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Subject[PATCH] kvm: allow RO page when atomic && !write_fault

Atomic-able hva_to_pfn() patches and allow-read-only-page patches
are merged almost the same time. But hva_to_pfn() does not handle
these two issues well together.

When @atomic && !@write_fault && host-is-read-only-page-mapped
the code will return fault_page, actually, it will be better
if we return the pfn of the read-only-page.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
---
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 1fa0d29..f49cfc0 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1060,31 +1060,27 @@ static pfn_t hva_to_pfn(struct kvm *kvm, unsigned long addr, bool atomic,
BUG_ON(!write_fault && !writable);

if (writable)
- *writable = true;
+ *writable = write_fault;

if (atomic || async)
- npages = __get_user_pages_fast(addr, 1, 1, page);
+ npages = __get_user_pages_fast(addr, 1, write_fault, page);

if (unlikely(npages != 1) && !atomic) {
might_sleep();
-
- if (writable)
- *writable = write_fault;
-
npages = get_user_pages_fast(addr, 1, write_fault, page);
+ }

- /* map read fault as writable if possible */
- if (unlikely(!write_fault) && npages == 1) {
- struct page *wpage[1];
+ /* map read fault as writable if possible */
+ if (unlikely(!write_fault) && npages == 1) {
+ struct page *wpage[1];

- npages = __get_user_pages_fast(addr, 1, 1, wpage);
- if (npages == 1) {
- *writable = true;
- put_page(page[0]);
- page[0] = wpage[0];
- }
- npages = 1;
+ npages = __get_user_pages_fast(addr, 1, 1, wpage);
+ if (npages == 1) {
+ *writable = true;
+ put_page(page[0]);
+ page[0] = wpage[0];
}
+ npages = 1;
}

if (unlikely(npages != 1)) {

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