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SubjectRE: [PATCH 3/5] misc: vop: simply return the saved dma address instead of virt_to_phys
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Hi Greg,

> -----Original Message-----
> On Fri, Sep 25, 2020 at 03:26:28PM +0800, Sherry Sun wrote:
> > For noncoherent platform, the device page and vring should allocated
> > by dma_alloc_coherent, when user space wants to get its physical
> > address, virt_to_phys cannot be used, should simply return the saved
> > device page dma address by get_dp_dma callback and the vring dma
> > address saved in mic_vqconfig.
> >
> > Signed-off-by: Sherry Sun <sherry.sun@nxp.com>
> > Signed-off-by: Joakim Zhang <qiangqing.zhang@nxp.com>
> > ---
> > drivers/misc/mic/bus/vop_bus.h | 2 ++
> > drivers/misc/mic/host/mic_boot.c | 8 ++++++++
> > drivers/misc/mic/vop/vop_vringh.c | 12 ++++++++++--
> > 3 files changed, 20 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/misc/mic/bus/vop_bus.h
> > b/drivers/misc/mic/bus/vop_bus.h index 4fa02808c1e2..d891eacae358
> > 100644
> > --- a/drivers/misc/mic/bus/vop_bus.h
> > +++ b/drivers/misc/mic/bus/vop_bus.h
> > @@ -75,6 +75,7 @@ struct vop_driver {
> > * node to add/remove/configure virtio devices.
> > * @get_dp: Get access to the virtio device page used by the self
> > * node to add/remove/configure virtio devices.
> > + * @get_dp_dma: Get dma address of the virtio device page.
> > * @send_intr: Send an interrupt to the peer node on a specified doorbell.
> > * @remap: Map a buffer with the specified DMA address and length.
> > * @unmap: Unmap a buffer previously mapped.
> > @@ -92,6 +93,7 @@ struct vop_hw_ops {
> > void (*ack_interrupt)(struct vop_device *vpdev, int num);
> > void __iomem * (*get_remote_dp)(struct vop_device *vpdev);
> > void * (*get_dp)(struct vop_device *vpdev);
> > + dma_addr_t (*get_dp_dma)(struct vop_device *vpdev);
> > void (*send_intr)(struct vop_device *vpdev, int db);
> > void __iomem * (*remap)(struct vop_device *vpdev,
> > dma_addr_t pa, size_t len);
> > diff --git a/drivers/misc/mic/host/mic_boot.c
> > b/drivers/misc/mic/host/mic_boot.c
> > index fb5b3989753d..ced03662cd8f 100644
> > --- a/drivers/misc/mic/host/mic_boot.c
> > +++ b/drivers/misc/mic/host/mic_boot.c
> > @@ -88,6 +88,13 @@ static void *__mic_get_dp(struct vop_device *vpdev)
> > return mdev->dp;
> > }
> >
> > +static dma_addr_t __mic_get_dp_dma(struct vop_device *vpdev) {
> > + struct mic_device *mdev = vpdev_to_mdev(&vpdev->dev);
> > +
> > + return mdev->dp_dma_addr;
> > +}
> > +
> > static void __iomem *__mic_get_remote_dp(struct vop_device *vpdev) {
> > return NULL;
> > @@ -119,6 +126,7 @@ static struct vop_hw_ops vop_hw_ops = {
> > .ack_interrupt = __mic_ack_interrupt,
> > .next_db = __mic_next_db,
> > .get_dp = __mic_get_dp,
> > + .get_dp_dma = __mic_get_dp_dma,
> > .get_remote_dp = __mic_get_remote_dp,
> > .send_intr = __mic_send_intr,
> > .remap = __mic_ioremap,
> > diff --git a/drivers/misc/mic/vop/vop_vringh.c
> > b/drivers/misc/mic/vop/vop_vringh.c
> > index fc8d8ff9ded3..aa2dd240c11e 100644
> > --- a/drivers/misc/mic/vop/vop_vringh.c
> > +++ b/drivers/misc/mic/vop/vop_vringh.c
> > @@ -1076,6 +1076,7 @@ vop_query_offset(struct vop_vdev *vdev,
> unsigned long offset,
> > unsigned long *size, unsigned long *pa) {
> > struct vop_device *vpdev = vdev->vpdev;
> > + struct mic_vqconfig *vqconfig = mic_vq_config(vdev->dd);
> > unsigned long start = MIC_DP_SIZE;
> > int i;
> >
> > @@ -1088,7 +1089,14 @@ vop_query_offset(struct vop_vdev *vdev,
> unsigned long offset,
> > * ....
> > */
> > if (!offset) {
> > - *pa = virt_to_phys(vpdev->hw_ops->get_dp(vpdev));
> > + if (vpdev->hw_ops->get_dp_dma)
> > + *pa = vpdev->hw_ops->get_dp_dma(vpdev);
> > + else {
> > + dev_err(vop_dev(vdev), "can't get device page
> physical address\n");
> > + WARN_ON(1);
>
> Don't crash kernels that have panic_on_warn set for things you can recover
> from.
>

Do you mean that we should avoid to use WARN_ON here?

> > + return -1;
>
> Use a real error value, do not make them up.

Ok, will change it. Thanks.

Best regards
Sherry

>
> thanks,
>
> greg k-h

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