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Message-ID:
<BL1PR12MB5849DFA05D02F1BD9A416122E76C2@BL1PR12MB5849.namprd12.prod.outlook.com>
Date: Fri, 20 Sep 2024 09:38:23 +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 2024/9/19 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.
>
>
>
>> +int pcistub_get_gsi_from_sbdf(unsigned int sbdf)
>> +{
>> + struct pcistub_device *psdev;
>> + int domain = (sbdf >> 16) & 0xffff;
>> + int bus = PCI_BUS_NUM(sbdf);
>> + int slot = PCI_SLOT(sbdf);
>> + int func = PCI_FUNC(sbdf);
>> +
>> + psdev = pcistub_device_find(domain, bus, slot, func);
>> +
>> + if (!psdev)
>> + return -ENODEV;
>> +
>> + return psdev->gsi;
>> +}
>> +EXPORT_SYMBOL_GPL(pcistub_get_gsi_from_sbdf);
>> +#endif
>> +
>> struct pci_dev *pcistub_get_pci_dev_by_slot(struct xen_pcibk_device *pdev,
>> int domain, int bus,
>> int slot, int func)
>> @@ -367,14 +392,20 @@ static int pcistub_match(struct pci_dev *dev)
>> return found;
>> }
>>
>> -static int pcistub_init_device(struct pci_dev *dev)
>> +static int pcistub_init_device(struct pcistub_device *psdev)
>> {
>> struct xen_pcibk_dev_data *dev_data;
>> + struct pci_dev *dev;
>> #ifdef CONFIG_XEN_ACPI
>> int gsi, trigger, polarity;
>> #endif
>> int err = 0;
>>
>> + if (!psdev)
>> + return -EINVAL;
>> +
>> + dev = psdev->dev;
>> +
>> dev_dbg(&dev->dev, "initializing...\n");
>>
>> /* The PCI backend is not intended to be a module (or to work with
>> @@ -452,6 +483,7 @@ static int pcistub_init_device(struct pci_dev *dev)
>> err = xen_pvh_setup_gsi(gsi, trigger, polarity);
>> if (err)
>> goto config_release;
>> + psdev->gsi = gsi;
>> }
>> #endif
>>
>> @@ -494,7 +526,7 @@ static int __init pcistub_init_devices_late(void)
>>
>> spin_unlock_irqrestore(&pcistub_devices_lock, flags);
>>
>> - err = pcistub_init_device(psdev->dev);
>> + err = pcistub_init_device(psdev);
>> if (err) {
>> dev_err(&psdev->dev->dev,
>> "error %d initializing device\n", err);
>> @@ -564,7 +596,7 @@ static int pcistub_seize(struct pci_dev *dev,
>> spin_unlock_irqrestore(&pcistub_devices_lock, flags);
>>
>> /* don't want irqs disabled when calling pcistub_init_device */
>> - err = pcistub_init_device(psdev->dev);
>> + err = pcistub_init_device(psdev);
>>
>> spin_lock_irqsave(&pcistub_devices_lock, flags);
>>
>> diff --git a/include/uapi/xen/privcmd.h b/include/uapi/xen/privcmd.h
>> index 8b8c5d1420fe..8e2c8fd44764 100644
>> --- a/include/uapi/xen/privcmd.h
>> +++ b/include/uapi/xen/privcmd.h
>> @@ -126,6 +126,11 @@ struct privcmd_ioeventfd {
>> __u8 pad[2];
>> };
>>
>> +struct privcmd_pcidev_get_gsi {
>> + __u32 sbdf;
>> + __u32 gsi;
>> +};
>> +
>> /*
>> * @cmd: IOCTL_PRIVCMD_HYPERCALL
>> * @arg: &privcmd_hypercall_t
>> @@ -157,5 +162,7 @@ struct privcmd_ioeventfd {
>> _IOW('P', 8, struct privcmd_irqfd)
>> #define IOCTL_PRIVCMD_IOEVENTFD \
>> _IOW('P', 9, struct privcmd_ioeventfd)
>> +#define IOCTL_PRIVCMD_PCIDEV_GET_GSI \
>> + _IOC(_IOC_NONE, 'P', 10, sizeof(struct privcmd_pcidev_get_gsi))
>>
>> #endif /* __LINUX_PUBLIC_PRIVCMD_H__ */
>> diff --git a/include/xen/acpi.h b/include/xen/acpi.h
>> index 3bcfe82d9078..393a73bfda24 100644
>> --- a/include/xen/acpi.h
>> +++ b/include/xen/acpi.h
>> @@ -91,4 +91,13 @@ static inline int xen_acpi_get_gsi_info(struct pci_dev *dev,
>> }
>> #endif
>>
>> +#ifdef CONFIG_XEN_PCIDEV_BACKEND
>> +int pcistub_get_gsi_from_sbdf(unsigned int sbdf);
>> +#else
>> +static inline int pcistub_get_gsi_from_sbdf(unsigned int sbdf)
>> +{
>> + return -1;
>> +}
>> +#endif
>> +
>> #endif /* _XEN_ACPI_H */
>> --
>> 2.34.1
>>
--
Best regards,
Jiqian Chen.
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