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Message-ID: <6b847d37-ecad-83ab-ae98-96cdd8123591@redhat.com>
Date: Thu, 3 Sep 2020 21:55:06 +0200
From: Auger Eric <eric.auger@...hat.com>
To: Diana Craciun <diana.craciun@....nxp.com>,
alex.williamson@...hat.com, kvm@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, bharatb.linux@...il.com,
laurentiu.tudor@....com
Subject: Re: [PATCH v4 06/10] vfio/fsl-mc: Added lock support in preparation
for interrupt handling
Hi Diana
On 8/26/20 11:33 AM, Diana Craciun wrote:
> Only the DPRC object allocates interrupts from the MSI
> interrupt domain. The interrupts are managed by the DPRC in
> a pool of interrupts. The access to this pool of interrupts
> has to be protected with a lock.
> This patch extends the current lock implementation to have a
> lock per DPRC.
>
> Signed-off-by: Diana Craciun <diana.craciun@....nxp.com>
> ---
> drivers/vfio/fsl-mc/vfio_fsl_mc.c | 91 +++++++++++++++++++++--
> drivers/vfio/fsl-mc/vfio_fsl_mc_private.h | 8 +-
> 2 files changed, 91 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/vfio/fsl-mc/vfio_fsl_mc.c b/drivers/vfio/fsl-mc/vfio_fsl_mc.c
> index 64d5c1fff51f..bbd3365e877e 100644
> --- a/drivers/vfio/fsl-mc/vfio_fsl_mc.c
> +++ b/drivers/vfio/fsl-mc/vfio_fsl_mc.c
> @@ -17,6 +17,77 @@
>
> static struct fsl_mc_driver vfio_fsl_mc_driver;
>
> +static DEFINE_MUTEX(reflck_lock);
> +
> +static void vfio_fsl_mc_reflck_get(struct vfio_fsl_mc_reflck *reflck)
> +{
> + kref_get(&reflck->kref);
> +}
> +
> +static void vfio_fsl_mc_reflck_release(struct kref *kref)
> +{
> + struct vfio_fsl_mc_reflck *reflck = container_of(kref,
> + struct vfio_fsl_mc_reflck,
> + kref);
> +
> + mutex_destroy(&reflck->lock);
> + kfree(reflck);
> + mutex_unlock(&reflck_lock);
> +}
> +
> +static void vfio_fsl_mc_reflck_put(struct vfio_fsl_mc_reflck *reflck)
> +{
> + kref_put_mutex(&reflck->kref, vfio_fsl_mc_reflck_release, &reflck_lock);
> +}
> +
> +static struct vfio_fsl_mc_reflck *vfio_fsl_mc_reflck_alloc(void)
> +{
> + struct vfio_fsl_mc_reflck *reflck;
> +
> + reflck = kzalloc(sizeof(*reflck), GFP_KERNEL);
> + if (!reflck)
> + return ERR_PTR(-ENOMEM);
> +
> + kref_init(&reflck->kref);
> + mutex_init(&reflck->lock);
> +
> + return reflck;
> +}
> +
> +static int vfio_fsl_mc_reflck_attach(struct vfio_fsl_mc_device *vdev)
> +{
> + int ret = 0;
> +
> + mutex_lock(&reflck_lock);
> + if (is_fsl_mc_bus_dprc(vdev->mc_dev)) {
> + vdev->reflck = vfio_fsl_mc_reflck_alloc();
this can fail and if this happens I guess you shouldn't return 0.
> + } else {
> + struct device *mc_cont_dev = vdev->mc_dev->dev.parent;
> + struct vfio_device *device;
> + struct vfio_fsl_mc_device *cont_vdev;
> +
> + device = vfio_device_get_from_dev(mc_cont_dev);
> + if (!device) {
> + ret = -ENODEV;
> + goto unlock;
> + }
> +
> + cont_vdev = vfio_device_data(device);
are we sure cont_mdev always is != NULL?
