[Intel-gfx] [PATCH V4] drm/i915: Enhanced disable access to stolen memory as a guest

[Daniel Vetter]

On Wed, Apr 05, 2017 at 10:08:26AM +0800, Xiong Zhang wrote:
> Stolen memory is in RMRR and has identity mapping in iommu, so
> gt could access stolen memory in host OS. While RMRR isn't supported
> by kvm, both EPT and guest iommu domain lack of maaping for stolen memory,
> so both vcpu and gt couldn't access stolen memory in guest.
> 
> commit "04a68a3 drm/i915/gvt: Disable access to stolen memory as a guest"
> isn't enough in IGD passthrough environment where vgt code doesn't run. This
> patch detects i915 running as a guest through the existence of emulated ISA
> bridge.
> 
> v2:GVT-g may run in non qemu (Zhenyu)
> v3:Make commit message clear (Daniel)
> v4:Fix typo	
> 
> References: c875d2c iommu/vt-d: Exclude devices using RMRRs from IOMMU API domains
> Link: https://access.redhat.com/sites/default/files/attachments/rmrr-wp1.pdf
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=99028
> 
> Signed-off-by: Xiong Zhang <xiong.y.zhang at intel.com>
> Reviewed-by: Zhenyu Wang <zhenyuw at linux.intel.com>
> Cc: stable at vger.kernel.org

Yeah, commit message is now much improved.

Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>

> ---
>  drivers/gpu/drm/i915/i915_drv.c        | 1 +
>  drivers/gpu/drm/i915/i915_drv.h        | 1 +
>  drivers/gpu/drm/i915/i915_gem_stolen.c | 4 ++--
>  3 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index 03d9e45..8b807a9 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -223,6 +223,7 @@ static void intel_detect_pch(struct drm_i915_private *dev_priv)
>  					    PCI_SUBVENDOR_ID_REDHAT_QUMRANET &&
>  				    pch->subsystem_device ==
>  					    PCI_SUBDEVICE_ID_QEMU)) {
> +				dev_priv->run_on_qemu = true;
>  				dev_priv->pch_type =
>  					intel_virt_detect_pch(dev_priv);
>  			} else
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index a5947a4..ad95c87 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -2145,6 +2145,7 @@ struct drm_i915_private {
>  	struct intel_uncore uncore;
>  
>  	struct i915_virtual_gpu vgpu;
> +	bool run_on_qemu;
>  
>  	struct intel_gvt *gvt;
>  
> diff --git a/drivers/gpu/drm/i915/i915_gem_stolen.c b/drivers/gpu/drm/i915/i915_gem_stolen.c
> index f3abdc2..6a011b0 100644
> --- a/drivers/gpu/drm/i915/i915_gem_stolen.c
> +++ b/drivers/gpu/drm/i915/i915_gem_stolen.c
> @@ -409,8 +409,8 @@ int i915_gem_init_stolen(struct drm_i915_private *dev_priv)
>  
>  	mutex_init(&dev_priv->mm.stolen_lock);
>  
> -	if (intel_vgpu_active(dev_priv)) {
> -		DRM_INFO("iGVT-g active, disabling use of stolen memory\n");
> +	if (dev_priv->run_on_qemu || intel_vgpu_active(dev_priv)) {
> +		DRM_INFO("Running in guest, disabling use of stolen memory\n");
>  		return 0;
>  	}
>  
> -- 
> 1.9.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch