Re: [PATCH V2] KVM: ARM: Remove pgtable page standard functions from stage-2 page tables

[Yu Zhao <yuzhao@google.com>]

On Mon, Apr 01, 2019 at 05:16:38PM +0100, Will Deacon wrote:
> [+KVM/ARM folks, since I can't take this without an Ack in place from them]
> 
> My understanding is that this patch is intended to replace patch 3/4 in
> this series:
> 
> http://lists.infradead.org/pipermail/linux-arm-kernel/2019-March/638083.html

Yes, and sorry for the confusion. I could send an updated series once
this patch is merged. Thanks.

> On Tue, Mar 12, 2019 at 06:55:45PM +0530, Anshuman Khandual wrote:
> > ARM64 standard pgtable functions are going to use pgtable_page_[ctor|dtor]
> > or pgtable_pmd_page_[ctor|dtor] constructs. At present KVM guest stage-2
> > PUD|PMD|PTE level page tabe pages are allocated with __get_free_page()
> > via mmu_memory_cache_alloc() but released with standard pud|pmd_free() or
> > pte_free_kernel(). These will fail once they start calling into pgtable_
> > [pmd]_page_dtor() for pages which never originally went through respective
> > constructor functions. Hence convert all stage-2 page table page release
> > functions to call buddy directly while freeing pages.
> > 
> > Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> > Acked-by: Yu Zhao <yuzhao@google.com>
> > Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
> > ---
> > Changes in V2:
> > 
> > - Updated stage2_pud_free() with NOP as per Suzuki
> > - s/__free_page/free_page/ in clear_stage2_pmd_entry() for uniformity
> > 
> >  arch/arm/include/asm/stage2_pgtable.h   | 4 ++--
> >  arch/arm64/include/asm/stage2_pgtable.h | 4 ++--
> >  virt/kvm/arm/mmu.c                      | 2 +-
> >  3 files changed, 5 insertions(+), 5 deletions(-)
> > 
> > diff --git a/arch/arm/include/asm/stage2_pgtable.h b/arch/arm/include/asm/stage2_pgtable.h
> > index de2089501b8b..fed02c3b4600 100644
> > --- a/arch/arm/include/asm/stage2_pgtable.h
> > +++ b/arch/arm/include/asm/stage2_pgtable.h
> > @@ -32,14 +32,14 @@
> >  #define stage2_pgd_present(kvm, pgd)		pgd_present(pgd)
> >  #define stage2_pgd_populate(kvm, pgd, pud)	pgd_populate(NULL, pgd, pud)
> >  #define stage2_pud_offset(kvm, pgd, address)	pud_offset(pgd, address)
> > -#define stage2_pud_free(kvm, pud)		pud_free(NULL, pud)
> > +#define stage2_pud_free(kvm, pud)		do { } while (0)
> >  
> >  #define stage2_pud_none(kvm, pud)		pud_none(pud)
> >  #define stage2_pud_clear(kvm, pud)		pud_clear(pud)
> >  #define stage2_pud_present(kvm, pud)		pud_present(pud)
> >  #define stage2_pud_populate(kvm, pud, pmd)	pud_populate(NULL, pud, pmd)
> >  #define stage2_pmd_offset(kvm, pud, address)	pmd_offset(pud, address)
> > -#define stage2_pmd_free(kvm, pmd)		pmd_free(NULL, pmd)
> > +#define stage2_pmd_free(kvm, pmd)		free_page((unsigned long)pmd)
> >  
> >  #define stage2_pud_huge(kvm, pud)		pud_huge(pud)
> >  
> > diff --git a/arch/arm64/include/asm/stage2_pgtable.h b/arch/arm64/include/asm/stage2_pgtable.h
> > index 5412fa40825e..915809e4ac32 100644
> > --- a/arch/arm64/include/asm/stage2_pgtable.h
> > +++ b/arch/arm64/include/asm/stage2_pgtable.h
> > @@ -119,7 +119,7 @@ static inline pud_t *stage2_pud_offset(struct kvm *kvm,
> >  static inline void stage2_pud_free(struct kvm *kvm, pud_t *pud)
> >  {
> >  	if (kvm_stage2_has_pud(kvm))
> > -		pud_free(NULL, pud);
> > +		free_page((unsigned long)pud);
> >  }
> >  
> >  static inline bool stage2_pud_table_empty(struct kvm *kvm, pud_t *pudp)
> > @@ -192,7 +192,7 @@ static inline pmd_t *stage2_pmd_offset(struct kvm *kvm,
> >  static inline void stage2_pmd_free(struct kvm *kvm, pmd_t *pmd)
> >  {
> >  	if (kvm_stage2_has_pmd(kvm))
> > -		pmd_free(NULL, pmd);
> > +		free_page((unsigned long)pmd);
> >  }
> >  
> >  static inline bool stage2_pud_huge(struct kvm *kvm, pud_t pud)
> > diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
> > index e9d28a7ca673..cbfbdadca8a5 100644
> > --- a/virt/kvm/arm/mmu.c
> > +++ b/virt/kvm/arm/mmu.c
> > @@ -191,7 +191,7 @@ static void clear_stage2_pmd_entry(struct kvm *kvm, pmd_t *pmd, phys_addr_t addr
> >  	VM_BUG_ON(pmd_thp_or_huge(*pmd));
> >  	pmd_clear(pmd);
> >  	kvm_tlb_flush_vmid_ipa(kvm, addr);
> > -	pte_free_kernel(NULL, pte_table);
> > +	free_page((unsigned long)pte_table);
> >  	put_page(virt_to_page(pmd));
> >  }
> >  
> > -- 
> > 2.20.1
> >