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Date:   Fri, 7 Aug 2020 09:07:53 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     FelixCui-oc <FelixCui-oc@...oxin.com>,
        Joerg Roedel <joro@...tes.org>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        David Woodhouse <dwmw2@...radead.org>
Cc:     baolu.lu@...ux.intel.com,
        RaymondPang-oc <RaymondPang-oc@...oxin.com>,
        CobeChen-oc <CobeChen-oc@...oxin.com>
Subject: Re: 答复: 答复: 答复: 答复: 答复: 答复: [PATCH] iommu/vt-d:Add support for ACPI device in RMRR

Hi Felix,

On 2020/8/6 14:51, FelixCui-oc wrote:
> Hi  baolu,
> 		>Sure. Before that, let me sync my understanding with you. You have an acpi namespace device in ANDD table, it also shows up in the device scope of a RMRR.
> 		>Current code doesn't enumerate that device for the RMRR, hence iommu_create_device_direct_mappings() doesn't work for this device.
> 
> 		>At the same time, probe_acpi_namespace_devices() doesn't work for this device, hence you want to add a home-made
> 		>acpi_device_create_direct_mappings() helper.
> 
> 		Your understanding is right.
> 		But there is a problem that even if the namespace device in rmrr is enumerated in the code, probe_acpi_namespace_devices() also doesn't work for this device.
> 		This is because the dev parameter of the iommu_create_device_direct_mappings() is not the namespace device in RMRR.
> 		The actual parameter passed in is the namespace device's physical node device.
> 		In iommu_create_device_direct_mappings(), the physical node device passed in cannot match the namespace device in rmrr->device[],right?
> 		We need acpi_device_create_direct_mappings() helper ?
> 
> 		In addition, adev->physical_node_list is related to the __HID of namespace device reported by the bios.
> 		For example, if the __HID reported by the bios belongs to acpi_pnp_device_ids[], adev->physical_node_list has no devices.
> 		So in acpi_device_create_direct_mappings(), I added the case that adev->physical_node_list is empty.

Got you. Thanks!

Have you ever tried to have probe_acpi_namespace_devices() handle the
case of empty adev->physical_node_list at the same time?

Best regards,
baolu

> 
> 
> Best regards
> Felix cui
> 
> 
>   
> 
> -----邮件原件-----
> 发件人: Lu Baolu <baolu.lu@...ux.intel.com>
> 发送时间: 2020年8月6日 10:36
> 收件人: FelixCui-oc <FelixCui-oc@...oxin.com>; Joerg Roedel <joro@...tes.org>; iommu@...ts.linux-foundation.org; linux-kernel@...r.kernel.org; David Woodhouse <dwmw2@...radead.org>
> 抄送: baolu.lu@...ux.intel.com; RaymondPang-oc <RaymondPang-oc@...oxin.com>; CobeChen-oc <CobeChen-oc@...oxin.com>
> 主题: Re: 答复: 答复: 答复: 答复: 答复: [PATCH] iommu/vt-d:Add support for ACPI device in RMRR
> 
> Hi Felix,
> 
> On 8/5/20 3:37 PM, FelixCui-oc wrote:
>> Hi baolu,
>> 		Let me talk about why acpi_device_create_direct_mappings() is needed and please tell me if there is an error.
> 
> Sure. Before that, let me sync my understanding with you. You have an acpi namespace device in ANDD table, it also shows up in the device scope of a RMRR. Current code doesn't enumerate that device for the RMRR, hence iommu_create_device_direct_mappings() doesn't work for this device.
> 
> At the same time, probe_acpi_namespace_devices() doesn't work for this device, hence you want to add a home-made
> acpi_device_create_direct_mappings() helper.
> 
> Did I get it right?
> 
>> 		In the probe_acpi_namespace_devices() function, only the device in the addev->physical_node_list is probed,
>> 		but we need to establish identity mapping for the namespace device in RMRR. These are two different devices.
> 
> The namespace device has been probed and put in one drhd's device list.
> Hence, it should be processed by probe_acpi_namespace_devices(). So the question is why there are no devices in addev->physical_node_list?
> 
>> 		Therefore, the namespace device in RMRR is not mapped in probe_acpi_namespace_devices().
>> 		acpi_device_create_direct_mappings() is to create direct mappings for namespace devices in RMRR.
> 
> Best regards,
> baolu
> 

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