> > http://ols.108.redhat.com/2007/Reprints/kivity-Reprint.pdf > Hi Avi,
I have a question about KVM architecture after reading your paper. It reads: ...... At the kernel level, the kernel causes the hardware to enter guest mode. If the processor exits guest mode due to an event such as an external interrupt or a shadow page table fault, the kernel performs the necessary handling and resumes guest execution. If the exit reason is due to an I/O instruction or a signal queued to the process, then the kernel exits to userspace. ...... After reading your paper my understanding of KVM architecture is that for a particular VM the user mode(QEMU), kernel mode and guest mode share the same process context from host linux kernel's point of view, right? If this is the case, see the below example: 1 physical NIC interrupt is received on physical CPU 0 and host kernel determines that this is a network packet targeted to the emulated NIC for a VM 2 at the same time this VM is running in guest mode on physical CPU 1 My question is: at this time can host kernel *actively* interrupt VM and make it run in user mode to handle the incoming network data packet in QEMU? Or host kernel has to wait for VM(because of external interrupt or shadow page table fault or I/O instruction) to quit guest mode and wait for VM to voluntarily detect that incoming network packet is pending and switch to user space? A further question is, how a VM detect the incoming pending network packet? In kernel space or in user space? Thanks, Forrest ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
