Re: [PATCH] treat AHCI controllers under VMD as part of VMD

[Mariusz Tkaczyk <mariusz.tkaczyk@linux.intel.com>]

On Thu, 9 Feb 2023 08:39:21 +0800
Xiao Ni <xni@redhat.com> wrote:

> On Tue, Feb 7, 2023 at 4:46 PM Mariusz Tkaczyk
> <mariusz.tkaczyk@linux.intel.com> wrote:
> >
> > Hi Kevin,
> > I found time to take a look into it closer. I think that it is not complete
> > solution. Please see my comments.
> >
> > On Wed, 25 Jan 2023 21:16:59 -0500
> > Kevin Friedberg <kev.friedberg@gmail.com> wrote:
> >  
> > > Detect when a SATA controller has been mapped under Intel Alderlake RST
> > > VMD and list it as part of the domain, instead of independently, so that
> > > it can use the VMD controller's RAID capabilities.
> > >
> > > Signed-off-by: Kevin Friedberg <kev.friedberg@gmail.com>
> > > ---
> > >  platform-intel.c | 15 +++++++++------
> > >  super-intel.c    | 25 ++++++++++++++++++++++++-
> > >  2 files changed, 33 insertions(+), 7 deletions(-)
> > >
> > > diff --git a/platform-intel.c b/platform-intel.c
> > > index 757f0b1b..859bf743 100644
> > > --- a/platform-intel.c
> > > +++ b/platform-intel.c
> > > @@ -64,10 +64,12 @@ struct sys_dev *find_driver_devices(const char *bus,
> > > const char *driver)
> > >       if (strcmp(driver, "isci") == 0)
> > >               type = SYS_DEV_SAS;
> > > -     else if (strcmp(driver, "ahci") == 0)
> > > +     else if (strcmp(driver, "ahci") == 0) {
> > > +             /* if looking for sata devs, ignore vmd */
> > > +             vmd = find_driver_devices("pci", "vmd");
> > >               type = SYS_DEV_SATA;
> > > -     else if (strcmp(driver, "nvme") == 0) {
> > > -             /* if looking for nvme devs, first look for vmd */
> > > +     } else if (strcmp(driver, "nvme") == 0) {
> > > +             /* if looking for nvme devs, also look for vmd */
> > >               vmd = find_driver_devices("pci", "vmd");
> > >               type = SYS_DEV_NVME;
> > >       } else if (strcmp(driver, "vmd") == 0)
> > > @@ -104,8 +106,8 @@ struct sys_dev *find_driver_devices(const char *bus,
> > > const char *driver) sprintf(path, "/sys/bus/%s/drivers/%s/%s",
> > >                       bus, driver, de->d_name);
> > >
> > > -             /* if searching for nvme - skip vmd connected one */
> > > -             if (type == SYS_DEV_NVME) {
> > > +             /* if searching for nvme or ahci - skip vmd connected one */
> > > +             if (type == SYS_DEV_NVME || type == SYS_DEV_SATA) {
> > >                       struct sys_dev *dev;
> > >                       char *rp = realpath(path, NULL);
> > >                       for (dev = vmd; dev; dev = dev->next) {
> > > @@ -166,7 +168,8 @@ struct sys_dev *find_driver_devices(const char *bus,
> > > const char *driver) }
> > >       closedir(driver_dir);
> > >
> > > -     if (vmd) {
> > > +     /* VMD adopts multiple types but should only be listed once */
> > > +     if (vmd && type == SYS_DEV_NVME) {
> > >               if (list)
> > >                       list->next = vmd;
> > >               else  
> >
> > The SATA behind VMD deserves own type, let say SYS_DEV_SATA_VMD. We cannot
> > use SYS_DEV_VMD because it will allow to use NVME devices behind VMD in
> > SATA Raid array. It means that if you have them connected, like:
> > VMD___ NVME0
> >     |_ NVME1
> >     |_ SATA___SATA0
> >            |__SATA1
> > You will be able to mix SATA and NVME drives together in RAID. Mdmonitor
> > could mix them too (if appropriate policy is set). That is not allowed from
> > at least VROC requirements PoV.  
> 
> 
> Hi Mariusz
> 
> Through the description of VMD
> (https://www.chipict.com/intel_vmd_vroc/), it looks like VMD only
> supports pcie nvme devices. Can it also connect sata devices?
> 
> And what's PoV?
> 
Hi Xiao,
Not directly, there must be SATA controller behind VMD.
In VROC on server platforms we don't use that. So far I know, the reason is to
have only one driver to handle all RST devices but it could be only part of
story.

Thanks,
Mariusz