Re: [PATCH 4/5] x86: pgtable: unconditionally use tlb_remove_table()

[Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>]

On 2025/1/24 19:38, Peter Zijlstra wrote:
> On Thu, Jan 23, 2025 at 09:26:17PM +0800, Qi Zheng wrote:
> > If the CONFIG_MMU_GATHER_TABLE_FREE is disabled, the tlb_remove_table()
> > will fall back to pagetable_dtor() + tlb_remove_page(). So let's use
> > tlb_remove_table() unconditionally to free page table pages.
> >
> > Signed-off-by: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
> > Suggested-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
>
> I think we can clean up more :-)

Yes, but Rik van Riel has already done the same thing in his patch 
series [1], so I was originally planning to wait for his patch to be
merged into the linux-next branch, and then rebase this series onto his
patch.

[1]. https://lore.kernel.org/lkml/20250120024104.1924753-1-riel@xxxxxxxxxxx/

Thanks!

> diff --git a/arch/x86/hyperv/mmu.c b/arch/x86/hyperv/mmu.c
> index cc8c3bd0e7c2..1f7c3082a36d 100644
> --- a/arch/x86/hyperv/mmu.c
> +++ b/arch/x86/hyperv/mmu.c
> @@ -239,5 +239,4 @@ void hyperv_setup_mmu_ops(void)
>   
>   	pr_info("Using hypercall for remote TLB flush\n");
>   	pv_ops.mmu.flush_tlb_multi = hyperv_flush_tlb_multi;
> -	pv_ops.mmu.tlb_remove_table = tlb_remove_table;
>   }
> diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
> index 041aff51eb50..38a632a282d4 100644
> --- a/arch/x86/include/asm/paravirt.h
> +++ b/arch/x86/include/asm/paravirt.h
> @@ -91,11 +91,6 @@ static inline void __flush_tlb_multi(const struct cpumask *cpumask,
>   	PVOP_VCALL2(mmu.flush_tlb_multi, cpumask, info);
>   }
>   
> -static inline void paravirt_tlb_remove_table(struct mmu_gather *tlb, void *table)
> -{
> -	PVOP_VCALL2(mmu.tlb_remove_table, tlb, table);
> -}
> -
>   static inline void paravirt_arch_exit_mmap(struct mm_struct *mm)
>   {
>   	PVOP_VCALL1(mmu.exit_mmap, mm);
> diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
> index fea56b04f436..e26633c00455 100644
> --- a/arch/x86/include/asm/paravirt_types.h
> +++ b/arch/x86/include/asm/paravirt_types.h
> @@ -134,8 +134,6 @@ struct pv_mmu_ops {
>   	void (*flush_tlb_multi)(const struct cpumask *cpus,
>   				const struct flush_tlb_info *info);
>   
> -	void (*tlb_remove_table)(struct mmu_gather *tlb, void *table);
> -
>   	/* Hook for intercepting the destruction of an mm_struct. */
>   	void (*exit_mmap)(struct mm_struct *mm);
>   	void (*notify_page_enc_status_changed)(unsigned long pfn, int npages, bool enc);
> diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
> index 7a422a6c5983..3be9b3342c67 100644
> --- a/arch/x86/kernel/kvm.c
> +++ b/arch/x86/kernel/kvm.c
> @@ -838,7 +838,6 @@ static void __init kvm_guest_init(void)
>   #ifdef CONFIG_SMP
>   	if (pv_tlb_flush_supported()) {
>   		pv_ops.mmu.flush_tlb_multi = kvm_flush_tlb_multi;
> -		pv_ops.mmu.tlb_remove_table = tlb_remove_table;
>   		pr_info("KVM setup pv remote TLB flush\n");
>   	}
>   
> diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
> index 527f5605aa3e..2aa251d0b308 100644
> --- a/arch/x86/kernel/paravirt.c
> +++ b/arch/x86/kernel/paravirt.c
> @@ -180,7 +180,6 @@ 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	= 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 3bc8ad282b27..b1c1f72c1fd1 100644
> --- a/arch/x86/mm/pgtable.c
> +++ b/arch/x86/mm/pgtable.c
> @@ -18,14 +18,6 @@ EXPORT_SYMBOL(physical_mask);
>   #define PGTABLE_HIGHMEM 0
>   #endif
>   
> -#ifndef CONFIG_PARAVIRT
> -static inline
> -void paravirt_tlb_remove_table(struct mmu_gather *tlb, void *table)
> -{
> -	tlb_remove_table(tlb, table);
> -}
> -#endif /* !CONFIG_PARAVIRT */
> -
>   gfp_t __userpte_alloc_gfp = GFP_PGTABLE_USER | PGTABLE_HIGHMEM;
>   
>   pgtable_t pte_alloc_one(struct mm_struct *mm)
> @@ -53,7 +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
> @@ -67,21 +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 */
> diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c
> index 2c70cd35e72c..a0b371557125 100644
> --- a/arch/x86/xen/mmu_pv.c
> +++ b/arch/x86/xen/mmu_pv.c
> @@ -2141,7 +2141,6 @@ static const typeof(pv_ops) xen_mmu_ops __initconst = {
>   		.flush_tlb_kernel = xen_flush_tlb,
>   		.flush_tlb_one_user = xen_flush_tlb_one_user,
>   		.flush_tlb_multi = xen_flush_tlb_multi,
> -		.tlb_remove_table = tlb_remove_table,
>   
>   		.pgd_alloc = xen_pgd_alloc,
>   		.pgd_free = xen_pgd_free,