target/riscv/kvm: fix timebase-frequency when using KVM acceleration

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>
Message-ID: <20240314061510.9800-1-yongxuan.wang@sifive.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

hw/riscv/virt.c

@@ -711,6 +711,8 @@ static void create_fdt_sockets(RISCVVirtState *s, const MemMapEntry *memmap,
 
     qemu_fdt_add_subnode(ms->fdt, "/cpus");
     qemu_fdt_setprop_cell(ms->fdt, "/cpus", "timebase-frequency",
+                          kvm_enabled() ?
+                          kvm_riscv_get_timebase_frequency(first_cpu) :
                           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);

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);

target/riscv/kvm/kvm_riscv.h

@@ -28,5 +28,6 @@ void kvm_riscv_aia_create(MachineState *machine, uint64_t group_shift,
 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);
+uint64_t kvm_riscv_get_timebase_frequency(CPUState *cs);
 
 #endif