Adding upstream version 6.8.9.upstream/6.8.9

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 129 insertions, 41 deletions

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 01ac18f561..e7ceee008b 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -61,6 +61,8 @@ EXPORT_SYMBOL_GPL(x86_spec_ctrl_current);
 u64 x86_pred_cmd __ro_after_init = PRED_CMD_IBPB;
 EXPORT_SYMBOL_GPL(x86_pred_cmd);
 
+static u64 __ro_after_init x86_arch_cap_msr;
+
 static DEFINE_MUTEX(spec_ctrl_mutex);
 
 void (*x86_return_thunk)(void) __ro_after_init = __x86_return_thunk;
@@ -144,6 +146,8 @@ void __init cpu_select_mitigations(void)
 		x86_spec_ctrl_base &= ~SPEC_CTRL_MITIGATIONS_MASK;
 	}
 
+	x86_arch_cap_msr = x86_read_arch_cap_msr();
+
 	/* Select the proper CPU mitigations before patching alternatives: */
 	spectre_v1_select_mitigation();
 	spectre_v2_select_mitigation();
@@ -301,8 +305,6 @@ static const char * const taa_strings[] = {
 
 static void __init taa_select_mitigation(void)
 {
-	u64 ia32_cap;
-
 	if (!boot_cpu_has_bug(X86_BUG_TAA)) {
 		taa_mitigation = TAA_MITIGATION_OFF;
 		return;
@@ -341,9 +343,8 @@ static void __init taa_select_mitigation(void)
 	 * On MDS_NO=1 CPUs if ARCH_CAP_TSX_CTRL_MSR is not set, microcode
 	 * update is required.
 	 */
-	ia32_cap = x86_read_arch_cap_msr();
-	if ( (ia32_cap & ARCH_CAP_MDS_NO) &&
-	    !(ia32_cap & ARCH_CAP_TSX_CTRL_MSR))
+	if ( (x86_arch_cap_msr & ARCH_CAP_MDS_NO) &&
+	    !(x86_arch_cap_msr & ARCH_CAP_TSX_CTRL_MSR))
 		taa_mitigation = TAA_MITIGATION_UCODE_NEEDED;
 
 	/*
@@ -401,8 +402,6 @@ static const char * const mmio_strings[] = {
 
 static void __init mmio_select_mitigation(void)
 {
-	u64 ia32_cap;
-
 	if (!boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA) ||
 	     boot_cpu_has_bug(X86_BUG_MMIO_UNKNOWN) ||
 	     cpu_mitigations_off()) {
@@ -413,8 +412,6 @@ static void __init mmio_select_mitigation(void)
 	if (mmio_mitigation == MMIO_MITIGATION_OFF)
 		return;
 
-	ia32_cap = x86_read_arch_cap_msr();
-
 	/*
 	 * Enable CPU buffer clear mitigation for host and VMM, if also affected
 	 * by MDS or TAA. Otherwise, enable mitigation for VMM only.
@@ -437,7 +434,7 @@ static void __init mmio_select_mitigation(void)
 	 * be propagated to uncore buffers, clearing the Fill buffers on idle
 	 * is required irrespective of SMT state.
 	 */
-	if (!(ia32_cap & ARCH_CAP_FBSDP_NO))
+	if (!(x86_arch_cap_msr & ARCH_CAP_FBSDP_NO))
 		static_branch_enable(&mds_idle_clear);
 
 	/*
@@ -447,10 +444,10 @@ static void __init mmio_select_mitigation(void)
 	 * FB_CLEAR or by the presence of both MD_CLEAR and L1D_FLUSH on MDS
 	 * affected systems.
 	 */
-	if ((ia32_cap & ARCH_CAP_FB_CLEAR) ||
+	if ((x86_arch_cap_msr & ARCH_CAP_FB_CLEAR) ||
 	    (boot_cpu_has(X86_FEATURE_MD_CLEAR) &&
 	     boot_cpu_has(X86_FEATURE_FLUSH_L1D) &&
-	     !(ia32_cap & ARCH_CAP_MDS_NO)))
+	     !(x86_arch_cap_msr & ARCH_CAP_MDS_NO)))
 		mmio_mitigation = MMIO_MITIGATION_VERW;
 	else
 		mmio_mitigation = MMIO_MITIGATION_UCODE_NEEDED;
@@ -508,7 +505,7 @@ static void __init rfds_select_mitigation(void)
 	if (rfds_mitigation == RFDS_MITIGATION_OFF)
 		return;
 
