savevm with hax saves wrong register state

I use qemu-i386 with IntelHaxm on Windows 10 x64 host with Windows 7 x86 guest. I run the guest till OS loads and create a snapshot with savevm, then close qemu, run it again and try to load the snapshot with loadvm. The guest crashes or freezes. I dumped registers on snapshot creation and loading (in Haxm) and found that they are different.
When returning from Haxm in hax_vcpu_hax_exec, there is no regular register read. I found hax_arch_get_registers function which reads registers from Haxm and is called from a synchronization procedure. I placed a breakpoint on it, ran qemu and found that it is hit one time during guest OS boot. Exactly these registers where saved in the snapshot.

cc'ing Colin and Yu for Hax info:

* Alex (<email address hidden>) wrote:
> Public bug reported:
> 
> I use qemu-i386 with IntelHaxm on Windows 10 x64 host with Windows 7 x86 guest. I run the guest till OS loads and create a snapshot with savevm, then close qemu, run it again and try to load the snapshot with loadvm. The guest crashes or freezes. I dumped registers on snapshot creation and loading (in Haxm) and found that they are different.
> When returning from Haxm in hax_vcpu_hax_exec, there is no regular register read. I found hax_arch_get_registers function which reads registers from Haxm and is called from a synchronization procedure. I placed a breakpoint on it, ran qemu and found that it is hit one time during guest OS boot. Exactly these registers where saved in the snapshot.
> 
> ** Affects: qemu
>      Importance: Undecided
>          Status: New
> 
> -- 
> You received this bug notification because you are a member of qemu-
> devel-ml, which is subscribed to QEMU.
> https://bugs.launchpad.net/bugs/1855617
> 
> Title:
>   savevm with hax saves wrong register state
> 
> Status in QEMU:
>   New
> 
> Bug description:
>   I use qemu-i386 with IntelHaxm on Windows 10 x64 host with Windows 7 x86 guest. I run the guest till OS loads and create a snapshot with savevm, then close qemu, run it again and try to load the snapshot with loadvm. The guest crashes or freezes. I dumped registers on snapshot creation and loading (in Haxm) and found that they are different.
>   When returning from Haxm in hax_vcpu_hax_exec, there is no regular register read. I found hax_arch_get_registers function which reads registers from Haxm and is called from a synchronization procedure. I placed a breakpoint on it, ran qemu and found that it is hit one time during guest OS boot. Exactly these registers where saved in the snapshot.
> 
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/qemu/+bug/1855617/+subscriptions
> 
--
Dr. David Alan Gilbert / <email address hidden> / Manchester, UK



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This is an automated cleanup. This bug report has been moved to QEMU's
new bug tracker on gitlab.com and thus gets marked as 'expired' now.
Please continue with the discussion here:

 https://gitlab.com/qemu-project/qemu/-/issues/188