Fixes

docs/backend/VirtGPU.md

@@ -152,7 +152,9 @@ Commands and data are serialized using a custom binary protocol with:
 - **VM-specific**: Only works in virtual machines with virtio-gpu support
 - **Host dependency**: Requires properly configured host-side backend
 - **Latency**: Small overhead from VM escaping for each operation
-
+- **Shared-memory size**: with the `libkrun` hypervisor, the RAM + VRAM
+  addressable memory is limited to 64 GB. So the maximum GPU memory
+  will be `64GB - RAM`, regardless of the hardware VRAM size.
 
 * This work is pending upstream changes in the VirglRenderer
   project.

ggml/include/ggml.h

@@ -730,10 +730,6 @@ extern "C" {
     GGML_API size_t  ggml_type_size(enum ggml_type type);             // size in bytes for all elements in a block
     GGML_API size_t  ggml_row_size (enum ggml_type type, int64_t ne); // size in bytes for all elements in a row
 
-    GGML_DEPRECATED(
-    GGML_API double ggml_type_sizef(enum ggml_type type), // ggml_type_size()/ggml_blck_size() as float
-    "use ggml_row_size() instead");
-
     GGML_API const char * ggml_type_name(enum ggml_type type);
     GGML_API const char * ggml_op_name  (enum ggml_op   op);
     GGML_API const char * ggml_op_symbol(enum ggml_op   op);

ggml/src/ggml-virtgpu/backend/backend-dispatched-backend.cpp

@@ -7,9 +7,21 @@
 
 #include <cstdint>
 
+static uint32_t validate_graph_operation(size_t cgraph_size, uint32_t shmem_res_id, const char * operation) {
+    if (cgraph_size == 0) {
+        GGML_LOG_ERROR(GGML_VIRTGPU_BCK "%s: Zero-size computation graph\n", operation);
+        return 1;
+    }
+
+    // place-holder: validate that the size of shmem_res_id is <= cgraph_size
+    // need to add another method in the Virgl->APIR callback interface
+    GGML_UNUSED(shmem_res_id);
+
+    return 0;  // Valid
+}
+
 uint32_t backend_backend_graph_compute(apir_encoder * enc, apir_decoder * dec, virgl_apir_context * ctx) {
     GGML_UNUSED(ctx);
-    GGML_UNUSED(enc);
 
     static bool async_backend_initialized = false;
     static bool async_backend;
@@ -34,28 +46,53 @@ uint32_t backend_backend_graph_compute(apir_encoder * enc, apir_decoder * dec, v
     size_t cgraph_size;
     apir_decode_size_t(dec, &cgraph_size);
 
+    if (validate_graph_operation(cgraph_size, shmem_res_id, __func__) != 0) {
+        apir_decoder_set_fatal(dec);
+        return 1;
+    }
+
     apir_decoder secondary_dec = apir_new_decoder((const char *) shmem_data, cgraph_size);
 
     ggml_cgraph * cgraph = apir_decode_ggml_cgraph(&secondary_dec, cgraph_size);
 
+    if (!cgraph || apir_decoder_get_fatal(&secondary_dec)) {
+        GGML_LOG_ERROR(GGML_VIRTGPU_BCK "%s: Failed to deserialize computation graph\n", __func__);
+        return 1;
+    }
+
+    if (cgraph->n_nodes < 0 || cgraph->n_leafs < 0) {
+        GGML_LOG_ERROR(GGML_VIRTGPU_BCK "%s: Invalid negative node/leaf count: nodes=%d leafs=%d\n", __func__,
+                       cgraph->n_nodes, cgraph->n_leafs);
+        return 1;
+    }
+
     ggml_status status;
 #if APIR_BACKEND_CHECK_SUPPORTS_OP == 1
     for (int idx = 0; idx < cgraph->n_nodes; idx++) {
         ggml_tensor * op = ggml_graph_node(cgraph, idx);
         if (dev->iface.supports_op(dev, op)) {
             continue;
         }
-        GGML_LOG_ERROR(GGML_VIRTGPU_BCK "%s: Graph node %d (%s) not supported by the backend\n", idx, ggml_op_desc(op));
+        GGML_LOG_ERROR(GGML_VIRTGPU_BCK "%s: Graph node %d (%s) not supported by the backend\n", __func__, idx,
+                       ggml_op_desc(op));
 
         status = GGML_STATUS_ABORTED;
         apir_encode_ggml_status(enc, &status);
 
         return 0;
     }
 #endif
+
+    // Check if backend is properly initialized
+    if (!bck) {
+        GGML_LOG_ERROR(GGML_VIRTGPU_BCK "%s: Backend not initialized (bck is null)\n", __func__);
+
+        return 1;
+    }
+
     status = bck->iface.graph_compute(bck, cgraph);
 