-	if (x86_read_arch_cap_msr() & ARCH_CAP_RFDS_CLEAR)
+	if (x86_arch_cap_msr & ARCH_CAP_RFDS_CLEAR)
 		setup_force_cpu_cap(X86_FEATURE_CLEAR_CPU_BUF);
 	else
 		rfds_mitigation = RFDS_MITIGATION_UCODE_NEEDED;
@@ -659,8 +656,6 @@ void update_srbds_msr(void)
 
 static void __init srbds_select_mitigation(void)
 {
-	u64 ia32_cap;
-
 	if (!boot_cpu_has_bug(X86_BUG_SRBDS))
 		return;
 
@@ -669,8 +664,7 @@ static void __init srbds_select_mitigation(void)
 	 * are only exposed to SRBDS when TSX is enabled or when CPU is affected
 	 * by Processor MMIO Stale Data vulnerability.
 	 */
-	ia32_cap = x86_read_arch_cap_msr();
-	if ((ia32_cap & ARCH_CAP_MDS_NO) && !boot_cpu_has(X86_FEATURE_RTM) &&
+	if ((x86_arch_cap_msr & ARCH_CAP_MDS_NO) && !boot_cpu_has(X86_FEATURE_RTM) &&
 	    !boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA))
 		srbds_mitigation = SRBDS_MITIGATION_TSX_OFF;
 	else if (boot_cpu_has(X86_FEATURE_HYPERVISOR))
@@ -813,7 +807,7 @@ static void __init gds_select_mitigation(void)
 	/* Will verify below that mitigation _can_ be disabled */
 
 	/* No microcode */
-	if (!(x86_read_arch_cap_msr() & ARCH_CAP_GDS_CTRL)) {
+	if (!(x86_arch_cap_msr & ARCH_CAP_GDS_CTRL)) {
 		if (gds_mitigation == GDS_MITIGATION_FORCE) {
 			/*
 			 * This only needs to be done on the boot CPU so do it
@@ -1543,20 +1537,25 @@ static enum spectre_v2_mitigation __init spectre_v2_select_retpoline(void)
 	return SPECTRE_V2_RETPOLINE;
 }
 
+static bool __ro_after_init rrsba_disabled;
+
 /* Disable in-kernel use of non-RSB RET predictors */
 static void __init spec_ctrl_disable_kernel_rrsba(void)
 {
-	u64 ia32_cap;
+	if (rrsba_disabled)
+		return;
 
-	if (!boot_cpu_has(X86_FEATURE_RRSBA_CTRL))
+	if (!(x86_arch_cap_msr & ARCH_CAP_RRSBA)) {
+		rrsba_disabled = true;
 		return;
+	}
 
-	ia32_cap = x86_read_arch_cap_msr();
+	if (!boot_cpu_has(X86_FEATURE_RRSBA_CTRL))
+		return;
 
-	if (ia32_cap & ARCH_CAP_RRSBA) {
-		x86_spec_ctrl_base |= SPEC_CTRL_RRSBA_DIS_S;
-		update_spec_ctrl(x86_spec_ctrl_base);
-	}
+	x86_spec_ctrl_base |= SPEC_CTRL_RRSBA_DIS_S;
+	update_spec_ctrl(x86_spec_ctrl_base);
+	rrsba_disabled = true;
 }
 
 static void __init spectre_v2_determine_rsb_fill_type_at_vmexit(enum spectre_v2_mitigation mode)
@@ -1606,6 +1605,74 @@ static void __init spectre_v2_determine_rsb_fill_type_at_vmexit(enum spectre_v2_
 	dump_stack();
 }
 
