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KVM: Avoid pfn_to_page() and vice versa when releasing pages

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Invert the order of KVM's page/pfn release helpers so that the "inner"
helper operates on a page instead of a pfn.  As pointed out by Linus[*],
converting between struct page and a pfn isn't necessarily cheap, and
that's not even counting the overhead of is_error_noslot_pfn() and
kvm_is_reserved_pfn().  Even if the checks were dirt cheap, there's no
reason to convert from a page to a pfn and back to a page, just to mark
the page dirty/accessed or to put a reference to the page.

Opportunistically drop a stale declaration of kvm_set_page_accessed()
from kvm_host.h (there was no implementation).

No functional change intended.

[*] https://lore.kernel.org/all/CAHk-=wifQimj2d6npq-wCi5onYPjzQg4vyO4tFcPJJZr268cRw@mail.gmail.com

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220429010416.2788472-5-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson
2022-04-29 01:04:10 +00:00
committed by Paolo Bonzini
parent a1040b0d42
commit 8e1c69149f
2 changed files with 43 additions and 22 deletions
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1
include/linux/kvm_host.h
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@@ -1139,7 +1139,6 @@ unsigned long gfn_to_hva_memslot_prot(struct kvm_memory_slot *slot, gfn_t gfn,
bool *writable);
void kvm_release_page_clean(struct page *page);
void kvm_release_page_dirty(struct page *page);
void kvm_set_page_accessed(struct page *page);
kvm_pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn);
kvm_pfn_t gfn_to_pfn_prot(struct kvm *kvm, gfn_t gfn, bool write_fault,