[Intel-gfx] Regression: gvt: vgpu 1: MI_LOAD_REGISTER_MEM handler error

[Alex Williamson]

On Mon, 12 Apr 2021 10:32:14 -0600
Alex Williamson <alex.williamson at redhat.com> wrote:

> Running a Windows guest on a i915-GVTg_V4_2 from an HD 5500 IGD on
> v5.12-rc6 results in host logs:
> 
> gvt: vgpu 1: lrm access to register (20c0)
> gvt: vgpu 1: MI_LOAD_REGISTER_MEM handler error
> gvt: vgpu 1: cmd parser error
> 0x0 
> 0x29 
> 
> gvt: vgpu 1: scan wa ctx error
> gvt: vgpu 1: failed to submit desc 0
> gvt: vgpu 1: fail submit workload on ring rcs0
> gvt: vgpu 1: fail to emulate MMIO write 00002230 len 4
> 
> The guest goes into a boot loop triggering this error before reaching
> the desktop and rebooting.  Guest using Intel driver 20.19.15.5171
> dated 11/4/2020 (from driver file 15.40.5171).
> 
> This VM works well with the same guest and userspace software stack on
> Fedora's kernel 5.11.11-200.fc33.x86_64.  Thanks,

Bisected to:

commit f18d417a57438498e0de481d3a0bc900c2b0e057
Author: Yan Zhao <yan.y.zhao at intel.com>
Date:   Wed Dec 23 11:45:08 2020 +0800

    drm/i915/gvt: filter cmds "srm" and "lrm" in cmd_handler
    
    do not allow "srm" and "lrm" except for GEN8_L3SQCREG4 and 0x21f0.
    
    Cc: Colin Xu <colin.xu at intel.com>
    Cc: Kevin Tian <kevin.tian at intel.com>
    Signed-off-by: Yan Zhao <yan.y.zhao at intel.com>
    Signed-off-by: Zhenyu Wang <zhenyuw at linux.intel.com>
    Link: http://patchwork.freedesktop.org/patch/msgid/20201223034508.17031-1-yan.y.zhao@intel.com
    Reviewed-by: Zhenyu Wang <zhenyuw at linux.intel.com>