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x86/fred: Add a machine check entry stub for FRED

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Like #DB, when occurred on different ring level, i.e., from user or kernel
context, #MCE needs to be handled on different stack: User #MCE on current
task stack, while kernel #MCE on a dedicated stack.

This is exactly how FRED event delivery invokes an exception handler: ring
3 event on level 0 stack, i.e., current task stack; ring 0 event on the
the FRED machine check entry stub doesn't do stack switch.

Signed-off-by: Xin Li <xin3.li@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Tested-by: Shan Kang <shan.kang@intel.com>
Link: https://lore.kernel.org/r/20231205105030.8698-26-xin3.li@intel.com
This commit is contained in:
Xin Li 2023-12-05 02:50:14 -08:00 committed by Borislav Petkov (AMD)
parent f8b8ee45f8
commit ffa4901f0e
1 changed files with 26 additions and 0 deletions
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26
arch/x86/kernel/cpu/mce/core.c
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@ -46,6 +46,7 @@
#include <linux/hardirq.h>
#include <linux/kexec.h>
#include <asm/fred.h>
#include <asm/intel-family.h>
#include <asm/processor.h>
#include <asm/traps.h>
@ -2166,6 +2167,31 @@ DEFINE_IDTENTRY_MCE_USER(exc_machine_check)
exc_machine_check_user(regs);
local_db_restore(dr7);
}
#ifdef CONFIG_X86_FRED
/*
* When occurred on different ring level, i.e., from user or kernel
* context, #MCE needs to be handled on different stack: User #MCE
* on current task stack, while kernel #MCE on a dedicated stack.
*
* This is exactly how FRED event delivery invokes an exception
* handler: ring 3 event on level 0 stack, i.e., current task stack;
* ring 0 event on the #MCE dedicated stack specified in the
* IA32_FRED_STKLVLS MSR. So unlike IDT, the FRED machine check entry
* stub doesn't do stack switch.
*/
DEFINE_FREDENTRY_MCE(exc_machine_check)
{
unsigned long dr7;
dr7 = local_db_save();
if (user_mode(regs))
exc_machine_check_user(regs);
else
exc_machine_check_kernel(regs);
local_db_restore(dr7);
}
#endif
#else
/* 32bit unified entry point */
DEFINE_IDTENTRY_RAW(exc_machine_check)