Intel Software Network - feed

Redirecting host interrupts to the guest

Sat, 31 Oct 2009 19:21:28 -0700

I am implementing thin hypervisor which runs under primary OS which is executed as guest. To implement such things as shadow paging I need hardware interrupts to be enabled in the host. I am trying to set a coresponding bit in the bitmap for each hardware interrupt delivered through the host IDT. On VM entry I am injecting to the guest all interrupts which have happened during VM exit processing and have corresponding bits set in the bitmap. Interrupts with higher priorities are injected first.

Everything works fine, but sometimes (very rarely) guest hangs without VM exits committed.

Question to experts: is this design right and what could be a reason for the hang?

Any CPU with both EPT and TXT support?

Thu, 29 Oct 2009 02:06:56 -0700

I'm wondering whether there is a processor that supports both EPT and TXT because I wanna build an efficient VMM with measurement.

Thanks.

Q8400 + DG31PR Virtualization Support

Wed, 28 Oct 2009 06:57:21 -0700

The Q8400 processor has VT built-in. The DG31PR motherboard has VT enabled in the bios.

But when I "cat /proc/cpuinfo" no vmx flag shows up.

???

values of genral purpose registers

Thu, 08 Oct 2009 08:11:06 -0700

hi my friends
when transitioning from a VM to the VMM, where are values of genral purpose registers stored ?
sincerely u

Question about sysenter/sysexit

Thu, 08 Oct 2009 07:51:36 -0700

Hi; in (http://www.intel.com/technology/itj/...3-software.htm ) it's declared that
Executions of SYSENTER by a guest application cause transitions to the VMM and not to the guest OS. The VMM must emulate every guest execution of SYSENTER.
It means that execution of sysenter instruction cause a VM Exit and transfer control to VMM to handle guest's system calls. Please say me how VMM handles guest's system calls?
Dose VMM uses guest system calls handler routines to handle guest's system calls?

best virtualization software over i7

Wed, 07 Oct 2009 04:49:20 -0700

Hello

I'am wondering if intel has a performance studdies about virtualization technologies and performance over i7 (kvm,xen, sun xvm, vmware, etc) and where can I find that?

thanks
best regards.

Virtual 8086 mode guest

Mon, 28 Sep 2009 10:56:33 -0700

Hi,

I have a system running Core i7 920 with VT enabled in the BIOS. I am trying to write
a simple hypervisor which sets up a context for a guest in Virtual 8086 mode. However,
when I set the VM bit (for Virtual 8086 mode) in the VMCS RFLAGS register and launch
the guest ( value of RFLAGS I am using is 0x0000000000020002) , the system seems to
be frozen (probably a VMX abort?). I dont have access
to a hardware debugger and hence cannot be sure whether it is a VMX abort or what
the abort code is.

However, I have success in launching a 32-bit protected mode guest with paging and
am even able to communicate with the hypervisor using VMCALLs from the 32-bit guest.
So, I am inclined to think that it is not failing due to a VMX abort when launching the
V86 guest.

I have even tried to launch a 32-bit guest and within that have setup a
V86 stack frame and tried to do a IRET to that with EFLAGS VM set. That also has
the same effect in the system being frozen when IRET executes. I am not sure
what I am missing in setting up a V86 guest. Any help will be greatly appreciated.

Thanks in advance!

Fraudulent Chip Descriptions

Sat, 26 Sep 2009 12:46:23 -0700

Some chips are labeled as having virtualization support when they do not. Consumers are getting duped into buying computers that can not meet their needs. I just bought a laptop (HP Pavilion dv7-7217us) convinced I could use KVM based virtual machines since its P7550 processor was clearly labeled as supporting virtualization.

http://ark.intel.com/Product.aspx?id=42014

(There are other threads with similar grumbles.)
Do we need to complaing to the Federal Trade Commissioin and other consumer fraud protection agencies?

Is Intel prepared to help with products bought under false representations?

Incorrect data update in ARK regarding PCNs adding VT support?

Sat, 19 Sep 2009 19:45:29 -0700

Intel added VT to the Q8300, E7400, E7500, E5300, and E5400 CPUs in two PCNs.
After PCN number 109337 adding VT support to tray processors was issued, ARK was correctly updated to add the new processors and to correctly indicate that they have VT.
Months later, PCN number 109359 was issued to add VT support to boxed processors. This time, when ARK was updated to add the new processors, it was incorrectly specified that the new boxed processors lack VT, which I suspect have VT.
This also confused the http://ark.intel.com/VTList.aspx too.

Possible error in SDM 3A

Tue, 15 Sep 2009 13:59:44 -0700

Suddenly found a little error in manual.

http://www.intel.com/Assets/PDF/manual/253668.pdf
Order Number: 253668-031US
June 2009

Page 4-34:
• U/S (bit2).
If a supervisor-mode (CPL< 3) access caused the page-fault exception, this flag is 1; it is 0 if a user-mode (CPL= 3) access did so. This bit describes the acces
causing the page-fault exception, not the access rights specified by paging.
---------------------
Right way should be like this, afaik:
• U/S (bit2).
If a supervisor-mode (CPL< 3) access caused the page-fault exception, this flag is 0; it is 1 if a user-mode (CPL= 3) access did so. This bit describes the acces
causing the page-fault exception, not the access rights specified by paging.