libnvdimm, pmem: Restore page attributes when clearing errors
Use clear_mce_nospec() to restore WB mode for the kernel linear mapping of a pmem page that was marked 'HWPoison'. A page with 'HWPoison' set has also been marked UC in PAT (page attribute table) via set_mce_nospec() to prevent speculative retrievals of poison. The 'HWPoison' flag is only cleared when overwriting an entire page. Signed-off-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
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@ -20,6 +20,7 @@
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#include <linux/hdreg.h>
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#include <linux/init.h>
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#include <linux/platform_device.h>
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#include <linux/set_memory.h>
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/badblocks.h>
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@ -51,6 +52,30 @@ static struct nd_region *to_region(struct pmem_device *pmem)
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return to_nd_region(to_dev(pmem)->parent);
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}
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static void hwpoison_clear(struct pmem_device *pmem,
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phys_addr_t phys, unsigned int len)
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{
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unsigned long pfn_start, pfn_end, pfn;
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/* only pmem in the linear map supports HWPoison */
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if (is_vmalloc_addr(pmem->virt_addr))
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return;
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pfn_start = PHYS_PFN(phys);
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pfn_end = pfn_start + PHYS_PFN(len);
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for (pfn = pfn_start; pfn < pfn_end; pfn++) {
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struct page *page = pfn_to_page(pfn);
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/*
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* Note, no need to hold a get_dev_pagemap() reference
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* here since we're in the driver I/O path and
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* outstanding I/O requests pin the dev_pagemap.
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*/
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if (test_and_clear_pmem_poison(page))
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clear_mce_nospec(pfn);
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}
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}
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static blk_status_t pmem_clear_poison(struct pmem_device *pmem,
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phys_addr_t offset, unsigned int len)
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{
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@ -65,6 +90,7 @@ static blk_status_t pmem_clear_poison(struct pmem_device *pmem,
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if (cleared < len)
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rc = BLK_STS_IOERR;
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if (cleared > 0 && cleared / 512) {
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hwpoison_clear(pmem, pmem->phys_addr + offset, cleared);
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cleared /= 512;
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dev_dbg(dev, "%#llx clear %ld sector%s\n",
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(unsigned long long) sector, cleared,
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@ -1,6 +1,7 @@
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/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __NVDIMM_PMEM_H__
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#define __NVDIMM_PMEM_H__
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#include <linux/page-flags.h>
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#include <linux/badblocks.h>
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#include <linux/types.h>
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#include <linux/pfn_t.h>
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@ -27,4 +28,16 @@ struct pmem_device {
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long __pmem_direct_access(struct pmem_device *pmem, pgoff_t pgoff,
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long nr_pages, void **kaddr, pfn_t *pfn);
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#ifdef CONFIG_MEMORY_FAILURE
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static inline bool test_and_clear_pmem_poison(struct page *page)
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{
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return TestClearPageHWPoison(page);
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}
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#else
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static inline bool test_and_clear_pmem_poison(struct page *page)
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{
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return false;
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}
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#endif
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#endif /* __NVDIMM_PMEM_H__ */
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