linux-kernel - Re: [PATCH 05/19] virtio: Implement get_shm

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Message-ID: <20190827115409.GB30873@redhat.com>
Date:   Tue, 27 Aug 2019 07:54:09 -0400
From:   Vivek Goyal <vgoyal@...hat.com>
To:     Cornelia Huck <cohuck@...hat.com>
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-nvdimm@...ts.01.org, virtio-fs@...hat.com, miklos@...redi.hu,
        stefanha@...hat.com, dgilbert@...hat.com,
        Sebastien Boeuf <sebastien.boeuf@...el.com>,
        kvm@...r.kernel.org
Subject: Re: [PATCH 05/19] virtio: Implement get_shm_region for MMIO transport

On Tue, Aug 27, 2019 at 10:39:43AM +0200, Cornelia Huck wrote:
> On Wed, 21 Aug 2019 13:57:06 -0400
> Vivek Goyal <vgoyal@...hat.com> wrote:
> 
> > From: Sebastien Boeuf <sebastien.boeuf@...el.com>
> > 
> > On MMIO a new set of registers is defined for finding SHM
> > regions.  Add their definitions and use them to find the region.
> > 
> > Cc: kvm@...r.kernel.org
> > Signed-off-by: Sebastien Boeuf <sebastien.boeuf@...el.com>
> > ---
> >  drivers/virtio/virtio_mmio.c     | 32 ++++++++++++++++++++++++++++++++
> >  include/uapi/linux/virtio_mmio.h | 11 +++++++++++
> >  2 files changed, 43 insertions(+)
> > 
> > diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
> > index e09edb5c5e06..5c07985c8cb8 100644
> > --- a/drivers/virtio/virtio_mmio.c
> > +++ b/drivers/virtio/virtio_mmio.c
> > @@ -500,6 +500,37 @@ static const char *vm_bus_name(struct virtio_device *vdev)
> >  	return vm_dev->pdev->name;
> >  }
> >  
> > +static bool vm_get_shm_region(struct virtio_device *vdev,
> > +			      struct virtio_shm_region *region, u8 id)
> > +{
> > +	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
> > +	u64 len, addr;
> > +
> > +	/* Select the region we're interested in */
> > +	writel(id, vm_dev->base + VIRTIO_MMIO_SHM_SEL);
> > +
> > +	/* Read the region size */
> > +	len = (u64) readl(vm_dev->base + VIRTIO_MMIO_SHM_LEN_LOW);
> > +	len |= (u64) readl(vm_dev->base + VIRTIO_MMIO_SHM_LEN_HIGH) << 32;
> > +
> > +	region->len = len;
> > +
> > +	/* Check if region length is -1. If that's the case, the shared memory
> > +	 * region does not exist and there is no need to proceed further.
> > +	 */
> > +	if (len == ~(u64)0) {
> > +		return false;
> > +	}
> 
> I think the curly braces should be dropped here.

Will do.

Thanks
Vivek