61 lines
2.0 KiB
Diff
61 lines
2.0 KiB
Diff
From 60fbdd9e9dc7074d4cd30ada3ba9547d5c007702 Mon Sep 17 00:00:00 2001
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From: Rik van Riel <riel@surriel.com>
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Date: Mon, 30 Dec 2024 12:53:02 -0500
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Subject: x86/mm: make MMU_GATHER_RCU_TABLE_FREE unconditional
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Currently x86 uses CONFIG_MMU_GATHER_TABLE_FREE when using
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paravirt, and not when running on bare metal.
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There is no real good reason to do things differently for
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each setup. Make them all the same.
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After this change, the synchronization between get_user_pages_fast
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and page table freeing is handled by RCU, which prevents page tables
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from being reused for other data while get_user_pages_fast is walking
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them.
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This allows us to invalidate page tables while other CPUs have
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interrupts disabled.
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Signed-off-by: Rik van Riel <riel@surriel.com>
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Suggested-by: Peter Zijlstra <peterz@infradead.org>
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---
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arch/x86/Kconfig | 2 +-
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arch/x86/kernel/paravirt.c | 7 +------
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2 files changed, 2 insertions(+), 7 deletions(-)
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--- a/arch/x86/Kconfig
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+++ b/arch/x86/Kconfig
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@@ -270,7 +270,7 @@ config X86
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select HAVE_PCI
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select HAVE_PERF_REGS
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select HAVE_PERF_USER_STACK_DUMP
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- select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
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+ select MMU_GATHER_RCU_TABLE_FREE
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select MMU_GATHER_MERGE_VMAS
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select HAVE_POSIX_CPU_TIMERS_TASK_WORK
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select HAVE_REGS_AND_STACK_ACCESS_API
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--- a/arch/x86/kernel/paravirt.c
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+++ b/arch/x86/kernel/paravirt.c
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@@ -59,11 +59,6 @@ void __init native_pv_lock_init(void)
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static_branch_enable(&virt_spin_lock_key);
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}
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-static void native_tlb_remove_table(struct mmu_gather *tlb, void *table)
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-{
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- tlb_remove_page(tlb, table);
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-}
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-
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struct static_key paravirt_steal_enabled;
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struct static_key paravirt_steal_rq_enabled;
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@@ -191,7 +186,7 @@ struct paravirt_patch_template pv_ops =
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.mmu.flush_tlb_kernel = native_flush_tlb_global,
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.mmu.flush_tlb_one_user = native_flush_tlb_one_user,
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.mmu.flush_tlb_multi = native_flush_tlb_multi,
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- .mmu.tlb_remove_table = native_tlb_remove_table,
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+ .mmu.tlb_remove_table = tlb_remove_table,
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.mmu.exit_mmap = paravirt_nop,
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.mmu.notify_page_enc_status_changed = paravirt_nop,
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