32-bit binaries failing in 64 bit guests after using vmport
Esteemed kvm developers!
I've been trying to debug this bug
https://bugs.launchpad.net/ubuntu/+source/kvm/+bug/219165
It originally revealed itself by failing to run grub (which is a 32 bit binary) when installing Ubuntu from our live cd. It turned out to be a more general problem of 32 bit binaries failing to run. The server install worked like a charm. I eventually discovered that loading the vmmouse driver triggered it and narrowed it down to the call to kvm_load_registers in vmport_ioport_read.
We're releasing on Thursday, and I needed a quick fix, so I reverted the calls to kvm_{save,load}_registers in vmport_ioport_read to the old code that simply saved the eax, ebx, ecx, edx, esi, and edi registers, but I'm supposing kvm_{load,save}_registers really should work here.
I dug a bit further into the code and tried disabling various pieces of the kvm_load_registers until it finally worked again. The problem seems to only arise when the lstar msr is loaded. I've looked at the code, but seeing as three days ago I didn't know there was such a thing as an lstar msr, I'm finding myself getting stuck. :)
Any pointers in the right direction would be lovely.
Signature · 3 lines
Soren Hansen | Virtualisation specialist | Ubuntu Server Team Canonical Ltd. | http://www.ubuntu.com/
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Quoted 13 lines · Soren Hansen
Esteemed kvm developers!
I've been trying to debug this bug
https://bugs.launchpad.net/ubuntu/+source/kvm/+bug/219165It originally revealed itself by failing to run grub (which is a 32 bit binary) when installing Ubuntu from our live cd. It turned out to be a more general problem of 32 bit binaries failing to run. The server install worked like a charm. I eventually discovered that loading the vmmouse driver triggered it and narrowed it down to the call to
kvm_load_registersinvmport_ioport_read.
Quoted 5 lines
We're releasing on Thursday, and I needed a quick fix, so I reverted the calls to kvm_{save,load}_registers in
vmport_ioport_readto the old code that simply saved the eax, ebx, ecx, edx, esi, and edi registers, but I'm supposing kvm_{load,save}_registers really should work here.
Ah, you may have missed the fix that updated the KVM load/save functions to deal with the in-kernel APIC.
It turns out, vmmouse was horribly broken with SMP guests too. See
commit 9949bd84ac4dfdfc60b2974557819637b8719911
Author: Anthony Liguori <[email protected]> Date: Thu Apr 3 18:37:16 2008 -0500
commit 5208ce19dca268f84a2b9441c2fbb6129161e44c
Author: Marcelo Tosatti <[email protected]> Date: Thu Apr 3 20:24:37 2008 -0300
commit 85a67aa2a1b942ddccfcbd625d280869367edc95
Author: Marcelo Tosatti <[email protected]> Date: Fri Apr 11 13:24:41 2008 -0300
Regards,
Anthony LIguori
Quoted 18 lines
I dug a bit further into the code and tried disabling various pieces of the
kvm_load_registersuntil it finally worked again. The problem seems to only arise when the lstar msr is loaded. I've looked at the code, but seeing as three days ago I didn't know there was such a thing as an lstar msr, I'm finding myself getting stuck. :)Any pointers in the right direction would be lovely.
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Quoted 5 lines
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Quoted 5 lines · Anthony Liguori
Quoted 5 lines
We're releasing on Thursday, and I needed a quick fix, so I reverted the calls to kvm_{save,load}_registers in
vmport_ioport_readto the old code that simply saved the eax, ebx, ecx, edx, esi, and edi registers, but I'm supposing kvm_{load,save}_registers really should work here.
/me sighs very deeply
Ok, first chance I get, I'm signing up for "Patch management 101". :( I got some tests mixed around, so it failing is actually dependent on whether EIP (not LSTAR as I originally thought) is restored or not.
I have a patch that fixes it, but I need to work a few things out first before I submit it.
Quoted 2 lines
Ah, you may have missed the fix that updated the KVM load/save functions to deal with the in-kernel APIC.
Indeed.
Quoted 9 lines
It turns out, vmmouse was horribly broken with SMP guests too. See
commit
9949bd84ac4dfdfc60b2974557819637b8719911Author: Anthony Liguori <[email protected]> Date: Thu Apr 3 18:37:16 2008 -0500commit
5208ce19dca268f84a2b9441c2fbb6129161e44cAuthor: Marcelo Tosatti <[email protected]> Date: Thu Apr 3 20:24:37 2008 -0300
I did my tests using kvm-65 userland and kernel, so these two should already be included, afaics.
Quoted 3 lines
commit
85a67aa2a1b942ddccfcbd625d280869367edc95Author: Marcelo Tosatti <[email protected]> Date: Fri Apr 11 13:24:41 2008 -0300
This did not change anything for me.
Signature · 3 lines
Soren Hansen | Virtualisation specialist | Ubuntu Server Team Canonical Ltd. | http://www.ubuntu.com/
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