Update Linux to v5.4.2
Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/arch/x86/kernel/cpu/tsx.c b/arch/x86/kernel/cpu/tsx.c
new file mode 100644
index 0000000..3e20d32
--- /dev/null
+++ b/arch/x86/kernel/cpu/tsx.c
@@ -0,0 +1,140 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Intel Transactional Synchronization Extensions (TSX) control.
+ *
+ * Copyright (C) 2019 Intel Corporation
+ *
+ * Author:
+ * Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
+ */
+
+#include <linux/cpufeature.h>
+
+#include <asm/cmdline.h>
+
+#include "cpu.h"
+
+enum tsx_ctrl_states tsx_ctrl_state __ro_after_init = TSX_CTRL_NOT_SUPPORTED;
+
+void tsx_disable(void)
+{
+ u64 tsx;
+
+ rdmsrl(MSR_IA32_TSX_CTRL, tsx);
+
+ /* Force all transactions to immediately abort */
+ tsx |= TSX_CTRL_RTM_DISABLE;
+
+ /*
+ * Ensure TSX support is not enumerated in CPUID.
+ * This is visible to userspace and will ensure they
+ * do not waste resources trying TSX transactions that
+ * will always abort.
+ */
+ tsx |= TSX_CTRL_CPUID_CLEAR;
+
+ wrmsrl(MSR_IA32_TSX_CTRL, tsx);
+}
+
+void tsx_enable(void)
+{
+ u64 tsx;
+
+ rdmsrl(MSR_IA32_TSX_CTRL, tsx);
+
+ /* Enable the RTM feature in the cpu */
+ tsx &= ~TSX_CTRL_RTM_DISABLE;
+
+ /*
+ * Ensure TSX support is enumerated in CPUID.
+ * This is visible to userspace and will ensure they
+ * can enumerate and use the TSX feature.
+ */
+ tsx &= ~TSX_CTRL_CPUID_CLEAR;
+
+ wrmsrl(MSR_IA32_TSX_CTRL, tsx);
+}
+
+static bool __init tsx_ctrl_is_supported(void)
+{
+ u64 ia32_cap = x86_read_arch_cap_msr();
+
+ /*
+ * TSX is controlled via MSR_IA32_TSX_CTRL. However, support for this
+ * MSR is enumerated by ARCH_CAP_TSX_MSR bit in MSR_IA32_ARCH_CAPABILITIES.
+ *
+ * TSX control (aka MSR_IA32_TSX_CTRL) is only available after a
+ * microcode update on CPUs that have their MSR_IA32_ARCH_CAPABILITIES
+ * bit MDS_NO=1. CPUs with MDS_NO=0 are not planned to get
+ * MSR_IA32_TSX_CTRL support even after a microcode update. Thus,
+ * tsx= cmdline requests will do nothing on CPUs without
+ * MSR_IA32_TSX_CTRL support.
+ */
+ return !!(ia32_cap & ARCH_CAP_TSX_CTRL_MSR);
+}
+
+static enum tsx_ctrl_states x86_get_tsx_auto_mode(void)
+{
+ if (boot_cpu_has_bug(X86_BUG_TAA))
+ return TSX_CTRL_DISABLE;
+
+ return TSX_CTRL_ENABLE;
+}
+
+void __init tsx_init(void)
+{
+ char arg[5] = {};
+ int ret;
+
+ if (!tsx_ctrl_is_supported())
+ return;
+
+ ret = cmdline_find_option(boot_command_line, "tsx", arg, sizeof(arg));
+ if (ret >= 0) {
+ if (!strcmp(arg, "on")) {
+ tsx_ctrl_state = TSX_CTRL_ENABLE;
+ } else if (!strcmp(arg, "off")) {
+ tsx_ctrl_state = TSX_CTRL_DISABLE;
+ } else if (!strcmp(arg, "auto")) {
+ tsx_ctrl_state = x86_get_tsx_auto_mode();
+ } else {
+ tsx_ctrl_state = TSX_CTRL_DISABLE;
+ pr_err("tsx: invalid option, defaulting to off\n");
+ }
+ } else {
+ /* tsx= not provided */
+ if (IS_ENABLED(CONFIG_X86_INTEL_TSX_MODE_AUTO))
+ tsx_ctrl_state = x86_get_tsx_auto_mode();
+ else if (IS_ENABLED(CONFIG_X86_INTEL_TSX_MODE_OFF))
+ tsx_ctrl_state = TSX_CTRL_DISABLE;
+ else
+ tsx_ctrl_state = TSX_CTRL_ENABLE;
+ }
+
+ if (tsx_ctrl_state == TSX_CTRL_DISABLE) {
+ tsx_disable();
+
+ /*
+ * tsx_disable() will change the state of the
+ * RTM CPUID bit. Clear it here since it is now
+ * expected to be not set.
+ */
+ setup_clear_cpu_cap(X86_FEATURE_RTM);
+ } else if (tsx_ctrl_state == TSX_CTRL_ENABLE) {
+
+ /*
+ * HW defaults TSX to be enabled at bootup.
+ * We may still need the TSX enable support
+ * during init for special cases like
+ * kexec after TSX is disabled.
+ */
+ tsx_enable();
+
+ /*
+ * tsx_enable() will change the state of the
+ * RTM CPUID bit. Force it here since it is now
+ * expected to be set.
+ */
+ setup_force_cpu_cap(X86_FEATURE_RTM);
+ }
+}