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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
This commit is contained in:
Pawan Gupta 2021-06-14 14:14:25 -07:00 committed by Borislav Petkov
parent ad3c2e1749
commit 293649307e
3 changed files with 40 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/x86/kernel/cpu/cpu.h
View File

@ -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 */

4
arch/x86/kernel/cpu/intel.c
View File

@ -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();

37
arch/x86/kernel/cpu/tsx.c
View File

@ -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) {