114 lines
3.8 KiB
Diff
114 lines
3.8 KiB
Diff
From 46cbda7b65998a5af4493f745d94417af697bd68 Mon Sep 17 00:00:00 2001
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From: Juergen Gross <jgross@suse.com>
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Date: Wed, 23 Nov 2022 07:45:10 +0100
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Subject: [PATCH 18/29] mm: introduce arch_has_hw_nonleaf_pmd_young()
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When running as a Xen PV guests commit eed9a328aa1a ("mm: x86: add
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CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG") can cause a protection violation in
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pmdp_test_and_clear_young():
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BUG: unable to handle page fault for address: ffff8880083374d0
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#PF: supervisor write access in kernel mode
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#PF: error_code(0x0003) - permissions violation
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PGD 3026067 P4D 3026067 PUD 3027067 PMD 7fee5067 PTE 8010000008337065
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Oops: 0003 [#1] PREEMPT SMP NOPTI
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CPU: 7 PID: 158 Comm: kswapd0 Not tainted 6.1.0-rc5-20221118-doflr+ #1
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RIP: e030:pmdp_test_and_clear_young+0x25/0x40
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This happens because the Xen hypervisor can't emulate direct writes to
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page table entries other than PTEs.
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This can easily be fixed by introducing arch_has_hw_nonleaf_pmd_young()
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similar to arch_has_hw_pte_young() and test that instead of
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CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG.
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Link: https://lkml.kernel.org/r/20221123064510.16225-1-jgross@suse.com
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Fixes: eed9a328aa1a ("mm: x86: add CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG")
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Signed-off-by: Juergen Gross <jgross@suse.com>
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Reported-by: Sander Eikelenboom <linux@eikelenboom.it>
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Acked-by: Yu Zhao <yuzhao@google.com>
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Tested-by: Sander Eikelenboom <linux@eikelenboom.it>
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Acked-by: David Hildenbrand <david@redhat.com> [core changes]
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Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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---
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arch/x86/include/asm/pgtable.h | 8 ++++++++
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include/linux/pgtable.h | 11 +++++++++++
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mm/vmscan.c | 10 +++++-----
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3 files changed, 24 insertions(+), 5 deletions(-)
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--- a/arch/x86/include/asm/pgtable.h
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+++ b/arch/x86/include/asm/pgtable.h
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@@ -1405,6 +1405,14 @@ static inline bool arch_has_hw_pte_young
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return true;
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}
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+#ifdef CONFIG_XEN_PV
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+#define arch_has_hw_nonleaf_pmd_young arch_has_hw_nonleaf_pmd_young
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+static inline bool arch_has_hw_nonleaf_pmd_young(void)
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+{
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+ return !cpu_feature_enabled(X86_FEATURE_XENPV);
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+}
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+#endif
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+
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#endif /* __ASSEMBLY__ */
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#endif /* _ASM_X86_PGTABLE_H */
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--- a/include/linux/pgtable.h
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+++ b/include/linux/pgtable.h
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@@ -266,6 +266,17 @@ static inline int pmdp_clear_flush_young
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#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
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#endif
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+#ifndef arch_has_hw_nonleaf_pmd_young
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+/*
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+ * Return whether the accessed bit in non-leaf PMD entries is supported on the
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+ * local CPU.
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+ */
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+static inline bool arch_has_hw_nonleaf_pmd_young(void)
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+{
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+ return IS_ENABLED(CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG);
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+}
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+#endif
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+
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#ifndef arch_has_hw_pte_young
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/*
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* Return whether the accessed bit is supported on the local CPU.
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--- a/mm/vmscan.c
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+++ b/mm/vmscan.c
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@@ -3727,7 +3727,7 @@ static void walk_pmd_range_locked(pud_t
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goto next;
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if (!pmd_trans_huge(pmd[i])) {
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- if (IS_ENABLED(CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG) &&
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+ if (arch_has_hw_nonleaf_pmd_young() &&
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get_cap(LRU_GEN_NONLEAF_YOUNG))
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pmdp_test_and_clear_young(vma, addr, pmd + i);
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goto next;
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@@ -3825,14 +3825,14 @@ restart:
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#endif
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walk->mm_stats[MM_NONLEAF_TOTAL]++;
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-#ifdef CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG
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- if (get_cap(LRU_GEN_NONLEAF_YOUNG)) {
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+ if (arch_has_hw_nonleaf_pmd_young() &&
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+ get_cap(LRU_GEN_NONLEAF_YOUNG)) {
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if (!pmd_young(val))
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continue;
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walk_pmd_range_locked(pud, addr, vma, args, bitmap, &pos);
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}
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-#endif
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+
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if (!walk->force_scan && !test_bloom_filter(walk->lruvec, walk->max_seq, pmd + i))
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continue;
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@@ -5132,7 +5132,7 @@ static ssize_t show_enabled(struct kobje
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if (arch_has_hw_pte_young() && get_cap(LRU_GEN_MM_WALK))
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caps |= BIT(LRU_GEN_MM_WALK);
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- if (IS_ENABLED(CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG) && get_cap(LRU_GEN_NONLEAF_YOUNG))
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+ if (arch_has_hw_nonleaf_pmd_young() && get_cap(LRU_GEN_NONLEAF_YOUNG))
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caps |= BIT(LRU_GEN_NONLEAF_YOUNG);
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return snprintf(buf, PAGE_SIZE, "0x%04x\n", caps);
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