x86/cpufeatures: Disentangle SSBD enumeration

commit 52817587 upstream

The SSBD enumeration is similarly to the other bits magically shared
between Intel and AMD though the mechanisms are different.

Make X86_FEATURE_SSBD synthetic and set it depending on the vendor specific
features or family dependent setup.

Change the Intel bit to X86_FEATURE_SPEC_CTRL_SSBD to denote that SSBD is
controlled via MSR_SPEC_CTRL and fix up the usage sites.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/x86/include/asm/cpufeatures.h

@@ -198,6 +198,7 @@
 #define X86_FEATURE_RETPOLINE_AMD ( 7*32+13) /* "" AMD Retpoline mitigation for Spectre variant 2 */
 
 #define X86_FEATURE_MSR_SPEC_CTRL ( 7*32+16) /* "" MSR SPEC_CTRL is implemented */
+#define X86_FEATURE_SSBD	( 7*32+17) /* Speculative Store Bypass Disable */
 
 #define X86_FEATURE_RSB_CTXSW	( 7*32+19) /* "" Fill RSB on context switches */
 
@@ -207,7 +208,7 @@
 #define X86_FEATURE_USE_IBPB	( 7*32+21) /* "" Indirect Branch Prediction Barrier enabled */
 #define X86_FEATURE_USE_IBRS_FW	( 7*32+22) /* "" Use IBRS during runtime firmware calls */
 #define X86_FEATURE_SPEC_STORE_BYPASS_DISABLE ( 7*32+23) /* "" Disable Speculative Store Bypass. */
-#define X86_FEATURE_AMD_SSBD	( 7*32+24) /* "" AMD SSBD implementation */
+#define X86_FEATURE_LS_CFG_SSBD	( 7*32+24) /* "" AMD SSBD implementation */
 #define X86_FEATURE_IBRS	( 7*32+25) /* Indirect Branch Restricted Speculation */
 #define X86_FEATURE_IBPB	( 7*32+26) /* Indirect Branch Prediction Barrier */
 #define X86_FEATURE_STIBP	( 7*32+27) /* Single Thread Indirect Branch Predictors */
@@ -314,7 +315,7 @@
 #define X86_FEATURE_SPEC_CTRL		(18*32+26) /* "" Speculation Control (IBRS + IBPB) */
 #define X86_FEATURE_INTEL_STIBP		(18*32+27) /* "" Single Thread Indirect Branch Predictors */
 #define X86_FEATURE_ARCH_CAPABILITIES	(18*32+29) /* IA32_ARCH_CAPABILITIES MSR (Intel) */
-#define X86_FEATURE_SSBD		(18*32+31) /* Speculative Store Bypass Disable */
+#define X86_FEATURE_SPEC_CTRL_SSBD	(18*32+31) /* "" Speculative Store Bypass Disable */
 
 /*
  * BUG word(s)

arch/x86/kernel/cpu/amd.c

@@ -558,8 +558,8 @@ static void bsp_init_amd(struct cpuinfo_x86 *c)
 		 * avoid RMW. If that faults, do not enable SSBD.
 		 */
 		if (!rdmsrl_safe(MSR_AMD64_LS_CFG, &x86_amd_ls_cfg_base)) {
+			setup_force_cpu_cap(X86_FEATURE_LS_CFG_SSBD);
 			setup_force_cpu_cap(X86_FEATURE_SSBD);
-			setup_force_cpu_cap(X86_FEATURE_AMD_SSBD);
 			x86_amd_ls_cfg_ssbd_mask = 1ULL << bit;
 		}
 	}
@@ -848,11 +848,6 @@ static void init_amd(struct cpuinfo_x86 *c)
 	/* AMD CPUs don't reset SS attributes on SYSRET, Xen does. */
 	if (!cpu_has(c, X86_FEATURE_XENPV))
 		set_cpu_bug(c, X86_BUG_SYSRET_SS_ATTRS);
-
-	if (boot_cpu_has(X86_FEATURE_AMD_SSBD)) {
-		set_cpu_cap(c, X86_FEATURE_SSBD);
-		set_cpu_cap(c, X86_FEATURE_AMD_SSBD);
-	}
 }
 
 #ifdef CONFIG_X86_32

arch/x86/kernel/cpu/bugs.c

@@ -158,8 +158,8 @@ void x86_spec_ctrl_set_guest(u64 guest_spec_ctrl)
 	if (!static_cpu_has(X86_FEATURE_MSR_SPEC_CTRL))
 		return;
 
-	/* Intel controls SSB in MSR_SPEC_CTRL */
-	if (static_cpu_has(X86_FEATURE_SPEC_CTRL))
+	/* SSBD controlled in MSR_SPEC_CTRL */
+	if (static_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD))
 		host |= ssbd_tif_to_spec_ctrl(current_thread_info()->flags);
 
 	if (host != guest_spec_ctrl)
@@ -175,8 +175,8 @@ void x86_spec_ctrl_restore_host(u64 guest_spec_ctrl)
 	if (!static_cpu_has(X86_FEATURE_MSR_SPEC_CTRL))
 		return;
 
-	/* Intel controls SSB in MSR_SPEC_CTRL */
-	if (static_cpu_has(X86_FEATURE_SPEC_CTRL))
+	/* SSBD controlled in MSR_SPEC_CTRL */
+	if (static_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD))
 		host |= ssbd_tif_to_spec_ctrl(current_thread_info()->flags);
 
 	if (host != guest_spec_ctrl)
@@ -188,7 +188,7 @@ static void x86_amd_ssb_disable(void)
 {
 	u64 msrval = x86_amd_ls_cfg_base | x86_amd_ls_cfg_ssbd_mask;
 
-	if (boot_cpu_has(X86_FEATURE_AMD_SSBD))
+	if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD))
 		wrmsrl(MSR_AMD64_LS_CFG, msrval);
 }
 

arch/x86/kernel/cpu/common.c

@@ -735,6 +735,9 @@ static void init_speculation_control(struct cpuinfo_x86 *c)
 	if (cpu_has(c, X86_FEATURE_INTEL_STIBP))
 		set_cpu_cap(c, X86_FEATURE_STIBP);
 
+	if (cpu_has(c, X86_FEATURE_SPEC_CTRL_SSBD))
+		set_cpu_cap(c, X86_FEATURE_SSBD);
+
 	if (cpu_has(c, X86_FEATURE_AMD_IBRS)) {
 		set_cpu_cap(c, X86_FEATURE_IBRS);
 		set_cpu_cap(c, X86_FEATURE_MSR_SPEC_CTRL);

arch/x86/kernel/cpu/intel.c

@@ -156,6 +156,7 @@ static void early_init_intel(struct cpuinfo_x86 *c)
 		setup_clear_cpu_cap(X86_FEATURE_MSR_SPEC_CTRL);
 		setup_clear_cpu_cap(X86_FEATURE_INTEL_STIBP);
 		setup_clear_cpu_cap(X86_FEATURE_SSBD);
+		setup_clear_cpu_cap(X86_FEATURE_SPEC_CTRL_SSBD);
 	}
 
 	/*

arch/x86/kernel/process.c

@@ -207,7 +207,7 @@ static __always_inline void __speculative_store_bypass_update(unsigned long tifn
 {
 	u64 msr;
 
-	if (static_cpu_has(X86_FEATURE_AMD_SSBD)) {
+	if (static_cpu_has(X86_FEATURE_LS_CFG_SSBD)) {
 		msr = x86_amd_ls_cfg_base | ssbd_tif_to_amd_ls_cfg(tifn);
 		wrmsrl(MSR_AMD64_LS_CFG, msr);
 	} else {