At present, the hpet_cfg is written unconditionally since 40ac17cd56eb
("pass info about hpets to seabios.]"), because it concerns ACPI HPET is
created unconditionally.

But that fact has changed since 51124bbfd2ea ("i386: acpi: Don't build
HPET ACPI entry if HPET is disabled") and ACPI checks if HPET device
exists in (hw/i386/acpi-build.c).

Therefore, configure HPET firmware information if and only if HPET is
enabled.

Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
---
Resend:
 * Resend the patch since it was missed on https://lore.kernel.org/qemu-devel/.
---
 hw/i386/fw_cfg.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/hw/i386/fw_cfg.c b/hw/i386/fw_cfg.c
index 91bf1df0f2e4..d2cb08715a21 100644
--- a/hw/i386/fw_cfg.c
+++ b/hw/i386/fw_cfg.c
@@ -149,7 +149,14 @@ FWCfgState *fw_cfg_arch_create(MachineState *ms,
 #endif
     fw_cfg_add_i32(fw_cfg, FW_CFG_IRQ0_OVERRIDE, 1);
 
-    fw_cfg_add_bytes(fw_cfg, FW_CFG_HPET, &hpet_cfg, sizeof(hpet_cfg));
+#ifdef CONFIG_HPET
+    PCMachineState *pcms =
+        (PCMachineState *)object_dynamic_cast(OBJECT(ms), TYPE_PC_MACHINE);
+    if (pcms && pcms->hpet_enabled) {
+        fw_cfg_add_bytes(fw_cfg, FW_CFG_HPET, &hpet_cfg, sizeof(hpet_cfg));
+    }
+#endif
+
     /* allocate memory for the NUMA channel: one (64bit) word for the number
      * of nodes, one word for each VCPU->node and one word for each node to
      * hold the amount of memory.
-- 
2.34.1