-    if (async_backend) {
+    if (async_backend && bck->iface.synchronize) {
         bck->iface.synchronize(bck);
     }
 

ggml/src/ggml-virtgpu/backend/backend-dispatched-buffer-type.cpp

@@ -85,7 +85,19 @@ uint32_t backend_buffer_type_get_alloc_size(apir_encoder * enc, apir_decoder * d
 
     const ggml_tensor * op = apir_decode_ggml_tensor_inplace(dec);
 
-    size_t value = buft->iface.get_alloc_size(buft, op);
+    // Check for decode error
+    if (op == nullptr) {
+        GGML_LOG_ERROR(GGML_VIRTGPU_BCK "%s: Failed to decode tensor\n", __func__);
+        apir_decoder_set_fatal(dec);
+        return 1;
+    }
+
+    size_t value;
+    if (buft->iface.get_alloc_size) {
+        value = buft->iface.get_alloc_size(buft, op);
+    } else {
+        value = ggml_nbytes(op);  // Default fallback
+    }
 
     apir_encode_size_t(enc, &value);
 

ggml/src/ggml-virtgpu/backend/backend-dispatched-buffer.cpp

@@ -6,11 +6,26 @@
 
 #include <cstdint>
 
+static uint32_t validate_buffer_operation(size_t offset, size_t size, const char * operation) {
+    // Only check for critical integer overflow - no arbitrary size limits
+    if (offset > SIZE_MAX - size) {
+        GGML_LOG_ERROR(GGML_VIRTGPU_BCK "%s: Integer overflow in offset+size: %zu + %zu\n", operation, offset, size);
+        return 1;
+    }
+
+    return 0;  // Valid
+}
+
 uint32_t backend_buffer_get_base(apir_encoder * enc, apir_decoder * dec, virgl_apir_context * ctx) {
     GGML_UNUSED(ctx);
     ggml_backend_buffer_t buffer;
     buffer = apir_decode_ggml_buffer(dec);
 
+    if (!buffer || apir_decoder_get_fatal(dec)) {
+        GGML_LOG_ERROR(GGML_VIRTGPU_BCK "%s: Invalid buffer handle from guest\n", __func__);
+        return 1;
+    }
+
     uintptr_t base = (uintptr_t) buffer->iface.get_base(buffer);
     apir_encode_uintptr_t(enc, &base);
 
@@ -24,6 +39,11 @@ uint32_t backend_buffer_set_tensor(apir_encoder * enc, apir_decoder * dec, virgl
     ggml_backend_buffer_t buffer;
     buffer = apir_decode_ggml_buffer(dec);
 
+    if (!buffer || apir_decoder_get_fatal(dec)) {
+        GGML_LOG_ERROR(GGML_VIRTGPU_BCK "%s: Invalid buffer handle from guest\n", __func__);
+        return 1;
+    }
+
     ggml_tensor * tensor;
     // safe to remove the const qualifier here
     tensor = (ggml_tensor *) (uintptr_t) apir_decode_ggml_tensor(dec);
@@ -37,6 +57,10 @@ uint32_t backend_buffer_set_tensor(apir_encoder * enc, apir_decoder * dec, virgl
     size_t size;
     apir_decode_size_t(dec, &size);
 
+    if (validate_buffer_operation(offset, size, __func__) != 0) {
+        return 1;
+    }
+
     void * shmem_data = ctx->iface->get_shmem_ptr(ctx->ctx_id, shmem_res_id);
 
     if (!shmem_data) {
@@ -56,6 +80,11 @@ uint32_t backend_buffer_get_tensor(apir_encoder * enc, apir_decoder * dec, virgl
     ggml_backend_buffer_t buffer;
     buffer = apir_decode_ggml_buffer(dec);
 
+    if (!buffer || apir_decoder_get_fatal(dec)) {
+        GGML_LOG_ERROR(GGML_VIRTGPU_BCK "%s: Invalid buffer handle from guest\n", __func__);
+        return 1;
+    }
+
     const ggml_tensor * tensor;
     // safe to remove the const qualifier here
     tensor = apir_decode_ggml_tensor(dec);
@@ -69,6 +98,10 @@ uint32_t backend_buffer_get_tensor(apir_encoder * enc, apir_decoder * dec, virgl
     size_t size;
     apir_decode_size_t(dec, &size);
 