+/*
+ * Set BHI_DIS_S to prevent indirect branches in kernel to be influenced by
+ * branch history in userspace. Not needed if BHI_NO is set.
+ */
+static bool __init spec_ctrl_bhi_dis(void)
+{
+	if (!boot_cpu_has(X86_FEATURE_BHI_CTRL))
+		return false;
+
+	x86_spec_ctrl_base |= SPEC_CTRL_BHI_DIS_S;
+	update_spec_ctrl(x86_spec_ctrl_base);
+	setup_force_cpu_cap(X86_FEATURE_CLEAR_BHB_HW);
+
+	return true;
+}
+
+enum bhi_mitigations {
+	BHI_MITIGATION_OFF,
+	BHI_MITIGATION_ON,
+};
+
+static enum bhi_mitigations bhi_mitigation __ro_after_init =
+	IS_ENABLED(CONFIG_MITIGATION_SPECTRE_BHI) ? BHI_MITIGATION_ON : BHI_MITIGATION_OFF;
+
+static int __init spectre_bhi_parse_cmdline(char *str)
+{
+	if (!str)
+		return -EINVAL;
+
+	if (!strcmp(str, "off"))
+		bhi_mitigation = BHI_MITIGATION_OFF;
+	else if (!strcmp(str, "on"))
+		bhi_mitigation = BHI_MITIGATION_ON;
+	else
+		pr_err("Ignoring unknown spectre_bhi option (%s)", str);
+
+	return 0;
+}
+early_param("spectre_bhi", spectre_bhi_parse_cmdline);
+
+static void __init bhi_select_mitigation(void)
+{
+	if (bhi_mitigation == BHI_MITIGATION_OFF)
+		return;
+
+	/* Retpoline mitigates against BHI unless the CPU has RRSBA behavior */
+	if (boot_cpu_has(X86_FEATURE_RETPOLINE) &&
+	    !boot_cpu_has(X86_FEATURE_RETPOLINE_LFENCE)) {
+		spec_ctrl_disable_kernel_rrsba();
+		if (rrsba_disabled)
+			return;
+	}
+
+	if (spec_ctrl_bhi_dis())
+		return;
+
+	if (!IS_ENABLED(CONFIG_X86_64))
+		return;
+
+	/* Mitigate KVM by default */
+	setup_force_cpu_cap(X86_FEATURE_CLEAR_BHB_LOOP_ON_VMEXIT);
+	pr_info("Spectre BHI mitigation: SW BHB clearing on vm exit\n");
+
+	/* Mitigate syscalls when the mitigation is forced =on */
+	setup_force_cpu_cap(X86_FEATURE_CLEAR_BHB_LOOP);
+	pr_info("Spectre BHI mitigation: SW BHB clearing on syscall\n");
+}
+
 static void __init spectre_v2_select_mitigation(void)
 {
 	enum spectre_v2_mitigation_cmd cmd = spectre_v2_parse_cmdline();
@@ -1717,6 +1784,9 @@ static void __init spectre_v2_select_mitigation(void)
 	    mode == SPECTRE_V2_RETPOLINE)
 		spec_ctrl_disable_kernel_rrsba();
 
+	if (boot_cpu_has(X86_BUG_BHI))
+		bhi_select_mitigation();
+
 	spectre_v2_enabled = mode;
 	pr_info("%s\n", spectre_v2_strings[mode]);
 
@@ -1831,8 +1901,6 @@ static void update_indir_branch_cond(void)
 /* Update the static key controlling the MDS CPU buffer clear in idle */
 static void update_mds_branch_idle(void)
 {
-	u64 ia32_cap = x86_read_arch_cap_msr();
-
 	/*
 	 * Enable the idle clearing if SMT is active on CPUs which are
 	 * affected only by MSBDS and not any other MDS variant.
@@ -1847,7 +1915,7 @@ static void update_mds_branch_idle(void)
 	if (sched_smt_active()) {
 		static_branch_enable(&mds_idle_clear);
 	} else if (mmio_mitigation == MMIO_MITIGATION_OFF ||
-		   (ia32_cap & ARCH_CAP_FBSDP_NO)) {
+		   (x86_arch_cap_msr & ARCH_CAP_FBSDP_NO)) {
 		static_branch_disable(&mds_idle_clear);
 	}
 }
@@ -2694,15 +2762,15 @@ static char *stibp_state(void)
 
