KVM: Add kvm_release_page_unused() API to put pages that KVM never consumes

Add an API to release an unused page, i.e. to put a page without marking
it accessed or dirty.  The API will be used when KVM faults-in a page but
bails before installing the guest mapping (and other similar flows).

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20241010182427.1434605-4-seanjc@google.com>

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 0b280e5bad0a52ca719494f7c101edd0b21a97b2..8de9acb0b35ec921a032597bd0401ad3128c7970 100644 (file)
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1216,6 +1216,15 @@ unsigned long gfn_to_hva_prot(struct kvm *kvm, gfn_t gfn, bool *writable);
 unsigned long gfn_to_hva_memslot(struct kvm_memory_slot *slot, gfn_t gfn);
 unsigned long gfn_to_hva_memslot_prot(struct kvm_memory_slot *slot, gfn_t gfn,
                                      bool *writable);
+
+static inline void kvm_release_page_unused(struct page *page)
+{
+       if (!page)
+               return;
+
+       put_page(page);
+}
+
 void kvm_release_page_clean(struct page *page);
 void kvm_release_page_dirty(struct page *page);