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Message-ID:
<BL1PR12MB584987F7DF08909143AC0E21E76F2@BL1PR12MB5849.namprd12.prod.outlook.com>
Date: Mon, 23 Sep 2024 05:49:09 +0000
From: "Chen, Jiqian" <Jiqian.Chen@....com>
To: Stefano Stabellini <sstabellini@...nel.org>
CC: Juergen Gross <jgross@...e.com>, "xen-devel@...ts.xenproject.org"
<xen-devel@...ts.xenproject.org>, "linux-kernel@...r.kernel.org"
<linux-kernel@...r.kernel.org>, "Huang, Ray" <Ray.Huang@....com>, "Chen,
Jiqian" <Jiqian.Chen@....com>
Subject: Re: [KERNEL PATCH v9 3/3] xen/privcmd: Add new syscall to get gsi
from dev
On 2024/9/21 05:17, Stefano Stabellini wrote:
> On Fri, 20 Sep 2024, Chen, Jiqian wrote:
>> On 2024/9/19 06:49, Stefano Stabellini wrote:
>>> On Thu, 12 Sep 2024, Jiqian Chen wrote:
>>>> On PVH dom0, when passthrough a device to domU, QEMU and xl tools
>>>> want to use gsi number to do pirq mapping, see QEMU code
>>>> xen_pt_realize->xc_physdev_map_pirq, and xl code
>>>> pci_add_dm_done->xc_physdev_map_pirq, but in current codes, the gsi
>>>> number is got from file /sys/bus/pci/devices/<sbdf>/irq, that is
>>>> wrong, because irq is not equal with gsi, they are in different
>>>> spaces, so pirq mapping fails.
>>>> And in current linux codes, there is no method to get gsi
>>>> for userspace.
>>>>
>>>> For above purpose, record gsi of pcistub devices when init
>>>> pcistub and add a new syscall into privcmd to let userspace
>>>> can get gsi when they have a need.
>>>>
>>>> Signed-off-by: Jiqian Chen <Jiqian.Chen@....com>
>>>> Signed-off-by: Huang Rui <ray.huang@....com>
>>>> Signed-off-by: Jiqian Chen <Jiqian.Chen@....com>
>>>> ---
>>>> v8->v9 changes:
>>>> Changed the syscall name from "IOCTL_PRIVCMD_GSI_FROM_DEV" to "IOCTL_PRIVCMD_PCIDEV_GET_GSI". Also changed the other functions name.
>>>> Changed the macro wrapping "pcistub_get_gsi_from_sbdf" from "CONFIG_XEN_ACPI" to "CONFIG_XEN_PCIDEV_BACKEND" to fix compile errors reported by CI robot.
>>>> Changed the parameter gsi of struct privcmd_pcidev_get_gsi from int to u32.
>>>>
>>>> v7->v8 changes:
>>>> In function privcmd_ioctl_gsi_from_dev, return -EINVAL when not confige CONFIG_XEN_ACPI.
>>>> Used PCI_BUS_NUM PCI_SLOT PCI_FUNC instead of open coding.
>>>>
>>>> v6->v7 changes:
>>>> Changed implementation to add a new parameter "gsi" to struct pcistub_device and set gsi when pcistub initialize device. Then when userspace wants to get gsi and pass sbdf, we can return that gsi.
>>>>
>>>> v5->v6 changes:
>>>> Changed implementation to add a new syscall to translate irq to gsi, instead adding a new gsi sysfs node, because the pci Maintainer didn't allow to add that sysfs node.
>>>>
>>>> v3->v5 changes:
>>>> No.
>>>>
>>>> v2->v3 changes:
>>>> Suggested by Roger: Abandoned previous implementations that added new syscall to get gsi from irq and changed to add a new sysfs node for gsi, then userspace can get gsi number from sysfs node.
