[PATCH 1/1] target/riscv/kvm: fix timebase-frequency when using KVM acceleration

[Yong-Xuan Wang]

The timebase-frequency of guest OS should be the same with host
machine. The timebase-frequency value in DTS should be got from
hypervisor when using KVM acceleration.

Signed-off-by: Yong-Xuan Wang <yongxuan.wang@sifive.com>
---
 hw/riscv/virt.c              | 11 +++++++++--
 target/riscv/kvm/kvm-cpu.c   |  9 +++++++++
 target/riscv/kvm/kvm_riscv.h | 13 +++++++++++++
 3 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/hw/riscv/virt.c b/hw/riscv/virt.c
index a094af97c32a..a7ed7fa13010 100644
--- a/hw/riscv/virt.c
+++ b/hw/riscv/virt.c
@@ -710,8 +710,15 @@ static void create_fdt_sockets(RISCVVirtState *s, const 
MemMapEntry *memmap,
     int socket_count = riscv_socket_count(ms);
 
     qemu_fdt_add_subnode(ms->fdt, "/cpus");
-    qemu_fdt_setprop_cell(ms->fdt, "/cpus", "timebase-frequency",
-                          RISCV_ACLINT_DEFAULT_TIMEBASE_FREQ);
+
+    if (kvm_enabled()) {
+        qemu_fdt_setprop_cell(ms->fdt, "/cpus", "timebase-frequency",
+                              kvm_riscv_get_timebase_frequency(first_cpu));
+    } else {
+        qemu_fdt_setprop_cell(ms->fdt, "/cpus", "timebase-frequency",
+                              RISCV_ACLINT_DEFAULT_TIMEBASE_FREQ);
+    }
+
     qemu_fdt_setprop_cell(ms->fdt, "/cpus", "#size-cells", 0x0);
     qemu_fdt_setprop_cell(ms->fdt, "/cpus", "#address-cells", 0x1);
     qemu_fdt_add_subnode(ms->fdt, "/cpus/cpu-map");
diff --git a/target/riscv/kvm/kvm-cpu.c b/target/riscv/kvm/kvm-cpu.c
index c7afdb1e81b7..bbb115eaa867 100644
--- a/target/riscv/kvm/kvm-cpu.c
+++ b/target/riscv/kvm/kvm-cpu.c
@@ -739,6 +739,15 @@ static void kvm_riscv_put_regs_timer(CPUState *cs)
     env->kvm_timer_dirty = false;
 }
 
+uint64_t kvm_riscv_get_timebase_frequency(CPUState *cs)
+{
+    uint64_t reg;
+
+    KVM_RISCV_GET_TIMER(cs, frequency, reg);
+
+    return reg;
+}
+
 static int kvm_riscv_get_regs_vector(CPUState *cs)
 {
     RISCVCPU *cpu = RISCV_CPU(cs);
diff --git a/target/riscv/kvm/kvm_riscv.h b/target/riscv/kvm/kvm_riscv.h
index 4bd98fddc776..130a4bde0480 100644
--- a/target/riscv/kvm/kvm_riscv.h
+++ b/target/riscv/kvm/kvm_riscv.h
@@ -29,4 +29,17 @@ void riscv_kvm_aplic_request(void *opaque, int irq, int 
level);
 int kvm_riscv_sync_mpstate_to_kvm(RISCVCPU *cpu, int state);
 void riscv_kvm_cpu_finalize_features(RISCVCPU *cpu, Error **errp);
 
+#ifdef CONFIG_KVM
+
+uint64_t kvm_riscv_get_timebase_frequency(CPUState *cs);
+
+#else
+
+static inline uint64_t kvm_riscv_get_timebase_frequency(CPUState *cs)
+{
+    g_assert_not_reached();
+}
+
+#endif
+
 #endif
-- 
2.17.1