• Xiong Zhang's avatar
    drm/i915: Don't deballoon unused ggtt drm_mm_node in linux guest · 0a3dfbb5
    Xiong Zhang authored
    The following call trace may exist in linux guest dmesg when guest i915
    driver is unloaded.
    [   90.776610] [drm:vgt_deballoon_space.isra.0 [i915]] deballoon space: range [0x0 - 0x0] 0 KiB.
    [   90.776621] BUG: unable to handle kernel NULL pointer dereference at 00000000000000c0
    [   90.776691] IP: drm_mm_remove_node+0x4d/0x320 [drm]
    [   90.776718] PGD 800000012c7d0067 P4D 800000012c7d0067 PUD 138e4c067 PMD 0
    [   90.777091] task: ffff9adab60f2f00 task.stack: ffffaf39c0fe0000
    [   90.777142] RIP: 0010:drm_mm_remove_node+0x4d/0x320 [drm]
    [   90.777573] Call Trace:
    [   90.777653]  intel_vgt_deballoon+0x4c/0x60 [i915]
    [   90.777729]  i915_ggtt_cleanup_hw+0x121/0x190 [i915]
    [   90.777792]  i915_driver_unload+0x145/0x180 [i915]
    [   90.777856]  i915_pci_remove+0x15/0x20 [i915]
    [   90.777890]  pci_device_remove+0x3b/0xc0
    [   90.777916]  device_release_driver_internal+0x157/0x220
    [   90.777945]  driver_detach+0x39/0x70
    [   90.777967]  bus_remove_driver+0x51/0xd0
    [   90.777990]  pci_unregister_driver+0x23/0x90
    [   90.778019]  SyS_delete_module+0x1da/0x240
    [   90.778045]  entry_SYSCALL_64_fastpath+0x24/0x87
    [   90.778072] RIP: 0033:0x7f34312af067
    [   90.778092] RSP: 002b:00007ffdea3da0d8 EFLAGS: 00000206
    [   90.778297] RIP: drm_mm_remove_node+0x4d/0x320 [drm] RSP: ffffaf39c0fe3dc0
    [   90.778344] ---[ end trace f4b1bc8305fc59dd ]---
    
    Four drm_mm_node are used to reserve guest ggtt space, but some of them
    may be skipped and not initialised due to space constraints in
    intel_vgt_balloon(). If drm_mm_remove_node() is called with
    uninitialized drm_mm_node, the above call trace occurs.
    
    This patch check drm_mm_node's validity before calling
    drm_mm_remove_node().
    
    Fixes: ff8f7975
    
    ("drm/i915: return the correct usable aperture size under gvt environment")
    Cc: stable@vger.kernel.org
    Signed-off-by: default avatarXiong Zhang <xiong.y.zhang@intel.com>
    Acked-by: default avatarZhenyu Wang <zhenyuw@linux.intel.com>
    Reviewed-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
    Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
    Link: https://patchwork.freedesktop.org/patch/msgid/1566279978-9659-1-git-send-email-xiong.y.zhang@intel.com
    
    
    (cherry picked from commit 4776f3529d6b1e47f02904ad1d264d25ea22b27b)
    Signed-off-by: default avatarJani Nikula <jani.nikula@intel.com>
    0a3dfbb5
i915_vgpu.c 9.6 KB