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

Merge tag 'libnvdimm-for-5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm

2022-05-27T22:49:30Z

Pull libnvdimm and DAX updates from Dan Williams: "New support for clearing memory errors when a file is in DAX mode, alongside with some other fixes and cleanups. Previously it was only possible to clear these errors using a truncate or hole-punch operation to trigger the filesystem to reallocate the block, now, any page aligned write can opportunistically clear errors as well. This change spans x86/mm, nvdimm, and fs/dax, and has received the appropriate sign-offs. Thanks to Jane for her work on this. Summary: - Add support for clearing memory error via pwrite(2) on DAX - Fix 'security overwrite' support in the presence of media errors - Miscellaneous cleanups and fixes for nfit_test (nvdimm unit tests)" * tag 'libnvdimm-for-5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm: pmem: implement pmem_recovery_write() pmem: refactor pmem_clear_poison() dax: add .recovery_write dax_operation dax: introduce DAX_RECOVERY_WRITE dax access mode mce: fix set_mce_nospec to always unmap the whole page x86/mce: relocate set{clear}_mce_nospec() functions acpi/nfit: rely on mce->misc to determine poison granularity testing: nvdimm: asm/mce.h is not needed in nfit.c testing: nvdimm: iomap: make __nfit_test_ioremap a macro nvdimm: Allow overwrite in the presence of disabled dimms tools/testing/nvdimm: remove unneeded flush_workqueue

mce: fix set_mce_nospec to always unmap the whole page

2022-05-16T18:46:44Z

The set_memory_uc() approach doesn't work well in all cases. As Dan pointed out when "The VMM unmapped the bad page from guest physical space and passed the machine check to the guest." "The guest gets virtual #MC on an access to that page. When the guest tries to do set_memory_uc() and instructs cpa_flush() to do clean caches that results in taking another fault / exception perhaps because the VMM unmapped the page from the guest." Since the driver has special knowledge to handle NP or UC, mark the poisoned page with NP and let driver handle it when it comes down to repair. Please refer to discussions here for more details. https://lore.kernel.org/all/CAPcyv4hrXPb1tASBZUg-GgdVs0OOFKXMXLiHmktg_kFi7YBMyQ@mail.gmail.com/ Now since poisoned page is marked as not-present, in order to avoid writing to a not-present page and trigger kernel Oops, also fix pmem_do_write(). Fixes: 284ce4011ba6 ("x86/memory_failure: Introduce {set, clear}_mce_nospec()") Reviewed-by: Christoph Hellwig Reviewed-by: Dan Williams Signed-off-by: Jane Chu Acked-by: Tony Luck Link: https://lore.kernel.org/r/165272615484.103830.2563950688772226611.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams

x86/mce: Avoid unnecessary padding in struct mce_bank

2022-04-05T19:23:34Z

Convert struct mce_bank member "init" from bool to a bitfield to get rid of unnecessary padding. $ pahole -C mce_bank arch/x86/kernel/cpu/mce/core.o before: /* size: 16, cachelines: 1, members: 2 */ /* padding: 7 */ /* last cacheline: 16 bytes */ after: /* size: 16, cachelines: 1, members: 3 */ /* last cacheline: 16 bytes */ No functional changes. Signed-off-by: Smita Koralahalli Signed-off-by: Borislav Petkov Link: https://lore.kernel.org/r/20220225193342.215780-2-Smita.KoralahalliChannabasappa@amd.com

Merge tag 'ras_core_for_v5.18_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2022-03-25T19:34:53Z

Pull RAS updates from Borislav Petkov: - More noinstr fixes - Add an erratum workaround for Intel CPUs which, in certain circumstances, end up consuming an unrelated uncorrectable memory error when using fast string copy insns - Remove the MCE tolerance level control as it is not really needed or used anymore * tag 'ras_core_for_v5.18_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/mce: Remove the tolerance level control x86/mce: Work around an erratum on fast string copy instructions x86/mce: Use arch atomic and bit helpers

Merge branch 'akpm' (patches from Andrew)

