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
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