KVM: PPC: Make the H_ENTER hcall more reliable

[mv-sheeva.git] / arch / powerpc / include / asm / kvm_book3s_64.h

diff --git a/arch/powerpc/include/asm/kvm_book3s_64.h b/arch/powerpc/include/asm/kvm_book3s_64.h
index fa3dc79af7026cfd640c0a9396e2700dcd18abc8..300ec04a8381e888551831e19a1922a442fa690e 100644 (file)
--- a/arch/powerpc/include/asm/kvm_book3s_64.h
+++ b/arch/powerpc/include/asm/kvm_book3s_64.h
@@ -43,6 +43,31 @@ static inline void svcpu_put(struct kvmppc_book3s_shadow_vcpu *svcpu)
 #define HPT_HASH_MASK  (HPT_NPTEG - 1)
 #endif
 
+/*
+ * We use a lock bit in HPTE dword 0 to synchronize updates and
+ * accesses to each HPTE, and another bit to indicate non-present
+ * HPTEs.
+ */
+#define HPTE_V_HVLOCK  0x40UL
+
+static inline long try_lock_hpte(unsigned long *hpte, unsigned long bits)
+{
+       unsigned long tmp, old;
+
+       asm volatile("  ldarx   %0,0,%2\n"
+                    "  and.    %1,%0,%3\n"
+                    "  bne     2f\n"
+                    "  ori     %0,%0,%4\n"
+                    "  stdcx.  %0,0,%2\n"
+                    "  beq+    2f\n"
+                    "  li      %1,%3\n"
+                    "2:        isync"
+                    : "=&r" (tmp), "=&r" (old)
+                    : "r" (hpte), "r" (bits), "i" (HPTE_V_HVLOCK)
+                    : "cc", "memory");
+       return old == 0;
+}
+
 static inline unsigned long compute_tlbie_rb(unsigned long v, unsigned long r,
                                             unsigned long pte_index)
 {