linux-kernel - Re: [PATCH v3 06/10] s390/pci: Update the logic for detecting passthrough device

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Message-ID: <772044e77530fe56ae398afa57deaf2d39d56d77.camel@linux.ibm.com>
Date: Mon, 15 Sep 2025 11:22:22 +0200
From: Niklas Schnelle <schnelle@...ux.ibm.com>
To: Farhan Ali <alifm@...ux.ibm.com>, linux-s390@...r.kernel.org,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-pci@...r.kernel.org
Cc: alex.williamson@...hat.com, helgaas@...nel.org, mjrosato@...ux.ibm.com
Subject: Re: [PATCH v3 06/10] s390/pci: Update the logic for detecting
 passthrough device

On Thu, 2025-09-11 at 11:33 -0700, Farhan Ali wrote:
> We can now have userspace drivers (vfio-pci based) on s390x. The userspace
> drivers will not have any KVM fd and so no kzdev associated with them. So
> we need to update the logic for detecting passthrough devices to not depend
> on struct kvm_zdev.
> 
> Signed-off-by: Farhan Ali <alifm@...ux.ibm.com>
> ---
>  arch/s390/include/asm/pci.h      |  1 +
>  arch/s390/pci/pci_event.c        | 14 ++++----------
>  drivers/vfio/pci/vfio_pci_zdev.c |  9 ++++++++-
>  3 files changed, 13 insertions(+), 11 deletions(-)
> 
> diff --git a/arch/s390/include/asm/pci.h b/arch/s390/include/asm/pci.h
> index aed19a1aa9d7..f47f62fc3bfd 100644
> --- a/arch/s390/include/asm/pci.h
> +++ b/arch/s390/include/asm/pci.h
> @@ -169,6 +169,7 @@ struct zpci_dev {
>  
>  	char res_name[16];
>  	bool mio_capable;
> +	bool mediated_recovery;
>  	struct zpci_bar_struct bars[PCI_STD_NUM_BARS];
>  
>  	u64		start_dma;	/* Start of available DMA addresses */
> diff --git a/arch/s390/pci/pci_event.c b/arch/s390/pci/pci_event.c
> index d930416d4c90..541d536be052 100644
> --- a/arch/s390/pci/pci_event.c
> +++ b/arch/s390/pci/pci_event.c
> @@ -61,16 +61,10 @@ static inline bool ers_result_indicates_abort(pci_ers_result_t ers_res)
>  	}
>  }
>  
> -static bool is_passed_through(struct pci_dev *pdev)
> +static bool needs_mediated_recovery(struct pci_dev *pdev)
>  {
>  	struct zpci_dev *zdev = to_zpci(pdev);
> -	bool ret;
> -
> -	mutex_lock(&zdev->kzdev_lock);
> -	ret = !!zdev->kzdev;
> -	mutex_unlock(&zdev->kzdev_lock);
> -
> -	return ret;
> +	return zdev->mediated_recovery;
>  }
>  
--- snip ---

Looks good to me.

Reviewed-by: Niklas Schnelle <schnelle@...ux.ibm.com>