From: "Michael S. Tsirkin" <mst@redhat.com> To: Paolo Bonzini <pbonzini@redhat.com> Cc: Igor Mammedov <imammedo@redhat.com>, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, andrey@xdel.ru Subject: Re: [PATCH 3/5] vhost: support upto 509 memory regions Date: Fri, 19 Jun 2015 15:34:52 +0200 [thread overview] Message-ID: <20150619153248-mutt-send-email-mst@redhat.com> (raw) In-Reply-To: <5583F28A.9080206@redhat.com> On Fri, Jun 19, 2015 at 12:44:26PM +0200, Paolo Bonzini wrote: > > > On 19/06/2015 12:14, Michael S. Tsirkin wrote: > > On Fri, Jun 19, 2015 at 10:52:47AM +0200, Paolo Bonzini wrote: > >> > >> > >> On 19/06/2015 10:05, Michael S. Tsirkin wrote: > >>>> No, only destruction of the memory region frees it. address_space_map > >>>> takes a reference to the memory region and address_space_unmap releases it. > >>>> > >>>> Paolo > >>> > >>> Confused. So can we call mmap(MAP_NORESERVE) in address_space_unmap > >>> after we detect refcount is 0? > >> > >> No, because in the meanwhile another DIMM could have been hotplugged > >> at the same place where the old one was. This is legal: > >> > >> user guest QEMU > >> ---------------------------------------------------------------------------------------- > >> start I/O > >> '---------------> address_space_map > >> device_del > >> '-------------------> receives SCI > >> executes _EJ0 > >> '---------------> memory_region_del_subregion > >> object_unparent > > > > So guest started DMA into memory, then ejected this memory while DMA > > is in progress? > > Yes. There is nothing that forbids doing that. > > Paolo Can we simply defer the next device_add using a hva until all IO completes? > >> device_add > >> '-----------------------------------------> device_set_realized > >> hotplug_handler_plug > >> pc_machine_device_plug_cb > >> pc_dimm_plug > >> memory_region_add_subregion > >> > >> I/O finishes > >> address_space_unmap > >> > >> Surprise removal similarly could be done in QEMU, but it will hold to > >> some resources for as long as the device backends need them. > >> > >> Paolo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in Please read the FAQ at http://www.tux.org/lkml/
WARNING: multiple messages have this Message-ID (diff)
From: "Michael S. Tsirkin" <mst@redhat.com> To: Paolo Bonzini <pbonzini@redhat.com> Cc: Igor Mammedov <imammedo@redhat.com>, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, andrey@xdel.ru Subject: Re: [PATCH 3/5] vhost: support upto 509 memory regions Date: Fri, 19 Jun 2015 15:34:52 +0200 [thread overview] Message-ID: <20150619153248-mutt-send-email-mst@redhat.com> (raw) In-Reply-To: <5583F28A.9080206@redhat.com> On Fri, Jun 19, 2015 at 12:44:26PM +0200, Paolo Bonzini wrote: > > > On 19/06/2015 12:14, Michael S. Tsirkin wrote: > > On Fri, Jun 19, 2015 at 10:52:47AM +0200, Paolo Bonzini wrote: > >> > >> > >> On 19/06/2015 10:05, Michael S. Tsirkin wrote: > >>>> No, only destruction of the memory region frees it. address_space_map > >>>> takes a reference to the memory region and address_space_unmap releases it. > >>>> > >>>> Paolo > >>> > >>> Confused. So can we call mmap(MAP_NORESERVE) in address_space_unmap > >>> after we detect refcount is 0? > >> > >> No, because in the meanwhile another DIMM could have been hotplugged > >> at the same place where the old one was. This is legal: > >> > >> user guest QEMU > >> ---------------------------------------------------------------------------------------- > >> start I/O > >> '---------------> address_space_map > >> device_del > >> '-------------------> receives SCI > >> executes _EJ0 > >> '---------------> memory_region_del_subregion > >> object_unparent > > > > So guest started DMA into memory, then ejected this memory while DMA > > is in progress? > > Yes. There is nothing that forbids doing that. > > Paolo Can we simply defer the next device_add using a hva until all IO completes? > >> device_add > >> '-----------------------------------------> device_set_realized > >> hotplug_handler_plug > >> pc_machine_device_plug_cb > >> pc_dimm_plug > >> memory_region_add_subregion > >> > >> I/O finishes > >> address_space_unmap > >> > >> Surprise removal similarly could be done in QEMU, but it will hold to > >> some resources for as long as the device backends need them. > >> > >> Paolo -- To unsubscribe from this list: send the line "unsubscribe kvm" in
