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Message-ID: <alpine.DEB.2.22.394.2409241538260.1417852@ubuntu-linux-20-04-desktop>
Date: Tue, 24 Sep 2024 15:38:30 -0700 (PDT)
From: Stefano Stabellini <sstabellini@...nel.org>
To: Jiqian Chen <Jiqian.Chen@....com>
cc: Juergen Gross <jgross@...e.com>,
Stefano Stabellini <sstabellini@...nel.org>,
Bjorn Helgaas <bhelgaas@...gle.com>,
"Rafael J . Wysocki" <rafael@...nel.org>, xen-devel@...ts.xenproject.org,
linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
linux-acpi@...r.kernel.org, Huang Rui <ray.huang@....com>
Subject: Re: [KERNEL PATCH v10 3/3] xen/privcmd: Add new syscall to get gsi
from dev
On Tue, 24 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>
This looks OK to me now. Assuming it passes the various possible
builds with different configuration combinations:
Reviewed-by: Stefano Stabellini <sstabellini@...nel.org>
> ---
> v9->v10 changes:
> Changed the macro wrapping "pcistub_get_gsi_from_sbdf" from "CONFIG_XEN_PCIDEV_BACKEND" to "CONFIG_XEN_ACPI".
> Added "imply CONFIG_XEN_PCIDEV_BACKEND" for CONFIG_XEN_PRIVCMD Kconfig definition.
> Added check "if (IS_REACHABLE(CONFIG_XEN_PCIDEV_BACKEND))" before calling pcistub_get_gsi_from_sbdf.
>
> 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.
> ---
> drivers/xen/Kconfig | 1 +
> drivers/xen/privcmd.c | 32 +++++++++++++++++++++++++
> drivers/xen/xen-pciback/pci_stub.c | 38 +++++++++++++++++++++++++++---
> include/uapi/xen/privcmd.h | 7 ++++++
> include/xen/acpi.h | 9 +++++++
> 5 files changed, 84 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
> index d5989871dd5d..fd83d51df2f4 100644
> --- a/drivers/xen/Kconfig
> +++ b/drivers/xen/Kconfig
> @@ -261,6 +261,7 @@ config XEN_SCSI_BACKEND
> config XEN_PRIVCMD
> tristate "Xen hypercall passthrough driver"
> depends on XEN
> + imply CONFIG_XEN_PCIDEV_BACKEND
> default m
> help
> The hypercall passthrough driver allows privileged user programs to
> diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
> index 9563650dfbaf..588f99a2b8df 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 +847,31 @@ static long privcmd_ioctl_mmap_resource(struct file *file,
> return rc;
> }
>
> +static long privcmd_ioctl_pcidev_get_gsi(struct file *file, void __user *udata)
> +{
> +#if defined(CONFIG_XEN_ACPI)
> + int rc = -EINVAL;
> + struct privcmd_pcidev_get_gsi kdata;
> +
> + if (copy_from_user(&kdata, udata, sizeof(kdata)))
> + return -EFAULT;
> +
> + if (IS_REACHABLE(CONFIG_XEN_PCIDEV_BACKEND))
> + 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 +1571,10 @@ 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..d003402ce66b 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_ACPI
> +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..daa96a22d257 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_PCI_STUB
> +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
>
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