kernel.git/arch/x86/kernel/cpu/mce, branch linux-5.9.y

x86/mce: Do not overwrite no_way_out if mce_end() fails

2020-12-02T07:52:02Z

commit 25bc65d8ddfc17cc1d7a45bd48e9bdc0e729ced3 upstream. Currently, if mce_end() fails, no_way_out - the variable denoting whether the machine can recover from this MCE - is determined by whether the worst severity that was found across the MCA banks associated with the current CPU, is of panic severity. However, at this point no_way_out could have been already set by mca_start() after looking at all severities of all CPUs that entered the MCE handler. If mce_end() fails, check first if no_way_out is already set and, if so, stick to it, otherwise use the local worst value. [ bp: Massage. ] Signed-off-by: Gabriele Paoloni Signed-off-by: Borislav Petkov Reviewed-by: Tony Luck Cc: Link: https://lkml.kernel.org/r/20201127161819.3106432-2-gabriele.paoloni@intel.com Signed-off-by: Greg Kroah-Hartman

x86, powerpc: Rename memcpy_mcsafe() to copy_mc_to_{user, kernel}()

2020-11-04T17:09:05Z

commit ec6347bb43395cb92126788a1a5b25302543f815 upstream. In reaction to a proposal to introduce a memcpy_mcsafe_fast() implementation Linus points out that memcpy_mcsafe() is poorly named relative to communicating the scope of the interface. Specifically what addresses are valid to pass as source, destination, and what faults / exceptions are handled. Of particular concern is that even though x86 might be able to handle the semantics of copy_mc_to_user() with its common copy_user_generic() implementation other archs likely need / want an explicit path for this case: On Fri, May 1, 2020 at 11:28 AM Linus Torvalds wrote: > > On Thu, Apr 30, 2020 at 6:21 PM Dan Williams wrote: > > > > However now I see that copy_user_generic() works for the wrong reason. > > It works because the exception on the source address due to poison > > looks no different than a write fault on the user address to the > > caller, it's still just a short copy. So it makes copy_to_user() work > > for the wrong reason relative to the name. > > Right. > > And it won't work that way on other architectures. On x86, we have a > generic function that can take faults on either side, and we use it > for both cases (and for the "in_user" case too), but that's an > artifact of the architecture oddity. > > In fact, it's probably wrong even on x86 - because it can hide bugs - > but writing those things is painful enough that everybody prefers > having just one function. Replace a single top-level memcpy_mcsafe() with either copy_mc_to_user(), or copy_mc_to_kernel(). Introduce an x86 copy_mc_fragile() name as the rename for the low-level x86 implementation formerly named memcpy_mcsafe(). It is used as the slow / careful backend that is supplanted by a fast copy_mc_generic() in a follow-on patch. One side-effect of this reorganization is that separating copy_mc_64.S to its own file means that perf no longer needs to track dependencies for its memcpy_64.S benchmarks. [ bp: Massage a bit. ] Signed-off-by: Dan Williams Signed-off-by: Borislav Petkov Reviewed-by: Tony Luck Acked-by: Michael Ellerman Cc: Link: http://lore.kernel.org/r/CAHk-=wjSqtXAqfUJxFtWNwmguFASTgB0dz1dT3V-78Quiezqbg@mail.gmail.com Link: https://lkml.kernel.org/r/160195561680.2163339.11574962055305783722.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Greg Kroah-Hartman

Revert "x86, powerpc: Rename memcpy_mcsafe() to copy_mc_to_{user, kernel}()"

2020-11-04T17:08:28Z

This reverts commit a85748ed9eb70108f9605558f2754ca94ee91401 which is commit ec6347bb43395cb92126788a1a5b25302543f815 upstream. We had a mistake when merging a later patch in this series due to some file movements, so revert this change for now, as we will add it back in a later commit. Signed-off-by: Greg Kroah-Hartman

x86, powerpc: Rename memcpy_mcsafe() to copy_mc_to_{user, kernel}()

