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From: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
To: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: linux-s390 <linux-s390@vger.kernel.org>,
	linux-samsung-soc <linux-samsung-soc@vger.kernel.org>,
	"Jan Kara" <jack@suse.cz>, "Kees Cook" <keescook@chromium.org>,
	"KVM list" <kvm@vger.kernel.org>, "Linux MM" <linux-mm@kvack.org>,
	"Linux PCI" <linux-pci@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	"DRI Development" <dri-devel@lists.freedesktop.org>,
	"Jason Gunthorpe" <jgg@ziepe.ca>,
	"Jérôme Glisse" <jglisse@redhat.com>,
	"John Hubbard" <jhubbard@nvidia.com>,
	"Bjorn Helgaas" <bhelgaas@google.com>,
	"Daniel Vetter" <daniel.vetter@intel.com>,
	"Dan Williams" <dan.j.williams@intel.com>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Linux ARM" <linux-arm-kernel@lists.infradead.org>,
	"open list:DMA BUFFER SHARING FRAMEWORK"
	<linux-media@vger.kernel.org>
Subject: Re: [PATCH v2 17/17] drm/i915: Properly request PCI BARs
Date: Fri, 9 Oct 2020 13:41:54 +0300	[thread overview]
Message-ID: <20201009104154.GR6112@intel.com> (raw)
In-Reply-To: <CAKMK7uH3o3hnRkTDqr93PR=wuRejpty+AbyMacoEFDDb6OgJeQ@mail.gmail.com>

On Fri, Oct 09, 2020 at 12:01:39PM +0200, Daniel Vetter wrote:
> On Fri, Oct 9, 2020 at 11:47 AM Ville Syrjälä
> <ville.syrjala@linux.intel.com> wrote:
> >
> > On Fri, Oct 09, 2020 at 09:59:34AM +0200, Daniel Vetter wrote:
> > > When trying to test my CONFIG_IO_STRICT_DEVMEM changes I realized they
> > > do nothing for i915. Because i915 doesn't request any regions, like
> > > pretty much all drm pci drivers. I guess this is some very old
> > > remnants from the userspace modesetting days, when we wanted to
> > > co-exist with the fbdev driver. Which usually requested these
> > > resources.
> > >
> > > But makes me wonder why the pci subsystem doesn't just request
> > > resource automatically when we map a bar and a pci driver is bound?
> > >
> > > Knowledge about which pci bars we need kludged together from
> > > intel_uncore.c and intel_gtt.c from i915 and intel-gtt.c over in the
> > > fake agp driver.
> > >
> > > Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> > > Cc: Jason Gunthorpe <jgg@ziepe.ca>
> > > Cc: Kees Cook <keescook@chromium.org>
> > > Cc: Dan Williams <dan.j.williams@intel.com>
> > > Cc: Andrew Morton <akpm@linux-foundation.org>
> > > Cc: John Hubbard <jhubbard@nvidia.com>
> > > Cc: Jérôme Glisse <jglisse@redhat.com>
> > > Cc: Jan Kara <jack@suse.cz>
> > > Cc: Dan Williams <dan.j.williams@intel.com>
> > > Cc: linux-mm@kvack.org
> > > Cc: linux-arm-kernel@lists.infradead.org
> > > Cc: linux-samsung-soc@vger.kernel.org
> > > Cc: linux-media@vger.kernel.org
> > > Cc: Bjorn Helgaas <bhelgaas@google.com>
> > > Cc: linux-pci@vger.kernel.org
> > > ---
> > >  drivers/gpu/drm/i915/intel_uncore.c | 25 +++++++++++++++++++++++--
> > >  1 file changed, 23 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
> > > index 54e201fdeba4..ce39049d8919 100644
> > > --- a/drivers/gpu/drm/i915/intel_uncore.c
> > > +++ b/drivers/gpu/drm/i915/intel_uncore.c
> > > @@ -1692,10 +1692,13 @@ static int uncore_mmio_setup(struct intel_uncore *uncore)
> > >       struct pci_dev *pdev = i915->drm.pdev;
> > >       int mmio_bar;
> > >       int mmio_size;
> > > +     int bar_selection;
> >
> > Signed bitmasks always make me uneasy. But looks like
> > that's what it is in the pci api. So meh.
> 
> Yeah it's surprising.
> 
> > > +     int ret;
> > >
> > >       mmio_bar = IS_GEN(i915, 2) ? 1 : 0;
> > > +     bar_selection = BIT (2) | BIT(mmio_bar);
> >                            ^
> > spurious space
> >
> > That's also not correct for gen2 I think.
> >
> > gen2:
> > 0 = GMADR
> > 1 = MMADR
> > 2 = IOBAR
> >
> > gen3:
> > 0 = MMADR
> > 1 = IOBAR
> > 2 = GMADR
> > 3 = GTTADR
> >
> > gen4+:
> > 0+1 = GTTMMADR
> > 2+3 = GMADR
> > 4 = IOBAR
> >
> > Maybe we should just have an explicit list of bars like that in a
> > comment?
> >
> > I'd also suggest sucking this bitmask calculation into a small helper
> > so you can reuse it for the release.
> 
> tbh I just hacked this up for testing. Given how almost no other drm
> driver does this, I'm wondering whether we should or not.
> 
> Also the only reason why I didn't just use the pci_request_regions
> helper is to avoid the vga ioport range, since that's managed by
> vgaarbiter.

VGA io range isn't part of any bar. Or do you mean just the io decode
enable bit in the pci command register? That should be just a matter
or pci_enable_device() vs. pci_enable_device_mem() I think. So nothing
to do with which bars we've requested IIRC.

