sema-svc: sema_vidmem_dump param to inspect emulated vidmem (CE data-path audit)

1 files changed, 36 insertions, 0 deletions

diff --git a/kernel/gsp_sema_service.c b/kernel/gsp_sema_service.c
index 6703403..56285bf 100644
--- a/kernel/gsp_sema_service.c
+++ b/kernel/gsp_sema_service.c
@@ -5052,6 +5052,42 @@ int gsp_sema_service_add_map(u64 gpu_va, u64 pa, u64 len, u32 ap)
 }
 
 /*
+ * Dump a range of the emulated vidmem (BAR1 shadow) into the kernel log.
+ * Debug aid for the CE data path: verifies whether a decoded fill/copy
+ * actually landed where the CE operand said it should.
+ */
+int gsp_sema_service_dump_vidmem(u64 addr, u64 len)
+{
+	struct nv_vgpu_device *vgpu = NULL;
+	struct nv_vgpu_device *d;
+	u8 *base;
+
+	if (!len || len > 4096)
+		return -EINVAL;
+
+	mutex_lock(&nv_vgpu_driver.lock);
+	list_for_each_entry(d, &nv_vgpu_driver.devices, list) {
+		if (atomic_read(&d->vfio_dev_open_count) > 0) {
+			vgpu = d;
+			break;
+		}
+	}
+	mutex_unlock(&nv_vgpu_driver.lock);
+	if (!vgpu)
+		return -ENODEV;
+
+	base = vgpu->bars[1].vaddr;
+	if (!base || addr + len > vgpu->bars[1].size)
+		return -EINVAL;
+
+	pr_info("sema-vidmem: dump addr=0x%llx len=%llu\n",
+		(unsigned long long)addr, (unsigned long long)len);
+	print_hex_dump(KERN_INFO, "sema-vidmem: ", DUMP_PREFIX_OFFSET,
+		       16, 1, base + addr, (size_t)len, false);
+	return 0;
+}
+
+/*
  * Register a channel's GPU completion counter (guest PA of the u32 the GPU
  * would advance as pushes complete). Called from the sema_counter debug
  * parameter; plain state update, so it runs in the caller's context.