[PATCH v3 07/21] KVM: arm64: Convert kvm_phys_addr_ioremap() to generic page-table API

[Alexandru Elisei]

Hi Will,

The patch looks correct to me. I also had another look at the pre-order visitor
for kvm_pgtable_stage2_map, and it will not try to map the address range using a
block mapping (kvm_block_mapping_supported returns false).

One nitpick below.

On 8/25/20 10:39 AM, Will Deacon wrote:
> Convert kvm_phys_addr_ioremap() to use kvm_pgtable_stage2_map() instead
> of stage2_set_pte().
>
> Cc: Marc Zyngier <maz at kernel.org>
> Cc: Quentin Perret <qperret at google.com>
> Signed-off-by: Will Deacon <will at kernel.org>
> ---
>  arch/arm64/kvm/hyp/pgtable.c | 14 +-------------
>  arch/arm64/kvm/mmu.c         | 29 ++++++++++++-----------------
>  2 files changed, 13 insertions(+), 30 deletions(-)
>
> diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
> index 41ee8f3c0369..6f65d3841ec9 100644
> --- a/arch/arm64/kvm/hyp/pgtable.c
> +++ b/arch/arm64/kvm/hyp/pgtable.c
> @@ -439,18 +439,6 @@ struct stage2_map_data {
>  	struct kvm_mmu_memory_cache	*memcache;
>  };
>  
> -static kvm_pte_t *stage2_memcache_alloc_page(struct stage2_map_data *data)
> -{
> -	kvm_pte_t *ptep = NULL;
> -	struct kvm_mmu_memory_cache *mc = data->memcache;
> -
> -	/* Allocated with GFP_PGTABLE_USER, so no need to zero */
> -	if (mc && mc->nobjs)
> -		ptep = mc->objects[--mc->nobjs];
> -
> -	return ptep;
> -}
> -
>  static int stage2_map_set_prot_attr(enum kvm_pgtable_prot prot,
>  				    struct stage2_map_data *data)
>  {
> @@ -531,7 +519,7 @@ static int stage2_map_walk_leaf(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
>  	if (WARN_ON(level == KVM_PGTABLE_MAX_LEVELS - 1))
>  		return -EINVAL;
>  
> -	childp = stage2_memcache_alloc_page(data);
> +	childp = kvm_mmu_memory_cache_alloc(data->memcache);

I think this hunk and the above could have been squashed in the previous patch, I
think we could have used kvm_mmu_memory_cache_alloc directly from the start.

Thanks,

Alex

>  	if (!childp)
>  		return -ENOMEM;
>  
> diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> index 4607e9ca60a2..33146d3dc93a 100644
> --- a/arch/arm64/kvm/mmu.c
> +++ b/arch/arm64/kvm/mmu.c
> @@ -1154,35 +1154,30 @@ static int stage2_pudp_test_and_clear_young(pud_t *pud)
>  int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
>  			  phys_addr_t pa, unsigned long size, bool writable)
>  {
> -	phys_addr_t addr, end;
> +	phys_addr_t addr;
>  	int ret = 0;
> -	unsigned long pfn;
>  	struct kvm_mmu_memory_cache cache = { 0, __GFP_ZERO, NULL, };
> +	struct kvm_pgtable *pgt = kvm->arch.mmu.pgt;
> +	enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_DEVICE |
> +				     KVM_PGTABLE_PROT_R |
> +				     (writable ? KVM_PGTABLE_PROT_W : 0);
>  
> -	end = (guest_ipa + size + PAGE_SIZE - 1) & PAGE_MASK;
> -	pfn = __phys_to_pfn(pa);
> -
> -	for (addr = guest_ipa; addr < end; addr += PAGE_SIZE) {
> -		pte_t pte = kvm_pfn_pte(pfn, PAGE_S2_DEVICE);
> -
> -		if (writable)
> -			pte = kvm_s2pte_mkwrite(pte);
> -
> +	for (addr = guest_ipa; addr < guest_ipa + size; addr += PAGE_SIZE) {
>  		ret = kvm_mmu_topup_memory_cache(&cache,
>  						 kvm_mmu_cache_min_pages(kvm));
>  		if (ret)
> -			goto out;
> +			break;
> +
>  		spin_lock(&kvm->mmu_lock);
> -		ret = stage2_set_pte(&kvm->arch.mmu, &cache, addr, &pte,
> -				     KVM_S2PTE_FLAG_IS_IOMAP);
> +		ret = kvm_pgtable_stage2_map(pgt, addr, PAGE_SIZE, pa, prot,
> +					     &cache);
>  		spin_unlock(&kvm->mmu_lock);
>  		if (ret)
> -			goto out;
> +			break;
>  
> -		pfn++;
> +		pa += PAGE_SIZE;
>  	}
>  
> -out:
>  	kvm_mmu_free_memory_cache(&cache);
>  	return ret;
>  }