From: Konrad Rzeszutek Wilk konrad.wilk@oracle.com
commit 108fab4b5c8f12064ef86e02cb0459992affb30f upstream.
Both AMD and Intel can have SPEC_CTRL_MSR for SSBD.
However AMD also has two more other ways of doing it - which are !SPEC_CTRL MSR ways.
Signed-off-by: Konrad Rzeszutek Wilk konrad.wilk@oracle.com Signed-off-by: Thomas Gleixner tglx@linutronix.de Cc: Kees Cook keescook@chromium.org Cc: kvm@vger.kernel.org Cc: KarimAllah Ahmed karahmed@amazon.de Cc: andrew.cooper3@citrix.com Cc: "H. Peter Anvin" hpa@zytor.com Cc: Borislav Petkov bp@suse.de Cc: David Woodhouse dwmw@amazon.co.uk Link: https://lkml.kernel.org/r/20180601145921.9500-4-konrad.wilk@oracle.com Signed-off-by: Ben Hutchings ben@decadent.org.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kernel/cpu/bugs.c | 11 +++-------- 1 file changed, 3 insertions(+), 8 deletions(-)
--- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -526,17 +526,12 @@ 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. */ - switch (boot_cpu_data.x86_vendor) { - case X86_VENDOR_INTEL: - case X86_VENDOR_AMD: - if (!static_cpu_has(X86_FEATURE_MSR_SPEC_CTRL)) { - x86_amd_ssb_disable(); - break; - } + if (!static_cpu_has(X86_FEATURE_MSR_SPEC_CTRL)) + x86_amd_ssb_disable(); + else { x86_spec_ctrl_base |= SPEC_CTRL_SSBD; x86_spec_ctrl_mask |= SPEC_CTRL_SSBD; wrmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base); - break; } }