> 
> So I think if we go for this for real we should:
> - register the vga ioport range in the vgaarbiter
> - have a pci_request_iomem_regions helper that grabs all mem bars
> - roll that out to all drm pci drivers
> 
> Or something like that. The other complication is when we resize the
> iobar. So not really sure what to do here.

We resize it?

-- 
Ville Syrjälä
Intel
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  reply	other threads:[~2020-10-09 10:42 UTC|newest]

Thread overview: 69+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-09  7:59 [PATCH v2 00/17] follow_pfn and other iomap races Daniel Vetter
2020-10-09  7:59 ` [PATCH v2 01/17] drm/exynos: Stop using frame_vector helpers Daniel Vetter
2020-10-16  7:42   ` John Hubbard
2020-10-09  7:59 ` [PATCH v2 02/17] drm/exynos: Use FOLL_LONGTERM for g2d cmdlists Daniel Vetter
2020-10-09  7:59 ` [PATCH v2 03/17] misc/habana: Stop using frame_vector helpers Daniel Vetter
2020-10-10 20:26   ` Oded Gabbay
2020-10-10 21:32     ` Daniel Vetter
2020-10-10 21:41       ` Daniel Vetter
2020-10-10 21:47         ` Oded Gabbay
2020-10-16  7:45   ` John Hubbard
2020-10-09  7:59 ` [PATCH v2 04/17] misc/habana: Use FOLL_LONGTERM for userptr Daniel Vetter
2020-10-09  7:59 ` [PATCH v2 05/17] mm/frame-vector: Use FOLL_LONGTERM Daniel Vetter
2020-10-16  7:54   ` John Hubbard
2020-10-16  8:03     ` Daniel Vetter
2020-10-09  7:59 ` [PATCH v2 06/17] media: videobuf2: Move frame_vector into media subsystem Daniel Vetter
2020-10-09 10:14   ` Mauro Carvalho Chehab
2020-10-09 16:57     ` Daniel Vetter
2020-10-09  7:59 ` [PATCH v2 07/17] mm: Close race in generic_access_phys Daniel Vetter
2020-10-09  7:59 ` [PATCH v2 08/17] s390/pci: Remove races against pte updates Daniel Vetter
2020-10-12 14:03   ` Niklas Schnelle
2020-10-12 14:19     ` Daniel Vetter
2020-10-12 14:39       ` Niklas Schnelle
2020-10-21  7:55       ` Niklas Schnelle
2020-10-22  7:39         ` Daniel Vetter
2020-10-09  7:59 ` [PATCH v2 09/17] mm: Add unsafe_follow_pfn Daniel Vetter
2020-10-09 10:34   ` Mauro Carvalho Chehab
2020-10-09 12:21     ` Jason Gunthorpe
2020-10-09 12:37       ` Mauro Carvalho Chehab
2020-10-09 12:39         ` Mauro Carvalho Chehab
2020-10-09 12:48         ` Jason Gunthorpe
2020-10-09 17:52           ` Daniel Vetter
2020-10-09 18:01             ` Jason Gunthorpe
2020-10-09 19:31               ` Daniel Vetter
2020-10-10  9:21             ` Mauro Carvalho Chehab
2020-10-10 10:53               ` Daniel Vetter
2020-10-10 11:39                 ` Mauro Carvalho Chehab
2020-10-10 11:56                   ` Daniel Vetter
2020-10-10 17:22             ` Tomasz Figa
2020-10-10 21:35               ` Laurent Pinchart
2020-10-10 21:50                 ` Daniel Vetter
2020-10-11  6:27                   ` Mauro Carvalho Chehab
2020-10-11  6:36                     ` Mauro Carvalho Chehab
2020-10-10 21:11             ` Laurent Pinchart
2020-10-12 10:46           ` Marek Szyprowski
2020-10-12 13:49             ` Daniel Vetter
2020-10-10 17:30         ` Tomasz Figa
2020-10-09  7:59 ` [PATCH v2 10/17] media/videbuf1|2: Mark follow_pfn usage as unsafe Daniel Vetter
2020-10-10  9:24   ` Mauro Carvalho Chehab
2020-10-09  7:59 ` [PATCH v2 11/17] vfio/type1: Mark follow_pfn " Daniel Vetter
2020-10-09  7:59 ` [PATCH v2 12/17] PCI: Obey iomem restrictions for procfs mmap Daniel Vetter
2020-10-09  7:59 ` [PATCH v2 13/17] /dev/mem: Only set filp->f_mapping Daniel Vetter
2020-10-09  7:59 ` [PATCH v2 14/17] resource: Move devmem revoke code to resource framework Daniel Vetter
2020-10-09 10:59   ` Greg Kroah-Hartman
2020-10-09 12:31   ` Jason Gunthorpe
2020-10-09 14:24     ` Daniel Vetter
2020-10-09 14:32       ` Jason Gunthorpe
2020-10-09 18:28         ` Dan Williams
2020-10-15  0:09           ` Jason Gunthorpe
2020-10-15  7:52             ` Daniel Vetter
2020-10-15  7:55               ` Daniel Vetter
2020-10-15 15:29             ` Daniel Vetter
2020-10-09  7:59 ` [PATCH v2 15/17] sysfs: Support zapping of binary attr mmaps Daniel Vetter
2020-10-09 10:58   ` Greg Kroah-Hartman
2020-10-09  7:59 ` [PATCH v2 16/17] PCI: Revoke mappings like devmem Daniel Vetter
2020-10-09  7:59 ` [PATCH v2 17/17] drm/i915: Properly request PCI BARs Daniel Vetter
2020-10-09  9:47   ` Ville Syrjälä
2020-10-09 10:01     ` Daniel Vetter
2020-10-09 10:41       ` Ville Syrjälä [this message]
2020-10-09 14:18         ` Daniel Vetter

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