[Workaround] Implement virtio-rng device

sysprog21 · Jan 29, 2025 · 261dcdc · 261dcdc
1 parent a1d688e
commit 261dcdc
Show file tree

Hide file tree

Showing 5 changed files with 360 additions and 0 deletions.
diff --git a/Makefile b/Makefile
@@ -34,6 +34,13 @@ ifeq ($(call has, VIRTIOBLK), 1)
     endif
 endif
 
+# virtio-rng
+ENABLE_VIRTIORNG ?= 1
+$(call set-feature, VIRTIORNG)
+ifeq ($(call has, VIRTIORNG), 1)
+    OBJS_EXTRA += virtio-rng.o
+endif
+
 NETDEV ?= tap
 # virtio-net
 ENABLE_VIRTIONET ?= 1

diff --git a/device.h b/device.h
@@ -286,6 +286,52 @@ void virtio_input_update_mouse_button_state(uint32_t button, bool pressed);
 void virtio_input_update_cursor(uint32_t x, uint32_t y);
 #endif /* SEMU_HAS(VIRTIOINPUT) */
 
+/* VirtIO-RNG */
+
+#if SEMU_HAS(VIRTIORNG)
+
+#define IRQ_VRNG 7
+#define IRQ_VRNG_BIT (1 << IRQ_VRNG)
+
+typedef struct {
+    uint32_t QueueNum;
+    uint32_t QueueDesc;
+    uint32_t QueueAvail;
+    uint32_t QueueUsed;
+    uint16_t last_avail;
+    bool ready;
+} virtio_rng_queue_t;
+
+typedef struct {
+    /* feature negotiation */
+    uint32_t DeviceFeaturesSel;
+    uint32_t DriverFeatures;
+    uint32_t DriverFeaturesSel;
+    /* queue config */
+    uint32_t QueueSel;
+    virtio_rng_queue_t queues[1];
+    /* status */
+    uint32_t Status;
+    uint32_t InterruptStatus;
+    /* supplied by environment */
+    uint32_t *ram;
+} virtio_rng_state_t;
+
+void virtio_rng_read(hart_t *vm,
+                     virtio_rng_state_t *rng,
+                     uint32_t addr,
+                     uint8_t width,
+                     uint32_t *value);
+
+void virtio_rng_write(hart_t *vm,
+                      virtio_rng_state_t *vrng,
+                      uint32_t addr,
+                      uint8_t width,
+                      uint32_t value);
+
+void virtio_rng_init(virtio_rng_state_t *vrng);
+#endif /* SEMU_HAS(VIRTIORNG) */
+
 /* ACLINT MTIMER */
 typedef struct {
     /* A MTIMER device has two separate base addresses: one for the MTIME
@@ -393,6 +439,9 @@ typedef struct {
 #if SEMU_HAS(VIRTIOINPUT)
     virtio_input_state_t vkeyboard;
     virtio_input_state_t vmouse;
+#endif
+#if SEMU_HAS(VIRTIORNG)
+    virtio_rng_state_t vrng;
 #endif
     /* ACLINT */
     mtimer_state_t mtimer;

diff --git a/main.c b/main.c
@@ -107,6 +107,18 @@ static void emu_update_vinput_mouse_interrupts(vm_t *vm)
 }
 #endif
 
+#if SEMU_HAS(VIRTIORNG)
+static void emu_update_vrng_interrupts(vm_t *vm)
+{
+    emu_state_t *data = PRIV(vm->hart[0]);
+    if (data->vrng.InterruptStatus)
+        data->plic.active |= IRQ_VRNG_BIT;
+    else
+        data->plic.active &= ~IRQ_VRNG_BIT;
+    plic_update_interrupts(vm, &data->plic);
+}
+#endif
+
 static void emu_update_timer_interrupt(hart_t *hart)
 {
     emu_state_t *data = PRIV(hart);
@@ -189,6 +201,12 @@ static void mem_load(hart_t *hart,
                               value);
             emu_update_vinput_mouse_interrupts(hart->vm);
             return;
+#endif
+#if SEMU_HAS(VIRTIORNG)
+        case 0x49: /* virtio-rng */
+            virtio_rng_read(hart, &data->vrng, addr & 0xFFFFF, width, value);
+            emu_update_vrng_interrupts(hart->vm);
+            return;
 #endif
         }
     }
@@ -261,6 +279,12 @@ static void mem_store(hart_t *hart,
                                value);
             emu_update_vinput_mouse_interrupts(hart->vm);
             return;
+#endif
+#if SEMU_HAS(VIRTIORNG)
+        case 0x49: /* virtio-rng */
+            virtio_rng_write(hart, &data->vrng, addr & 0xFFFFF, width, value);
+            emu_update_vrng_interrupts(hart->vm);
+            return;
 #endif
         }
     }
@@ -709,6 +733,10 @@ static int semu_start(int argc, char **argv)
     emu.vmouse.ram = emu.ram;
     virtio_input_init(&(emu.vmouse));
 #endif
+#if SEMU_HAS(VIRTIORNG)
+    emu.vrng.ram = emu.ram;
+    virtio_rng_init(&(emu.vrng));
+#endif
 
     /* Emulate */
     uint32_t peripheral_update_ctr = 0;

diff --git a/minimal.dts b/minimal.dts
@@ -86,5 +86,13 @@
             interrupts = <6>;
         };
 #endif
+
+#if SEMU_FEATURE_VIRTIORNG
+        rng0: virtio@4900000 {
+            compatible = "virtio,mmio";
+            reg = <0x4900000 0x200>;
+            interrupts = <7>;
+        };
+#endif
     };
 };