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

["Chen, Jiqian" <Jiqian.Chen@xxxxxxx>]

On 2023/11/30 20:25, Daniel P. Smith wrote:
> 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 all out of date compare with the real device state.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.
I will refer to xsm_resource_unplug_pci and try to add dummy policy in next 
version. I am looking forward your review and guide. Thank you very much!

> 
> v/r,
> dps

-- 
Best regards,
Jiqian Chen.