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authorXiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>2012-08-21 11:00:49 +0800
committerAvi Kivity <avi@redhat.com>2012-08-22 15:08:55 +0300
commit12ce13fea925ab629f2281be2b9b01cf647a86cd (patch)
tree5e67a57d09c890017524017acc22c78bf8cf0548 /virt
parent2fc843117d64b31c20d36c6b625c0626c9a41a41 (diff)
downloadvexpress-lsk-12ce13fea925ab629f2281be2b9b01cf647a86cd.tar.gz
KVM: use 'writable' as a hint to map writable pfn
In current code, we always map writable pfn for the read fault, in order to support readonly memslot, we map writable pfn only if 'writable' is not NULL Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/kvm_main.c24
1 files changed, 23 insertions, 1 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index aa4a38ad9d9..c89d1b5129e 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1054,6 +1054,14 @@ static bool hva_to_pfn_fast(unsigned long addr, bool atomic, bool *async,
if (!(async || atomic))
return false;
+ /*
+ * Fast pin a writable pfn only if it is a write fault request
+ * or the caller allows to map a writable pfn for a read fault
+ * request.
+ */
+ if (!(write_fault || writable))
+ return false;
+
npages = __get_user_pages_fast(addr, 1, 1, page);
if (npages == 1) {
*pfn = page_to_pfn(page[0]);
@@ -1093,7 +1101,7 @@ static int hva_to_pfn_slow(unsigned long addr, bool *async, bool write_fault,
return npages;
/* map read fault as writable if possible */
- if (unlikely(!write_fault)) {
+ if (unlikely(!write_fault) && writable) {
struct page *wpage[1];
npages = __get_user_pages_fast(addr, 1, 1, wpage);
@@ -1109,6 +1117,20 @@ static int hva_to_pfn_slow(unsigned long addr, bool *async, bool write_fault,
return npages;
}
+/*
+ * Pin guest page in memory and return its pfn.
+ * @addr: host virtual address which maps memory to the guest
+ * @atomic: whether this function can sleep
+ * @async: whether this function need to wait IO complete if the
+ * host page is not in the memory
+ * @write_fault: whether we should get a writable host page
+ * @writable: whether it allows to map a writable host page for !@write_fault
+ *
+ * The function will map a writable host page for these two cases:
+ * 1): @write_fault = true
+ * 2): @write_fault = false && @writable, @writable will tell the caller
+ * whether the mapping is writable.
+ */
static pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async,
bool write_fault, bool *writable)
{