host-utils: Add muldiv64_round_up

This will be used for converting time intervals in different base units
to host units, for the purpose of scheduling timers to emulate target
timers. Timers typically must not fire before their requested expiry
time but may fire some time afterward, so rounding up is the right way
to implement these.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Cédric Le Goater <clg@kaod.org>

include/qemu/host-utils.h

@@ -56,6 +56,11 @@ static inline uint64_t muldiv64(uint64_t a, uint32_t b, uint32_t c)
     return (__int128_t)a * b / c;
 }
 
+static inline uint64_t muldiv64_round_up(uint64_t a, uint32_t b, uint32_t c)
+{
+    return ((__int128_t)a * b + c - 1) / c;
+}
+
 static inline uint64_t divu128(uint64_t *plow, uint64_t *phigh,
                                uint64_t divisor)
 {
@@ -83,7 +88,8 @@ void mulu64(uint64_t *plow, uint64_t *phigh, uint64_t a, uint64_t b);
 uint64_t divu128(uint64_t *plow, uint64_t *phigh, uint64_t divisor);
 int64_t divs128(uint64_t *plow, int64_t *phigh, int64_t divisor);
 
-static inline uint64_t muldiv64(uint64_t a, uint32_t b, uint32_t c)
+static inline uint64_t __muldiv64(uint64_t a, uint32_t b, uint32_t c,
+                                  bool round_up)
 {
     union {
         uint64_t ll;
@@ -99,12 +105,25 @@ static inline uint64_t muldiv64(uint64_t a, uint32_t b, uint32_t c)
 
     u.ll = a;
     rl = (uint64_t)u.l.low * (uint64_t)b;
+    if (round_up) {
+        rl += c - 1;
+    }
     rh = (uint64_t)u.l.high * (uint64_t)b;
     rh += (rl >> 32);
     res.l.high = rh / c;
     res.l.low = (((rh % c) << 32) + (rl & 0xffffffff)) / c;
     return res.ll;
 }
+
+static inline uint64_t muldiv64(uint64_t a, uint32_t b, uint32_t c)
+{
+    return __muldiv64(a, b, c, false);
+}
+
+static inline uint64_t muldiv64_round_up(uint64_t a, uint32_t b, uint32_t c)
+{
+    return __muldiv64(a, b, c, true);
+}
 #endif
 
 /**