2022-03-22T23:11:53Z

Merge updates from Andrew Morton: - A few misc subsystems: kthread, scripts, ntfs, ocfs2, block, and vfs - Most the MM patches which precede the patches in Willy's tree: kasan, pagecache, gup, swap, shmem, memcg, selftests, pagemap, mremap, sparsemem, vmalloc, pagealloc, memory-failure, mlock, hugetlb, userfaultfd, vmscan, compaction, mempolicy, oom-kill, migration, thp, cma, autonuma, psi, ksm, page-poison, madvise, memory-hotplug, rmap, zswap, uaccess, ioremap, highmem, cleanups, kfence, hmm, and damon. * emailed patches from Andrew Morton : (227 commits) mm/damon/sysfs: remove repeat container_of() in damon_sysfs_kdamond_release() Docs/ABI/testing: add DAMON sysfs interface ABI document Docs/admin-guide/mm/damon/usage: document DAMON sysfs interface selftests/damon: add a test for DAMON sysfs interface mm/damon/sysfs: support DAMOS stats mm/damon/sysfs: support DAMOS watermarks mm/damon/sysfs: support schemes prioritization mm/damon/sysfs: support DAMOS quotas mm/damon/sysfs: support DAMON-based Operation Schemes mm/damon/sysfs: support the physical address space monitoring mm/damon/sysfs: link DAMON for virtual address spaces monitoring mm/damon: implement a minimal stub for sysfs-based DAMON interface mm/damon/core: add number of each enum type values mm/damon/core: allow non-exclusive DAMON start/stop Docs/damon: update outdated term 'regions update interval' Docs/vm/damon/design: update DAMON-Idle Page Tracking interference handling Docs/vm/damon: call low level monitoring primitives the operations mm/damon: remove unnecessary CONFIG_DAMON option mm/damon/paddr,vaddr: remove damon_{p,v}a_{target_valid,set_operations}() mm/damon/dbgfs-test: fix is_target_id() change ...

mm/hwpoison: avoid the impact of hwpoison_filter() return value on mce handler

2022-03-22T22:57:07Z

When the hwpoison page meets the filter conditions, it should not be regarded as successful memory_failure() processing for mce handler, but should return a distinct value, otherwise mce handler regards the error page has been identified and isolated, which may lead to calling set_mce_nospec() to change page attribute, etc. Here memory_failure() return -EOPNOTSUPP to indicate that the error event is filtered, mce handler should not take any action for this situation and hwpoison injector should treat as correct. Link: https://lkml.kernel.org/r/20220223082135.2769649-1-luofei@unicloud.com Signed-off-by: luofei Acked-by: Borislav Petkov Cc: Dave Hansen Cc: H. Peter Anvin Cc: Ingo Molnar Cc: Miaohe Lin Cc: Naoya Horiguchi Cc: Thomas Gleixner Cc: Tony Luck Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

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: Work around an erratum on fast string copy instructions

2022-02-19T13:26:42Z

A rare kernel panic scenario can happen when the following conditions are met due to an erratum on fast string copy instructions: 1) An uncorrected error. 2) That error must be in first cache line of a page. 3) Kernel must execute page_copy from the page immediately before that page. The fast string copy instructions ("REP; MOVS*") could consume an uncorrectable memory error in the cache line _right after_ the desired region to copy and raise an MCE. Bit 0 of MSR_IA32_MISC_ENABLE can be cleared to disable fast string copy and will avoid such spurious machine checks. However, that is less preferable due to the permanent performance impact. Considering memory poison is rare, it's desirable to keep fast string copy enabled until an MCE is seen. Intel has confirmed the following: 1. The CPU erratum of fast string copy only applies to Skylake, Cascade Lake and Cooper Lake generations. Directly return from the MCE handler: 2. Will result in complete execution of the "REP; MOVS*" with no data loss or corruption. 3. Will not result in another MCE firing on the next poisoned cache line due to "REP; MOVS*". 4. Will resume execution from a correct point in code. 5. Will result in the same instruction that triggered the MCE firing a second MCE immediately for any other software recoverable data fetch errors. 6. Is not safe without disabling the fast string copy, as the next fast string copy of the same buffer on the same CPU would result in a PANIC MCE. This should mitigate the erratum completely with the only caveat that the fast string copy is disabled on the affected hyper thread thus performance degradation. This is still better than the OS crashing on MCEs raised on an irrelevant process due to "REP; MOVS*' accesses in a kernel context, e.g., copy_page. Tested: Injected errors on 1st cache line of 8 anonymous pages of process 'proc1' and observed MCE consumption from 'proc2' with no panic (directly returned). Without the fix, the host panicked within a few minutes on a random 'proc2' process due to kernel access from copy_page. [ bp: Fix comment style + touch ups, zap an unlikely(), improve the quirk function's readability. ] Signed-off-by: Jue Wang Signed-off-by: Borislav Petkov Reviewed-by: Tony Luck Link: https://lore.kernel.org/r/20220218013209.2436006-1-juew@google.com

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/cpu: Read/save PPIN MSR during initialization

2022-02-01T15:29:26Z

Currently, the PPIN (Protected Processor Inventory Number) MSR is read by every CPU that processes a machine check, CMCI, or just polls machine check banks from a periodic timer. This is not a "fast" MSR, so this adds to overhead of processing errors. Add a new "ppin" field to the cpuinfo_x86 structure. Read and save the PPIN during initialization. Use this copy in mce_setup() instead of reading the MSR. Signed-off-by: Tony Luck Signed-off-by: Borislav Petkov Link: https://lore.kernel.org/r/20220131230111.2004669-4-tony.luck@intel.com