[PATCH v4 8/8] gpu: nova-core: run Booter Unloader and FWSEC-SB upon unbinding

[Alexandre Courbot <acourbot@nvidia.com>]

When probing the driver, the FWSEC-FRTS firmware creates a WPR2 secure
memory region to store the GSP firmware, and the Booter Loader loads and
starts that firmware into the GSP, making it run in RISC-V mode.

These operations need to be reverted upon unloading, particularly the
WPR2 secure region creation, as its presence prevents the driver from
subsequently probing.

Thus, prepare the Booter Unloader and FWSEC-SB firmwares when booting
the GSP, so they can be executed at unbind time to put the GPU into a
state where it can be probed again.

Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
---
 drivers/gpu/nova-core/firmware/booter.rs |   1 -
 drivers/gpu/nova-core/firmware/fwsec.rs  |   1 -
 drivers/gpu/nova-core/gpu.rs             |   2 +-
 drivers/gpu/nova-core/gsp.rs             |   3 +
 drivers/gpu/nova-core/gsp/boot.rs        |  18 +++-
 drivers/gpu/nova-core/gsp/hal.rs         |  21 ++++-
 drivers/gpu/nova-core/gsp/hal/gh100.rs   |   7 +-
 drivers/gpu/nova-core/gsp/hal/tu102.rs   | 141 ++++++++++++++++++++++++++++++-
 drivers/gpu/nova-core/regs.rs            |   5 ++
 9 files changed, 188 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/nova-core/firmware/booter.rs b/drivers/gpu/nova-core/firmware/booter.rs
index 6a41690e72c6..6f421906c272 100644
--- a/drivers/gpu/nova-core/firmware/booter.rs
+++ b/drivers/gpu/nova-core/firmware/booter.rs
@@ -281,7 +281,6 @@ fn new_booter(data: &[u8]) -> Result<Self> {
 #[derive(Copy, Clone, Debug, PartialEq)]
 pub(crate) enum BooterKind {
     Loader,
-    #[expect(unused)]
     Unloader,
 }
 
diff --git a/drivers/gpu/nova-core/firmware/fwsec.rs b/drivers/gpu/nova-core/firmware/fwsec.rs
index 8810cb49db67..4108f28cd338 100644
--- a/drivers/gpu/nova-core/firmware/fwsec.rs
+++ b/drivers/gpu/nova-core/firmware/fwsec.rs
@@ -144,7 +144,6 @@ pub(crate) enum FwsecCommand {
     /// image into it.
     Frts { frts_addr: u64, frts_size: u64 },
     /// Asks [`FwsecFirmware`] to load pre-OS apps on the PMU.
-    #[expect(dead_code)]
     Sb,
 }
 
diff --git a/drivers/gpu/nova-core/gpu.rs b/drivers/gpu/nova-core/gpu.rs
index 1dd25c93a67e..7cf994ba2fb0 100644
--- a/drivers/gpu/nova-core/gpu.rs
+++ b/drivers/gpu/nova-core/gpu.rs
@@ -330,7 +330,7 @@ pub(crate) fn unbind(&self, dev: &device::Device<device::Core>) {
         // Do not return upon error as the sysmem flush page must be unregistered in any case.
         let _ = self
             .gsp
-            .unload(dev, bar, &self.gsp_falcon)
+            .unload(dev, bar, &self.gsp_falcon, &self.sec2_falcon)
             .inspect_err(|e| dev_err!(dev, "failed to unload GSP: {:?}\n", e));
 
         // Unregister the sysmem flush page before the driver data is dropped.
diff --git a/drivers/gpu/nova-core/gsp.rs b/drivers/gpu/nova-core/gsp.rs
index 38378f104068..58b917172efb 100644
--- a/drivers/gpu/nova-core/gsp.rs
+++ b/drivers/gpu/nova-core/gsp.rs
@@ -126,6 +126,8 @@ pub(crate) struct Gsp {
     pub(crate) cmdq: Cmdq,
     /// RM arguments.
     rmargs: Coherent<GspArgumentsPadded>,
+    /// Ready-to-run GSP unload bundle, if any.
+    unload: Option<KBox<dyn hal::UnloadBundle>>,
 }
 
