On Mon, Oct 14, 2013 at 12:07:24PM +0300, Gleb Natapov wrote: > On Mon, Oct 14, 2013 at 10:28:57AM +0200, Jens Freimann wrote: > > On Sun, Oct 13, 2013 at 11:39:55AM +0300, Gleb Natapov wrote: > > > On Tue, Oct 08, 2013 at 04:54:55PM +0200, Christian Borntraeger wrote: > > > > From: Jens Freimann <jfrei@xxxxxxxxxxxxxxxxxx> > > > > > > > > This patch adds a floating irq controller as a kvm_device. > > > > It will be necessary for migration of floating interrupts as well > > > > as for hardening the reset code by allowing user space to explicitly > > > > remove all pending floating interrupts. > > > > > > > > Signed-off-by: Jens Freimann <jfrei@xxxxxxxxxxxxxxxxxx> > > > > Reviewed-by: Cornelia Huck <cornelia.huck@xxxxxxxxxx> > > > > Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx> > > > > --- > > > > Documentation/virtual/kvm/devices/s390_flic.txt | 36 +++ > > > > arch/s390/include/asm/kvm_host.h | 1 + > > > > arch/s390/include/uapi/asm/kvm.h | 5 + > > > > arch/s390/kvm/interrupt.c | 296 ++++++++++++++++++++---- > > > > arch/s390/kvm/kvm-s390.c | 1 + > > > > include/linux/kvm_host.h | 1 + > > > > include/uapi/linux/kvm.h | 1 + > > > > virt/kvm/kvm_main.c | 5 + > > > > 8 files changed, 295 insertions(+), 51 deletions(-) > > > > create mode 100644 Documentation/virtual/kvm/devices/s390_flic.txt > > > > > > > > diff --git a/Documentation/virtual/kvm/devices/s390_flic.txt b/Documentation/virtual/kvm/devices/s390_flic.txt > > > > new file mode 100644 > > > > index 0000000..06aef31 > > > > --- /dev/null > > > > +++ b/Documentation/virtual/kvm/devices/s390_flic.txt > > > > @@ -0,0 +1,36 @@ > > > > +FLIC (floating interrupt controller) > > > > +==================================== > > > > + > > > > +FLIC handles floating (non per-cpu) interrupts, i.e. I/O, service and some > > > > +machine check interruptions. All interrupts are stored in a per-vm list of > > > > +pending interrupts. FLIC performs operations on this list. > > > > + > > > > +Only one FLIC instance may be instantiated. > > > > + > > > > +FLIC provides support to > > > > +- add/delete interrupts (KVM_DEV_FLIC_ENQUEUE and _DEQUEUE) > > > > +- purge all pending floating interrupts (KVM_DEV_FLIC_CLEAR_IRQS) > > > > + > > > > +Groups: > > > > + KVM_DEV_FLIC_ENQUEUE > > > > + Adds one interrupt to the list of pending floating interrupts. Interrupts > > > > + are taken from this list for injection into the guest. attr contains > > > > + a struct kvm_s390_irq which contains all data relevant for > > > > + interrupt injection. > > > > + The format of the data structure kvm_s390_irq as it is copied from userspace > > > > + is defined in usr/include/linux/kvm.h. > > > > + For historic reasons list members are stored in a different data structure, i.e. > > > > + we need to copy the relevant data into a struct kvm_s390_interrupt_info > > > > + which can then be added to the list. > > > > + > > > > + KVM_DEV_FLIC_DEQUEUE > > > > + Takes one element off the pending interrupts list and copies it into userspace. > > > > + Dequeued interrupts are not injected into the guest. > > > > + attr->addr contains the userspace address of a struct kvm_s390_irq. > > > > + List elements are stored in the format of struct kvm_s390_interrupt_info > > > > + (arch/s390/include/asm/kvm_host.h) and are copied into a struct kvm_s390_irq > > > > + (usr/include/linux/kvm.h) > > > > + > > > Can interrupt be dequeued on real HW also? When this interface will be > > > used? > > > > We will it for migration. (See Christians mail) > > > For migration you do not need dequeue semantics though, dequeuing > does not hurt in case of migration, but what if we will want to add > QEMU monitor command that inspects interrupt queue (like we have for > inspecting processor's register state). The destructive nature of the > command will prevent us from doing so. We need non destructive way to > inspect the state, no? Inspection is a requirement that we didn't have in mind when we designed this. But yes, it should be non-destructive in that case. Christian and I agree that we should defer these patches for now. It would be good if we could discuss this interface next week at the KVM Forum. regards Jens > > -- > Gleb. > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
