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 <20180711094040.12506-9-ard.biesheuvel@linaro.org> <CADvTj4rmxgxoJMR4ehZuhHHP3s2KCqO=Vp2igf3-ev_o=+_Duw@mail.gmail.com>
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From:   Ard Biesheuvel <ard.biesheuvel@linaro.org>
Date:   Tue, 23 Apr 2019 08:50:41 +0200
Message-ID: <CAKv+Gu-tdB=2ep3MQY2iYteeupKhPHBzi6vouQhmmwy8bRfXDA@mail.gmail.com>
Subject: Re: [PATCH 8/8] fbdev/efifb: honour UEFI memory map attributes when
 mapping the fb
To:     James Hilliard <james.hilliard1@gmail.com>
Cc:     linux-efi <linux-efi@vger.kernel.org>,
        Ingo Molnar <mingo@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Peter Jones <pjones@redhat.com>
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Sender: linux-kernel-owner@vger.kernel.org
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On Sat, 20 Apr 2019 at 21:03, James Hilliard <james.hilliard1@gmail.com> wrote:
>
> This patch appears to introduce a regression on my
> system(https://www.jetwaycomputer.com/NF9B.html).
> My board uses an Intel gma3650 GPU.
> It causes a complete failure of all video output.
> With it reverted I get:
> [ 1.169444] efifb: probing for efifb
> [ 1.169499] efifb: framebuffer at 0xcf800000, using 1876k, total 1875k
> [ 1.169511] efifb: mode is 800x600x32, linelength=3200, pages=1
> [ 1.169519] efifb: scrolling: redraw
> [ 1.169528] efifb: Truecolor: size=8:8:8:8, shift=24:16:8:0
> Without it reverted I get:
> [ 1.173368] efifb: probing for efifb
> [ 1.173386] efifb: abort, cannot remap video memory 0x1d5000 @ 0xcf800000
> [ 1.173395] Trying to free nonexistent resource
> <00000000cf800000-00000000cf9d4bff>
> [ 1.173413] efi-framebuffer: probe of efi-framebuffer.0 failed with error -5
>

Could you please reboot with efi=debug passed on the kernel command
line and share the entire dmesg kernel log output?


> On Wed, Jul 11, 2018 at 11:40 AM Ard Biesheuvel
> <ard.biesheuvel@linaro.org> wrote:
> >
> > If the framebuffer address provided by the Graphics Output Protocol
> > (GOP) is covered by the UEFI memory map, it will tell us which memory
> > attributes are permitted when mapping this region. In some cases,
> > (KVM guest on ARM), violating this will result in loss of coherency,
> > which means that updates sent to the framebuffer by the guest will
> > not be observeable by the host, and the emulated display simply does
> > not work.
> >
> > So if the memory map contains such a description, take the attributes
> > field into account, and add support for creating WT or WB mappings of
> > the framebuffer region.
> >
> > Cc: Peter Jones <pjones@redhat.com>
> > Tested-by: Laszlo Ersek <lersek@redhat.com>
> > Acked-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
> > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> > ---
> >  drivers/video/fbdev/efifb.c | 51 +++++++++++++++++++++++++++++--------
> >  1 file changed, 41 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/video/fbdev/efifb.c b/drivers/video/fbdev/efifb.c
> > index 46a4484e3da7..c6f78d27947b 100644
> > --- a/drivers/video/fbdev/efifb.c
> > +++ b/drivers/video/fbdev/efifb.c
> > @@ -20,7 +20,7 @@
> >  #include <drm/drm_connector.h>  /* For DRM_MODE_PANEL_ORIENTATION_* */
> >
> >  static bool request_mem_succeeded = false;
> > -static bool nowc = false;
> > +static u64 mem_flags = EFI_MEMORY_WC | EFI_MEMORY_UC;
> >
> >  static struct fb_var_screeninfo efifb_defined = {
> >         .activate               = FB_ACTIVATE_NOW,
> > @@ -68,8 +68,12 @@ static int efifb_setcolreg(unsigned regno, unsigned red, unsigned green,
> >
> >  static void efifb_destroy(struct fb_info *info)
> >  {
> > -       if (info->screen_base)
> > -               iounmap(info->screen_base);
> > +       if (info->screen_base) {
> > +               if (mem_flags & (EFI_MEMORY_UC | EFI_MEMORY_WC))
> > +                       iounmap(info->screen_base);
> > +               else