+    if (validate_buffer_operation(offset, size, __func__) != 0) {
+        return 1;
+    }
+
     void * shmem_data = ctx->iface->get_shmem_ptr(ctx->ctx_id, shmem_res_id);
     if (!shmem_data) {
         GGML_LOG_ERROR(GGML_VIRTGPU_BCK "%s: Couldn't get the shmem addr from virgl\n", __func__);
@@ -86,6 +119,11 @@ uint32_t backend_buffer_cpy_tensor(apir_encoder * enc, apir_decoder * dec, virgl
     ggml_backend_buffer_t buffer;
     buffer = apir_decode_ggml_buffer(dec);
 
+    if (!buffer || apir_decoder_get_fatal(dec)) {
+        GGML_LOG_ERROR(GGML_VIRTGPU_BCK "%s: Invalid buffer handle from guest\n", __func__);
+        return 1;
+    }
+
     const ggml_tensor * src;
     // safe to remove the const qualifier here
     src               = apir_decode_ggml_tensor(dec);
@@ -105,6 +143,11 @@ uint32_t backend_buffer_clear(apir_encoder * enc, apir_decoder * dec, virgl_apir
     ggml_backend_buffer_t buffer;
     buffer = apir_decode_ggml_buffer(dec);
 
+    if (!buffer || apir_decoder_get_fatal(dec)) {
+        GGML_LOG_ERROR(GGML_VIRTGPU_BCK "%s: Invalid buffer handle from guest\n", __func__);
+        return 1;
+    }
+
     uint8_t value;
     apir_decode_uint8_t(dec, &value);
 
@@ -120,6 +163,11 @@ uint32_t backend_buffer_free_buffer(apir_encoder * enc, apir_decoder * dec, virg
     ggml_backend_buffer_t buffer;
     buffer = apir_decode_ggml_buffer(dec);
 
+    if (!buffer || apir_decoder_get_fatal(dec)) {
+        GGML_LOG_ERROR(GGML_VIRTGPU_BCK "%s: Invalid buffer handle from guest\n", __func__);
+        return 1;
+    }
+
     if (!apir_untrack_backend_buffer(buffer)) {
         GGML_LOG_WARN(GGML_VIRTGPU_BCK "%s: unknown buffer %p\n", __func__, (void *) buffer);
         return 1;

ggml/src/ggml-virtgpu/backend/backend-dispatched.cpp

@@ -1,6 +1,6 @@
 #include "backend-dispatched.h"
-#include "backend-virgl-apir.h"
 
+#include "backend-virgl-apir.h"
 #include "ggml-backend-impl.h"
 #include "ggml-backend.h"
 #include "ggml-impl.h"
@@ -28,19 +28,24 @@ uint32_t backend_dispatch_initialize(void * ggml_backend_reg_fct_p) {
         return APIR_BACKEND_INITIALIZE_BACKEND_REG_FAILED;
     }
 
-    if (!reg->iface.get_device_count(reg)) {
-        GGML_LOG_ERROR(GGML_VIRTGPU_BCK "%s: backend initialization failed: no device found\n", __func__);
+    size_t device_count = reg->iface.get_device_count(reg);
+    if (!device_count) {
+        GGML_LOG_ERROR(GGML_VIRTGPU_BCK "%s: no device found\n", __func__);
         return APIR_BACKEND_INITIALIZE_NO_DEVICE;
     }
 
     dev = reg->iface.get_device(reg, 0);
 
     if (!dev) {
-        GGML_LOG_ERROR(GGML_VIRTGPU_BCK "%s: backend initialization failed: no device received\n", __func__);
+        GGML_LOG_ERROR(GGML_VIRTGPU_BCK "%s: failed to get device\n", __func__);
         return APIR_BACKEND_INITIALIZE_NO_DEVICE;
     }
 
     bck = dev->iface.init_backend(dev, NULL);
+    if (!bck) {
+        GGML_LOG_ERROR(GGML_VIRTGPU_BCK "%s: backend initialization failed\n", __func__);
+        return APIR_BACKEND_INITIALIZE_BACKEND_INIT_FAILED;
+    }
 
     return APIR_BACKEND_INITIALIZE_SUCCESS;
 }

ggml/src/ggml-virtgpu/backend/backend-dispatched.gen.h

@@ -32,64 +32,6 @@ uint32_t backend_buffer_free_buffer(apir_encoder * enc, apir_decoder * dec, virg
 /* backend */
 uint32_t backend_backend_graph_compute(apir_encoder * enc, apir_decoder * dec, virgl_apir_context * ctx);
 
