From 291b3abed657cb3c485cce7753e0913dc408cf85 Mon Sep 17 00:00:00 2001 From: Kevin Brodsky Date: Mon, 15 Dec 2025 15:03:22 +0000 Subject: [PATCH] x86/xen: use lazy_mmu_state when context-switching We currently set a TIF flag when scheduling out a task that is in lazy MMU mode, in order to restore it when the task is scheduled again. The generic lazy_mmu layer now tracks whether a task is in lazy MMU mode in task_struct::lazy_mmu_state. We can therefore check that state when switching to the new task, instead of using a separate TIF flag. Link: https://lkml.kernel.org/r/20251215150323.2218608-14-kevin.brodsky@arm.com Signed-off-by: Kevin Brodsky Acked-by: David Hildenbrand (Red Hat) Reviewed-by: Juergen Gross Reviewed-by: Yeoreum Yun Cc: Alexander Gordeev Cc: Andreas Larsson Cc: Anshuman Khandual Cc: Borislav Betkov Cc: Boris Ostrovsky Cc: Catalin Marinas Cc: Christophe Leroy Cc: David Hildenbrand Cc: David S. Miller Cc: David Woodhouse Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Jann Horn Cc: Liam Howlett Cc: Lorenzo Stoakes Cc: Madhavan Srinivasan Cc: Michael Ellerman Cc: Michal Hocko Cc: Mike Rapoport Cc: Nicholas Piggin Cc: Peter Zijlstra Cc: Ritesh Harjani (IBM) Cc: Ryan Roberts Cc: Suren Baghdasaryan Cc: Thomas Gleinxer Cc: Venkat Rao Bagalkote Cc: Vlastimil Babka Cc: Will Deacon Signed-off-by: Andrew Morton --- arch/x86/include/asm/thread_info.h | 4 +--- arch/x86/xen/enlighten_pv.c | 3 +-- 2 files changed, 2 insertions(+), 5 deletions(-) diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h index e71e0e8362ed8..0067684afb5b7 100644 --- a/arch/x86/include/asm/thread_info.h +++ b/arch/x86/include/asm/thread_info.h @@ -100,8 +100,7 @@ struct thread_info { #define TIF_FORCED_TF 24 /* true if TF in eflags artificially */ #define TIF_SINGLESTEP 25 /* reenable singlestep on user return*/ #define TIF_BLOCKSTEP 26 /* set when we want DEBUGCTLMSR_BTF */ -#define TIF_LAZY_MMU_UPDATES 27 /* task is updating the mmu lazily */ -#define TIF_ADDR32 28 /* 32-bit address space on 64 bits */ +#define TIF_ADDR32 27 /* 32-bit address space on 64 bits */ #define _TIF_SSBD BIT(TIF_SSBD) #define _TIF_SPEC_IB BIT(TIF_SPEC_IB) @@ -114,7 +113,6 @@ struct thread_info { #define _TIF_FORCED_TF BIT(TIF_FORCED_TF) #define _TIF_BLOCKSTEP BIT(TIF_BLOCKSTEP) #define _TIF_SINGLESTEP BIT(TIF_SINGLESTEP) -#define _TIF_LAZY_MMU_UPDATES BIT(TIF_LAZY_MMU_UPDATES) #define _TIF_ADDR32 BIT(TIF_ADDR32) /* flags to check in __switch_to() */ diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c index b74ff8bc7f2a8..ae52436a741f0 100644 --- a/arch/x86/xen/enlighten_pv.c +++ b/arch/x86/xen/enlighten_pv.c @@ -426,7 +426,6 @@ static void xen_start_context_switch(struct task_struct *prev) if (this_cpu_read(xen_lazy_mode) == XEN_LAZY_MMU) { arch_leave_lazy_mmu_mode(); - set_ti_thread_flag(task_thread_info(prev), TIF_LAZY_MMU_UPDATES); } enter_lazy(XEN_LAZY_CPU); } @@ -437,7 +436,7 @@ static void xen_end_context_switch(struct task_struct *next) xen_mc_flush(); leave_lazy(XEN_LAZY_CPU); - if (test_and_clear_ti_thread_flag(task_thread_info(next), TIF_LAZY_MMU_UPDATES)) + if (__task_lazy_mmu_mode_active(next)) arch_enter_lazy_mmu_mode(); } -- 2.47.3