Re: [Qemu-devel] [PATCH v9] vhost: used_memslots refactoring

["Zhoujian (jay)" <jianjay.zhou@huawei.com>]

> -----Original Message-----
> From: Michael S. Tsirkin [mailto:mst@redhat.com]
> Sent: Tuesday, March 20, 2018 11:14 AM
> To: Zhoujian (jay) <jianjay.zhou@huawei.com>
> Cc: qemu-devel@nongnu.org; imammedo@redhat.com; Huangweidong (C)
> <weidong.huang@huawei.com>; wangxin (U) <wangxinxin.wang@huawei.com>; Gonglei
> (Arei) <arei.gonglei@huawei.com>; Liuzhe (Ahriy, Euler) <liuzhe13@huawei.com>
> Subject: Re: [PATCH v9] vhost: used_memslots refactoring
> 
> On Tue, Mar 20, 2018 at 02:09:34AM +0000, Zhoujian (jay) wrote:
> > Hi Michael,
> >
> > > -----Original Message-----
> > > From: Michael S. Tsirkin [mailto:mst@redhat.com]
> > > Sent: Tuesday, March 20, 2018 9:34 AM
> > > To: Zhoujian (jay) <jianjay.zhou@huawei.com>
> > > Cc: qemu-devel@nongnu.org; imammedo@redhat.com; Huangweidong (C)
> > > <weidong.huang@huawei.com>; wangxin (U)
> > > <wangxinxin.wang@huawei.com>; Gonglei
> > > (Arei) <arei.gonglei@huawei.com>; Liuzhe (Ahriy, Euler)
> > > <liuzhe13@huawei.com>
> > > Subject: Re: [PATCH v9] vhost: used_memslots refactoring
> > >
> > > On Mon, Mar 05, 2018 at 05:12:49PM +0800, Jay Zhou wrote:
> > > > Used_memslots is shared by vhost kernel and user, it is equal to
> > > > dev->mem->nregions, which is correct for vhost kernel, but not for
> > > > vhost user, the latter one uses memory regions that have file
> > > > descriptor. E.g. a VM has a vhost-user NIC and 8(vhost user
> > > > memslot upper limit) memory slots, it will be failed to hotplug a
> > > > new DIMM device since vhost_has_free_slot() finds no free slot
> > > > left. It should be successful if only part of memory slots have
> > > > file descriptor, so setting used memslots for vhost-user and vhost-
> kernel respectively.
> > >
> > >
> > > Below should go after ---
> >
> > Thanks for reminding.
> >
> > >
> > > > v7 ... v9:
> > > >  - rebased on the master
> > > > v2 ... v6:
> > > >  - delete the "used_memslots" global variable, and add it
> > > >    for vhost-user and vhost-kernel separately
> > > >  - refine the function, commit log
> > > >  - used_memslots refactoring
> > > >
> > > > Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> > > > Signed-off-by: Jay Zhou <jianjay.zhou@huawei.com>
> > > > Signed-off-by: Liuzhe <liuzhe13@huawei.com>
> > >
> > > When built with clang this causes runtime warnings (during make
> > > check) about misaligned access to structures.
> > >
> > > The issue is that vhost_user_prepare_msg requests VhostUserMemory
> > > which compiler assumes but is then used with a pointer into a packed
> > > structure - where fields are not aligned.
> >
> > Sorry I missed the patch you have sent to fix the alignment, I have
> > replied to that thread.
> 
> I've dropped this from the pull for now.  Sorry about that.  Once next pull
> is merged, pls rebase and post a version fixing up the alignment issues.
> 
> Thanks for your effort!

Hi Michael,
Sorry for the trouble, it's okay for me, will fix the alignment issues
in the next version.

Regards,
Jay

> 
> --
> MST