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    SubjectRE: [PATCH v2 02/27] KVM: x86/mmu: Factor out helper to get max mapping size of a memslot
    Date
    On Saturday, March 11, 2023 8:23 AM, Sean Christopherson wrote:
    > Extract the memslot-related logic of kvm_mmu_max_mapping_level() into a
    > new helper so that KVMGT can determine whether or not mapping a 2MiB
    > page into the guest is (dis)allowed per KVM's memslots.
    >
    > No functional change intended.
    >
    > Signed-off-by: Sean Christopherson <seanjc@google.com>
    > ---
    > arch/x86/kvm/mmu/mmu.c | 21 +++++++++++++++------
    > arch/x86/kvm/mmu/mmu_internal.h | 2 ++
    > 2 files changed, 17 insertions(+), 6 deletions(-)
    >
    > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index
    > c8ebe542c565..4685c80e441b 100644
    > --- a/arch/x86/kvm/mmu/mmu.c
    > +++ b/arch/x86/kvm/mmu/mmu.c
    > @@ -3083,20 +3083,29 @@ static int host_pfn_mapping_level(struct kvm
    > *kvm, gfn_t gfn,
    > return level;
    > }
    >
    > +int kvm_mmu_max_slot_mapping_level(const struct kvm_memory_slot *slot,
    > + gfn_t gfn, int max_level)

    It seems more common to be named "kvm_mmu_slot_max_mapping_level"
    (we have other kvm_mmu_slot_* functions defined already)


    > +{
    > + struct kvm_lpage_info *linfo;
    > +
    > + for ( ; max_level > PG_LEVEL_4K; max_level--) {
    > + linfo = lpage_info_slot(gfn, slot, max_level);
    > + if (!linfo->disallow_lpage)
    > + break;
    > + }
    > + return max_level;
    > +}
    > +
    > int kvm_mmu_max_mapping_level(struct kvm *kvm,
    > const struct kvm_memory_slot *slot, gfn_t gfn,
    > int max_level)
    > {
    > - struct kvm_lpage_info *linfo;
    > int host_level;
    >
    > max_level = min(max_level, max_huge_page_level);

    Better to also have this min(,) moved to the helper?
    E.g. if max_huge_page_level has been 4KB, no need to check into lpage_info in the helper.
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