From: Rik van Riel riel@surriel.com
[ Upstream commit a37259732a7dc33047fa1e4f9a338088f452e017 ]
Currently x86 uses CONFIG_MMU_GATHER_TABLE_FREE when using paravirt, and not when running on bare metal.
There is no real good reason to do things differently for each setup. Make them all the same.
Currently get_user_pages_fast synchronizes against page table freeing in two different ways:
- on bare metal, by blocking IRQs, which block TLB flush IPIs - on paravirt, with MMU_GATHER_RCU_TABLE_FREE
This is done because some paravirt TLB flush implementations handle the TLB flush in the hypervisor, and will do the flush even when the target CPU has interrupts disabled.
Always handle page table freeing with MMU_GATHER_RCU_TABLE_FREE. Using RCU synchronization between page table freeing and get_user_pages_fast() allows bare metal to also do TLB flushing while interrupts are disabled.
Various places in the mm do still block IRQs or disable preemption as an implicit way to block RCU frees.
That makes it safe to use INVLPGB on AMD CPUs.
Suggested-by: Peter Zijlstra peterz@infradead.org Signed-off-by: Rik van Riel riel@surriel.com Signed-off-by: Ingo Molnar mingo@kernel.org Tested-by: Manali Shukla Manali.Shukla@amd.com Tested-by: Brendan Jackman jackmanb@google.com Tested-by: Michael Kelley mhklinux@outlook.com Link: https://lore.kernel.org/r/20250213161423.449435-2-riel@surriel.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/Kconfig | 2 +- arch/x86/kernel/paravirt.c | 17 +---------------- arch/x86/mm/pgtable.c | 27 ++++----------------------- 3 files changed, 6 insertions(+), 40 deletions(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index aeb95b6e55369..088f7555e1ac0 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -277,7 +277,7 @@ config X86 select HAVE_PCI select HAVE_PERF_REGS select HAVE_PERF_USER_STACK_DUMP - select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT + select MMU_GATHER_RCU_TABLE_FREE select MMU_GATHER_MERGE_VMAS select HAVE_POSIX_CPU_TIMERS_TASK_WORK select HAVE_REGS_AND_STACK_ACCESS_API diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c index c5bb980b8a673..6669d251c4f75 100644 --- a/arch/x86/kernel/paravirt.c +++ b/arch/x86/kernel/paravirt.c @@ -59,21 +59,6 @@ void __init native_pv_lock_init(void) static_branch_enable(&virt_spin_lock_key); }
-#ifndef CONFIG_PT_RECLAIM -static void native_tlb_remove_table(struct mmu_gather *tlb, void *table) -{ - struct ptdesc *ptdesc = (struct ptdesc *)table; - - pagetable_dtor(ptdesc); - tlb_remove_page(tlb, ptdesc_page(ptdesc)); -} -#else -static void native_tlb_remove_table(struct mmu_gather *tlb, void *table) -{ - tlb_remove_table(tlb, table); -} -#endif - struct static_key paravirt_steal_enabled; struct static_key paravirt_steal_rq_enabled;
@@ -197,7 +182,7 @@ struct paravirt_patch_template pv_ops = { .mmu.flush_tlb_kernel = native_flush_tlb_global, .mmu.flush_tlb_one_user = native_flush_tlb_one_user, .mmu.flush_tlb_multi = native_flush_tlb_multi, - .mmu.tlb_remove_table = native_tlb_remove_table, + .mmu.tlb_remove_table = tlb_remove_table,
.mmu.exit_mmap = paravirt_nop, .mmu.notify_page_enc_status_changed = paravirt_nop, diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c index 9b0ee41b545c7..1ddbd799acdf5 100644 --- a/arch/x86/mm/pgtable.c +++ b/arch/x86/mm/pgtable.c @@ -18,25 +18,6 @@ EXPORT_SYMBOL(physical_mask); #define PGTABLE_HIGHMEM 0 #endif
-#ifndef CONFIG_PARAVIRT -#ifndef CONFIG_PT_RECLAIM -static inline -void paravirt_tlb_remove_table(struct mmu_gather *tlb, void *table) -{ - struct ptdesc *ptdesc = (struct ptdesc *)table; - - pagetable_dtor(ptdesc); - tlb_remove_page(tlb, ptdesc_page(ptdesc)); -} -#else -static inline -void paravirt_tlb_remove_table(struct mmu_gather *tlb, void *table) -{ - tlb_remove_table(tlb, table); -} -#endif /* !CONFIG_PT_RECLAIM */ -#endif /* !CONFIG_PARAVIRT */ - gfp_t __userpte_alloc_gfp = GFP_PGTABLE_USER | PGTABLE_HIGHMEM;
pgtable_t pte_alloc_one(struct mm_struct *mm) @@ -64,7 +45,7 @@ early_param("userpte", setup_userpte); void ___pte_free_tlb(struct mmu_gather *tlb, struct page *pte) { paravirt_release_pte(page_to_pfn(pte)); - paravirt_tlb_remove_table(tlb, page_ptdesc(pte)); + tlb_remove_table(tlb, page_ptdesc(pte)); }
#if CONFIG_PGTABLE_LEVELS > 2 @@ -78,21 +59,21 @@ void ___pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd) #ifdef CONFIG_X86_PAE tlb->need_flush_all = 1; #endif - paravirt_tlb_remove_table(tlb, virt_to_ptdesc(pmd)); + tlb_remove_table(tlb, virt_to_ptdesc(pmd)); }
#if CONFIG_PGTABLE_LEVELS > 3 void ___pud_free_tlb(struct mmu_gather *tlb, pud_t *pud) { paravirt_release_pud(__pa(pud) >> PAGE_SHIFT); - paravirt_tlb_remove_table(tlb, virt_to_ptdesc(pud)); + tlb_remove_table(tlb, virt_to_ptdesc(pud)); }
#if CONFIG_PGTABLE_LEVELS > 4 void ___p4d_free_tlb(struct mmu_gather *tlb, p4d_t *p4d) { paravirt_release_p4d(__pa(p4d) >> PAGE_SHIFT); - paravirt_tlb_remove_table(tlb, virt_to_ptdesc(p4d)); + tlb_remove_table(tlb, virt_to_ptdesc(p4d)); } #endif /* CONFIG_PGTABLE_LEVELS > 4 */ #endif /* CONFIG_PGTABLE_LEVELS > 3 */