Mark poisoned page as not present, and to reverse the 'np' effect, restate the _PAGE_PRESENT bit. Please refer to discussions here for reason behind the decision. https://lore.kernel.org/all/CAPcyv4hrXPb1tASBZUg-GgdVs0OOFKXMXLiHmktg_kFi7YBMyQ@xxxxxxxxxxxxxx/ Now since poisoned page is marked as not-present, in order to avoid writing to a 'np' page and trigger kernel Oops, also fix pmem_do_write(). Fixes: 284ce4011ba6 ("x86/memory_failure: Introduce {set, clear}_mce_nospec()") Signed-off-by: Jane Chu <jane.chu@xxxxxxxxxx> --- arch/x86/kernel/cpu/mce/core.c | 6 +++--- arch/x86/mm/pat/set_memory.c | 21 +++++++++------------ drivers/nvdimm/pmem.c | 31 +++++++------------------------ include/linux/set_memory.h | 4 ++-- 4 files changed, 21 insertions(+), 41 deletions(-) diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c index 5818b837fd4d..8d12739f283d 100644 --- a/arch/x86/kernel/cpu/mce/core.c +++ b/arch/x86/kernel/cpu/mce/core.c @@ -613,7 +613,7 @@ static int uc_decode_notifier(struct notifier_block *nb, unsigned long val, pfn = mce->addr >> PAGE_SHIFT; if (!memory_failure(pfn, 0)) { - set_mce_nospec(pfn, whole_page(mce)); + set_mce_nospec(pfn); mce->kflags |= MCE_HANDLED_UC; } @@ -1297,7 +1297,7 @@ static void kill_me_maybe(struct callback_head *cb) ret = memory_failure(p->mce_addr >> PAGE_SHIFT, flags); if (!ret) { - set_mce_nospec(p->mce_addr >> PAGE_SHIFT, p->mce_whole_page); + set_mce_nospec(p->mce_addr >> PAGE_SHIFT); sync_core(); return; } @@ -1321,7 +1321,7 @@ static void kill_me_never(struct callback_head *cb) p->mce_count = 0; pr_err("Kernel accessed poison in user space at %llx\n", p->mce_addr); if (!memory_failure(p->mce_addr >> PAGE_SHIFT, 0)) - set_mce_nospec(p->mce_addr >> PAGE_SHIFT, p->mce_whole_page); + set_mce_nospec(p->mce_addr >> PAGE_SHIFT); } static void queue_task_work(struct mce *m, char *msg, void (*func)(struct callback_head *)) diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c index 9abc6077d768..747614c3dd83 100644 --- a/arch/x86/mm/pat/set_memory.c +++ b/arch/x86/mm/pat/set_memory.c @@ -1925,14 +1925,14 @@ int set_memory_wb(unsigned long addr, int numpages) } EXPORT_SYMBOL(set_memory_wb); +static int _set_memory_present(unsigned long addr, int numpages) +{ + return change_page_attr_set(&addr, numpages, __pgprot(_PAGE_PRESENT), 0); +} + #ifdef CONFIG_X86_64 -/* - * Prevent speculative access to the page by either unmapping - * it (if we do not require access to any part of the page) or - * marking it uncacheable (if we want to try to retrieve data - * from non-poisoned lines in the page). - */ -int set_mce_nospec(unsigned long pfn, bool unmap) +/* Prevent speculative access to a page by marking it not-present */ +int set_mce_nospec(unsigned long pfn) { unsigned long decoy_addr; int rc; @@ -1954,10 +1954,7 @@ int set_mce_nospec(unsigned long pfn, bool unmap) */ decoy_addr = (pfn << PAGE_SHIFT) + (PAGE_OFFSET ^ BIT(63)); - if (unmap) - rc = set_memory_np(decoy_addr, 1); - else - rc = set_memory_uc(decoy_addr, 1); + rc = set_memory_np(decoy_addr, 1); if (rc) pr_warn("Could not invalidate pfn=0x%lx from 1:1 map\n", pfn); return rc; @@ -1967,7 +1964,7 @@ EXPORT_SYMBOL(set_mce_nospec); /* Restore full speculative operation to the pfn. */ int clear_mce_nospec(unsigned long pfn) { - return set_memory_wb((unsigned long) pfn_to_kaddr(pfn), 1); + return _set_memory_present((unsigned long) pfn_to_kaddr(pfn), 1); } EXPORT_SYMBOL(clear_mce_nospec); diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c index 58d95242a836..30c71a68175b 100644 --- a/drivers/nvdimm/pmem.c +++ b/drivers/nvdimm/pmem.c @@ -158,36 +158,19 @@ static blk_status_t pmem_do_write(struct pmem_device *pmem, struct page *page, unsigned int page_off, sector_t sector, unsigned int len) { - blk_status_t rc = BLK_STS_OK; - bool bad_pmem = false; phys_addr_t pmem_off = sector * 512 + pmem->data_offset; void *pmem_addr = pmem->virt_addr + pmem_off; - if (unlikely(is_bad_pmem(&pmem->bb, sector, len))) - bad_pmem = true; + if (unlikely(is_bad_pmem(&pmem->bb, sector, len))) { + blk_status_t rc = pmem_clear_poison(pmem, pmem_off, len); - /* - * Note that we write the data both before and after - * clearing poison. The write before clear poison - * handles situations where the latest written data is - * preserved and the clear poison operation simply marks - * the address range as valid without changing the data. - * In this case application software can assume that an - * interrupted write will either return the new good - * data or an error. - * - * However, if pmem_clear_poison() leaves the data in an - * indeterminate state we need to perform the write - * after clear poison. - */ + if (rc != BLK_STS_OK) + pr_warn_ratelimited("%s: failed to clear poison\n", __func__); + return rc; + } flush_dcache_page(page); write_pmem(pmem_addr, page, page_off, len); - if (unlikely(bad_pmem)) { - rc = pmem_clear_poison(pmem, pmem_off, len); - write_pmem(pmem_addr, page, page_off, len); - } - - return rc; + return BLK_STS_OK; } static void pmem_submit_bio(struct bio *bio) diff --git a/include/linux/set_memory.h b/include/linux/set_memory.h index d6263d7afb55..cde2d8687a7b 100644 --- a/include/linux/set_memory.h +++ b/include/linux/set_memory.h @@ -43,10 +43,10 @@ static inline bool can_set_direct_map(void) #endif /* CONFIG_ARCH_HAS_SET_DIRECT_MAP */ #ifdef CONFIG_X86_64 -int set_mce_nospec(unsigned long pfn, bool unmap); +int set_mce_nospec(unsigned long pfn); int clear_mce_nospec(unsigned long pfn); #else -static inline int set_mce_nospec(unsigned long pfn, bool unmap) +static inline int set_mce_nospec(unsigned long pfn) { return 0; } -- 2.18.4