2020-11-01T11:47:03Z

x86/mce: Make mce_rdmsrl() panic on an inaccessible MSR

2020-10-29T09:12:11Z

[ Upstream commit e2def7d49d0812ea40a224161b2001b2e815dce2 ] If an exception needs to be handled while reading an MSR - which is in most of the cases caused by a #GP on a non-existent MSR - then this is most likely the incarnation of a BIOS or a hardware bug. Such bug violates the architectural guarantee that MCA banks are present with all MSRs belonging to them. The proper fix belongs in the hardware/firmware - not in the kernel. Handling an #MC exception which is raised while an NMI is being handled would cause the nasty NMI nesting issue because of the shortcoming of IRET of reenabling NMIs when executed. And the machine is in an #MC context already so be at its side. Tracing MSR accesses while in #MC is another no-no due to tracing being inherently a bad idea in atomic context: vmlinux.o: warning: objtool: do_machine_check()+0x4a: call to mce_rdmsrl() leaves .noinstr.text section so remove all that "additional" functionality from mce_rdmsrl() and provide it with a special exception handler which panics the machine when that MSR is not accessible. The exception handler prints a human-readable message explaining what the panic reason is but, what is more, it panics while in the #GP handler and latter won't have executed an IRET, thus opening the NMI nesting issue in the case when the #MC has happened while handling an NMI. (#MC itself won't be reenabled until MCG_STATUS hasn't been cleared). Suggested-by: Andy Lutomirski Suggested-by: Peter Zijlstra [ Add missing prototypes for ex_handler_* ] Reported-by: kernel test robot Signed-off-by: Borislav Petkov Reviewed-by: Tony Luck Link: https://lkml.kernel.org/r/20200906212130.GA28456@zn.tnic Signed-off-by: Sasha Levin

x86/mce: Annotate mce_rd/wrmsrl() with noinstr

2020-10-29T09:12:10Z

[ Upstream commit e100777016fdf6ec3a9d7c1773b15a2b5eca6c55 ] They do get called from the #MC handler which is already marked "noinstr". Commit e2def7d49d08 ("x86/mce: Make mce_rdmsrl() panic on an inaccessible MSR") already got rid of the instrumentation in the MSR accessors, fix the annotation now too, in order to get rid of: vmlinux.o: warning: objtool: do_machine_check()+0x4a: call to mce_rdmsrl() leaves .noinstr.text section Signed-off-by: Borislav Petkov Link: https://lkml.kernel.org/r/20200915194020.28807-1-bp@alien8.de Signed-off-by: Sasha Levin

x86/mce: Add Skylake quirk for patrol scrub reported errors

2020-10-29T09:12:08Z

[ Upstream commit fd258dc4442c5c1c069c6b5b42bfe7d10cddda95 ] The patrol scrubber in Skylake and Cascade Lake systems can be configured to report uncorrected errors using a special signature in the machine check bank and to signal using CMCI instead of machine check. Update the severity calculation mechanism to allow specifying the model, minimum stepping and range of machine check bank numbers. Add a new rule to detect the special signature (on model 0x55, stepping >=4 in any of the memory controller banks). [ bp: Rewrite it. aegl: Productize it. ] Suggested-by: Youquan Song Signed-off-by: Borislav Petkov Co-developed-by: Tony Luck Signed-off-by: Tony Luck Signed-off-by: Borislav Petkov Link: https://lkml.kernel.org/r/20200930021313.31810-2-tony.luck@intel.com Signed-off-by: Sasha Levin

x86/mce: Use idtentry_nmi_enter/exit()

2020-09-30T08:41:56Z

The recent fix for NMI vs. IRQ state tracking missed to apply the cure to the MCE handler. Fixes: ba1f2b2eaa2a ("x86/entry: Fix NMI vs IRQ state tracking") Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov Link: https://lkml.kernel.org/r/87mu17ism2.fsf@nanos.tec.linutronix.de

treewide: Use fallthrough pseudo-keyword

2020-08-23T22:36:59Z

Replace the existing /* fall through */ comments and its variants with the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary fall-through markings when it is the case. [1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through Signed-off-by: Gustavo A. R. Silva

Merge tag 'x86-entry-2020-08-04' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2020-08-05T04:05:46Z

Pull x86 conversion to generic entry code from Thomas Gleixner: "The conversion of X86 syscall, interrupt and exception entry/exit handling to the generic code. Pretty much a straight-forward 1:1 conversion plus the consolidation of the KVM handling of pending work before entering guest mode" * tag 'x86-entry-2020-08-04' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/kvm: Use __xfer_to_guest_mode_work_pending() in kvm_run_vcpu() x86/kvm: Use generic xfer to guest work function x86/entry: Cleanup idtentry_enter/exit x86/entry: Use generic interrupt entry/exit code x86/entry: Cleanup idtentry_entry/exit_user x86/entry: Use generic syscall exit functionality x86/entry: Use generic syscall entry function x86/ptrace: Provide pt_regs helper for entry/exit x86/entry: Move user return notifier out of loop x86/entry: Consolidate 32/64 bit syscall entry x86/entry: Consolidate check_user_regs() x86: Correct noinstr qualifiers x86/idtentry: Remove stale comment