i386/fw_cfg: move hpet_cfg definition to hpet.c

HPET device needs to access and update hpet_cfg variable, but now it is
defined in hw/i386/fw_cfg.c and Rust code can't access it.

Move hpet_cfg definition to hpet.c (and rename it to hpet_fw_cfg). This
allows Rust HPET device implements its own global hpet_fw_cfg variable,
and will further reduce the use of unsafe C code access and calls in the
Rust HPET implementation.

Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Link: https://lore.kernel.org/r/20250210030051.2562726-2-zhao1.liu@intel.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

3 files changed, 14 insertions, 10 deletions

diff --git a/hw/i386/fw_cfg.c b/hw/i386/fw_cfg.c
index 91bf1df..d08aefa 100644
--- a/hw/i386/fw_cfg.c
+++ b/hw/i386/fw_cfg.c
@@ -26,7 +26,9 @@
 #include CONFIG_DEVICES
 #include "target/i386/cpu.h"
 
-struct hpet_fw_config hpet_cfg = {.count = UINT8_MAX};
+#if !defined(CONFIG_HPET) && !defined(CONFIG_X_HPET_RUST)
+struct hpet_fw_config hpet_fw_cfg = {.count = UINT8_MAX};
+#endif
 
 const char *fw_cfg_arch_key_name(uint16_t key)
 {
@@ -149,7 +151,7 @@ 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));
+    fw_cfg_add_bytes(fw_cfg, FW_CFG_HPET, &hpet_fw_cfg, sizeof(hpet_fw_cfg));
     /* 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.
diff --git a/hw/timer/hpet.c b/hw/timer/hpet.c
index 1c8c6c6..dcff18a 100644
--- a/hw/timer/hpet.c
+++ b/hw/timer/hpet.c
@@ -40,6 +40,8 @@
 #include "qom/object.h"
 #include "trace.h"
 
+struct hpet_fw_config hpet_fw_cfg = {.count = UINT8_MAX};
+
 #define HPET_MSI_SUPPORT        0
 
 OBJECT_DECLARE_SIMPLE_TYPE(HPETState, HPET)
@@ -278,7 +280,7 @@ static int hpet_post_load(void *opaque, int version_id)
     /* Push number of timers into capability returned via HPET_ID */
     s->capability &= ~HPET_ID_NUM_TIM_MASK;
     s->capability |= (s->num_timers - 1) << HPET_ID_NUM_TIM_SHIFT;
-    hpet_cfg.hpet[s->hpet_id].event_timer_block_id = (uint32_t)s->capability;
+    hpet_fw_cfg.hpet[s->hpet_id].event_timer_block_id = (uint32_t)s->capability;
 
     /* Derive HPET_MSI_SUPPORT from the capability of the first timer. */
     s->flags &= ~(1 << HPET_MSI_SUPPORT);
@@ -665,8 +667,8 @@ static void hpet_reset(DeviceState *d)
     s->hpet_counter = 0ULL;
     s->hpet_offset = 0ULL;
     s->config = 0ULL;
-    hpet_cfg.hpet[s->hpet_id].event_timer_block_id = (uint32_t)s->capability;
-    hpet_cfg.hpet[s->hpet_id].address = sbd->mmio[0].addr;
+    hpet_fw_cfg.hpet[s->hpet_id].event_timer_block_id = (uint32_t)s->capability;
+    hpet_fw_cfg.hpet[s->hpet_id].address = sbd->mmio[0].addr;
 
     /* to document that the RTC lowers its output on reset as well */
     s->rtc_irq_level = 0;
@@ -708,17 +710,17 @@ static void hpet_realize(DeviceState *dev, Error **errp)
     if (!s->intcap) {
         warn_report("Hpet's intcap not initialized");
     }
-    if (hpet_cfg.count == UINT8_MAX) {
+    if (hpet_fw_cfg.count == UINT8_MAX) {
         /* first instance */
-        hpet_cfg.count = 0;
+        hpet_fw_cfg.count = 0;
     }
 
-    if (hpet_cfg.count == 8) {
+    if (hpet_fw_cfg.count == 8) {
         error_setg(errp, "Only 8 instances of HPET is allowed");
         return;
     }
 
-    s->hpet_id = hpet_cfg.count++;
+    s->hpet_id = hpet_fw_cfg.count++;
 
     for (i = 0; i < HPET_NUM_IRQ_ROUTES; i++) {
         sysbus_init_irq(sbd, &s->irqs[i]);
diff --git a/include/hw/timer/hpet.h b/include/hw/timer/hpet.h
index 71e8c62..c2656f7 100644
--- a/include/hw/timer/hpet.h
+++ b/include/hw/timer/hpet.h
@@ -73,7 +73,7 @@ struct hpet_fw_config
     struct hpet_fw_entry hpet[8];
 } QEMU_PACKED;
 
-extern struct hpet_fw_config hpet_cfg;
+extern struct hpet_fw_config hpet_fw_cfg;
 
 #define TYPE_HPET "hpet"