Re: [PATCH 13/17] kvm-arm: Add stage2 page table modifiers

[Christoffer Dall <christoffer.dall@linaro.org>]

On Mon, Apr 04, 2016 at 05:26:13PM +0100, Suzuki K Poulose wrote:
> Now that the hyp page table is handled by different set of
> routines, rename the original shared routines to stage2 handlers.
> Also make explicit use of the stage2 page table helpers.
> 
> unmap_range has been merged to existing unmap_stage2_range.
> 
> Cc: Marc Zyngier <marc.zyngier@arm.com>
> Cc: Christoffer Dall <christoffer.dall@linaro.org>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> ---
>  arch/arm/kvm/mmu.c |   97 ++++++++++++++++++++++++----------------------------
>  1 file changed, 44 insertions(+), 53 deletions(-)
> 
> diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
> index 2b491e5..0009a24 100644
> --- a/arch/arm/kvm/mmu.c
> +++ b/arch/arm/kvm/mmu.c
> @@ -152,26 +152,26 @@ static void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc)
>  	return p;
>  }
>  
> -static void clear_pgd_entry(struct kvm *kvm, pgd_t *pgd, phys_addr_t addr)
> +static void clear_stage2_pgd_entry(struct kvm *kvm, pgd_t *pgd, phys_addr_t addr)
>  {
> -	pud_t *pud_table __maybe_unused = pud_offset(pgd, 0);
> -	pgd_clear(pgd);
> +	pud_t *pud_table __maybe_unused = stage2_pud_offset(pgd, 0UL);
> +	stage2_pgd_clear(pgd);
>  	kvm_tlb_flush_vmid_ipa(kvm, addr);
> -	pud_free(NULL, pud_table);
> +	stage2_pud_free(NULL, pud_table);
>  	put_page(virt_to_page(pgd));
>  }
>  
> -static void clear_pud_entry(struct kvm *kvm, pud_t *pud, phys_addr_t addr)
> +static void clear_stage2_pud_entry(struct kvm *kvm, pud_t *pud, phys_addr_t addr)
>  {
> -	pmd_t *pmd_table = pmd_offset(pud, 0);
> -	VM_BUG_ON(pud_huge(*pud));
> -	pud_clear(pud);
> +	pmd_t *pmd_table __maybe_unused = stage2_pmd_offset(pud, 0);

The __maybe_unused are slightly ugly, so it may be nicer to create the
stage2_pmd_free() as static inline's if they're defined to do nothing
instead.


