[Qemu-devel] [QUESTION]stuck in SeaBIOS because of losing a SMI

[Xulei (Stone)]

Hi, all:
Recently I use a shell script to continuously reset a vm to see what may happen.
After one day, the vm is stuck. Looking from the following seabios log and
kvm trace log, it seems like losing a SMI or SeaBIOS can not handle a SMI.
This problem is reproducible on my machine (SeaBIOS 1.9.1, Qemu 2.6.0,
Kmod 4.4.11).

==================my shell script===
#!/bin/bash
while((1))
do
virsh reset VMNAME
sleep 1
done

==================kvm trace log===
CPU 0/KVM-13843 [020] d... 1025056.813494: kvm_entry: vcpu 0
CPU 0/KVM-13843 [020] .... 1025056.813495: kvm_exit: reason IO_INSTRUCTION rip 
0xef10e info b30048 0
CPU 0/KVM-13843 [020] .... 1025056.813495: kvm_emulate_insn: 0:ef10e:e4 b3 
(prot32)
CPU 0/KVM-13843 [020] .... 1025056.813496: kvm_userspace_exit: reason 
KVM_EXIT_IO (2)
CPU 0/KVM-13843 [020] .... 1025056.813496: kvm_fpu: unload
CPU 0/KVM-13843 [020] .... 1025056.813497: kvm_pio: pio_read at 0xb3 size 1 
count 1 val 0x1
CPU 0/KVM-13843 [020] .... 1025056.813497: kvm_fpu: load
CPU 0/KVM-13843 [020] d... 1025056.813497: kvm_entry: vcpu 0
CPU 0/KVM-13843 [020] .... 1025056.813498: kvm_exit: reason IO_INSTRUCTION rip 
0xef10e info b30048 0
CPU 0/KVM-13843 [020] .... 1025056.813498: kvm_emulate_insn: 0:ef10e:e4 b3 
(prot32)
CPU 0/KVM-13843 [020] .... 1025056.813499: kvm_userspace_exit: reason 
KVM_EXIT_IO (2)
CPU 0/KVM-13843 [020] .... 1025056.813499: kvm_fpu: unload
CPU 0/KVM-13843 [020] .... 1025056.813500: kvm_pio: pio_read at 0xb3 size 1 
count 1 val 0x1
CPU 0/KVM-13843 [020] .... 1025056.813500: kvm_fpu: load

==================my seabios log===
--- a/roms/seabios/src/fw/smm.c
+++ b/roms/seabios/src/fw/smm.c
@@ -65,7 +65,8 @@ handle_smi(u16 cs)
     u8 cmd = inb(PORT_SMI_CMD);
     struct smm_layout *smm = MAKE_FLATPTR(cs, 0);
     u32 rev = smm->cpu.i32.smm_rev & SMM_REV_MASK;
-    dprintf(DEBUG_HDL_smi, "handle_smi cmd=%x smbase=%p\n", cmd, smm);
+    if(cmd == 0x00) {
+       dprintf(1, "handle_smi cmd=%x smbase=%p\n", cmd, smm);
+    }
 
     if (smm == (void*)BUILD_SMM_INIT_ADDR) {
         // relocate SMBASE to 0xa0000
@@ -147,14 +148,14 @@ smm_relocate_and_restore(void)
 {
     /* init APM status port */
     outb(0x01, PORT_SMI_STATUS);
+   dprintf(1,"before SMI====\n");

     /* raise an SMI interrupt */
     outb(0x00, PORT_SMI_CMD);
+    dprintf(1,"after SMI=====\n");

     /* wait until SMM code executed */
     while (inb(PORT_SMI_STATUS) != 0x00)
         ;
+   dprintf(1,"smm code executes complete====\n");

And the log output like this:
2016-08-03 16:23:15PCI: Using 00:02.0 for primary VGA
2016-08-03 16:23:15smm_device_setup start
2016-08-03 16:23:15init smm
2016-08-03 16:23:15before SMI====
2016-08-03 16:23:15after SMI=====     <----always stuck here, unless i destroy 
it

As above, it is obviously that if bios doesn't handle_smi, PORT_SMI_STATUS is
always 0x01. smm_relocate_and_restore() will always in the while loop.

Why does bios handle_smi at this point, is this a kvm bug? or SeaBIOS bug?

--------------
Xulei (Stone)