From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34669) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1evKZv-00063o-KS for qemu-devel@nongnu.org; Mon, 12 Mar 2018 06:21:16 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1evKZs-000639-EQ for qemu-devel@nongnu.org; Mon, 12 Mar 2018 06:21:15 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:49256 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1evKZs-00062F-97 for qemu-devel@nongnu.org; Mon, 12 Mar 2018 06:21:12 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 6282A8D6D7 for ; Mon, 12 Mar 2018 10:21:08 +0000 (UTC) Date: Mon, 12 Mar 2018 18:20:59 +0800 From: Peter Xu Message-ID: <20180312102059.GD11787@xz-mi> References: <20180308195811.24894-1-dgilbert@redhat.com> <20180308195811.24894-15-dgilbert@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20180308195811.24894-15-dgilbert@redhat.com> Subject: Re: [Qemu-devel] [PATCH v4 14/29] libvhost-user+postcopy: Register new regions with the ufd List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Dr. David Alan Gilbert (git)" Cc: qemu-devel@nongnu.org, mst@redhat.com, maxime.coquelin@redhat.com, marcandre.lureau@redhat.com, quintela@redhat.com, aarcange@redhat.com On Thu, Mar 08, 2018 at 07:57:56PM +0000, Dr. David Alan Gilbert (git) wrote: > From: "Dr. David Alan Gilbert" > > When new regions are sent to the client using SET_MEM_TABLE, register > them with the userfaultfd. > > Signed-off-by: Dr. David Alan Gilbert > --- > contrib/libvhost-user/libvhost-user.c | 34 ++++++++++++++++++++++++++++++++++ > 1 file changed, 34 insertions(+) > > diff --git a/contrib/libvhost-user/libvhost-user.c b/contrib/libvhost-user/libvhost-user.c > index 4922b2c722..a18bc74a7c 100644 > --- a/contrib/libvhost-user/libvhost-user.c > +++ b/contrib/libvhost-user/libvhost-user.c > @@ -494,6 +494,40 @@ vu_set_mem_table_exec_postcopy(VuDev *dev, VhostUserMsg *vmsg) > close(vmsg->fds[i]); > } > > + /* TODO: Get address back to QEMU */ > + for (i = 0; i < dev->nregions; i++) { > + VuDevRegion *dev_region = &dev->regions[i]; > +#ifdef UFFDIO_REGISTER > + /* We should already have an open ufd. Mark each memory > + * range as ufd. > + * Note: Do we need any madvises? Well it's not been accessed > + * yet, still probably need no THP to be safe, discard to be safe? > + */ > + struct uffdio_register reg_struct; > + reg_struct.range.start = (uintptr_t)dev_region->mmap_addr; > + reg_struct.range.len = dev_region->size + dev_region->mmap_offset; Do we really care the page faults between offset zero to mmap_offset? I'm thinking whether we should add that mmap_offset into range.start instead of range.len. Also, I see that in current vu_set_mem_table_exec(): /* We don't use offset argument of mmap() since the * mapped address has to be page aligned, and we use huge * pages. */ mmap_addr = mmap(0, dev_region->size + dev_region->mmap_offset, PROT_READ | PROT_WRITE, MAP_SHARED, vmsg->fds[i], 0); So adding the mmap_offset will help to make sure we'll use huge pages? Could it? Or say, how could we be sure that size+mmap_offset would be page aligned? Thanks, > + reg_struct.mode = UFFDIO_REGISTER_MODE_MISSING; > + > + if (ioctl(dev->postcopy_ufd, UFFDIO_REGISTER, ®_struct)) { > + vu_panic(dev, "%s: Failed to userfault region %d " > + "@%p + size:%zx offset: %zx: (ufd=%d)%s\n", > + __func__, i, > + dev_region->mmap_addr, > + dev_region->size, dev_region->mmap_offset, > + dev->postcopy_ufd, strerror(errno)); > + return false; > + } > + if (!(reg_struct.ioctls & ((__u64)1 << _UFFDIO_COPY))) { > + vu_panic(dev, "%s Region (%d) doesn't support COPY", > + __func__, i); > + return false; > + } > + DPRINT("%s: region %d: Registered userfault for %llx + %llx\n", > + __func__, i, reg_struct.range.start, reg_struct.range.len); > + /* TODO: Stash 'zero' support flags somewhere */ > +#endif > + } > + > return false; > } > > -- > 2.14.3 > -- Peter Xu