205 lines
6.1 KiB
Diff
205 lines
6.1 KiB
Diff
From f253c70a143d461e840630e9aded0ed3beb06b40 Mon Sep 17 00:00:00 2001
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From: Thomas Gleixner <tglx@linutronix.de>
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Date: Mon, 17 Sep 2018 16:29:12 +0200
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Subject: [PATCH 007/550] x86/mm/cpa: Add large page preservation statistics
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The large page preservation mechanism is just magic and provides no
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information at all. Add optional statistic output in debugfs so the magic can
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be evaluated. Defaults is off.
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Output:
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1G pages checked: 2
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1G pages sameprot: 0
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1G pages preserved: 0
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2M pages checked: 540
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2M pages sameprot: 466
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2M pages preserved: 47
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4K pages checked: 800770
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4K pages set-checked: 7668
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Reviewed-by: Dave Hansen <dave.hansen@intel.com>
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Cc: Peter Zijlstra <peterz@infradead.org>
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Cc: Bin Yang <bin.yang@intel.com>
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Cc: Mark Gross <mark.gross@intel.com>
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Link: https://lkml.kernel.org/r/20180917143546.160867778@linutronix.de
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Cc: Zhang Ning <ning.a.zhang@intel.com>
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Signed-off-by: Lili Li <lili.li@intel.com>
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---
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arch/x86/Kconfig | 8 ++++
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arch/x86/mm/pageattr.c | 99 +++++++++++++++++++++++++++++++++++++++++-
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2 files changed, 105 insertions(+), 2 deletions(-)
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diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
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index 1a0be022f91d..65728bb1182c 100644
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--- a/arch/x86/Kconfig
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+++ b/arch/x86/Kconfig
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@@ -1491,6 +1491,14 @@ config X86_DIRECT_GBPAGES
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supports them), so don't confuse the user by printing
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that we have them enabled.
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+config X86_CPA_STATISTICS
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+ bool "Enable statistic for Change Page Attribute"
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+ depends on DEBUG_FS
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+ ---help---
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+ Expose statistics about the Change Page Attribute mechanims, which
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+ helps to determine the effectivness of preserving large and huge
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+ page mappings when mapping protections are changed.
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+
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config ARCH_HAS_MEM_ENCRYPT
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def_bool y
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diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
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index 1f2519055b30..cdf52eb86f3a 100644
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--- a/arch/x86/mm/pageattr.c
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+++ b/arch/x86/mm/pageattr.c
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@@ -101,6 +101,95 @@ void arch_report_meminfo(struct seq_file *m)
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static inline void split_page_count(int level) { }
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#endif
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+#ifdef CONFIG_X86_CPA_STATISTICS
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+
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+static unsigned long cpa_1g_checked;
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+static unsigned long cpa_1g_sameprot;
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+static unsigned long cpa_1g_preserved;
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+static unsigned long cpa_2m_checked;
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+static unsigned long cpa_2m_sameprot;
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+static unsigned long cpa_2m_preserved;
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+static unsigned long cpa_4k_checked;
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+static unsigned long cpa_4k_install;
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+
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+static inline void cpa_inc_1g_checked(void)
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+{
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+ cpa_1g_checked++;
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+}
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+
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+static inline void cpa_inc_2m_checked(void)
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+{
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+ cpa_2m_checked++;
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+}
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+
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+static inline void cpa_inc_4k_checked(void)
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+{
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+ cpa_4k_checked++;
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+}
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+
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+static inline void cpa_inc_4k_install(void)
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+{
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+ cpa_4k_install++;
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+}
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+
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+static inline void cpa_inc_lp_sameprot(int level)
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+{
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+ if (level == PG_LEVEL_1G)
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+ cpa_1g_sameprot++;
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+ else
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+ cpa_2m_sameprot++;
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+}
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+
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+static inline void cpa_inc_lp_preserved(int level)
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+{
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+ if (level == PG_LEVEL_1G)
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+ cpa_1g_preserved++;
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+ else
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+ cpa_2m_preserved++;