 impl Gsp {
@@ -181,6 +183,7 @@ pub(crate) fn new(pdev: &pci::Device<device::Bound>) -> impl PinInit<Self, Error
                         dir.read_binary_file(c"logrm", &logs.logrm.0);
                     })
                 },
+                unload: None,
             }))
         })
     }
diff --git a/drivers/gpu/nova-core/gsp/boot.rs b/drivers/gpu/nova-core/gsp/boot.rs
index 59c1b4d030ae..c8555d76b3a2 100644
--- a/drivers/gpu/nova-core/gsp/boot.rs
+++ b/drivers/gpu/nova-core/gsp/boot.rs
@@ -56,8 +56,8 @@ pub(crate) fn boot(
 
         let wpr_meta = Coherent::init(dev, GFP_KERNEL, GspFwWprMeta::new(&gsp_fw, &fb_layout))?;
 
-        // Perform the chipset-specific boot sequence.
-        hal.boot(
+        // Perform the chipset-specific boot sequence, and retrieve the unload bundle.
+        let unload_bundle = hal.boot(
             self.as_mut(),
             dev,
             bar,
@@ -67,6 +67,7 @@ pub(crate) fn boot(
             gsp_falcon,
             sec2_falcon,
         )?;
+        *self.as_mut().project().unload = unload_bundle;
 
         gsp_falcon.write_os_version(bar, gsp_fw.bootloader.app_version);
 
@@ -129,6 +130,7 @@ pub(crate) fn unload(
         dev: &device::Device<device::Bound>,
         bar: &Bar0,
         gsp_falcon: &Falcon<Gsp>,
+        sec2_falcon: &Falcon<Sec2>,
     ) -> Result {
         // Shut down the GSP.
         Self::shutdown_gsp(
@@ -139,6 +141,18 @@ pub(crate) fn unload(
         )
         .inspect_err(|e| dev_err!(dev, "Unload guest driver failed: {:?}\n", e))?;
 
+        // With the GSP shut down, reset the GSP so it can be restarted.
+        if let Some(unload_bundle) = self.unload.as_ref() {
+            unload_bundle.run(dev, bar, gsp_falcon, sec2_falcon)?;
+        } else {
+            dev_warn!(
+                dev,
+                "Unload bundle is missing, GSP won't be properly reset.\n"
+            );
+        }
+
+        dev_info!(dev, "successfully unloaded\n");
+
         Ok(())
     }
 }
diff --git a/drivers/gpu/nova-core/gsp/hal.rs b/drivers/gpu/nova-core/gsp/hal.rs
index 4d8c1998f4cf..d9c324226dda 100644
--- a/drivers/gpu/nova-core/gsp/hal.rs
+++ b/drivers/gpu/nova-core/gsp/hal.rs
@@ -29,9 +29,28 @@
     },
 };
 
+/// Trait for types containing the resources and code required to fully reset the GSP.
+///
+/// The GSP unload code might run in a situation where we cannot load firmware dynamically (e.g.
+/// because we are in shutdown and the file system is not accessible anymore). Thus, the firmware
+/// required for unloading is prepared at load time, and stored here until it needs to be run.
+pub(super) trait UnloadBundle: Send {
+    /// Performs the steps required to properly reset the GSP after it has been stopped.
+    fn run(
+        &self,
+        dev: &device::Device<device::Bound>,
+        bar: &Bar0,
+        gsp_falcon: &Falcon<GspEngine>,
+        sec2_falcon: &Falcon<Sec2>,
+    ) -> Result;
+}
+
 /// Trait implemented by GSP HALs.
 pub(super) trait GspHal: Send {
     /// Performs the GSP boot process, loading and running the required firmwares as needed.
+    ///
+    /// Upon success, returns the [`UnloadBundle`] to be run (if any) in order to properly reset the
+    /// GSP after it has been stopped.
     #[allow(clippy::too_many_arguments)]
     fn boot(
         &self,
@@ -43,7 +62,7 @@ fn boot(
         wpr_meta: &Coherent<GspFwWprMeta>,
         gsp_falcon: &Falcon<GspEngine>,
         sec2_falcon: &Falcon<Sec2>,
-    ) -> Result;
+    ) -> Result<Option<KBox<dyn UnloadBundle>>>;
 
