linux-kernel - Re: [RFC 20/33] KVM: x86/mmu: Decouple hugepage_has_attrs() from struct kvm's mem_attr

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Message-ID: <9efb185b80e88d32a5c57f10f361e144004193c3.camel@redhat.com>
Date:   Tue, 28 Nov 2023 09:43:37 +0200
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     Nicolas Saenz Julienne <nsaenz@...zon.com>, kvm@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, linux-hyperv@...r.kernel.org,
        pbonzini@...hat.com, seanjc@...gle.com, vkuznets@...hat.com,
        anelkz@...zon.com, graf@...zon.com, dwmw@...zon.co.uk,
        jgowans@...zon.com, corbert@....net, kys@...rosoft.com,
        haiyangz@...rosoft.com, decui@...rosoft.com, x86@...nel.org,
        linux-doc@...r.kernel.org
Subject: Re: [RFC 20/33] KVM: x86/mmu: Decouple hugepage_has_attrs() from
 struct kvm's mem_attr_array

On Wed, 2023-11-08 at 11:17 +0000, Nicolas Saenz Julienne wrote:
> Decouple hugepage_has_attrs() from struct kvm's mem_attr_array to
> allow other memory attribute sources to use the function.
> 
> Signed-off-by: Nicolas Saenz Julienne <nsaenz@...zon.com>
> ---
>  arch/x86/kvm/mmu/mmu.c | 18 ++++++++++--------
>  1 file changed, 10 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index 4ace2f8660b0..c0fd3afd6be5 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -7290,19 +7290,19 @@ static void hugepage_set_mixed(struct kvm_memory_slot *slot, gfn_t gfn,
>  	lpage_info_slot(gfn, slot, level)->disallow_lpage |= KVM_LPAGE_MIXED_FLAG;
>  }
>  
> -static bool hugepage_has_attrs(struct kvm *kvm, struct kvm_memory_slot *slot,
> -			       gfn_t gfn, int level, unsigned long attrs)
> +static bool hugepage_has_attrs(struct xarray *mem_attr_array,
> +			       struct kvm_memory_slot *slot, gfn_t gfn,
> +			       int level, unsigned long attrs)
>  {
>  	const unsigned long start = gfn;
>  	const unsigned long end = start + KVM_PAGES_PER_HPAGE(level);
>  
>  	if (level == PG_LEVEL_2M)
> -		return kvm_range_has_memory_attributes(&kvm->mem_attr_array,
> -						       start, end, attrs);
> +		return kvm_range_has_memory_attributes(mem_attr_array, start, end, attrs);
>  
>  	for (gfn = start; gfn < end; gfn += KVM_PAGES_PER_HPAGE(level - 1)) {
>  		if (hugepage_test_mixed(slot, gfn, level - 1) ||
> -		    attrs != kvm_get_memory_attributes(&kvm->mem_attr_array, gfn))
> +		    attrs != kvm_get_memory_attributes(mem_attr_array, gfn))
>  			return false;
>  	}
>  	return true;
> @@ -7344,7 +7344,8 @@ bool kvm_arch_post_set_memory_attributes(struct kvm *kvm,
>  			 * misaligned address regardless of memory attributes.
>  			 */
>  			if (gfn >= slot->base_gfn) {
> -				if (hugepage_has_attrs(kvm, slot, gfn, level, attrs))
> +				if (hugepage_has_attrs(&kvm->mem_attr_array,
> +						       slot, gfn, level, attrs))
>  					hugepage_clear_mixed(slot, gfn, level);
>  				else
>  					hugepage_set_mixed(slot, gfn, level);
> @@ -7366,7 +7367,8 @@ bool kvm_arch_post_set_memory_attributes(struct kvm *kvm,
>  		 */
>  		if (gfn < range->end &&
>  		    (gfn + nr_pages) <= (slot->base_gfn + slot->npages)) {
> -			if (hugepage_has_attrs(kvm, slot, gfn, level, attrs))
> +			if (hugepage_has_attrs(&kvm->mem_attr_array, slot, gfn,
> +					       level, attrs))
>  				hugepage_clear_mixed(slot, gfn, level);
>  			else
>  				hugepage_set_mixed(slot, gfn, level);
> @@ -7405,7 +7407,7 @@ void kvm_mmu_init_memslot_memory_attributes(struct kvm *kvm,
>  			unsigned long attrs =
>  				kvm_get_memory_attributes(&kvm->mem_attr_array, gfn);
>  
> -			if (hugepage_has_attrs(kvm, slot, gfn, level, attrs))
> +			if (hugepage_has_attrs(&kvm->mem_attr_array, slot, gfn, level, attrs))
>  				hugepage_clear_mixed(slot, gfn, level);
>  			else
>  				hugepage_set_mixed(slot, gfn, level);

hugepage_has_attrs is also not a name that conveys the meaning of what it does IMHO,
but I don't know a better name to be honest.

Same remarks as for other two patches apply here as well.

Best regards,
	Maxim Levitsky