load hpet info for HPET ACPI table from qemu

diff --git a/src/acpi.c b/src/acpi.c
index 0559443..eeecca1 100644
--- a/src/acpi.c
+++ b/src/acpi.c
@@ -469,7 +469,7 @@  build_ssdt(void)
 
 #define HPET_SIGNATURE 0x54455048 //HPET
 static void*
-build_hpet(void)
+build_hpet(struct hpet_fw_entry *e, u8 id)
 {
     struct acpi_20_hpet *hpet = malloc_high(sizeof(*hpet));
     if (!hpet) {
@@ -478,11 +478,11 @@  build_hpet(void)
     }
 
     memset(hpet, 0, sizeof(*hpet));
-    /* Note timer_block_id value must be kept in sync with value advertised by
-     * emulated hpet
-     */
-    hpet->timer_block_id = cpu_to_le32(0x8086a201);
-    hpet->addr.address = cpu_to_le32(ACPI_HPET_ADDRESS);
+    hpet->timer_block_id = cpu_to_le32(e->event_timer_block_id);
+    hpet->addr.address = cpu_to_le32(e->address);
+    hpet->min_tick = cpu_to_le32(e->min_tick);
+    hpet->hpet_number = id;
+    hpet->page_protect = e->page_prot;
     build_header((void*)hpet, HPET_SIGNATURE, sizeof(*hpet), 1);
 
     return hpet;
@@ -637,9 +637,28 @@  acpi_bios_init(void)
     ACPI_INIT_TABLE(build_fadt(bdf));
     ACPI_INIT_TABLE(build_ssdt());
     ACPI_INIT_TABLE(build_madt());
-    ACPI_INIT_TABLE(build_hpet());
     ACPI_INIT_TABLE(build_srat());
 
+    u8 hpet_id = 0;
+    u32 c =  qemu_cfg_hpet_entries();
+    struct hpet_fw_entry e;
+
+    if (c == ~0) {
+        /* qemu do not provide hpet description */
+        e.event_timer_block_id = 0x8086a201;
+        e.address = ACPI_HPET_ADDRESS;
+        e.min_tick = 0;
+        c = 1;
+    } else if (c != 0)
+        qemu_cfg_hpet_load_next(&e);
+
+    while (c--) {
+        ACPI_INIT_TABLE(build_hpet(&e, hpet_id++));
+        if (c)
+            qemu_cfg_hpet_load_next(&e);
+    }
+
+
     u16 i, external_tables = qemu_cfg_acpi_additional_tables();
 
     for(i = 0; i < external_tables; i++) {
diff --git a/src/paravirt.c b/src/paravirt.c
index 5c77b5c..13a4916 100644
--- a/src/paravirt.c
+++ b/src/paravirt.c
@@ -149,6 +149,26 @@  void* qemu_cfg_e820_load_next(void *addr)
     return addr;
 }
 
+u32 qemu_cfg_hpet_entries(void)
+{
+    u8 cnt;
+
+    if (!qemu_cfg_present)
+        return 0;
+
+    /* read valid flags */
+    qemu_cfg_read_entry(&cnt, QEMU_CFG_HPET, sizeof(cnt));
+    if (!cnt)
+        return ~0;
+    qemu_cfg_read(&cnt, sizeof(cnt));
+    return cnt;
+}
+
+void qemu_cfg_hpet_load_next(struct hpet_fw_entry *e)
+{
+    qemu_cfg_read((u8*)e, sizeof(*e));
+}
+
 struct smbios_header {
     u16 length;
     u8 type;
diff --git a/src/paravirt.h b/src/paravirt.h
index c46418f..2fd98cc 100644
--- a/src/paravirt.h
+++ b/src/paravirt.h
@@ -37,6 +37,7 @@  static inline int kvm_para_available(void)
 #define QEMU_CFG_SMBIOS_ENTRIES		(QEMU_CFG_ARCH_LOCAL + 1)
 #define QEMU_CFG_IRQ0_OVERRIDE		(QEMU_CFG_ARCH_LOCAL + 2)
 #define QEMU_CFG_E820_TABLE		(QEMU_CFG_ARCH_LOCAL + 3)
+#define QEMU_CFG_HPET			(QEMU_CFG_ARCH_LOCAL + 4)
 
 extern int qemu_cfg_present;
 
@@ -68,10 +69,20 @@  struct e820_reservation {
     u32 type;
 };
 
+struct hpet_fw_entry
+{
+    u32 event_timer_block_id;
+    u64 address;
+    u16 min_tick;
+    u8 page_prot;
+} __attribute__ ((packed));
+
 u16 qemu_cfg_first_file(QemuCfgFile *entry);
 u16 qemu_cfg_next_file(QemuCfgFile *entry);
 u32 qemu_cfg_read_file(QemuCfgFile *entry, void *dst, u32 maxlen);
 u32 qemu_cfg_e820_entries(void);
 void* qemu_cfg_e820_load_next(void *addr);
+u32 qemu_cfg_hpet_entries(void);
+void qemu_cfg_hpet_load_next(struct hpet_fw_entry *e);
 
 #endif