Re: [PATCH 21/21] KVM: MIPS: Use common KVM implementation of MMU memory caches

[Huacai Chen]

Reviewed-by: Huacai Chen <chenhc@xxxxxxxxxx>

On Sat, Jun 6, 2020 at 5:41 AM Sean Christopherson
<sean.j.christopherson@xxxxxxxxx> wrote:
>
> Move to the common MMU memory cache implementation now that the common
> code and MIPS's existing code are semantically compatible.
>
> No functional change intended.
>
> Suggested-by: Christoffer Dall <christoffer.dall@xxxxxxx>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
> ---
>  arch/mips/include/asm/kvm_host.h  | 11 ---------
>  arch/mips/include/asm/kvm_types.h |  2 ++
>  arch/mips/kvm/mmu.c               | 40 ++++---------------------------
>  3 files changed, 7 insertions(+), 46 deletions(-)
>
> diff --git a/arch/mips/include/asm/kvm_host.h b/arch/mips/include/asm/kvm_host.h
> index 363e7a89d173..f49617175f60 100644
> --- a/arch/mips/include/asm/kvm_host.h
> +++ b/arch/mips/include/asm/kvm_host.h
> @@ -335,17 +335,6 @@ struct kvm_mips_tlb {
>         long tlb_lo[2];
>  };
>
> -#define KVM_NR_MEM_OBJS     4
> -
> -/*
> - * We don't want allocation failures within the mmu code, so we preallocate
> - * enough memory for a single page fault in a cache.
> - */
> -struct kvm_mmu_memory_cache {
> -       int nobjs;
> -       void *objects[KVM_NR_MEM_OBJS];
> -};
> -
>  #define KVM_MIPS_AUX_FPU       0x1
>  #define KVM_MIPS_AUX_MSA       0x2
>
> diff --git a/arch/mips/include/asm/kvm_types.h b/arch/mips/include/asm/kvm_types.h
> index 5efeb32a5926..213754d9ef6b 100644
> --- a/arch/mips/include/asm/kvm_types.h
> +++ b/arch/mips/include/asm/kvm_types.h
> @@ -2,4 +2,6 @@
>  #ifndef _ASM_MIPS_KVM_TYPES_H
>  #define _ASM_MIPS_KVM_TYPES_H
>
> +#define KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE     4
> +
>  #endif /* _ASM_MIPS_KVM_TYPES_H */
> diff --git a/arch/mips/kvm/mmu.c b/arch/mips/kvm/mmu.c
> index 41a4a063a730..d6acd88c0c46 100644
> --- a/arch/mips/kvm/mmu.c
> +++ b/arch/mips/kvm/mmu.c
> @@ -25,39 +25,9 @@
>  #define KVM_MMU_CACHE_MIN_PAGES 2
>  #endif
>
> -static int mmu_topup_memory_cache(struct kvm_mmu_memory_cache *cache, int min)
> -{
> -       void *page;
> -
> -       if (cache->nobjs >= min)
> -               return 0;
> -       while (cache->nobjs < ARRAY_SIZE(cache->objects)) {
> -               page = (void *)__get_free_page(GFP_KERNEL_ACCOUNT);
> -               if (!page)
> -                       return -ENOMEM;
> -               cache->objects[cache->nobjs++] = page;
> -       }
> -       return 0;
> -}
> -
> -static void mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc)
> -{
> -       while (mc->nobjs)
> -               free_page((unsigned long)mc->objects[--mc->nobjs]);
> -}
> -
> -static void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc)
> -{
> -       void *p;
> -
> -       BUG_ON(!mc || !mc->nobjs);
> -       p = mc->objects[--mc->nobjs];
> -       return p;
> -}
> -
>  void kvm_mmu_free_memory_caches(struct kvm_vcpu *vcpu)
>  {
> -       mmu_free_memory_cache(&vcpu->arch.mmu_page_cache);
> +       kvm_mmu_free_memory_cache(&vcpu->arch.mmu_page_cache);
>  }
>
>  /**
> @@ -151,7 +121,7 @@ static pte_t *kvm_mips_walk_pgd(pgd_t *pgd, struct kvm_mmu_memory_cache *cache,
>
>                 if (!cache)
>                         return NULL;
> -               new_pmd = mmu_memory_cache_alloc(cache);
> +               new_pmd = kvm_mmu_memory_cache_alloc(cache);
>                 pmd_init((unsigned long)new_pmd,
>                          (unsigned long)invalid_pte_table);
>                 pud_populate(NULL, pud, new_pmd);
> @@ -162,7 +132,7 @@ static pte_t *kvm_mips_walk_pgd(pgd_t *pgd, struct kvm_mmu_memory_cache *cache,
>
>                 if (!cache)
>                         return NULL;
> -               new_pte = mmu_memory_cache_alloc(cache);
> +               new_pte = kvm_mmu_memory_cache_alloc(cache);
>                 clear_page(new_pte);
>                 pmd_populate_kernel(NULL, pmd, new_pte);
>         }
> @@ -709,7 +679,7 @@ static int kvm_mips_map_page(struct kvm_vcpu *vcpu, unsigned long gpa,
>                 goto out;
>
>         /* We need a minimum of cached pages ready for page table creation */
> -       err = mmu_topup_memory_cache(memcache, KVM_MMU_CACHE_MIN_PAGES);
> +       err = kvm_mmu_topup_memory_cache(memcache, KVM_MMU_CACHE_MIN_PAGES);
>         if (err)
>                 goto out;
>
> @@ -793,7 +763,7 @@ static pte_t *kvm_trap_emul_pte_for_gva(struct kvm_vcpu *vcpu,
>         int ret;
>
>         /* We need a minimum of cached pages ready for page table creation */
> -       ret = mmu_topup_memory_cache(memcache, KVM_MMU_CACHE_MIN_PAGES);
> +       ret = kvm_mmu_topup_memory_cache(memcache, KVM_MMU_CACHE_MIN_PAGES);
>         if (ret)
>                 return NULL;
>
> --
> 2.26.0
>