linux-kernel - Re: [PATCH] s390/vfio-ap: fix sysfs status attribute for AP queue devices

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Date:   Mon, 6 Nov 2023 11:03:39 -0500
From:   Tony Krowiak <akrowiak@...ux.ibm.com>
To:     linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     jjherne@...ux.ibm.com, pasic@...ux.ibm.com,
        borntraeger@...ux.ibm.com, frankja@...ux.ibm.com,
        imbrenda@...ux.ibm.com, david@...hat.com, stable@...r.kernel.org
Subject: Re: [PATCH] s390/vfio-ap: fix sysfs status attribute for AP queue
 devices

PING
This patch is pretty straight forward, does anyone see a reason why this 
shouldn't be integrated?

On 10/20/23 16:48, Tony Krowiak wrote:
> The 'status' attribute for AP queue devices bound to the vfio_ap device
> driver displays incorrect status when the mediated device is attached to a
> guest, but the queue device is not passed through. In the current
> implementation, the status displayed is 'in_use' which is not correct; it
> should be 'assigned'. This can happen if one of the queue devices
> associated with a given adapter is not bound to the vfio_ap device driver.
> For example:
> 
> Queues listed in /sys/bus/ap/drivers/vfio_ap:
> 14.0005
> 14.0006
> 14.000d
> 16.0006
> 16.000d
> 
> Queues listed in /sys/devices/vfio_ap/matrix/$UUID/matrix
> 14.0005
> 14.0006
> 14.000d
> 16.0005
> 16.0006
> 16.000d
> 
> Queues listed in /sys/devices/vfio_ap/matrix/$UUID/guest_matrix
> 14.0005
> 14.0006
> 14.000d
> 
> The reason no queues for adapter 0x16 are listed in the guest_matrix is
> because queue 16.0005 is not bound to the vfio_ap device driver, so no
> queue associated with the adapter is passed through to the guest;
> therefore, each queue device for adapter 0x16 should display 'assigned'
> instead of 'in_use', because those queues are not in use by a guest, but
> only assigned to the mediated device.
> 
> Let's check the AP configuration for the guest to determine whether a
> queue device is passed through before displaying a status of 'in_use'.
> 
> Signed-off-by: Tony Krowiak <akrowiak@...ux.ibm.com>
> Fixes: f139862b92cf ("s390/vfio-ap: add status attribute to AP queue device's sysfs dir")
> Cc: stable@...r.kernel.org
> ---
>   drivers/s390/crypto/vfio_ap_ops.c | 7 ++++++-
>   1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
> index 4db538a55192..871c14a6921f 100644
> --- a/drivers/s390/crypto/vfio_ap_ops.c
> +++ b/drivers/s390/crypto/vfio_ap_ops.c
> @@ -1976,6 +1976,7 @@ static ssize_t status_show(struct device *dev,
>   {
>   	ssize_t nchars = 0;
>   	struct vfio_ap_queue *q;
> +	unsigned long apid, apqi;
>   	struct ap_matrix_mdev *matrix_mdev;
>   	struct ap_device *apdev = to_ap_dev(dev);
>   
> @@ -1984,7 +1985,11 @@ static ssize_t status_show(struct device *dev,
>   	matrix_mdev = vfio_ap_mdev_for_queue(q);
>   
>   	if (matrix_mdev) {
> -		if (matrix_mdev->kvm)
> +		apid = AP_QID_CARD(q->apqn);
> +		apqi = AP_QID_QUEUE(q->apqn);
> +		if (matrix_mdev->kvm &&
> +		    test_bit_inv(apid, matrix_mdev->shadow_apcb.apm) &&
> +		    test_bit_inv(apqi, matrix_mdev->shadow_apcb.aqm))
>   			nchars = scnprintf(buf, PAGE_SIZE, "%s\n",
>   					   AP_QUEUE_IN_USE);
>   		else