> +	VM_BUG_ON(stage2_pud_huge(*pud));
> +	stage2_pud_clear(pud);
>  	kvm_tlb_flush_vmid_ipa(kvm, addr);
> -	pmd_free(NULL, pmd_table);
> +	stage2_pmd_free(NULL, pmd_table);
>  	put_page(virt_to_page(pud));
>  }
>  
> -static void clear_pmd_entry(struct kvm *kvm, pmd_t *pmd, phys_addr_t addr)
> +static void clear_stage2_pmd_entry(struct kvm *kvm, pmd_t *pmd, phys_addr_t addr)
>  {
>  	pte_t *pte_table = pte_offset_kernel(pmd, 0);
>  	VM_BUG_ON(pmd_thp_or_huge(*pmd));
> @@ -201,7 +201,7 @@ static void clear_pmd_entry(struct kvm *kvm, pmd_t *pmd, phys_addr_t addr)
>   * the corresponding TLBs, we call kvm_flush_dcache_p*() to make sure
>   * the IO subsystem will never hit in the cache.
>   */
> -static void unmap_ptes(struct kvm *kvm, pmd_t *pmd,
> +static void unmap_stage2_ptes(struct kvm *kvm, pmd_t *pmd,
>  		       phys_addr_t addr, phys_addr_t end)
>  {
>  	phys_addr_t start_addr = addr;
> @@ -223,19 +223,19 @@ static void unmap_ptes(struct kvm *kvm, pmd_t *pmd,
>  		}
>  	} while (pte++, addr += PAGE_SIZE, addr != end);
>  
> -	if (kvm_pte_table_empty(kvm, start_pte))
> -		clear_pmd_entry(kvm, pmd, start_addr);
> +	if (stage2_pte_table_empty(start_pte))
> +		clear_stage2_pmd_entry(kvm, pmd, start_addr);
>  }
>  
> -static void unmap_pmds(struct kvm *kvm, pud_t *pud,
> +static void unmap_stage2_pmds(struct kvm *kvm, pud_t *pud,
>  		       phys_addr_t addr, phys_addr_t end)
>  {
>  	phys_addr_t next, start_addr = addr;
>  	pmd_t *pmd, *start_pmd;
>  
> -	start_pmd = pmd = pmd_offset(pud, addr);
> +	start_pmd = pmd = stage2_pmd_offset(pud, addr);
>  	do {
> -		next = kvm_pmd_addr_end(addr, end);
> +		next = stage2_pmd_addr_end(addr, end);
>  		if (!pmd_none(*pmd)) {
>  			if (pmd_thp_or_huge(*pmd)) {
>  				pmd_t old_pmd = *pmd;
> @@ -247,57 +247,64 @@ static void unmap_pmds(struct kvm *kvm, pud_t *pud,
>  
>  				put_page(virt_to_page(pmd));
>  			} else {
> -				unmap_ptes(kvm, pmd, addr, next);
> +				unmap_stage2_ptes(kvm, pmd, addr, next);
>  			}
>  		}
>  	} while (pmd++, addr = next, addr != end);
>  
> -	if (kvm_pmd_table_empty(kvm, start_pmd))
> -		clear_pud_entry(kvm, pud, start_addr);
> +	if (stage2_pmd_table_empty(start_pmd))
> +		clear_stage2_pud_entry(kvm, pud, start_addr);
>  }
>  
> -static void unmap_puds(struct kvm *kvm, pgd_t *pgd,
> +static void unmap_stage2_puds(struct kvm *kvm, pgd_t *pgd,
>  		       phys_addr_t addr, phys_addr_t end)
>  {
>  	phys_addr_t next, start_addr = addr;
>  	pud_t *pud, *start_pud;
>  
> -	start_pud = pud = pud_offset(pgd, addr);
> +	start_pud = pud = stage2_pud_offset(pgd, addr);
>  	do {
> -		next = kvm_pud_addr_end(addr, end);
> -		if (!pud_none(*pud)) {
> -			if (pud_huge(*pud)) {
> +		next = stage2_pud_addr_end(addr, end);
> +		if (!stage2_pud_none(*pud)) {
> +			if (stage2_pud_huge(*pud)) {
>  				pud_t old_pud = *pud;
>  
> -				pud_clear(pud);
> +				stage2_pud_clear(pud);
>  				kvm_tlb_flush_vmid_ipa(kvm, addr);
> -
>  				kvm_flush_dcache_pud(old_pud);
> -
>  				put_page(virt_to_page(pud));
>  			} else {
> -				unmap_pmds(kvm, pud, addr, next);
> +				unmap_stage2_pmds(kvm, pud, addr, next);
>  			}
>  		}
>  	} while (pud++, addr = next, addr != end);
>  
> -	if (kvm_pud_table_empty(kvm, start_pud))
> -		clear_pgd_entry(kvm, pgd, start_addr);
> +	if (stage2_pud_table_empty(start_pud))
> +		clear_stage2_pgd_entry(kvm, pgd, start_addr);
>  }
>  
> -
> -static void unmap_range(struct kvm *kvm, pgd_t *pgdp,
> -			phys_addr_t start, u64 size)
> +/**
> + * unmap_stage2_range -- Clear stage2 page table entries to unmap a range
> + * @kvm:   The VM pointer
> + * @start: The intermediate physical base address of the range to unmap
> + * @size:  The size of the area to unmap
> + *
> + * Clear a range of stage-2 mappings, lowering the various ref-counts.  Must
> + * be called while holding mmu_lock (unless for freeing the stage2 pgd before
> + * destroying the VM), otherwise another faulting VCPU may come in and mess
> + * with things behind our backs.
> + */
> +static void unmap_stage2_range(struct kvm *kvm, phys_addr_t start, u64 size)
>  {
>  	pgd_t *pgd;
>  	phys_addr_t addr = start, end = start + size;
>  	phys_addr_t next;
>  
> -	pgd = pgdp + kvm_pgd_index(addr);
> +	pgd = kvm->arch.pgd + stage2_pgd_index(addr);
>  	do {
> -		next = kvm_pgd_addr_end(addr, end);
> -		if (!pgd_none(*pgd))
> -			unmap_puds(kvm, pgd, addr, next);
> +		next = stage2_pgd_addr_end(addr, end);
> +		if (!stage2_pgd_none(*pgd))
> +			unmap_stage2_puds(kvm, pgd, addr, next);
>  	} while (pgd++, addr = next, addr != end);
>  }
>  
> @@ -811,22 +818,6 @@ int kvm_alloc_stage2_pgd(struct kvm *kvm)
>  	return 0;
>  }
>  
> -/**
> - * unmap_stage2_range -- Clear stage2 page table entries to unmap a range
> - * @kvm:   The VM pointer
> - * @start: The intermediate physical base address of the range to unmap
> - * @size:  The size of the area to unmap
> - *
> - * Clear a range of stage-2 mappings, lowering the various ref-counts.  Must
> - * be called while holding mmu_lock (unless for freeing the stage2 pgd before
> - * destroying the VM), otherwise another faulting VCPU may come in and mess
> - * with things behind our backs.
> - */
> -static void unmap_stage2_range(struct kvm *kvm, phys_addr_t start, u64 size)
> -{
> -	unmap_range(kvm, kvm->arch.pgd, start, size);
> -}
> -
>  static void stage2_unmap_memslot(struct kvm *kvm,
>  				 struct kvm_memory_slot *memslot)
>  {
> -- 
> 1.7.9.5
> 

Acked-by: Christoffer Dall <christoffer.dall@linaro.org>