEATURE_IBRS)) - x86_spec_ctrl_set(x86_spec_ctrl_base & (SPEC_CTRL_IBRS | SPEC_CTRL_RDS)); + x86_spec_ctrl_set(x86_spec_ctrl_base & ~x86_spec_ctrl_mask); }
#ifdef CONFIG_SYSFS