| Message ID | 1498601083-11799-1-git-send-email-sstabellini@kernel.org |
|---|---|
| State | New |
| Headers | show |
28.06.2017 01:04, Stefano Stabellini wrote: > Rather than constructing a local structure instance on the stack, fill > the fields directly on the shared ring, just like other (Linux) > backends do. Build on the fact that all response structure flavors are > actually identical (aside from alignment and padding at the end). > > This is XSA-216. > > Reported by: Anthony Perard <anthony.perard@citrix.com> > Signed-off-by: Jan Beulich <jbeulich@suse.com> > Signed-off-by: Stefano Stabellini <sstabellini@kernel.org> > Acked-by: Anthony PERARD <anthony.perard@citrix.com> Reportedly, after this patch, HVM DomUs running with qemu-system-i386 (note i386, not x86_64), are leaking memory and host is running out of memory rather fast. See for example https://bugs.debian.org/871702 I've asked for details, let's see... For one, I've no idea how xen hvm works, and whenever -i386 version can be choosen in config or how. Thanks, /mjt
23.09.2017 19:05, Michael Tokarev wrote: > 28.06.2017 01:04, Stefano Stabellini wrote: >> Rather than constructing a local structure instance on the stack, fill >> the fields directly on the shared ring, just like other (Linux) >> backends do. Build on the fact that all response structure flavors are >> actually identical (aside from alignment and padding at the end). >> >> This is XSA-216. >> >> Reported by: Anthony Perard <anthony.perard@citrix.com> >> Signed-off-by: Jan Beulich <jbeulich@suse.com> >> Signed-off-by: Stefano Stabellini <sstabellini@kernel.org> >> Acked-by: Anthony PERARD <anthony.perard@citrix.com> > > Reportedly, after this patch, HVM DomUs running with qemu-system-i386 > (note i386, not x86_64), are leaking memory and host is running out of > memory rather fast. See for example https://bugs.debian.org/871702 Looks like this is a false alarm, the problem actually is with 04bf2526ce87f21b32c9acba1c5518708c243ad0 (exec: use qemu_ram_ptr_length to access guest ram) without f5aa69bdc3418773f26747ca282c291519626ece (exec: Add lock parameter to qemu_ram_ptr_length). I applied only 04bf2526ce87f to 2.8, without realizing that we also need f5aa69bdc3418). Now when I try to backport f5aa69bdc3418 to 2.8 (on top of 04bf2526ce87f), I face an interesting logic without also applying 1ff7c5986a515d2d936eba0 (xen/mapcache: store dma information in revmapcache entries for debugging), the arguments for xen_map_cache in qemu_ram_ptr_length() in these two patches are quite fun.. :) Thanks, /mjt
On Sun, 24 Sep 2017, Michael Tokarev wrote: > 23.09.2017 19:05, Michael Tokarev wrote: > > 28.06.2017 01:04, Stefano Stabellini wrote: > >> Rather than constructing a local structure instance on the stack, fill > >> the fields directly on the shared ring, just like other (Linux) > >> backends do. Build on the fact that all response structure flavors are > >> actually identical (aside from alignment and padding at the end). > >> > >> This is XSA-216. > >> > >> Reported by: Anthony Perard <anthony.perard@citrix.com> > >> Signed-off-by: Jan Beulich <jbeulich@suse.com> > >> Signed-off-by: Stefano Stabellini <sstabellini@kernel.org> > >> Acked-by: Anthony PERARD <anthony.perard@citrix.com> > > > > Reportedly, after this patch, HVM DomUs running with qemu-system-i386 > > (note i386, not x86_64), are leaking memory and host is running out of > > memory rather fast. See for example https://bugs.debian.org/871702 > > Looks like this is a false alarm, the problem actually is with > 04bf2526ce87f21b32c9acba1c5518708c243ad0 (exec: use qemu_ram_ptr_length > to access guest ram) without f5aa69bdc3418773f26747ca282c291519626ece > (exec: Add lock parameter to qemu_ram_ptr_length). > > I applied only 04bf2526ce87f to 2.8, without realizing that we also > need f5aa69bdc3418). > > Now when I try to backport f5aa69bdc3418 to 2.8 (on top of 04bf2526ce87f), > I face an interesting logic without also applying 1ff7c5986a515d2d936eba0 > (xen/mapcache: store dma information in revmapcache entries for debugging), > the arguments for xen_map_cache in qemu_ram_ptr_length() in these two patches > are quite fun.. :) Sorry about that. Let me know if you need any help with those backport. Thank you! - Stefano
diff --git a/hw/block/xen_disk.c b/hw/block/xen_disk.c index 3a22805..9200511 100644 --- a/hw/block/xen_disk.c +++ b/hw/block/xen_disk.c @@ -769,31 +769,30 @@ static int blk_send_response_one(struct ioreq *ioreq) struct XenBlkDev *blkdev = ioreq->blkdev; int send_notify = 0; int have_requests = 0; - blkif_response_t resp; - void *dst; - - resp.id = ioreq->req.id; - resp.operation = ioreq->req.operation; - resp.status = ioreq->status; + blkif_response_t *resp; /* Place on the response ring for the relevant domain. */ switch (blkdev->protocol) { case BLKIF_PROTOCOL_NATIVE: - dst = RING_GET_RESPONSE(&blkdev->rings.native, blkdev->rings.native.rsp_prod_pvt); + resp = (blkif_response_t *) RING_GET_RESPONSE(&blkdev->rings.native, + blkdev->rings.native.rsp_prod_pvt); break; case BLKIF_PROTOCOL_X86_32: - dst = RING_GET_RESPONSE(&blkdev->rings.x86_32_part, - blkdev->rings.x86_32_part.rsp_prod_pvt); + resp = (blkif_response_t *) RING_GET_RESPONSE(&blkdev->rings.x86_32_part, + blkdev->rings.x86_32_part.rsp_prod_pvt); break; case BLKIF_PROTOCOL_X86_64: - dst = RING_GET_RESPONSE(&blkdev->rings.x86_64_part, - blkdev->rings.x86_64_part.rsp_prod_pvt); + resp = (blkif_response_t *) RING_GET_RESPONSE(&blkdev->rings.x86_64_part, + blkdev->rings.x86_64_part.rsp_prod_pvt); break; default: - dst = NULL; return 0; } - memcpy(dst, &resp, sizeof(resp)); + + resp->id = ioreq->req.id; + resp->operation = ioreq->req.operation; + resp->status = ioreq->status; + blkdev->rings.common.rsp_prod_pvt++; RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&blkdev->rings.common, send_notify);