x86/tsx: Clear CPUID bits when TSX always force aborts

As a result of TSX deprecation, some processors always abort TSX
transactions by default after a microcode update.

When TSX feature cannot be used it is better to hide it. Clear CPUID.RTM
and CPUID.HLE bits when TSX transactions always abort.

 [ bp: Massage commit message and comments. ]

Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Tested-by: Neelima Krishnan <neelima.krishnan@intel.com>
Link: https://lkml.kernel.org/r/5209b3d72ffe5bd3cafdcc803f5b883f785329c3.1623704845.git-series.pawan.kumar.gupta@linux.intel.com

diff --git a/arch/x86/kernel/cpu/cpu.h b/arch/x86/kernel/cpu/cpu.h
index 67944128876d7300e29545c7d5336a52a81daa75..95521302630d4c548bcdf6e86c2172707b533f09 100644 (file)
--- a/arch/x86/kernel/cpu/cpu.h
+++ b/arch/x86/kernel/cpu/cpu.h
@@ -48,6 +48,7 @@ extern const struct cpu_dev *const __x86_cpu_dev_start[],
 enum tsx_ctrl_states {
        TSX_CTRL_ENABLE,
        TSX_CTRL_DISABLE,
+       TSX_CTRL_RTM_ALWAYS_ABORT,
        TSX_CTRL_NOT_SUPPORTED,
 };
 
@@ -56,6 +57,7 @@ extern __ro_after_init enum tsx_ctrl_states tsx_ctrl_state;
 extern void __init tsx_init(void);
 extern void tsx_enable(void);
 extern void tsx_disable(void);
+extern void tsx_clear_cpuid(void);
 #else
 static inline void tsx_init(void) { }
 #endif /* CONFIG_CPU_SUP_INTEL */

diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 8adffc17fa8b82a38d1d513b911013eb2fde8797..861e919eba9accc7f52ca6ec850b5013f7f164c1 100644 (file)
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -717,8 +717,10 @@ static void init_intel(struct cpuinfo_x86 *c)
 
        if (tsx_ctrl_state == TSX_CTRL_ENABLE)
                tsx_enable();
-       if (tsx_ctrl_state == TSX_CTRL_DISABLE)
+       else if (tsx_ctrl_state == TSX_CTRL_DISABLE)
                tsx_disable();
+       else if (tsx_ctrl_state == TSX_CTRL_RTM_ALWAYS_ABORT)
+               tsx_clear_cpuid();
 
        split_lock_init();
        bus_lock_init();

diff --git a/arch/x86/kernel/cpu/tsx.c b/arch/x86/kernel/cpu/tsx.c
index e2ad30e474f82f14b9cfc01702d175c8f1f2b10c..9c7a5f049292966362384cb81e396630ff3e7a92 100644 (file)
--- a/arch/x86/kernel/cpu/tsx.c
+++ b/arch/x86/kernel/cpu/tsx.c
@@ -2,7 +2,7 @@
 /*
  * Intel Transactional Synchronization Extensions (TSX) control.
  *
- * Copyright (C) 2019 Intel Corporation
+ * Copyright (C) 2019-2021 Intel Corporation
  *
  * Author:
  *     Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
@@ -84,13 +84,46 @@ static enum tsx_ctrl_states x86_get_tsx_auto_mode(void)
        return TSX_CTRL_ENABLE;
 }
 
+void tsx_clear_cpuid(void)
+{
+       u64 msr;
+
+       /*
+        * MSR_TFA_TSX_CPUID_CLEAR bit is only present when both CPUID
+        * bits RTM_ALWAYS_ABORT and TSX_FORCE_ABORT are present.
+        */
+       if (boot_cpu_has(X86_FEATURE_RTM_ALWAYS_ABORT) &&
+           boot_cpu_has(X86_FEATURE_TSX_FORCE_ABORT)) {
+               rdmsrl(MSR_TSX_FORCE_ABORT, msr);
+               msr |= MSR_TFA_TSX_CPUID_CLEAR;
+               wrmsrl(MSR_TSX_FORCE_ABORT, msr);
+       }
+}
+
 void __init tsx_init(void)
 {
        char arg[5] = {};
        int ret;
 
-       if (!tsx_ctrl_is_supported())
+       /*
+        * Hardware will always abort a TSX transaction if both CPUID bits
+        * RTM_ALWAYS_ABORT and TSX_FORCE_ABORT are set. In this case, it is
+        * better not to enumerate CPUID.RTM and CPUID.HLE bits. Clear them
+        * here.
+        */
+       if (boot_cpu_has(X86_FEATURE_RTM_ALWAYS_ABORT) &&
+           boot_cpu_has(X86_FEATURE_TSX_FORCE_ABORT)) {
+               tsx_ctrl_state = TSX_CTRL_RTM_ALWAYS_ABORT;
+               tsx_clear_cpuid();
+               setup_clear_cpu_cap(X86_FEATURE_RTM);
+               setup_clear_cpu_cap(X86_FEATURE_HLE);
                return;
+       }
+
+       if (!tsx_ctrl_is_supported()) {
+               tsx_ctrl_state = TSX_CTRL_NOT_SUPPORTED;
+               return;
+       }
 
        ret = cmdline_find_option(boot_command_line, "tsx", arg, sizeof(arg));
        if (ret >= 0) {