next prev parent reply other threads:[~2015-06-19 13:35 UTC|newest] Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-06-16 16:33 [PATCH 0/5] vhost: support upto 509 memory regions Igor Mammedov 2015-06-16 16:33 ` [PATCH 1/5] vhost: use binary search instead of linear in find_region() Igor Mammedov 2015-06-16 21:07 ` Michael S. Tsirkin 2015-06-16 21:13 ` Igor Mammedov 2015-06-16 16:33 ` [PATCH 2/5] vhost: extend memory regions allocation to vmalloc Igor Mammedov 2015-06-16 16:33 ` [PATCH 3/5] vhost: support upto 509 memory regions Igor Mammedov 2015-06-16 21:14 ` Michael S. Tsirkin 2015-06-16 22:00 ` Igor Mammedov 2015-06-17 6:34 ` Michael S. Tsirkin 2015-06-17 7:28 ` Igor Mammedov 2015-06-17 7:39 ` Michael S. Tsirkin 2015-06-17 8:54 ` Igor Mammedov 2015-06-17 10:11 ` Michael S. Tsirkin 2015-06-17 10:37 ` Igor Mammedov 2015-06-17 10:46 ` Michael S. Tsirkin 2015-06-17 11:48 ` Igor Mammedov 2015-06-17 11:51 ` Michael S. Tsirkin 2015-06-17 12:23 ` Igor Mammedov 2015-06-17 13:13 ` Michael S. Tsirkin 2015-06-17 13:20 ` Paolo Bonzini 2015-06-17 14:32 ` Michael S. Tsirkin 2015-06-17 15:12 ` Igor Mammedov 2015-06-17 15:38 ` Michael S. Tsirkin 2015-06-17 16:09 ` Igor Mammedov 2015-06-17 16:30 ` Michael S. Tsirkin 2015-06-17 16:31 ` Paolo Bonzini 2015-06-17 16:34 ` Michael S. Tsirkin 2015-06-17 16:38 ` Paolo Bonzini 2015-06-17 16:41 ` Michael S. Tsirkin 2015-06-17 16:47 ` Paolo Bonzini 2015-06-17 17:32 ` Igor Mammedov 2015-06-17 19:11 ` Michael S. Tsirkin 2015-06-17 17:30 ` Igor Mammedov 2015-06-18 9:12 ` Igor Mammedov 2015-06-18 9:50 ` Michael S. Tsirkin 2015-06-18 10:03 ` Paolo Bonzini 2015-06-18 11:39 ` Igor Mammedov 2015-06-18 11:41 ` Michael S. Tsirkin 2015-06-18 11:50 ` Paolo Bonzini 2015-06-18 13:19 ` Michael S. Tsirkin 2015-06-18 13:46 ` Paolo Bonzini 2015-06-18 14:47 ` Michael S. Tsirkin 2015-06-18 15:54 ` Igor Mammedov 2015-06-18 16:02 ` Paolo Bonzini 2015-06-19 7:56 ` Michael S. Tsirkin 2015-06-19 7:57 ` Paolo Bonzini 2015-06-19 8:05 ` Michael S. Tsirkin 2015-06-19 8:52 ` Paolo Bonzini 2015-06-19 10:14 ` Michael S. Tsirkin 2015-06-19 10:44 ` Paolo Bonzini 2015-06-19 13:34 ` Michael S. Tsirkin [this message] 2015-06-19 13:34 ` Michael S. Tsirkin 2015-06-19 15:19 ` Paolo Bonzini 2015-06-19 15:19 ` Paolo Bonzini 2015-06-19 16:20 ` Michael S. Tsirkin 2015-06-19 16:20 ` Michael S. Tsirkin 2015-06-19 16:26 ` Paolo Bonzini 2015-06-19 16:26 ` Paolo Bonzini 2015-06-19 16:33 ` Michael S. Tsirkin 2015-06-19 16:33 ` Michael S. Tsirkin 2015-06-19 16:44 ` Paolo Bonzini 2015-06-19 16:44 ` Paolo Bonzini 2015-06-22 7:10 ` Igor Mammedov 2015-06-22 7:10 ` Igor Mammedov 2015-06-22 9:45 ` Paolo Bonzini 2015-06-22 9:45 ` Paolo Bonzini 2015-06-19 16:45 ` Michael S. Tsirkin 2015-06-19 16:45 ` Michael S. Tsirkin 2015-06-19 16:50 ` Paolo Bonzini 2015-06-19 16:50 ` Paolo Bonzini 2015-06-18 12:02 ` Igor Mammedov 2015-06-17 8:53 ` Paolo Bonzini 2015-06-16 16:33 ` [PATCH 4/5] vhost: add per VQ memory region caching Igor Mammedov 2015-06-16 16:33 ` [PATCH 5/5] vhost: translate_desc: optimization for desc.len < region size Igor Mammedov 2015-06-16 21:11 ` Michael S. Tsirkin 2015-06-16 21:16 ` [PATCH 0/5] vhost: support upto 509 memory regions Michael S. Tsirkin 2015-06-16 22:19 ` Igor Mammedov 2015-06-17 6:31 ` Michael S. Tsirkin 2015-06-17 7:33 ` Igor Mammedov 2015-06-17 7:40 ` Michael S. Tsirkin
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20150619153248-mutt-send-email-mst@redhat.com \ --to=mst@redhat.com \ --cc=andrey@xdel.ru \ --cc=imammedo@redhat.com \ --cc=kvm@vger.kernel.org \ --cc=linux-kernel@vger.kernel.org \ --cc=pbonzini@redhat.com \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.