KVM: introduce gfn_to_pfn_memslot

Which takes a memslot pointer instead of using kvm->memslots.

To be used by SRCU convertion later.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

include/linux/kvm_host.h

@@ -273,6 +273,8 @@ void kvm_set_page_dirty(struct page *page);
 void kvm_set_page_accessed(struct page *page);
 
 pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn);
+pfn_t gfn_to_pfn_memslot(struct kvm *kvm,
+			 struct kvm_memory_slot *slot, gfn_t gfn);
 void kvm_release_pfn_dirty(pfn_t);
 void kvm_release_pfn_clean(pfn_t pfn);
 void kvm_set_pfn_dirty(pfn_t pfn);

virt/kvm/kvm_main.c

@@ -835,21 +835,14 @@ unsigned long gfn_to_hva(struct kvm *kvm, gfn_t gfn)
 }
 EXPORT_SYMBOL_GPL(gfn_to_hva);
 
-pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn)
+static pfn_t hva_to_pfn(struct kvm *kvm, unsigned long addr)
 {
 	struct page *page[1];
-	unsigned long addr;
 	int npages;
 	pfn_t pfn;
 
 	might_sleep();
 
-	addr = gfn_to_hva(kvm, gfn);
-	if (kvm_is_error_hva(addr)) {
-		get_page(bad_page);
-		return page_to_pfn(bad_page);
-	}
-
 	npages = get_user_pages_fast(addr, 1, 1, page);
 
 	if (unlikely(npages != 1)) {
@@ -874,8 +867,32 @@ pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn)
 	return pfn;
 }
 
+pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn)
+{
+	unsigned long addr;
+
+	addr = gfn_to_hva(kvm, gfn);
+	if (kvm_is_error_hva(addr)) {
+		get_page(bad_page);
+		return page_to_pfn(bad_page);
+	}
+
+	return hva_to_pfn(kvm, addr);
+}
 EXPORT_SYMBOL_GPL(gfn_to_pfn);
 
+static unsigned long gfn_to_hva_memslot(struct kvm_memory_slot *slot, gfn_t gfn)
+{
+	return (slot->userspace_addr + (gfn - slot->base_gfn) * PAGE_SIZE);
+}
+
+pfn_t gfn_to_pfn_memslot(struct kvm *kvm,
+			 struct kvm_memory_slot *slot, gfn_t gfn)
+{
+	unsigned long addr = gfn_to_hva_memslot(slot, gfn);
+	return hva_to_pfn(kvm, addr);
+}
+
 struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn)
 {
 	pfn_t pfn;