     /// Performs HAL-specific post-GSP boot tasks.
     ///
diff --git a/drivers/gpu/nova-core/gsp/hal/gh100.rs b/drivers/gpu/nova-core/gsp/hal/gh100.rs
index 9d7e9f4454b1..51e1099cda0d 100644
--- a/drivers/gpu/nova-core/gsp/hal/gh100.rs
+++ b/drivers/gpu/nova-core/gsp/hal/gh100.rs
@@ -17,7 +17,10 @@
     fb::FbLayout,
     gpu::Chipset,
     gsp::{
-        hal::GspHal,
+        hal::{
+            GspHal,
+            UnloadBundle, //
+        },
         Gsp,
         GspFwWprMeta, //
     },
@@ -40,7 +43,7 @@ fn boot(
         _wpr_meta: &Coherent<GspFwWprMeta>,
         _gsp_falcon: &Falcon<GspEngine>,
         _sec2_falcon: &Falcon<Sec2>,
-    ) -> Result {
+    ) -> Result<Option<KBox<dyn UnloadBundle>>> {
         Err(ENOTSUPP)
     }
 }
diff --git a/drivers/gpu/nova-core/gsp/hal/tu102.rs b/drivers/gpu/nova-core/gsp/hal/tu102.rs
index d5da23cd8c90..c6c947696ba8 100644
--- a/drivers/gpu/nova-core/gsp/hal/tu102.rs
+++ b/drivers/gpu/nova-core/gsp/hal/tu102.rs
@@ -31,7 +31,10 @@
     },
     gpu::Chipset,
     gsp::{
-        hal::GspHal,
+        hal::{
+            GspHal,
+            UnloadBundle, //
+        },
         sequencer::{
             GspSequencer,
             GspSequencerParams, //
@@ -43,6 +46,124 @@
     vbios::Vbios, //
 };
 
+// A ready-to-run FWSEC unload firmware.
+//
+// Since there are two variants of the prepared firmware (with and without a bootloader), this type
+// abstracts the difference.
+enum FwsecUnloadFirmware {
+    WithoutBl(FwsecFirmware),
+    WithBl(FwsecFirmwareWithBl),
+}
+
+impl FwsecUnloadFirmware {
+    /// Loads the FWSEC SB firmware, as well as its bootloader if `chipset` requires it.
+    fn new(
+        dev: &device::Device<device::Bound>,
+        bar: &Bar0,
+        chipset: Chipset,
+        bios: &Vbios,
+        gsp_falcon: &Falcon<GspEngine>,
+    ) -> Result<Self> {
+        let fwsec_sb = FwsecFirmware::new(dev, gsp_falcon, bar, bios, FwsecCommand::Sb)?;
+
+        Ok(if chipset.needs_fwsec_bootloader() {
+            Self::WithBl(FwsecFirmwareWithBl::new(fwsec_sb, dev, chipset)?)
+        } else {
+            Self::WithoutBl(fwsec_sb)
+        })
+    }
+
+    /// Runs the FWSEC SB firmware.
+    fn run(
+        &self,
+        dev: &device::Device<device::Bound>,
+        bar: &Bar0,
+        gsp_falcon: &Falcon<GspEngine>,
+    ) -> Result<()> {
+        match self {
+            Self::WithoutBl(fw) => fw.run(dev, gsp_falcon, bar),
+            Self::WithBl(fw) => fw.run(dev, gsp_falcon, bar),
+        }
+    }
+}
+
+// Contains the firmware required to fully reset GSP on chipsets where the GSP is started using
+// FWSEC/Booter.
+pub(super) struct Sec2UnloadBundle {
+    fwsec_sb: FwsecUnloadFirmware,
+    booter_unloader: BooterFirmware,
+}
+
+impl Sec2UnloadBundle {
+    /// Load and prepare the resources required to properly reset the GSP after it has been stopped.
+    fn build(
+        dev: &device::Device<device::Bound>,
+        bar: &Bar0,
+        chipset: Chipset,
+        bios: &Vbios,
+        gsp_falcon: &Falcon<GspEngine>,
+        sec2_falcon: &Falcon<Sec2>,
+    ) -> Result<KBox<dyn UnloadBundle>> {
+        KBox::new(
+            Self {
+                fwsec_sb: FwsecUnloadFirmware::new(dev, bar, chipset, bios, gsp_falcon)?,
+                booter_unloader: BooterFirmware::new(
+                    dev,
+                    BooterKind::Unloader,
+                    chipset,
+                    FIRMWARE_VERSION,
+                    sec2_falcon,
+                    bar,
+                )?,
+            },
+            GFP_KERNEL,
+        )
+        .map(|b| b as KBox<dyn UnloadBundle>)
+        .map_err(Into::into)
+    }
+}
+
+impl UnloadBundle for Sec2UnloadBundle {
+    fn run(
+        &self,
+        dev: &device::Device<device::Bound>,
+        bar: &Bar0,
+        gsp_falcon: &Falcon<GspEngine>,
+        sec2_falcon: &Falcon<Sec2>,
+    ) -> Result<()> {
+        // Run FWSEC-SB to reset the GSP falcon to its pre-libos state.
+        self.fwsec_sb.run(dev, bar, gsp_falcon)?;
+
+        // Remove WPR2 region if set.
+        let wpr2_hi = bar.read(regs::NV_PFB_PRI_MMU_WPR2_ADDR_HI);
+        if wpr2_hi.is_wpr2_set() {
+            sec2_falcon.reset(bar)?;
+            sec2_falcon.load(dev, bar, &self.booter_unloader)?;
+
+            // Sentinel value to confirm that Booter Unloader has run.
+            const MAILBOX_SENTINEL: u32 = 0xff;
+            let (mbox0, _) =
+                sec2_falcon.boot(bar, Some(MAILBOX_SENTINEL), Some(MAILBOX_SENTINEL))?;
+            if mbox0 != 0 {
+                dev_err!(dev, "Booter Unloader returned error 0x{:x}\n", mbox0);
+                return Err(EINVAL);
+            }
+
+            // Confirm that the WPR2 region has been removed.
+            let wpr2_hi = bar.read(regs::NV_PFB_PRI_MMU_WPR2_ADDR_HI);
+            if wpr2_hi.is_wpr2_set() {
+                dev_err!(
+                    dev,
+                    "WPR2 region still set after Booter Unloader returned\n"
+                );
+                return Err(EBUSY);
+            }
+        }
+
+        Ok(())
+    }
+}
+
 /// Helper function to load and run the FWSEC-FRTS firmware and confirm that it has properly
 /// created the WPR2 region.
 fn run_fwsec_frts(
@@ -161,7 +282,7 @@ fn boot(
         wpr_meta: &Coherent<GspFwWprMeta>,
         gsp_falcon: &Falcon<GspEngine>,
         sec2_falcon: &Falcon<Sec2>,
-    ) -> Result {
+    ) -> Result<Option<KBox<dyn UnloadBundle>>> {
         let bios = Vbios::new(dev, bar)?;
 
