RE: [PATCH 05/13] soc/fsl/bqman: page align iommu mapping sizes

[Laurentiu Tudor]

Hi Leo,

> -----Original Message-----
> From: Li Yang [mailto:leoyang.li@xxxxxxx]
> Sent: Saturday, March 30, 2019 12:07 AM
> To: Laurentiu Tudor <laurentiu.tudor@xxxxxxx>
> Cc: Netdev <netdev@xxxxxxxxxxxxxxx>; Madalin-cristian Bucur
> <madalin.bucur@xxxxxxx>; Roy Pledge <roy.pledge@xxxxxxx>; Camelia
> Alexandra Groza <camelia.groza@xxxxxxx>; David Miller
> <davem@xxxxxxxxxxxxx>; Linux IOMMU <iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx>;
> moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE <linux-arm-
> kernel@xxxxxxxxxxxxxxxxxxx>; linuxppc-dev <linuxppc-dev@xxxxxxxxxxxxxxxx>;
> lkml <linux-kernel@xxxxxxxxxxxxxxx>
> Subject: Re: [PATCH 05/13] soc/fsl/bqman: page align iommu mapping sizes
> Importance: High
> 
> On Fri, Mar 29, 2019 at 9:01 AM <laurentiu.tudor@xxxxxxx> wrote:
> >
> > From: Laurentiu Tudor <laurentiu.tudor@xxxxxxx>
> >
> > Prior to calling iommu_map()/iommu_unmap() page align the size or
> > failures such as below could happen:
> >
> > iommu: unaligned: iova 0x... pa 0x... size 0x4000 min_pagesz 0x10000
> > qman_portal 500000000.qman-portal: failed to iommu_map() -22
> >
> > Seen when booted a kernel compiled with 64K page size support.
> 
> This will silently incease the actual space mapped to 64K when the
> driver is actually trying to map 4K.  Will this potentially cause
> security breaches?  If it is really safe to map 64K, probably the
> better way is to increase the region size to 64k in the device tree
> explicitly.

Not sure if such small reserved areas are practical, so I wouldn't worry 
much. As an example, currently on ls1046a we reserve the following memory:
bman 16MB, qman fqd 8MB, qman pdfr 32MB.
But just to be on the safe side, maybe we could add an error check for 
device trees that specify < 64KB reserved memory.

---
Best Regards, Laurentiu

> >
> > Signed-off-by: Laurentiu Tudor <laurentiu.tudor@xxxxxxx>
> > ---
> >  drivers/soc/fsl/qbman/bman_ccsr.c   | 2 +-
> >  drivers/soc/fsl/qbman/qman_ccsr.c   | 4 ++--
> >  drivers/soc/fsl/qbman/qman_portal.c | 2 +-
> >  3 files changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/soc/fsl/qbman/bman_ccsr.c
> b/drivers/soc/fsl/qbman/bman_ccsr.c
> > index b209c79511bb..3a6e01bde32d 100644
> > --- a/drivers/soc/fsl/qbman/bman_ccsr.c
> > +++ b/drivers/soc/fsl/qbman/bman_ccsr.c
> > @@ -230,7 +230,7 @@ static int fsl_bman_probe(struct platform_device
> *pdev)
> >         /* Create an 1-to-1 iommu mapping for FBPR area */
> >         domain = iommu_get_domain_for_dev(dev);
> >         if (domain) {
> > -               ret = iommu_map(domain, fbpr_a, fbpr_a, fbpr_sz,
> > +               ret = iommu_map(domain, fbpr_a, fbpr_a,
> PAGE_ALIGN(fbpr_sz),
> >                                 IOMMU_READ | IOMMU_WRITE | IOMMU_CACHE);
> >                 if (ret)
> >                         dev_warn(dev, "failed to iommu_map() %d\n",
> ret);
> > diff --git a/drivers/soc/fsl/qbman/qman_ccsr.c
> b/drivers/soc/fsl/qbman/qman_ccsr.c
> > index eec7700507e1..8d3c950ce52d 100644
> > --- a/drivers/soc/fsl/qbman/qman_ccsr.c
> > +++ b/drivers/soc/fsl/qbman/qman_ccsr.c
> > @@ -783,11 +783,11 @@ static int fsl_qman_probe(struct platform_device
> *pdev)
> >         /* Create an 1-to-1 iommu mapping for fqd and pfdr areas */
> >         domain = iommu_get_domain_for_dev(dev);
> >         if (domain) {
> > -               ret = iommu_map(domain, fqd_a, fqd_a, fqd_sz,
> > +               ret = iommu_map(domain, fqd_a, fqd_a,
> PAGE_ALIGN(fqd_sz),
> >                                 IOMMU_READ | IOMMU_WRITE | IOMMU_CACHE);
> >                 if (ret)
> >                         dev_warn(dev, "iommu_map(fqd) failed %d\n",
> ret);
> > -               ret = iommu_map(domain, pfdr_a, pfdr_a, pfdr_sz,
> > +               ret = iommu_map(domain, pfdr_a, pfdr_a,
> PAGE_ALIGN(pfdr_sz),
> >                                 IOMMU_READ | IOMMU_WRITE | IOMMU_CACHE);
> >                 if (ret)
> >                         dev_warn(dev, "iommu_map(pfdr) failed %d\n",
> ret);
> > diff --git a/drivers/soc/fsl/qbman/qman_portal.c
> b/drivers/soc/fsl/qbman/qman_portal.c
> > index dfb62f9815e9..bce56da2b01f 100644
> > --- a/drivers/soc/fsl/qbman/qman_portal.c
> > +++ b/drivers/soc/fsl/qbman/qman_portal.c
> > @@ -297,7 +297,7 @@ static int qman_portal_probe(struct platform_device
> *pdev)
> >                  */
> >                 err = iommu_map(domain,
> >                                 addr_phys[0]->start, addr_phys[0]-
> >start,
> > -                               resource_size(addr_phys[0]),
> > +                               PAGE_ALIGN(resource_size(addr_phys[0])),
> >                                 IOMMU_READ | IOMMU_WRITE | IOMMU_CACHE);
> >                 if (err)
> >                         dev_warn(dev, "failed to iommu_map() %d\n",
> err);
> > --
> > 2.17.1
> >