> > +                       memunmap(info->screen_base);
> > +       }
> >         if (request_mem_succeeded)
> >                 release_mem_region(info->apertures->ranges[0].base,
> >                                    info->apertures->ranges[0].size);
> > @@ -104,7 +108,7 @@ static int efifb_setup(char *options)
> >                         else if (!strncmp(this_opt, "width:", 6))
> >                                 screen_info.lfb_width = simple_strtoul(this_opt+6, NULL, 0);
> >                         else if (!strcmp(this_opt, "nowc"))
> > -                               nowc = true;
> > +                               mem_flags &= ~EFI_MEMORY_WC;
> >                 }
> >         }
> >
> > @@ -164,6 +168,7 @@ static int efifb_probe(struct platform_device *dev)
> >         unsigned int size_remap;
> >         unsigned int size_total;
> >         char *option = NULL;
> > +       efi_memory_desc_t md;
> >
> >         if (screen_info.orig_video_isVGA != VIDEO_TYPE_EFI || pci_dev_disabled)
> >                 return -ENODEV;
> > @@ -272,12 +277,35 @@ static int efifb_probe(struct platform_device *dev)
> >         info->apertures->ranges[0].base = efifb_fix.smem_start;
> >         info->apertures->ranges[0].size = size_remap;
> >
> > -       if (nowc)
> > -               info->screen_base = ioremap(efifb_fix.smem_start, efifb_fix.smem_len);
> > -       else
> > -               info->screen_base = ioremap_wc(efifb_fix.smem_start, efifb_fix.smem_len);
> > +       if (!efi_mem_desc_lookup(efifb_fix.smem_start, &md)) {
> > +               if ((efifb_fix.smem_start + efifb_fix.smem_len) >
> > +                   (md.phys_addr + (md.num_pages << EFI_PAGE_SHIFT))) {
> > +                       pr_err("efifb: video memory @ 0x%lx spans multiple EFI memory regions\n",
> > +                              efifb_fix.smem_start);
> > +                       err = -EIO;
> > +                       goto err_release_fb;
> > +               }
> > +               /*
> > +                * If the UEFI memory map covers the efifb region, we may only
> > +                * remap it using the attributes the memory map prescribes.
> > +                */
> > +               mem_flags |= EFI_MEMORY_WT | EFI_MEMORY_WB;
> > +               mem_flags &= md.attribute;
> > +       }
> > +       if (mem_flags & EFI_MEMORY_WC)
> > +               info->screen_base = ioremap_wc(efifb_fix.smem_start,
> > +                                              efifb_fix.smem_len);
> > +       else if (mem_flags & EFI_MEMORY_UC)
> > +               info->screen_base = ioremap(efifb_fix.smem_start,
> > +                                           efifb_fix.smem_len);
> > +       else if (mem_flags & EFI_MEMORY_WT)
> > +               info->screen_base = memremap(efifb_fix.smem_start,
> > +                                            efifb_fix.smem_len, MEMREMAP_WT);
> > +       else if (mem_flags & EFI_MEMORY_WB)
> > +               info->screen_base = memremap(efifb_fix.smem_start,
> > +                                            efifb_fix.smem_len, MEMREMAP_WB);
> >         if (!info->screen_base) {
> > -               pr_err("efifb: abort, cannot ioremap video memory 0x%x @ 0x%lx\n",
> > +               pr_err("efifb: abort, cannot remap video memory 0x%x @ 0x%lx\n",
> >                         efifb_fix.smem_len, efifb_fix.smem_start);
> >                 err = -EIO;
> >                 goto err_release_fb;
> > @@ -371,7 +399,10 @@ static int efifb_probe(struct platform_device *dev)
> >  err_groups:
> >         sysfs_remove_groups(&dev->dev.kobj, efifb_groups);
> >  err_unmap:
> > -       iounmap(info->screen_base);
> > +       if (mem_flags & (EFI_MEMORY_UC | EFI_MEMORY_WC))
> > +               iounmap(info->screen_base);
> > +       else
> > +               memunmap(info->screen_base);
> >  err_release_fb:
> >         framebuffer_release(info);
> >  err_release_mem:
> > --
> > 2.17.1
> >
> >
> >
> >