From: Tom Lendacky thomas.lendacky@amd.com
commit 612bc3b3d4be749f73a513a17d9b3ee1330d3487 upstream.
On AMD, the presence of the MSR_SPEC_CTRL feature does not imply that the SSBD mitigation support should use the SPEC_CTRL MSR. Other features could have caused the MSR_SPEC_CTRL feature to be set, while a different SSBD mitigation option is in place.
Update the SSBD support to check for the actual SSBD features that will use the SPEC_CTRL MSR.
Signed-off-by: Tom Lendacky thomas.lendacky@amd.com Cc: Borislav Petkov bpetkov@suse.de Cc: David Woodhouse dwmw@amazon.co.uk Cc: Konrad Rzeszutek Wilk konrad.wilk@oracle.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Peter Zijlstra peterz@infradead.org Cc: Thomas Gleixner tglx@linutronix.de Fixes: 6ac2f49edb1e ("x86/bugs: Add AMD's SPEC_CTRL MSR usage") Link: http://lkml.kernel.org/r/20180702213602.29202.33151.stgit@tlendack-t1.amdoff... Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Ben Hutchings ben@decadent.org.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kernel/cpu/bugs.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)
--- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -157,7 +157,8 @@ x86_virt_spec_ctrl(u64 guest_spec_ctrl, guestval |= guest_spec_ctrl & x86_spec_ctrl_mask;
/* SSBD controlled in MSR_SPEC_CTRL */ - if (static_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD)) + if (static_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD) || + static_cpu_has(X86_FEATURE_AMD_SSBD)) hostval |= ssbd_tif_to_spec_ctrl(ti->flags);
if (hostval != guestval) { @@ -526,9 +527,10 @@ static enum ssb_mitigation __init __ssb_ * Intel uses the SPEC CTRL MSR Bit(2) for this, while AMD may * use a completely different MSR and bit dependent on family. */ - if (!static_cpu_has(X86_FEATURE_MSR_SPEC_CTRL)) + if (!static_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD) && + !static_cpu_has(X86_FEATURE_AMD_SSBD)) { x86_amd_ssb_disable(); - else { + } else { x86_spec_ctrl_base |= SPEC_CTRL_SSBD; x86_spec_ctrl_mask |= SPEC_CTRL_SSBD; wrmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base);