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

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

On 2023/12/4 19:10, Roger Pau Monné wrote:
> On Mon, Dec 04, 2023 at 06:57:03AM +0000, Chen, Jiqian wrote:
>> Hi Daniel P. Smith,
>>
>> On 2023/11/30 22:52, Roger Pau Monné wrote:
>>> On Thu, Nov 30, 2023 at 07:39:38AM -0500, Daniel P. Smith wrote:
>>>> On 11/30/23 07:25, 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 all out of date compare with the real device state.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.
>>>>
>>>> Apologies, thinking about for a moment and was thinking the hook should be
>>>> called xsm_resource_config_pci. I would reset as a config operation and
>>>> there might be new ones in the future. I do not believe there is a need to
>>>> have fine grain access control down to individual config operation, thus
>>>> they could all be captured under this one hook. Roger, what are your
>>>> thoughts about this, in particular how you see vpci evolving?
>>>
>>> So the configuration space reset should only be done by the domain
>>> that's also capable of triggering the physical device reset, usually
>>> the hardware domain.  I don't think it's possible ATM to allow a
>>> domain different than the hardware domain to perform a PCI reset, as
>>> doing it requires unmediated access to the PCI config space.
>>>
>>> So resetting the vPCI state should either be limited to the hardware
>>> domain, or to a pci reset capability explicitly
>>> (xsm_resource_reset_pci or some such?).  Or maybe
>>> xsm_resource_config_pci if that denotes unmediated access to the PCI
>>> config space.
>>>
>>> Thanks, Roger.
>>
>> Is it like below that I need to add for XSM?
>> diff --git a/xen/xsm/dummy.c b/xen/xsm/dummy.c
>> index e6ffa948f7..7a289ba5d8 100644
>> --- a/xen/xsm/dummy.c
>> +++ b/xen/xsm/dummy.c
>> @@ -91,6 +91,7 @@ static const struct xsm_ops __initconst_cf_clobber 
>> dummy_ops = {
>>      .resource_plug_pci             = xsm_resource_plug_pci,
>>      .resource_unplug_pci           = xsm_resource_unplug_pci,
>>      .resource_setup_pci            = xsm_resource_setup_pci,
>> +    .resource_config_pci            = xsm_resource_config_pci,
> 
> Now that I look at it, using the existing xsm_resource_setup_pci might
> be enough, no need to introduce a xsm_resource_config_pci.
Ok, thank you. I will add xsm_resource_setup_pci check into 
PHYSDEVOP_pci_device_state_reset next step.

> 
> Thanks, Roger.

-- 
Best regards,
Jiqian Chen.