[PATCH v1 3/3] x86/bugs: Switch the selection of mitigation from CPU vendor to CPU features

[Konrad Rzeszutek Wilk]

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@xxxxxxxxxx>

---
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Cc: David Woodhouse <dwmw@xxxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: KarimAllah Ahmed <karahmed@xxxxxxxxx>
---
 arch/x86/kernel/cpu/bugs.c | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 6bea81855cdd..cd0fda1fff6d 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -532,17 +532,12 @@ static enum ssb_mitigation __init __ssb_select_mitigation(void)
 		 * 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;
 		}
 	}
 
-- 
2.13.4