On Wed, Jan 29, 2020 at 05:22:13PM +0100, Frédéric Pierret wrote: > Dear Ben Skeggs, > > Please find attached a patch solving a blocking issue I encountered: > https://bugzilla.kernel.org/show_bug.cgi?id=206299 > > Basically, running at least a RTX2080TI on Xen makes a bad mmio error > which causes having 'mthd' pointer to be NULL in 'channv50.c'. From the > code, it's assumed to be not NULL by accessing directly 'mthd->data[0]' > which is the reason of the kernel panic. I simply check if the pointer > is not NULL before continuing. > > Best regards, > > Frédéric Pierret > > From: =?UTF-8?q?Fr=C3=A9d=C3=A9ric=20Pierret=20=28fepitre=29?= > <frederic.pierret@xxxxxxxxxxxx> > Date: Sun, 26 Jan 2020 23:24:33 +0100 > Subject: [PATCH] nv50_disp_chan_mthd: ensure mthd is not NULL > MIME-Version: 1.0 > Content-Type: text/plain; charset=UTF-8 > Content-Transfer-Encoding: 8bit > > Pointer to structure array is assumed not NULL by default. It has > the consequence to raise a kernel panic when it's not the case. > > BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=206299 > Signed-off-by: Frédéric Pierret (fepitre) <frederic.pierret@xxxxxxxxxxxx> > --- > drivers/gpu/drm/nouveau/nvkm/engine/disp/channv50.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/gpu/drm/nouveau/nvkm/engine/disp/channv50.c b/drivers/gpu/drm/nouveau/nvkm/engine/disp/channv50.c > index bcf32d92ee5a..50e3539f33d2 100644 > --- a/drivers/gpu/drm/nouveau/nvkm/engine/disp/channv50.c > +++ b/drivers/gpu/drm/nouveau/nvkm/engine/disp/channv50.c > @@ -74,6 +74,8 @@ nv50_disp_chan_mthd(struct nv50_disp_chan *chan, int debug) > > if (debug > subdev->debug) > return; > + if (!mthd) > + return; > > for (i = 0; (list = mthd->data[i].mthd) != NULL; i++) { > u32 base = chan->head * mthd->addr; > -- > 2.21.0 > <formletter> This is not the correct way to submit patches for inclusion in the stable kernel tree. Please read: https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html for how to do this properly. </formletter>
