[PATCH v2 1/5] kvm: Add gfn_to_page_no_pin() to translate gfn to page without pinning.

Tang Chen
2014-07-08T13:00:40Z

gfn_to_page() will finally call hva_to_pfn() to get the pfn, and pin the page
in memory by calling GUP functions. This function unpins the page.

Will be used by the followed patches.

Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
---
include/linux/kvm_host.h | 1 +
virt/kvm/kvm_main.c | 17 ++++++++++++++++-
2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index ec4e3bd..7c58d9d 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -541,6 +541,7 @@ int gfn_to_page_many_atomic(struct kvm *kvm, gfn_t gfn, struct page **pages,
int nr_pages);

struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn);
+struct page *gfn_to_page_no_pin(struct kvm *kvm, gfn_t gfn);
unsigned long gfn_to_hva(struct kvm *kvm, gfn_t gfn);
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);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 4b6c01b..6091849 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1371,9 +1371,24 @@ struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn)

return kvm_pfn_to_page(pfn);
}
-
EXPORT_SYMBOL_GPL(gfn_to_page);

+struct page *gfn_to_page_no_pin(struct kvm *kvm, gfn_t gfn)
+{
+ struct page *page = gfn_to_page(kvm, gfn);
+
+ /*
+ * gfn_to_page() will finally call hva_to_pfn() to get the pfn, and pin
+ * the page in memory by calling GUP functions. This function unpins
+ * the page.
+ */
+ if (!is_error_page(page))
+ put_page(page);
+
+ return page;
+}
+EXPORT_SYMBOL_GPL(gfn_to_page_no_pin);
+
void kvm_release_page_clean(struct page *page)
{
WARN_ON(is_error_page(page));
--
1.8.3.1