>>>> ---
>>>> | Reported-by: kernel test robot <lkp@...el.com>
>>>> | Closes: https://lore.kernel.org/oe-kbuild-all/202406090826.whl6Cb7R-lkp@intel.com/
>>>> ---
>>>> | Reported-by: kernel test robot <lkp@...el.com>
>>>> | Closes: https://lore.kernel.org/oe-kbuild-all/202405171113.T431PC8O-lkp@intel.com/
>>>> ---
>>>> drivers/xen/privcmd.c | 30 +++++++++++++++++++++++
>>>> drivers/xen/xen-pciback/pci_stub.c | 38 +++++++++++++++++++++++++++---
>>>> include/uapi/xen/privcmd.h | 7 ++++++
>>>> include/xen/acpi.h | 9 +++++++
>>>> 4 files changed, 81 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
>>>> index 9563650dfbaf..1ed612d21543 100644
>>>> --- a/drivers/xen/privcmd.c
>>>> +++ b/drivers/xen/privcmd.c
>>>> @@ -46,6 +46,9 @@
>>>> #include <xen/page.h>
>>>> #include <xen/xen-ops.h>
>>>> #include <xen/balloon.h>
>>>> +#ifdef CONFIG_XEN_ACPI
>>>> +#include <xen/acpi.h>
>>>> +#endif
>>>>
>>>> #include "privcmd.h"
>>>>
>>>> @@ -844,6 +847,29 @@ static long privcmd_ioctl_mmap_resource(struct file *file,
>>>> return rc;
>>>> }
>>>>
>>>> +static long privcmd_ioctl_pcidev_get_gsi(struct file *file, void __user *udata)
>>>> +{
>>>> +#ifdef CONFIG_XEN_ACPI
>>>> + int rc;
>>>> + struct privcmd_pcidev_get_gsi kdata;
>>>> +
>>>> + if (copy_from_user(&kdata, udata, sizeof(kdata)))
>>>> + return -EFAULT;
>>>> +
>>>> + rc = pcistub_get_gsi_from_sbdf(kdata.sbdf);
>>>> + if (rc < 0)
>>>> + return rc;
>>>> +
>>>> + kdata.gsi = rc;
>>>> + if (copy_to_user(udata, &kdata, sizeof(kdata)))
>>>> + return -EFAULT;
>>>> +
>>>> + return 0;
>>>> +#else
>>>> + return -EINVAL;
>>>> +#endif
>>>> +}
>>>> +
>>>> #ifdef CONFIG_XEN_PRIVCMD_EVENTFD
>>>> /* Irqfd support */
>>>> static struct workqueue_struct *irqfd_cleanup_wq;
>>>> @@ -1543,6 +1569,10 @@ static long privcmd_ioctl(struct file *file,
>>>> ret = privcmd_ioctl_ioeventfd(file, udata);
>>>> break;
>>>>
>>>> + case IOCTL_PRIVCMD_PCIDEV_GET_GSI:
>>>> + ret = privcmd_ioctl_pcidev_get_gsi(file, udata);
>>>> + break;
>>>> +
>>>> default:
>>>> break;
>>>> }
>>>> diff --git a/drivers/xen/xen-pciback/pci_stub.c b/drivers/xen/xen-pciback/pci_stub.c
>>>> index 8ce27333f54b..2ea8e4075adc 100644
>>>> --- a/drivers/xen/xen-pciback/pci_stub.c
>>>> +++ b/drivers/xen/xen-pciback/pci_stub.c
>>>> @@ -56,6 +56,9 @@ struct pcistub_device {
>>>>
>>>> struct pci_dev *dev;
>>>> struct xen_pcibk_device *pdev;/* non-NULL if struct pci_dev is in use */
>>>> +#ifdef CONFIG_XEN_ACPI
>>>> + int gsi;
>>>> +#endif
>>>> };
>>>>
>>>> /* Access to pcistub_devices & seized_devices lists and the initialize_devices
>>>> @@ -88,6 +91,9 @@ static struct pcistub_device *pcistub_device_alloc(struct pci_dev *dev)
>>>>
>>>> kref_init(&psdev->kref);
>>>> spin_lock_init(&psdev->lock);
>>>> +#ifdef CONFIG_XEN_ACPI
>>>> + psdev->gsi = -1;
>>>> +#endif
>>>>
>>>> return psdev;
>>>> }
>>>> @@ -220,6 +226,25 @@ static struct pci_dev *pcistub_device_get_pci_dev(struct xen_pcibk_device *pdev,
>>>> return pci_dev;
>>>> }
>>>>
>>>> +#ifdef CONFIG_XEN_PCIDEV_BACKEND
>>>
>>>
>>> This breaks configurations without CONFIG_ACPI and with
>>> CONFIG_XEN_PCIDEV_BACKEND.
>>>
>>> Also there should be no dependency between PCIDEV_BACKEND and
>>> pcistub_get_gsi_from_sbdf.
