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Re: [PATCH v2] x86/paravirt: merge activate_mm and dup_mmap callbacks



On 2/6/23 11:59 PM, Juergen Gross wrote:
> The two paravirt callbacks .mmu.activate_mm and .mmu.dup_mmap are
> sharing the same implementations in all cases: for Xen PV guests they
> are pinning the PGD of the new mm_struct, and for all other cases
> they are a NOP.
> 
> In the end both callbacks are meant to register an address space with
> the underlying hypervisor, so there needs to be only a single callback
> for that purpose.
> 
> So merge them to a common callback .mmu.enter_mmap (in contrast to the
> corresponding already existing .mmu.exit_mmap).
> 
> As the first parameter of the old callbacks isn't used, drop it from
> the replacement one.
> 
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>


Reviewed-by: Srivatsa S. Bhat (VMware) <srivatsa@xxxxxxxxxxxxx>

Regards,
Srivatsa
VMware Photon OS

> ---
> V2:
> - expand commit message (Srivatsa S. Bhat)
> ---
>  arch/x86/include/asm/mmu_context.h    |  4 ++--
>  arch/x86/include/asm/paravirt.h       | 14 +++-----------
>  arch/x86/include/asm/paravirt_types.h |  7 ++-----
>  arch/x86/kernel/paravirt.c            |  3 +--
>  arch/x86/mm/init.c                    |  2 +-
>  arch/x86/xen/mmu_pv.c                 | 12 ++----------
>  6 files changed, 11 insertions(+), 31 deletions(-)
> 
> diff --git a/arch/x86/include/asm/mmu_context.h 
> b/arch/x86/include/asm/mmu_context.h
> index b8d40ddeab00..6a14b6c2165c 100644
> --- a/arch/x86/include/asm/mmu_context.h
> +++ b/arch/x86/include/asm/mmu_context.h
> @@ -134,7 +134,7 @@ extern void switch_mm_irqs_off(struct mm_struct *prev, 
> struct mm_struct *next,
>  
>  #define activate_mm(prev, next)                      \
>  do {                                         \
> -     paravirt_activate_mm((prev), (next));   \
> +     paravirt_enter_mmap(next);              \
>       switch_mm((prev), (next), NULL);        \
>  } while (0);
>  
> @@ -167,7 +167,7 @@ static inline void arch_dup_pkeys(struct mm_struct *oldmm,
>  static inline int arch_dup_mmap(struct mm_struct *oldmm, struct mm_struct 
> *mm)
>  {
>       arch_dup_pkeys(oldmm, mm);
> -     paravirt_arch_dup_mmap(oldmm, mm);
> +     paravirt_enter_mmap(mm);
>       return ldt_dup_context(oldmm, mm);
>  }
>  
> diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
> index 73e9522db7c1..07bbdceaf35a 100644
> --- a/arch/x86/include/asm/paravirt.h
> +++ b/arch/x86/include/asm/paravirt.h
> @@ -332,16 +332,9 @@ static inline void tss_update_io_bitmap(void)
>  }
>  #endif
>  
> -static inline void paravirt_activate_mm(struct mm_struct *prev,
> -                                     struct mm_struct *next)
> +static inline void paravirt_enter_mmap(struct mm_struct *next)
>  {
> -     PVOP_VCALL2(mmu.activate_mm, prev, next);
> -}
> -
> -static inline void paravirt_arch_dup_mmap(struct mm_struct *oldmm,
> -                                       struct mm_struct *mm)
> -{
> -     PVOP_VCALL2(mmu.dup_mmap, oldmm, mm);
> +     PVOP_VCALL1(mmu.enter_mmap, next);
>  }
>  
>  static inline int paravirt_pgd_alloc(struct mm_struct *mm)
> @@ -787,8 +780,7 @@ extern void default_banner(void);
>  
>  #ifndef __ASSEMBLY__
>  #ifndef CONFIG_PARAVIRT_XXL
> -static inline void paravirt_arch_dup_mmap(struct mm_struct *oldmm,
> -                                       struct mm_struct *mm)
> +static inline void paravirt_enter_mmap(struct mm_struct *mm)
>  {
>  }
>  #endif
> diff --git a/arch/x86/include/asm/paravirt_types.h 
> b/arch/x86/include/asm/paravirt_types.h
> index 8c1da419260f..71bf64b963df 100644
> --- a/arch/x86/include/asm/paravirt_types.h
> +++ b/arch/x86/include/asm/paravirt_types.h
> @@ -164,11 +164,8 @@ struct pv_mmu_ops {
>       unsigned long (*read_cr3)(void);
>       void (*write_cr3)(unsigned long);
>  
> -     /* Hooks for intercepting the creation/use of an mm_struct. */
> -     void (*activate_mm)(struct mm_struct *prev,
> -                         struct mm_struct *next);
> -     void (*dup_mmap)(struct mm_struct *oldmm,
> -                      struct mm_struct *mm);
> +     /* Hook for intercepting the creation/use of an mm_struct. */
> +     void (*enter_mmap)(struct mm_struct *mm);
>  
>       /* Hooks for allocating and freeing a pagetable top-level */
>       int  (*pgd_alloc)(struct mm_struct *mm);
> diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
> index 327757afb027..ff1109b9c6cd 100644
> --- a/arch/x86/kernel/paravirt.c
> +++ b/arch/x86/kernel/paravirt.c
> @@ -352,8 +352,7 @@ struct paravirt_patch_template pv_ops = {
>       .mmu.make_pte           = PTE_IDENT,
>       .mmu.make_pgd           = PTE_IDENT,
>  
> -     .mmu.dup_mmap           = paravirt_nop,
> -     .mmu.activate_mm        = paravirt_nop,
> +     .mmu.enter_mmap         = paravirt_nop,
>  
>       .mmu.lazy_mode = {
>               .enter          = paravirt_nop,
> diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
> index cb258f58fdc8..cbc53da4c1b4 100644
> --- a/arch/x86/mm/init.c
> +++ b/arch/x86/mm/init.c
> @@ -806,7 +806,7 @@ void __init poking_init(void)
>       BUG_ON(!poking_mm);
>  
>       /* Xen PV guests need the PGD to be pinned. */
> -     paravirt_arch_dup_mmap(NULL, poking_mm);
> +     paravirt_enter_mmap(poking_mm);
>  
>       /*
>        * Randomize the poking address, but make sure that the following page
> diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c
> index ee29fb558f2e..b3b8d289b9ab 100644
> --- a/arch/x86/xen/mmu_pv.c
> +++ b/arch/x86/xen/mmu_pv.c
> @@ -885,14 +885,7 @@ void xen_mm_unpin_all(void)
>       spin_unlock(&pgd_lock);
>  }
>  
> -static void xen_activate_mm(struct mm_struct *prev, struct mm_struct *next)
> -{
> -     spin_lock(&next->page_table_lock);
> -     xen_pgd_pin(next);
> -     spin_unlock(&next->page_table_lock);
> -}
> -
> -static void xen_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm)
> +static void xen_enter_mmap(struct mm_struct *mm)
>  {
>       spin_lock(&mm->page_table_lock);
>       xen_pgd_pin(mm);
> @@ -2153,8 +2146,7 @@ static const typeof(pv_ops) xen_mmu_ops __initconst = {
>               .make_p4d = PV_CALLEE_SAVE(xen_make_p4d),
>  #endif
>  
> -             .activate_mm = xen_activate_mm,
> -             .dup_mmap = xen_dup_mmap,
> +             .enter_mmap = xen_enter_mmap,
>               .exit_mmap = xen_exit_mmap,
>  
>               .lazy_mode = {
> 




 


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