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5898b43af9
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: 284ce4011b ("x86/memory_failure: Introduce {set, clear}_mce_nospec()")
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Jane Chu <jane.chu@oracle.com>
Acked-by: Tony Luck <tony.luck@intel.com>
Link: https://lore.kernel.org/r/165272615484.103830.2563950688772226611.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
71 lines
1.7 KiB
C
71 lines
1.7 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Copyright 2017, Michael Ellerman, IBM Corporation.
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*/
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#ifndef _LINUX_SET_MEMORY_H_
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#define _LINUX_SET_MEMORY_H_
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#ifdef CONFIG_ARCH_HAS_SET_MEMORY
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#include <asm/set_memory.h>
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#else
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static inline int set_memory_ro(unsigned long addr, int numpages) { return 0; }
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static inline int set_memory_rw(unsigned long addr, int numpages) { return 0; }
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static inline int set_memory_x(unsigned long addr, int numpages) { return 0; }
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static inline int set_memory_nx(unsigned long addr, int numpages) { return 0; }
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#endif
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#ifndef CONFIG_ARCH_HAS_SET_DIRECT_MAP
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static inline int set_direct_map_invalid_noflush(struct page *page)
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{
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return 0;
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}
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static inline int set_direct_map_default_noflush(struct page *page)
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{
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return 0;
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}
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static inline bool kernel_page_present(struct page *page)
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{
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return true;
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}
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#else /* CONFIG_ARCH_HAS_SET_DIRECT_MAP */
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/*
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* Some architectures, e.g. ARM64 can disable direct map modifications at
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* boot time. Let them overrive this query.
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*/
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#ifndef can_set_direct_map
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static inline bool can_set_direct_map(void)
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{
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return true;
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}
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#define can_set_direct_map can_set_direct_map
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#endif
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#endif /* CONFIG_ARCH_HAS_SET_DIRECT_MAP */
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#ifdef CONFIG_X86_64
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int set_mce_nospec(unsigned long pfn);
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int clear_mce_nospec(unsigned long pfn);
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#else
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static inline int set_mce_nospec(unsigned long pfn)
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{
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return 0;
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}
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static inline int clear_mce_nospec(unsigned long pfn)
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{
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return 0;
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}
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#endif
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#ifndef CONFIG_ARCH_HAS_MEM_ENCRYPT
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static inline int set_memory_encrypted(unsigned long addr, int numpages)
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{
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return 0;
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}
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static inline int set_memory_decrypted(unsigned long addr, int numpages)
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{
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return 0;
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}
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#endif /* CONFIG_ARCH_HAS_MEM_ENCRYPT */
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#endif /* _LINUX_SET_MEMORY_H_ */
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