Re: [RFC XEN PATCH v2 1/3] xen/vpci: Clear all vpci status of device

["Daniel P. Smith" <dpsmith@xxxxxxxxxxxxxxxxxxxx>]

On 11/30/23 01:22, Chen, Jiqian wrote:
> Hi Roger and Daniel P. Smith,
>
> On 2023/11/28 22:08, Roger Pau Monné wrote:
> > On Fri, Nov 24, 2023 at 06:41:34PM +0800, Jiqian Chen wrote:
> > > When a device has been reset on dom0 side, the vpci on Xen
> > > side won't get notification, so the cached state in vpci is
> > > all out of date compare with the real device state.
> > > To solve that problem, this patch add new hypercall to clear
> > > all vpci device state. And when reset device happens on dom0
> > > side, dom0 can call this hypercall to notify vpci.
> > >
> > > Signed-off-by: Jiqian Chen <Jiqian.Chen@xxxxxxx>
> > > Signed-off-by: Huang Rui <ray.huang@xxxxxxx>
> > > ---
> > >   xen/arch/x86/hvm/hypercall.c  |  1 +
> > >   xen/drivers/passthrough/pci.c | 21 +++++++++++++++++++++
> > >   xen/drivers/pci/physdev.c     | 14 ++++++++++++++
> > >   xen/drivers/vpci/vpci.c       |  9 +++++++++
> > >   xen/include/public/physdev.h  |  2 ++
> > >   xen/include/xen/pci.h         |  1 +
> > >   xen/include/xen/vpci.h        |  6 ++++++
> > >   7 files changed, 54 insertions(+)
> > >
> > > diff --git a/xen/arch/x86/hvm/hypercall.c b/xen/arch/x86/hvm/hypercall.c
> > > index eeb73e1aa5..6ad5b4d5f1 100644
> > > --- a/xen/arch/x86/hvm/hypercall.c
> > > +++ b/xen/arch/x86/hvm/hypercall.c
> > > @@ -84,6 +84,7 @@ long hvm_physdev_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
> > >       case PHYSDEVOP_pci_mmcfg_reserved:
> > >       case PHYSDEVOP_pci_device_add:
> > >       case PHYSDEVOP_pci_device_remove:
> > > +    case PHYSDEVOP_pci_device_state_reset:
> > >       case PHYSDEVOP_dbgp_op:
> > >           if ( !is_hardware_domain(currd) )
> > >               return -ENOSYS;
> > > diff --git a/xen/drivers/passthrough/pci.c b/xen/drivers/passthrough/pci.c
> > > index 04d00c7c37..f871715585 100644
> > > --- a/xen/drivers/passthrough/pci.c
> > > +++ b/xen/drivers/passthrough/pci.c
> > > @@ -824,6 +824,27 @@ int pci_remove_device(u16 seg, u8 bus, u8 devfn)
> > >       return ret;
> > >   }
> > >   
> > > +int pci_reset_device_state(u16 seg, u8 bus, u8 devfn)
> > You could use pci_sbdf_t here instead of 3 parameters.
> Will change in next version, thank you.
>
> > I'm however unsure whether we really need this helper just to fetch
> > the pdev and call vpci_reset_device_state(), I think you could place
> > this logic directly in pci_physdev_op().  Unless there are plans to
> > use such logic outside of pci_physdev_op().
> If I place the logic of pci_reset_device_state directly in pci_physdev_op. I 
> think I need to declare vpci_reset_device_state in pci.h? If it is suitable, I 
> will change in next version.
>
> > > +{
> > > +    struct pci_dev *pdev;
> > > +    int ret = -ENODEV;
> > Some XSM check should be introduced fro this operation, as none of the
> > existing ones is suitable.  See xsm_resource_unplug_pci() for example.
> >
> > xsm_resource_reset_state_pci() or some such I would assume.
> I don't know what I should do in XSM function(assume it is 
> xsm_resource_reset_state_pci).
> Hi Daniel P. Smith, could you please give me some suggestions?
> Just to check the XSM_PRIV action?
Roger, thank you for seeing this and adding me in!

Jiqian, I just wanted to let you know I have seen your post but I have 
been a little tied up this week. Just with the cursory look, I think 
Roger is suggesting a new XSM check/hook is warranted.
If you would like to attempt at writing the dummy policy side, mimic 
xsm_resource_plug_pci in xen/include/xsm/dummy.h and 
xen/include/xsm/xsm.h, then I can look at handling the FLASK portion 
next week and provide it to you for inclusion into the series. If you 
are not comfortable with it, I can look at the whole thing next week. 
Just let me know what you would be comfortable with.
v/r,
dps