On Sun, Dec 22, 2024 at 09:55:07PM -0500, Rik van Riel wrote:
> Currently x86 usse 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.
More importantly, the changes you're proposing very much rely on this.
Without TLBi IPIs nothing serializes GUP-fast vs TLBi and this RCU-ish
table free scheme is required.
> Signed-off-by: Rik van Riel <riel@xxxxxxxxxxx>
> Suggested-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> ---
> arch/x86/Kconfig | 2 +-
> arch/x86/kernel/paravirt.c | 7 +------
> 2 files changed, 2 insertions(+), 7 deletions(-)
>
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 9d7bd0ae48c4..e8743f8c9fd0 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -274,7 +274,7 @@ 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 fec381533555..2b78a6b466ed 100644
> --- a/arch/x86/kernel/paravirt.c
> +++ b/arch/x86/kernel/paravirt.c
> @@ -59,11 +59,6 @@ void __init native_pv_lock_init(void)
> static_branch_enable(&virt_spin_lock_key);
> }
>
> -static void native_tlb_remove_table(struct mmu_gather *tlb, void *table)
> -{
> - tlb_remove_page(tlb, table);
> -}
> -
> struct static_key paravirt_steal_enabled;
> struct static_key paravirt_steal_rq_enabled;
>
> @@ -191,7 +186,7 @@ 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,
> --
> 2.47.1
>
