drm/asahi: Signal soft fault support to userspace

Signed-off-by: Asahi Lina <lina@asahilina.net>

Author: hoshinolina

drivers/gpu/drm/asahi/file.rs

@@ -9,7 +9,7 @@
 
 use crate::debug::*;
 use crate::driver::AsahiDevice;
-use crate::{alloc, buffer, driver, gem, mmu, queue, util::RangeExt};
+use crate::{alloc, buffer, driver, gem, hw, mmu, queue, util::RangeExt};
 use core::mem::MaybeUninit;
 use core::ops::Range;
 use kernel::dma_fence::RawDmaFence;
@@ -280,6 +280,10 @@ impl File {
             params.firmware_version[i] = *gpu.get_dyncfg().firmware_version.get(i).unwrap_or(&0);
         }
 
+        if *crate::fault_control.read() == 0xb {
+            params.feat_compat |= hw::feat::compat::SOFT_FAULTS;
+        }
+
         let size = core::mem::size_of::<uapi::drm_asahi_params_global>().min(data.size.try_into()?);
 
         // SAFETY: We only write to this userptr once, so there are no TOCTOU issues.

drivers/gpu/drm/asahi/hw/mod.rs

@@ -90,7 +90,13 @@ pub(crate) enum GpuRevisionID {
 /// GPU driver/hardware features, from the UABI.
 pub(crate) mod feat {
     /// Backwards-compatible features.
-    pub(crate) mod compat {}
+    pub(crate) mod compat {
+        use kernel::uapi;
+
+        /// Soft MMU faults enabled.
+        pub(crate) const SOFT_FAULTS: u64 =
+            uapi::drm_asahi_feat_compat_DRM_ASAHI_FEAT_SOFT_FAULTS as u64;
+    }
 
     /// Backwards-incompatible features.
     pub(crate) mod incompat {