> + if (!cont_vdev->reflck) {
> + vfio_device_put(device);
> + ret = -ENODEV;
> + goto unlock;
> + }
> + vfio_fsl_mc_reflck_get(cont_vdev->reflck);
> + vdev->reflck = cont_vdev->reflck;
> + vfio_device_put(device);
> + }
> +
> +unlock:
> + mutex_unlock(&reflck_lock);
> + return ret;
> +}
> +
> static int vfio_fsl_mc_regions_init(struct vfio_fsl_mc_device *vdev)
> {
> struct fsl_mc_device *mc_dev = vdev->mc_dev;
> @@ -55,7 +126,7 @@ static int vfio_fsl_mc_open(void *device_data)
> if (!try_module_get(THIS_MODULE))
> return -ENODEV;
>
> - mutex_lock(&vdev->driver_lock);
> + mutex_lock(&vdev->reflck->lock);
> if (!vdev->refcnt) {
> ret = vfio_fsl_mc_regions_init(vdev);
> if (ret)
> @@ -63,12 +134,12 @@ static int vfio_fsl_mc_open(void *device_data)
> }
> vdev->refcnt++;
>
> - mutex_unlock(&vdev->driver_lock);
> + mutex_unlock(&vdev->reflck->lock);
>
> return 0;
>
> err_reg_init:
> - mutex_unlock(&vdev->driver_lock);
> + mutex_unlock(&vdev->reflck->lock);
> module_put(THIS_MODULE);
> return ret;
> }
> @@ -77,12 +148,12 @@ static void vfio_fsl_mc_release(void *device_data)
> {
> struct vfio_fsl_mc_device *vdev = device_data;
>
> - mutex_lock(&vdev->driver_lock);
> + mutex_lock(&vdev->reflck->lock);
>
> if (!(--vdev->refcnt))
> vfio_fsl_mc_regions_cleanup(vdev);
>
> - mutex_unlock(&vdev->driver_lock);
> + mutex_unlock(&vdev->reflck->lock);
>
> module_put(THIS_MODULE);
> }
> @@ -329,12 +400,18 @@ static int vfio_fsl_mc_probe(struct fsl_mc_device *mc_dev)
> return ret;
> }
>
> + ret = vfio_fsl_mc_reflck_attach(vdev);
> + if (ret) {
> + vfio_iommu_group_put(group, dev);
> + return ret;
> + }
> +
> ret = vfio_fsl_mc_init_device(vdev);
> if (ret < 0) {
> + vfio_fsl_mc_reflck_put(vdev->reflck);
> vfio_iommu_group_put(group, dev);
> return ret;
> }
> - mutex_init(&vdev->driver_lock);
>
> return ret;
> }
> @@ -358,7 +435,7 @@ static int vfio_fsl_mc_remove(struct fsl_mc_device *mc_dev)
>
> mc_dev->mc_io = NULL;
>
> - mutex_destroy(&vdev->driver_lock);
> + vfio_fsl_mc_reflck_put(vdev->reflck);
>
> vfio_iommu_group_put(mc_dev->dev.iommu_group, dev);
>
> diff --git a/drivers/vfio/fsl-mc/vfio_fsl_mc_private.h b/drivers/vfio/fsl-mc/vfio_fsl_mc_private.h
> index 818dfd3df4db..3b85d930e060 100644
> --- a/drivers/vfio/fsl-mc/vfio_fsl_mc_private.h
> +++ b/drivers/vfio/fsl-mc/vfio_fsl_mc_private.h
> @@ -15,6 +15,11 @@
> #define VFIO_FSL_MC_INDEX_TO_OFFSET(index) \
> ((u64)(index) << VFIO_FSL_MC_OFFSET_SHIFT)
>
> +struct vfio_fsl_mc_reflck {
> + struct kref kref;
> + struct mutex lock;
> +};
> +
> struct vfio_fsl_mc_region {
> u32 flags;
> u32 type;
> @@ -28,7 +33,8 @@ struct vfio_fsl_mc_device {
> int refcnt;
> u32 num_regions;
> struct vfio_fsl_mc_region *regions;
> - struct mutex driver_lock;
> + struct vfio_fsl_mc_reflck *reflck;
> +
> };
>
> #endif /* VFIO_FSL_MC_PRIVATE_H */
>
Thanks
Eric
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