 	switch (spectre_v2_user_stibp) {
 	case SPECTRE_V2_USER_NONE:
-		return ", STIBP: disabled";
+		return "; STIBP: disabled";
 	case SPECTRE_V2_USER_STRICT:
-		return ", STIBP: forced";
+		return "; STIBP: forced";
 	case SPECTRE_V2_USER_STRICT_PREFERRED:
-		return ", STIBP: always-on";
+		return "; STIBP: always-on";
 	case SPECTRE_V2_USER_PRCTL:
 	case SPECTRE_V2_USER_SECCOMP:
 		if (static_key_enabled(&switch_to_cond_stibp))
-			return ", STIBP: conditional";
+			return "; STIBP: conditional";
 	}
 	return "";
 }
@@ -2711,10 +2779,10 @@ static char *ibpb_state(void)
 {
 	if (boot_cpu_has(X86_FEATURE_IBPB)) {
 		if (static_key_enabled(&switch_mm_always_ibpb))
-			return ", IBPB: always-on";
+			return "; IBPB: always-on";
 		if (static_key_enabled(&switch_mm_cond_ibpb))
-			return ", IBPB: conditional";
-		return ", IBPB: disabled";
+			return "; IBPB: conditional";
+		return "; IBPB: disabled";
 	}
 	return "";
 }
@@ -2724,14 +2792,32 @@ static char *pbrsb_eibrs_state(void)
 	if (boot_cpu_has_bug(X86_BUG_EIBRS_PBRSB)) {
 		if (boot_cpu_has(X86_FEATURE_RSB_VMEXIT_LITE) ||
 		    boot_cpu_has(X86_FEATURE_RSB_VMEXIT))
-			return ", PBRSB-eIBRS: SW sequence";
+			return "; PBRSB-eIBRS: SW sequence";
 		else
-			return ", PBRSB-eIBRS: Vulnerable";
+			return "; PBRSB-eIBRS: Vulnerable";
 	} else {
-		return ", PBRSB-eIBRS: Not affected";
+		return "; PBRSB-eIBRS: Not affected";
 	}
 }
 
+static const char *spectre_bhi_state(void)
+{
+	if (!boot_cpu_has_bug(X86_BUG_BHI))
+		return "; BHI: Not affected";
+	else if (boot_cpu_has(X86_FEATURE_CLEAR_BHB_HW))
+		return "; BHI: BHI_DIS_S";
+	else if (boot_cpu_has(X86_FEATURE_CLEAR_BHB_LOOP))
+		return "; BHI: SW loop, KVM: SW loop";
+	else if (boot_cpu_has(X86_FEATURE_RETPOLINE) &&
+		 !boot_cpu_has(X86_FEATURE_RETPOLINE_LFENCE) &&
+		 rrsba_disabled)
+		return "; BHI: Retpoline";
+	else if (boot_cpu_has(X86_FEATURE_CLEAR_BHB_LOOP_ON_VMEXIT))
+		return "; BHI: Vulnerable, KVM: SW loop";
+
+	return "; BHI: Vulnerable";
+}
+
 static ssize_t spectre_v2_show_state(char *buf)
 {
 	if (spectre_v2_enabled == SPECTRE_V2_LFENCE)
@@ -2744,13 +2830,15 @@ static ssize_t spectre_v2_show_state(char *buf)
 	    spectre_v2_enabled == SPECTRE_V2_EIBRS_LFENCE)
 		return sysfs_emit(buf, "Vulnerable: eIBRS+LFENCE with unprivileged eBPF and SMT\n");
 
-	return sysfs_emit(buf, "%s%s%s%s%s%s%s\n",
+	return sysfs_emit(buf, "%s%s%s%s%s%s%s%s\n",
 			  spectre_v2_strings[spectre_v2_enabled],
 			  ibpb_state(),
-			  boot_cpu_has(X86_FEATURE_USE_IBRS_FW) ? ", IBRS_FW" : "",
+			  boot_cpu_has(X86_FEATURE_USE_IBRS_FW) ? "; IBRS_FW" : "",
 			  stibp_state(),
-			  boot_cpu_has(X86_FEATURE_RSB_CTXSW) ? ", RSB filling" : "",
+			  boot_cpu_has(X86_FEATURE_RSB_CTXSW) ? "; RSB filling" : "",
 			  pbrsb_eibrs_state(),
+			  spectre_bhi_state(),
+			  /* this should always be at the end */
 			  spectre_v2_module_string());
 }