Anthony Liguori wrote: > Jun Koi wrote: > >> On 10/1/07, Anthony Liguori <[EMAIL PROTECTED]> wrote: >> >> >>> Cameron Macdonell wrote: >>> >>> >>>> Hi, >>>> >>>> I'm trying to understand guest virtualization at the lower levels. I >>>> have a somewhat basic question: How does KVM virtualize an int80 >>>> instruction from a guest? A pointer to an answer is just as good as >>>> an answer itself. >>>> >>>> >>>> >>> The same thing happens as it does on normal hardware. >>> >>> The way VT/SVM works (at a high level), is that certain instructions and >>> events check a special area called the VMCS/VMCB to determine whether >>> the event should generate a vmexit which is really just a special type >>> of trap. >>> >>> There are no hooks for interrupts 32-255 so the hardware operates as it >>> normally would. If you're interested in getting a trap for int80 within >>> KVM, you'll have to trap sidt/lidt and virtualize the IDT. You'll need >>> to setup a fake IDT and have the int80 handler do a hypercall. This is >>> complicated if the guest is using a fast-syscall mechanism. It may be a >>> little challenging finding a piece of guest memory to take over that has >>> a valid virtual mapping. >>> >>> >> This is a bit vague to me. Why do you need "a piece of guest memory" here? >> >> > > You don't just need guest memory, you need a valid guest virtual address > too. The IDTR contains a guest VA. If you want to create your own IDT, > then it has to be a valid VA in the guest's address space. > >
You can set the guest idt size to zero and trap the double fault exception. -- error compiling committee.c: too many arguments to function ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ kvm-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/kvm-devel
