On Tue, Jan 29, 2019 at 06:44:50PM +0100, Cédric Le Goater wrote: > On 1/29/19 5:12 AM, Paul Mackerras wrote: > > On Mon, Jan 28, 2019 at 07:26:00PM +0100, Cédric Le Goater wrote: > >> > >> Is clearing the PTEs and repopulating the VMA unsafe ? > > > > Actually, now that I come to think of it, there could be any number of > > VMAs (well, up to almost 64k of them), since once you have a file > > descriptor you can call mmap on it multiple times. > > > > The more I think about it, the more I think that getting userspace to > > manage the mappings with mmap() and munmap() is the right idea if it > > can be made to work. > > We might be able to mmap() and munmap() regions of ESB pages in the RTAS > call "ibm,change-msi". I think that's the right spot for it. I was thinking that the ESB pages should be mmapped for device interrupts at VM startup or when a device is hot-plugged in, and munmapped when the device is hot-removed. Maybe the mmap could be done in conjunction with the KVM_IRQFD call? What is the reasoning behind doing it in the ibm,change-msi call? Paul.
