kernel: Present physical TU104 to guest + emulate GSP boot (FWSEC/Booter) + VBIOS serving

Guest driver probe fixes (unmodified 570.144 open driver on physical path):

- kernel/main.c: add show_description to the mdev driver. Userspace mdev
  management tools parse 'framebuffer=<n>M' from every mdev type's
  description sysfs file before creating an mdev; the missing file made
  such tools fail to create the vGPU. Also fix create_mdev.sh for the real
  type dir name pci-nvidia-vgpu-* (mdev core names dirs
  dev_driver_string(parent)-<sysfs_name>; the parent registers before
  nvidia.ko binds so dev_driver_string == 'pci').

- kernel/bar_emulation.c: seed BAR0 shadow so guest sees a REAL, PHYSICAL,
  non-virtual TU104 (user directive: no PV/VF vGPU paths, unmodified driver):
  * PMC_BOOT_0/1/42 = physical TU104 values captured from host hardware
    (0x164000a1 / 0x0 / 0x164a1000). Without these, halmgrGetHalForGpu()
    fails and probe aborts with 'does not include the required GSP'.
  * Serve a valid VBIOS at the PROM window (BAR0+0x300000) loaded from
    /lib/firmware/tu104_vbios.bin (dump of host TU104 ROM). Guest's
    kgspExtractVbiosFromRom_TU102 needs it for the mandatory FWSEC ucode
    (kgspGetFrtsSize is hardwired to 1MB on Turing).
  * Pre-set GSP secure-boot (GFW) completion state: PGC6 PLM (0x118128)=1,
    GFW_BOOT progress (0x118234)=0xFF, GSP falcon CPUCTL HALTED (0x110100).
    The driver's post-FLR GFW wait only *waits* (never kicks), so the
    pre-set state satisfies it immediately.

- kernel/gsp_emulation.c/h: physical GSP boot emulation.
  * Falcon boot-watch: poll GSP falcon/PGC6/WPR2/scratch registers and log
    changes (guest BAR0 is mmap-based, otherwise invisible to host).
  * gsp_emu_poll_boot: STARTCPU auto-complete state machine. Guest kicks
    FWSEC then Booter Load via GSP falcon CPUCTL; detect each kick and
    complete the stage (HALTED + FRTS err NONE + WPR2 + mailbox +
    RISCV-active) so the guest believes its ucodes ran.

Diagnosis that led here (documented in Handoff-vGPU-IO.md):
- Open nvidia.ko can never be an SR-IOV VF vGPU guest: os_is_grid_supported()
  is a stub returning FALSE in the open build (disassembled). PV path also
  rejected per user directive. Only the physical path with a fully emulated
  local GSP boot remains.

1 files changed, 15 insertions, 0 deletions

diff --git a/kernel/gsp_emulation.h b/kernel/gsp_emulation.h
index 12bce63..53560e9 100644
--- a/kernel/gsp_emulation.h
+++ b/kernel/gsp_emulation.h
@@ -34,6 +34,12 @@
 #define GSP_EMU_POLL_SLEEP_MIN_US   50
 #define GSP_EMU_POLL_SLEEP_MAX_US   100
 
+/* GSP falcon boot-watch: registers polled for change logging so the guest's
+ * physical GSP boot sequence is visible on the host (guest BAR0 access is
+ * mmap-based and otherwise invisible). Offsets are BAR0-relative, GSP falcon
+ * block at 0x110000. */
+#define GSP_EMU_FALCON_WATCH_COUNT  17
+
 /* ============================================================
  * GSP Emulation Context
  * ============================================================ */
@@ -63,6 +69,15 @@ struct gsp_emu_context {
 
     /* MSI-X injection */
     struct eventfd_ctx *msix_trigger[NV_VGPU_MAX_IRQS];
+
+    /* Falcon boot-watch: last-sampled values for change detection */
+    u32 falcon_watch_last[GSP_EMU_FALCON_WATCH_COUNT];
+    bool falcon_watch_valid;
+
+    /* Physical GSP boot emulation state (gsp_emu_poll_boot) */
+    u32 boot_stage;         /* enum gsp_emu_boot_stage */
+    u32 flcn_kick_count;    /* STARTCPU kicks seen since last ENGINE reset */
+    u32 wpr2_addr_lo;       /* WPR2_ADDR_LO value to report after FWSEC */
 };
 
 /* ============================================================