-static inline const char * backend_dispatch_command_name(ApirBackendCommandType type) {
-    switch (type) {
-        /* device */
-        case APIR_COMMAND_TYPE_DEVICE_GET_DEVICE_COUNT:
-            return "backend_device_get_device_count";
-        case APIR_COMMAND_TYPE_DEVICE_GET_COUNT:
-            return "backend_device_get_count";
-        case APIR_COMMAND_TYPE_DEVICE_GET_NAME:
-            return "backend_device_get_name";
-        case APIR_COMMAND_TYPE_DEVICE_GET_DESCRIPTION:
-            return "backend_device_get_description";
-        case APIR_COMMAND_TYPE_DEVICE_GET_TYPE:
-            return "backend_device_get_type";
-        case APIR_COMMAND_TYPE_DEVICE_GET_MEMORY:
-            return "backend_device_get_memory";
-        case APIR_COMMAND_TYPE_DEVICE_SUPPORTS_OP:
-            return "backend_device_supports_op";
-        case APIR_COMMAND_TYPE_DEVICE_GET_BUFFER_TYPE:
-            return "backend_device_get_buffer_type";
-        case APIR_COMMAND_TYPE_DEVICE_GET_PROPS:
-            return "backend_device_get_props";
-        case APIR_COMMAND_TYPE_DEVICE_BUFFER_FROM_PTR:
-            return "backend_device_buffer_from_ptr";
-        /* buffer-type */
-        case APIR_COMMAND_TYPE_BUFFER_TYPE_GET_NAME:
-            return "backend_buffer_type_get_name";
-        case APIR_COMMAND_TYPE_BUFFER_TYPE_GET_ALIGNMENT:
-            return "backend_buffer_type_get_alignment";
-        case APIR_COMMAND_TYPE_BUFFER_TYPE_GET_MAX_SIZE:
-            return "backend_buffer_type_get_max_size";
-        case APIR_COMMAND_TYPE_BUFFER_TYPE_IS_HOST:
-            return "backend_buffer_type_is_host (DEPRECATED)";
-        case APIR_COMMAND_TYPE_BUFFER_TYPE_ALLOC_BUFFER:
-            return "backend_buffer_type_alloc_buffer";
-        case APIR_COMMAND_TYPE_BUFFER_TYPE_GET_ALLOC_SIZE:
-            return "backend_buffer_type_get_alloc_size";
-        /* buffer */
-        case APIR_COMMAND_TYPE_BUFFER_GET_BASE:
-            return "backend_buffer_get_base";
-        case APIR_COMMAND_TYPE_BUFFER_SET_TENSOR:
-            return "backend_buffer_set_tensor";
-        case APIR_COMMAND_TYPE_BUFFER_GET_TENSOR:
-            return "backend_buffer_get_tensor";
-        case APIR_COMMAND_TYPE_BUFFER_CPY_TENSOR:
-            return "backend_buffer_cpy_tensor";
-        case APIR_COMMAND_TYPE_BUFFER_CLEAR:
-            return "backend_buffer_clear";
-        case APIR_COMMAND_TYPE_BUFFER_FREE_BUFFER:
-            return "backend_buffer_free_buffer";
-        /* backend */
-        case APIR_COMMAND_TYPE_BACKEND_GRAPH_COMPUTE:
-            return "backend_backend_graph_compute";
-
-        default:
-            return "unknown";
-    }
-}
-
 extern "C" {
 static const backend_dispatch_t apir_backend_dispatch_table[APIR_BACKEND_DISPATCH_TABLE_COUNT] = {
 

ggml/src/ggml-virtgpu/backend/backend-dispatched.h

@@ -1,5 +1,6 @@
 #pragma once
 
+// clang-format off
 #include <cstdint>
 #include <cstddef>
 
@@ -10,6 +11,7 @@
 #include "shared/apir_backend.h"
 #include "shared/apir_cs.h"
 #include "shared/apir_cs_ggml.h"
+// clang-format on
 
 #define GGML_VIRTGPU_BCK "ggml-virtgpu-backend: "
 

ggml/src/ggml-virtgpu/backend/backend-virgl-apir.h

@@ -19,7 +19,7 @@ struct virgl_apir_callbacks {
 };
 
 extern "C" {
-ApirLoadLibraryReturnCode apir_backend_initialize(uint32_t virgl_ctx_id, struct virgl_apir_callbacks *virgl_cbs);
+ApirLoadLibraryReturnCode apir_backend_initialize(uint32_t virgl_ctx_id, struct virgl_apir_callbacks * virgl_cbs);
 void                      apir_backend_deinit(uint32_t virgl_ctx_id);
 uint32_t                  apir_backend_dispatcher(uint32_t               virgl_ctx_id,
                                                   virgl_apir_callbacks * virgl_cbs,