         // FWSEC-FRTS is not executed on chips where the FRTS region size is 0 (e.g. GA100).
@@ -185,7 +306,21 @@ fn boot(
 
         run_booter(dev, bar, chipset, sec2_falcon, wpr_meta)?;
 
-        Ok(())
+        // Last, try and prepare the unload bundle. If this fails, the GPU will need to be reset
+        // before the driver can be probed again.
+        let unload_bundle =
+            Sec2UnloadBundle::build(dev, bar, chipset, &bios, gsp_falcon, sec2_falcon)
+                .inspect_err(|e| {
+                    dev_warn!(dev, "Failed to prepare unload firmware: {:?}\n", e);
+                    dev_warn!(dev, "The GSP won't be able to unload properly on unbind.\n");
+                    dev_warn!(
+                        dev,
+                        "The GPU will need to be reset before the driver can bind again.\n"
+                    );
+                })
+                .ok();
+
+        Ok(unload_bundle)
     }
 
     fn post_boot(
diff --git a/drivers/gpu/nova-core/regs.rs b/drivers/gpu/nova-core/regs.rs
index 6faeed73901d..356fbf364ea5 100644
--- a/drivers/gpu/nova-core/regs.rs
+++ b/drivers/gpu/nova-core/regs.rs
@@ -175,6 +175,11 @@ impl NV_PFB_PRI_MMU_WPR2_ADDR_HI {
     pub(crate) fn higher_bound(self) -> u64 {
         u64::from(self.hi_val()) << 12
     }
+
+    /// Returns whether the WPR2 region is currently set.
+    pub(crate) fn is_wpr2_set(self) -> bool {
+        self.hi_val() != 0
+    }
 }
 
 // PGSP

-- 
2.54.0