linux-dev/arch/x86/kernel/cpu/mce/severity.c, branch linus/master

x86/mce: Add messages for panic errors in AMD's MCE grading

2022-04-25T10:40:48Z

When a machine error is graded as PANIC by the AMD grading logic, the MCE handler calls mce_panic(). The notification chain does not come into effect so the AMD EDAC driver does not decode the errors. In these cases, the messages displayed to the user are more cryptic and miss information that might be relevant, like the context in which the error took place. Add messages to the grading logic for machine errors so that it is clear what error it was. [ bp: Massage commit message. ] Signed-off-by: Carlos Bilbao Signed-off-by: Borislav Petkov Reviewed-by: Yazen Ghannam Link: https://lore.kernel.org/r/20220405183212.354606-3-carlos.bilbao@amd.com

x86/mce: Simplify AMD severity grading logic

2022-04-25T10:32:03Z

The MCE handler needs to understand the severity of the machine errors to act accordingly. Simplify the AMD grading logic following a logic that closely resembles the descriptions of the public PPR documents. This will help include more fine-grained grading of errors in the future. [ bp: Touchups. ] Signed-off-by: Carlos Bilbao Signed-off-by: Borislav Petkov Reviewed-by: Yazen Ghannam Link: https://lore.kernel.org/r/20220405183212.354606-2-carlos.bilbao@amd.com

x86/mce: Remove the tolerance level control

2022-02-23T10:09:25Z

This is pretty much unused and not really useful. What is more, all relevant MCA hardware has recoverable machine checks support so there's no real need to tweak MCA tolerance levels in order to *maybe* extend machine lifetime. So rip it out. Signed-off-by: Borislav Petkov Link: https://lore.kernel.org/r/YcDq8PxvKtTENl/e@zn.tnic

x86/mce: Use arch atomic and bit helpers

2022-02-13T21:08:27Z

The arch helpers do not have explicit KASAN instrumentation. Use them in noinstr code. Inline a couple more functions with single call sites, while at it: mce_severity_amd_smca() has a single call-site which is noinstr so force the inlining and fix: vmlinux.o: warning: objtool: mce_severity_amd.constprop.0()+0xca: call to \ mce_severity_amd_smca() leaves .noinstr.text section Always inline mca_msr_reg(): text data bss dec hex filename 16065240 128031326 36405368 180501934 ac23dae vmlinux.before 16065240 128031294 36405368 180501902 ac23d8e vmlinux.after and mce_no_way_out() as the latter one is used only once, to fix: vmlinux.o: warning: objtool: mce_read_aux()+0x53: call to mca_msr_reg() leaves .noinstr.text section vmlinux.o: warning: objtool: do_machine_check()+0xc9: call to mce_no_way_out() leaves .noinstr.text section Signed-off-by: Borislav Petkov Acked-by: Marco Elver Link: https://lore.kernel.org/r/20220204083015.17317-4-bp@alien8.de

x86/mce: Check regs before accessing it

2021-12-20T10:41:02Z

Commit in Fixes accesses pt_regs before checking whether it is NULL or not. Make sure the NULL pointer check happens first. Fixes: 0a5b288e85bb ("x86/mce: Prevent severity computation from being instrumented") Reported-by: Dan Carpenter Signed-off-by: Borislav Petkov Reviewed-by: Tony Luck Link: https://lore.kernel.org/r/20211217102029.GA29708@kili

x86/mce: Prevent severity computation from being instrumented

2021-12-13T13:12:48Z

Mark all the MCE severity computation logic noinstr and allow instrumentation when it "calls out". Fixes vmlinux.o: warning: objtool: do_machine_check()+0xc5d: call to mce_severity() leaves .noinstr.text section Signed-off-by: Borislav Petkov Link: https://lore.kernel.org/r/20211208111343.8130-7-bp@alien8.de

x86/mce: Use mce_rdmsrl() in severity checking code

2021-12-13T13:12:08Z

MCA has its own special MSR accessors. Use them. No functional changes. Signed-off-by: Borislav Petkov Link: https://lore.kernel.org/r/20211208111343.8130-4-bp@alien8.de

Merge tag 'ras_core_for_v5.16_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2021-11-01T22:12:04Z

Pull RAS updates from Borislav Petkov: - Get rid of a bunch of function pointers used in MCA land in favor of normal functions. This is in preparation of making the MCA code noinstr-aware - When the kernel copies data from user addresses and it encounters a machine check, a SIGBUS is sent to that process. Change this action to either an -EFAULT which is returned to the user or a short write, making the recovery action a lot more user-friendly * tag 'ras_core_for_v5.16_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/mce: Sort mca_config members to get rid of unnecessary padding x86/mce: Get rid of the ->quirk_no_way_out() indirect call x86/mce: Get rid of msr_ops x86/mce: Get rid of machine_check_vector x86/mce: Get rid of the mce_severity function pointer x86/mce: Drop copyin special case for #MC x86/mce: Change to not send SIGBUS error during copy from user

x86/mce: Get rid of the mce_severity function pointer

2021-09-23T09:03:51Z

Turn it into a normal function which calls an AMD- or Intel-specific variant depending on the CPU it runs on. No functional changes. Signed-off-by: Borislav Petkov Reviewed-by: Tony Luck Link: https://lkml.kernel.org/r/20210922165101.18951-2-bp@alien8.de

x86/extable: Remove EX_TYPE_FAULT from MCE safe fixups

2021-09-13T16:23:00Z

Now that the MC safe copy and FPU have been converted to use the MCE safe fixup types remove EX_TYPE_FAULT from the list of types which MCE considers to be safe to be recovered in kernel. This removes the SGX exception handling of ENCLS from the #MC safe handling, but according to the SGX wizards the current SGX implementations cannot survive #MC on ENCLS: https://lore.kernel.org/r/YS+upEmTfpZub3s9@google.com The code relies on the trap number being stored if ENCLS raised an exception. That's still working, but it does no longer trick the MCE code into assuming that #MC is handled correctly for ENCLS. Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov Link: https://lkml.kernel.org/r/20210908132525.445255957@linutronix.de