summaryrefslogtreecommitdiff
path: root/arch/x86/include/asm/set_memory.h
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2018-08-26 04:43:59 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2018-08-26 04:43:59 +0300
commit2923b27e54242acf27fd16b299e102117c82f52f (patch)
tree86b3e27575814dab74307a7928bf579455b70e24 /arch/x86/include/asm/set_memory.h
parent828bf6e904eb8fc8969333568802689fbbf07a40 (diff)
parentc953cc987ab87d180e1d5de2f1c217abe33aac77 (diff)
downloadlinux-2923b27e54242acf27fd16b299e102117c82f52f.tar.xz
Merge tag 'libnvdimm-for-4.19_dax-memory-failure' of gitolite.kernel.org:pub/scm/linux/kernel/git/nvdimm/nvdimm
Pull libnvdimm memory-failure update from Dave Jiang: "As it stands, memory_failure() gets thoroughly confused by dev_pagemap backed mappings. The recovery code has specific enabling for several possible page states and needs new enabling to handle poison in dax mappings. In order to support reliable reverse mapping of user space addresses: 1/ Add new locking in the memory_failure() rmap path to prevent races that would typically be handled by the page lock. 2/ Since dev_pagemap pages are hidden from the page allocator and the "compound page" accounting machinery, add a mechanism to determine the size of the mapping that encompasses a given poisoned pfn. 3/ Given pmem errors can be repaired, change the speculatively accessed poison protection, mce_unmap_kpfn(), to be reversible and otherwise allow ongoing access from the kernel. A side effect of this enabling is that MADV_HWPOISON becomes usable for dax mappings, however the primary motivation is to allow the system to survive userspace consumption of hardware-poison via dax. Specifically the current behavior is: mce: Uncorrected hardware memory error in user-access at af34214200 {1}[Hardware Error]: It has been corrected by h/w and requires no further action mce: [Hardware Error]: Machine check events logged {1}[Hardware Error]: event severity: corrected Memory failure: 0xaf34214: reserved kernel page still referenced by 1 users [..] Memory failure: 0xaf34214: recovery action for reserved kernel page: Failed mce: Memory error not recovered <reboot> ...and with these changes: Injecting memory failure for pfn 0x20cb00 at process virtual address 0x7f763dd00000 Memory failure: 0x20cb00: Killing dax-pmd:5421 due to hardware memory corruption Memory failure: 0x20cb00: recovery action for dax page: Recovered Given all the cross dependencies I propose taking this through nvdimm.git with acks from Naoya, x86/core, x86/RAS, and of course dax folks" * tag 'libnvdimm-for-4.19_dax-memory-failure' of gitolite.kernel.org:pub/scm/linux/kernel/git/nvdimm/nvdimm: libnvdimm, pmem: Restore page attributes when clearing errors x86/memory_failure: Introduce {set, clear}_mce_nospec() x86/mm/pat: Prepare {reserve, free}_memtype() for "decoy" addresses mm, memory_failure: Teach memory_failure() about dev_pagemap pages filesystem-dax: Introduce dax_lock_mapping_entry() mm, memory_failure: Collect mapping size in collect_procs() mm, madvise_inject_error: Let memory_failure() optionally take a page reference mm, dev_pagemap: Do not clear ->mapping on final put mm, madvise_inject_error: Disable MADV_SOFT_OFFLINE for ZONE_DEVICE pages filesystem-dax: Set page->index device-dax: Set page->index device-dax: Enable page_mapping() device-dax: Convert to vmf_insert_mixed and vm_fault_t
Diffstat (limited to 'arch/x86/include/asm/set_memory.h')
-rw-r--r--arch/x86/include/asm/set_memory.h42
1 files changed, 42 insertions, 0 deletions
diff --git a/arch/x86/include/asm/set_memory.h b/arch/x86/include/asm/set_memory.h
index 34cffcef7375..07a25753e85c 100644
--- a/arch/x86/include/asm/set_memory.h
+++ b/arch/x86/include/asm/set_memory.h
@@ -89,4 +89,46 @@ extern int kernel_set_to_readonly;
void set_kernel_text_rw(void);
void set_kernel_text_ro(void);
+#ifdef CONFIG_X86_64
+static inline int set_mce_nospec(unsigned long pfn)
+{
+ unsigned long decoy_addr;
+ int rc;
+
+ /*
+ * Mark the linear address as UC to make sure we don't log more
+ * errors because of speculative access to the page.
+ * We would like to just call:
+ * set_memory_uc((unsigned long)pfn_to_kaddr(pfn), 1);
+ * but doing that would radically increase the odds of a
+ * speculative access to the poison page because we'd have
+ * the virtual address of the kernel 1:1 mapping sitting
+ * around in registers.
+ * Instead we get tricky. We create a non-canonical address
+ * that looks just like the one we want, but has bit 63 flipped.
+ * This relies on set_memory_uc() properly sanitizing any __pa()
+ * results with __PHYSICAL_MASK or PTE_PFN_MASK.
+ */
+ decoy_addr = (pfn << PAGE_SHIFT) + (PAGE_OFFSET ^ BIT(63));
+
+ rc = set_memory_uc(decoy_addr, 1);
+ if (rc)
+ pr_warn("Could not invalidate pfn=0x%lx from 1:1 map\n", pfn);
+ return rc;
+}
+#define set_mce_nospec set_mce_nospec
+
+/* Restore full speculative operation to the pfn. */
+static inline int clear_mce_nospec(unsigned long pfn)
+{
+ return set_memory_wb((unsigned long) pfn_to_kaddr(pfn), 1);
+}
+#define clear_mce_nospec clear_mce_nospec
+#else
+/*
+ * Few people would run a 32-bit kernel on a machine that supports
+ * recoverable errors because they have too much memory to boot 32-bit.
+ */
+#endif
+
#endif /* _ASM_X86_SET_MEMORY_H */