KVM: propagate fault r/w information to gup(), allow read-only memory
As suggested by Andrea, pass r/w error code to gup(), upgrading read fault
to writable if host pte allows it.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 475a100..2803b4d 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -959,7 +959,7 @@
}
static pfn_t hva_to_pfn(struct kvm *kvm, unsigned long addr, bool atomic,
- bool *async)
+ bool *async, bool write_fault, bool *writable)
{
struct page *page[1];
int npages = 0;
@@ -968,12 +968,34 @@
/* we can do it either atomically or asynchronously, not both */
BUG_ON(atomic && async);
+ BUG_ON(!write_fault && !writable);
+
+ if (writable)
+ *writable = true;
+
if (atomic || async)
npages = __get_user_pages_fast(addr, 1, 1, page);
if (unlikely(npages != 1) && !atomic) {
might_sleep();
- npages = get_user_pages_fast(addr, 1, 1, page);
+
+ 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];
+
+ 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)) {
@@ -1011,11 +1033,12 @@
pfn_t hva_to_pfn_atomic(struct kvm *kvm, unsigned long addr)
{
- return hva_to_pfn(kvm, addr, true, NULL);
+ return hva_to_pfn(kvm, addr, true, NULL, true, NULL);
}
EXPORT_SYMBOL_GPL(hva_to_pfn_atomic);
-static pfn_t __gfn_to_pfn(struct kvm *kvm, gfn_t gfn, bool atomic, bool *async)
+static pfn_t __gfn_to_pfn(struct kvm *kvm, gfn_t gfn, bool atomic, bool *async,
+ bool write_fault, bool *writable)
{
unsigned long addr;
@@ -1028,32 +1051,40 @@
return page_to_pfn(bad_page);
}
- return hva_to_pfn(kvm, addr, atomic, async);
+ return hva_to_pfn(kvm, addr, atomic, async, write_fault, writable);
}
pfn_t gfn_to_pfn_atomic(struct kvm *kvm, gfn_t gfn)
{
- return __gfn_to_pfn(kvm, gfn, true, NULL);
+ return __gfn_to_pfn(kvm, gfn, true, NULL, true, NULL);
}
EXPORT_SYMBOL_GPL(gfn_to_pfn_atomic);
-pfn_t gfn_to_pfn_async(struct kvm *kvm, gfn_t gfn, bool *async)
+pfn_t gfn_to_pfn_async(struct kvm *kvm, gfn_t gfn, bool *async,
+ bool write_fault, bool *writable)
{
- return __gfn_to_pfn(kvm, gfn, false, async);
+ return __gfn_to_pfn(kvm, gfn, false, async, write_fault, writable);
}
EXPORT_SYMBOL_GPL(gfn_to_pfn_async);
pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn)
{
- return __gfn_to_pfn(kvm, gfn, false, NULL);
+ return __gfn_to_pfn(kvm, gfn, false, NULL, true, NULL);
}
EXPORT_SYMBOL_GPL(gfn_to_pfn);
+pfn_t gfn_to_pfn_prot(struct kvm *kvm, gfn_t gfn, bool write_fault,
+ bool *writable)
+{
+ return __gfn_to_pfn(kvm, gfn, false, NULL, write_fault, writable);
+}
+EXPORT_SYMBOL_GPL(gfn_to_pfn_prot);
+
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, false, NULL);
+ return hva_to_pfn(kvm, addr, false, NULL, true, NULL);
}
int gfn_to_page_many_atomic(struct kvm *kvm, gfn_t gfn, struct page **pages,