On 16/08/18 13:27, Jan Beulich wrote: >>>> On 16.08.18 at 12:56, <andrew.coop...@citrix.com> wrote: >> On 16/08/18 11:29, Jan Beulich wrote: >>> Following some further discussion with Andrew, he looks to be >>> convinced that the issue is to be fixed in the balloon driver, >>> which so far (intentionally afaict) does not remove the direct >>> map entries for ballooned out pages in the HVM case. I'm not >>> convinced of this, but I'd nevertheless like to inquire whether >>> such a change (resulting in shattered super page mappings) >>> would be acceptable in the first place. >> >> We don't tolerate anything else in the directmap pointing to >> invalid/unimplemented frames. Why should ballooning be any different? > > Because ballooning is something virtualization specific, which > doesn't have any equivalent on bare hardware (memory hot > unplug doesn't come quite close enough imo, not the least > because that doesn't work on a page granular basis). Hence > we're to define the exact behavior here, and hence such a > definition could as well include special behavior of accesses > to the involved guest-physical addresses.
If I read drivers/virtio/virtio_balloon.c correctly KVM does the same as Xen: ballooned pages are _not_ removed from the direct mappings. Juergen _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
