linux-kernel - Re: [PATCH 1/3] KVM: only retrieve memslots once when initializing cache

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Date:   Thu, 16 Feb 2017 17:31:29 +0100
From:   Radim Krčmář <rkrcmar@...hat.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: Re: [PATCH 1/3] KVM: only retrieve memslots once when initializing
 cache

2017-02-15 23:00+0100, Paolo Bonzini:
> This will make it a bit simpler to handle multiple address spaces
> in gfn_to_hva_cache.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
> ---

Reviewed-by: Radim Krčmář <rkrcmar@...hat.com>

>  virt/kvm/kvm_main.c | 21 ++++++++++++++-------
>  1 file changed, 14 insertions(+), 7 deletions(-)
> 
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 482612b4e496..e21bac7ed5d3 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -1937,10 +1937,10 @@ int kvm_vcpu_write_guest(struct kvm_vcpu *vcpu, gpa_t gpa, const void *data,
>  }
>  EXPORT_SYMBOL_GPL(kvm_vcpu_write_guest);
>  
> -int kvm_gfn_to_hva_cache_init(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
> -			      gpa_t gpa, unsigned long len)
> +static int __kvm_gfn_to_hva_cache_init(struct kvm_memslots *slots,
> +				       struct gfn_to_hva_cache *ghc,
> +				       gpa_t gpa, unsigned long len)
>  {
> -	struct kvm_memslots *slots = kvm_memslots(kvm);
>  	int offset = offset_in_page(gpa);
>  	gfn_t start_gfn = gpa >> PAGE_SHIFT;
>  	gfn_t end_gfn = (gpa + len - 1) >> PAGE_SHIFT;
> @@ -1950,7 +1950,7 @@ int kvm_gfn_to_hva_cache_init(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
>  	ghc->gpa = gpa;
>  	ghc->generation = slots->generation;
>  	ghc->len = len;
> -	ghc->memslot = gfn_to_memslot(kvm, start_gfn);
> +	ghc->memslot = __gfn_to_memslot(slots, start_gfn);
>  	ghc->hva = gfn_to_hva_many(ghc->memslot, start_gfn, NULL);
>  	if (!kvm_is_error_hva(ghc->hva) && nr_pages_needed <= 1) {
>  		ghc->hva += offset;
> @@ -1960,7 +1960,7 @@ int kvm_gfn_to_hva_cache_init(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
>  		 * verify that the entire region is valid here.
>  		 */
>  		while (start_gfn <= end_gfn) {
> -			ghc->memslot = gfn_to_memslot(kvm, start_gfn);
> +			ghc->memslot = __gfn_to_memslot(slots, start_gfn);
>  			ghc->hva = gfn_to_hva_many(ghc->memslot, start_gfn,
>  						   &nr_pages_avail);
>  			if (kvm_is_error_hva(ghc->hva))
> @@ -1972,6 +1972,13 @@ int kvm_gfn_to_hva_cache_init(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
>  	}
>  	return 0;
>  }
> +
> +int kvm_gfn_to_hva_cache_init(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
> +			      gpa_t gpa, unsigned long len)
> +{
> +	struct kvm_memslots *slots = kvm_memslots(kvm);
> +	return __kvm_gfn_to_hva_cache_init(slots, ghc, gpa, len);
> +}
>  EXPORT_SYMBOL_GPL(kvm_gfn_to_hva_cache_init);
>  
>  int kvm_write_guest_offset_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
> @@ -1984,7 +1991,7 @@ int kvm_write_guest_offset_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
>  	BUG_ON(len + offset > ghc->len);
>  
>  	if (slots->generation != ghc->generation)
> -		kvm_gfn_to_hva_cache_init(kvm, ghc, ghc->gpa, ghc->len);
> +		__kvm_gfn_to_hva_cache_init(slots, ghc, ghc->gpa, ghc->len);
>  
>  	if (unlikely(!ghc->memslot))
>  		return kvm_write_guest(kvm, gpa, data, len);
> @@ -2017,7 +2024,7 @@ int kvm_read_guest_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
>  	BUG_ON(len > ghc->len);
>  
>  	if (slots->generation != ghc->generation)
> -		kvm_gfn_to_hva_cache_init(kvm, ghc, ghc->gpa, ghc->len);
> +		__kvm_gfn_to_hva_cache_init(slots, ghc, ghc->gpa, ghc->len);
>  
>  	if (unlikely(!ghc->memslot))
>  		return kvm_read_guest(kvm, ghc->gpa, data, len);
> -- 
> 1.8.3.1
> 
>