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+}
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+
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+static int cpastats_show(struct seq_file *m, void *p)
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+{
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+ seq_printf(m, "1G pages checked: %16lu\n", cpa_1g_checked);
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+ seq_printf(m, "1G pages sameprot: %16lu\n", cpa_1g_sameprot);
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+ seq_printf(m, "1G pages preserved: %16lu\n", cpa_1g_preserved);
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+ seq_printf(m, "2M pages checked: %16lu\n", cpa_2m_checked);
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+ seq_printf(m, "2M pages sameprot: %16lu\n", cpa_2m_sameprot);
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+ seq_printf(m, "2M pages preserved: %16lu\n", cpa_2m_preserved);
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+ seq_printf(m, "4K pages checked: %16lu\n", cpa_4k_checked);
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+ seq_printf(m, "4K pages set-checked: %16lu\n", cpa_4k_install);
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+ return 0;
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+}
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+
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+static int cpastats_open(struct inode *inode, struct file *file)
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+{
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+ return single_open(file, cpastats_show, NULL);
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+}
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+
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+static const struct file_operations cpastats_fops = {
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+ .open = cpastats_open,
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+ .read = seq_read,
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+ .llseek = seq_lseek,
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+ .release = single_release,
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+};
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+
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+static int __init cpa_stats_init(void)
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+{
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+ debugfs_create_file("cpa_stats", S_IRUSR, arch_debugfs_dir, NULL,
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+ &cpastats_fops);
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+ return 0;
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+}
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+late_initcall(cpa_stats_init);
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+#else
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+static inline void cpa_inc_1g_checked(void) { }
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+static inline void cpa_inc_2m_checked(void) { }
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+static inline void cpa_inc_4k_checked(void) { }
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+static inline void cpa_inc_4k_install(void) { }
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+static inline void cpa_inc_lp_sameprot(int level) { }
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+static inline void cpa_inc_lp_preserved(int level) { }
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+#endif
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+
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+
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static inline int
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within(unsigned long addr, unsigned long start, unsigned long end)
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{
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@@ -664,10 +753,12 @@ static int __should_split_large_page(pte_t *kpte, unsigned long address,
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case PG_LEVEL_2M:
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old_prot = pmd_pgprot(*(pmd_t *)kpte);
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old_pfn = pmd_pfn(*(pmd_t *)kpte);
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+ cpa_inc_2m_checked();
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break;
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case PG_LEVEL_1G:
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old_prot = pud_pgprot(*(pud_t *)kpte);
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old_pfn = pud_pfn(*(pud_t *)kpte);
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+ cpa_inc_1g_checked();
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break;
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default:
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return -EINVAL;
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@@ -732,14 +823,16 @@ static int __should_split_large_page(pte_t *kpte, unsigned long address,
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for (i = 0, addr = lpaddr; i < numpages; i++, addr += PAGE_SIZE, pfn++) {
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pgprot_t chk_prot = static_protections(req_prot, addr, pfn, 1,
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CPA_DETECT);
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-
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+ cpa_inc_4k_checked();
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if (pgprot_val(chk_prot) != pgprot_val(new_prot))
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return 1;
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}
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/* If there are no changes, return. */
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- if (pgprot_val(new_prot) == pgprot_val(old_prot))
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+ if (pgprot_val(new_prot) == pgprot_val(old_prot)) {
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+ cpa_inc_lp_sameprot(level);
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return 0;
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+ }
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/*
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* Verify that the address is aligned and the number of pages
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@@ -752,6 +845,7 @@ static int __should_split_large_page(pte_t *kpte, unsigned long address,
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new_pte = pfn_pte(old_pfn, new_prot);
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__set_pmd_pte(kpte, address, new_pte);
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cpa->flags |= CPA_FLUSHTLB;
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+ cpa_inc_lp_preserved(level);
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return 0;
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}
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@@ -1341,6 +1435,7 @@ static int __change_page_attr(struct cpa_data *cpa, int primary)
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pgprot_val(new_prot) &= ~pgprot_val(cpa->mask_clr);
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pgprot_val(new_prot) |= pgprot_val(cpa->mask_set);
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+ cpa_inc_4k_install();
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new_prot = static_protections(new_prot, address, pfn, 1,
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CPA_PROTECT);
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--
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2.19.1
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