Re: [SeaBIOS] [Qemu-devel] [PATCH] SeaBios: Fix reset procedure reentrancy problem on qemu-kvm platform

[Kevin O'Connor]

On Mon, Dec 21, 2015 at 09:41:32AM +0000, Gonglei (Arei) wrote:
> When the gurb of OS is booting, then the softirq and C function send_disk_op()
> may use extra stack of SeaBIOS. If we inject a NMI, romlayout.S: irqentry_extrastack
> is invoked, and the extra stack will be used again. And the stack of first calling
> will be broken, so that the SeaBIOS stuck.
>
> You can easily reproduce the problem.
> start on guest
> reset the guest
> inject a NMI when the guest show the grub surface
> then the guest stuck

Does the SeaBIOS patch below help?  I'm not familiar with how to
"inject a NMI" - can you describe the process in more detail?

-Kevin

--- a/src/romlayout.S
+++ b/src/romlayout.S
@@ -548,7 +548,9 @@ entry_post:
         ENTRY_INTO32 _cfunc32flat_handle_post   // Normal entry point

ORG 0xe2c3
-        IRQ_ENTRY 02
+        .global entry_02
+entry_02:
+        ENTRY handle_02  // NMI handler does not switch onto extra stack

ORG 0xe3fe
         .global entry_13_official

[Qemu-devel] [PATCH] SeaBios: Fix reset procedure reentrancy problem on qemu-kvm platform

[Gonglei (Arei)]

> -----Original Message-----
> From: Kevin O'Connor [mailto:[e-mail]]
> Sent: Tuesday, December 22, 2015 2:47 AM
> To: Gonglei (Arei)
> Cc: Xulei (Stone); Paolo Bonzini; qemu-devel; [e-mail];
> Huangweidong (C); [e-mail]; Radim Krcmar
> Subject: Re: [Qemu-devel] [PATCH] SeaBios: Fix reset procedure reentrancy
> problem on qemu-kvm platform
>
> On Mon, Dec 21, 2015 at 09:41:32AM +0000, Gonglei (Arei) wrote:
> > When the gurb of OS is booting, then the softirq and C function
> > send_disk_op() may use extra stack of SeaBIOS. If we inject a NMI,
> > romlayout.S: irqentry_extrastack is invoked, and the extra stack will
> > be used again. And the stack of first calling will be broken, so that the
>
> SeaBIOS stuck.
> > You can easily reproduce the problem.
> > start on guest
> > reset the guest
> > inject a NMI when the guest show the grub surface 4. then the guest
> >
> > stuck
>
> Does the SeaBIOS patch below help?

Sorry, it doesn't work. What's worse is we cannot stop SeaBIOS stuck by
Setting "CONFIG_ENTRY_EXTRASTACK=n" after applying this patch.
> I'm not familiar with how to "inject a
> NMI" - can you describe the process in more detail?

1. Qemu Command line:

#: /home/qemu/x86_64-softmmu/qemu-system-x86_64 -enable-kvm -m 4096 -smp 8 -name suse -vnc 0.0.0.0:10 \
-device virtio-scsi-pci,id=scsi0 -drive file=/home/suse11_sp3_32_2,if=none,id=drive-scsi0-0-0-0,format=raw,cache=none,aio=native \
-device scsi-hd,bus=scsi0.0,drive=drive-scsi0-0-0-0,id=scsi0-0-0-0 \
-chardev file,id=seabios,path=/home/seabios.log -device isa-debugcon,iobase=0x402,chardev=seabios \
-monitor stdio -qmp unix:/tmp/qmp,server,nowait

2. Inject a NMI by QMP:

#: /home/qemu/scripts/qmp # ./qmp-shell /tmp/qmp
Welcome to the QMP low-level shell!
Connected to QEMU 2.5.0

(QEMU) system_reset
{"return": {}}
(QEMU) inject-nmi  
{"return": {}}
(QEMU) inject-nmi
{"return": {}}

Regards,
-Gonglei
> -Kevin
>
> --- a/src/romlayout.S
> +++ b/src/romlayout.S
> @@ -548,7 +548,9 @@ entry_post:
>          ENTRY_INTO32 _cfunc32flat_handle_post   // Normal entry point
>      ORG 0xe2c3
>    IRQ_ENTRY 02
>    .global entry_02
>
> +entry_02:
>    ENTRY handle_02  // NMI handler does not switch onto extra
>
> +stack
>      ORG 0xe3fe
>      .global entry_13_official