[PATCH v4 11/12] x86/xen: use lazy_mmu_state when context-switching
From: Kevin Brodsky <hidden>
Date: 2025-10-29 10:10:49
Also in:
linux-arm-kernel, linux-mm, lkml, sparclinux, xen-devel
Subsystem:
the rest, x86 architecture (32-bit and 64-bit), xen hypervisor x86 · Maintainers:
Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, Juergen Gross
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. Signed-off-by: Kevin Brodsky <redacted> --- 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 e71e0e8362ed..0067684afb5b 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 4806cc28d7ca..f40f5999352e 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 (next->lazy_mmu_state.active) arch_enter_lazy_mmu_mode(); }
--
2.47.0