>>>
>>> I think we should solve the build issues this way:
>>>
>>> - privcmd_ioctl_pcidev_get_gsi should have:
>>> #if defined(CONFIG_XEN_ACPI) && defined(CONFIG_XEN_PCI_STUB)
>>>
>>> - here we should have #ifdef CONFIG_XEN_ACPI as you had before
>>>
>>>
>>> As far as I can tell the above should be able to address all valid
>>> combinations.
>> This can't pass a combination that:
>> CONFIG_XEN_ACPI=y
>> CONFIG_XEN_PCI_STUB=y
>> CONFIG_XEN_PCIDEV_BACKEND=m
>> Reported by robot https://lore.kernel.org/oe-kbuild-all/202406090826.whl6Cb7R-lkp@intel.com/
>>
>> At this combination, privcmd_ioctl_pcidev_get_gsi can call pcistub_get_gsi_from_sbdf because CONFIG_XEN_ACPI and CONFIG_XEN_PCI_STUB are both "y".
>> But when the compiler tries to find the implementation of pcistub_get_gsi_from_sbdf, it fails (ld: vmlinux.o: in function `privcmd_ioctl_pcidev_get_gsi':
>> /home/cjq/code/upstream/kernel_test_robot/linux_xen/build_dir/../drivers/xen/privcmd.c:859: undefined reference to `pcistub_get_gsi_from_sbdf'), because the value of CONFIG_XEN_PCIDEV_BACKEND is "m" (file drivers/xen/xen-pciback/Makefile shows "obj-$(CONFIG_XEN_PCIDEV_BACKEND) += xen-pciback.o"), so that xen-pciback is built as a module.
>
>
> The attached .config, with the appended changes on top of your patch
> work for me. I have CONFIG_XEN_PCIDEV_BACKEND=m.
Using your attached .config, it also works for me.
The difference between your .config and the config reported by Robot (https://download.01.org/0day-ci/archive/20240609/202406090826.whl6Cb7R-lkp@intel.com/config) is that your CONFIG_XEN_PRIVCMD=m, but Robot's CONFIG_XEN_PRIVCMD=y.
It seems that, with my patch changes, privcmd uses the function implemented by xen-pciback, so if the configuration is "CONFIG_XEN_PRIVCMD=m & CONFIG_XEN_PCIDEV_BACKEND=m" or "CONFIG_XEN_PRIVCMD=y & CONFIG_XEN_PCIDEV_BACKEND=y", the compilation is OK, but if the configuration is "CONFIG_XEN_PRIVCMD=y & CONFIG_XEN_PCIDEV_BACKEND=m", issue happens.
You can change CONFIG_XEN_PRIVCMD from "m" to "y" in your .config, then you will fail at:
ld: vmlinux.o: in function `privcmd_ioctl':
privcmd.c:(.text+0x665e42): undefined reference to `pcistub_get_gsi_from_sbdf'
>
>
> diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
> index 1ed612d21543..49e1c5e0c32a 100644
> --- a/drivers/xen/privcmd.c
> +++ b/drivers/xen/privcmd.c
> @@ -849,7 +849,7 @@ static long privcmd_ioctl_mmap_resource(struct file *file,
>
> static long privcmd_ioctl_pcidev_get_gsi(struct file *file, void __user *udata)
> {
> -#ifdef CONFIG_XEN_ACPI
> +#if defined(CONFIG_XEN_ACPI) && defined(CONFIG_XEN_PCI_STUB)
> int rc;
> struct privcmd_pcidev_get_gsi kdata;
>
> diff --git a/drivers/xen/xen-pciback/pci_stub.c b/drivers/xen/xen-pciback/pci_stub.c
> index 2ea8e4075adc..d5807b622a59 100644
> --- a/drivers/xen/xen-pciback/pci_stub.c
> +++ b/drivers/xen/xen-pciback/pci_stub.c
> @@ -226,7 +226,7 @@ static struct pci_dev *pcistub_device_get_pci_dev(struct xen_pcibk_device *pdev,
> return pci_dev;
> }
>
> -#ifdef CONFIG_XEN_PCIDEV_BACKEND
> +#ifdef CONFIG_ACPI
> int pcistub_get_gsi_from_sbdf(unsigned int sbdf)
> {
> struct pcistub_device *psdev;
--
Best regards,
Jiqian Chen.
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