KVM: do not treat noslot pfn as a error pfn

This patch filters noslot pfn out from error pfns based on Marcelo comment:
noslot pfn is not a error pfn

After this patch,
- is_noslot_pfn indicates that the gfn is not in slot
- is_error_pfn indicates that the gfn is in slot but the error is occurred
  when translate the gfn to pfn
- is_error_noslot_pfn indicates that the pfn either it is error pfns or it
  is noslot pfn
And is_invalid_pfn can be removed, it makes the code more clean

Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

1 files changed, 20 insertions, 8 deletions

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 82e2c783a21e..99a47627e046 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -58,28 +58,40 @@
 
 /*
  * For the normal pfn, the highest 12 bits should be zero,
- * so we can mask these bits to indicate the error.
+ * so we can mask bit 62 ~ bit 52  to indicate the error pfn,
+ * mask bit 63 to indicate the noslot pfn.
  */
-#define KVM_PFN_ERR_MASK        (0xfffULL << 52)
+#define KVM_PFN_ERR_MASK        (0x7ffULL << 52)
+#define KVM_PFN_ERR_NOSLOT_MASK (0xfffULL << 52)
+#define KVM_PFN_NOSLOT          (0x1ULL << 63)
 
 #define KVM_PFN_ERR_FAULT       (KVM_PFN_ERR_MASK)
 #define KVM_PFN_ERR_HWPOISON    (KVM_PFN_ERR_MASK + 1)
-#define KVM_PFN_ERR_BAD         (KVM_PFN_ERR_MASK + 2)
-#define KVM_PFN_ERR_RO_FAULT    (KVM_PFN_ERR_MASK + 3)
+#define KVM_PFN_ERR_RO_FAULT    (KVM_PFN_ERR_MASK + 2)
 
+/*
+ * error pfns indicate that the gfn is in slot but faild to
+ * translate it to pfn on host.
+ */
 static inline bool is_error_pfn(pfn_t pfn)
 {
         return !!(pfn & KVM_PFN_ERR_MASK);
 }
 
-static inline bool is_noslot_pfn(pfn_t pfn)
+/*
+ * error_noslot pfns indicate that the gfn can not be
+ * translated to pfn - it is not in slot or failed to
+ * translate it to pfn.
+ */
+static inline bool is_error_noslot_pfn(pfn_t pfn)
 {
-        return pfn == KVM_PFN_ERR_BAD;
+        return !!(pfn & KVM_PFN_ERR_NOSLOT_MASK);
 }
 
-static inline bool is_invalid_pfn(pfn_t pfn)
+/* noslot pfn indicates that the gfn is not in slot. */
+static inline bool is_noslot_pfn(pfn_t pfn)
 {
-        return !is_noslot_pfn(pfn) && is_error_pfn(pfn);
+        return pfn == KVM_PFN_NOSLOT;
 }
 
 #define KVM_HVA_ERR_BAD         (PAGE_OFFSET)