[BugFix] [Kernel] Fix GPU SEGV occurring in int8 kernels (vllm-projec…

…t#9391)

csrc/quantization/compressed_tensors/int8_quant_kernels.cu

@@ -96,12 +96,15 @@ __global__ void static_scaled_int8_quant_kernel(
     scalar_t const* __restrict__ input, int8_t* __restrict__ out,
     scale_type const* scale_ptr, const int hidden_size) {
   int const tid = threadIdx.x;
-  int const token_idx = blockIdx.x;
+  int64_t const token_idx = blockIdx.x;
   scale_type const scale = *scale_ptr;
 
+  // Must be performed using 64-bit math to avoid integer overflow.
+  out += token_idx * hidden_size;
+  input += token_idx * hidden_size;
+
   for (int i = tid; i < hidden_size; i += blockDim.x) {
-    out[token_idx * hidden_size + i] = float_to_int8_rn(
-        static_cast<float>(input[token_idx * hidden_size + i]) / scale);
+    out[i] = float_to_int8_rn(static_cast<float>(input[i]) / scale);
   }
 }
 
@@ -111,14 +114,18 @@ __global__ void static_scaled_int8_azp_quant_kernel(
     scale_type const* scale_ptr, azp_type const* azp_ptr,
     const int hidden_size) {
   int const tid = threadIdx.x;
-  int const token_idx = blockIdx.x;
+  int64_t const token_idx = blockIdx.x;
   scale_type const scale = *scale_ptr;
   azp_type const azp = *azp_ptr;
 
+  // Must be performed using 64-bit math to avoid integer overflow.
+  out += token_idx * hidden_size;
+  input += token_idx * hidden_size;
+
   for (int i = tid; i < hidden_size; i += blockDim.x) {
-    auto const val = static_cast<float>(input[token_idx * hidden_size + i]);
+    auto const val = static_cast<float>(input[i]);
     auto const quant_val = int32_to_int8(float_to_int32_rn(val / scale) + azp);
-    out[token_idx * hidden_size + i] = quant_val;
+    out[i] = quant_val;
   }
 }
 
@@ -127,12 +134,16 @@ __global__ void dynamic_scaled_int8_quant_kernel(
     scalar_t const* __restrict__ input, int8_t* __restrict__ out,
     scale_type* scale, const int hidden_size) {
   int const tid = threadIdx.x;
-  int const token_idx = blockIdx.x;
+  int64_t const token_idx = blockIdx.x;
   float absmax_val = 0.0f;
   float const zero = 0.0f;
 
+  // Must be performed using 64-bit math to avoid integer overflow.
+  out += token_idx * hidden_size;
+  input += token_idx * hidden_size;
+
   for (int i = tid; i < hidden_size; i += blockDim.x) {
-    float val = static_cast<float>(input[token_idx * hidden_size + i]);
+    float val = static_cast<float>(input[i]);
     val = val > zero ? val : -val;
     absmax_val = val > absmax_val ? val : absmax_val;
   }
@@ -150,22 +161,25 @@ __global__ void dynamic_scaled_int8_quant_kernel(
 
   float const tmp_scale = 127.0f / block_absmax_val;
   for (int i = tid; i < hidden_size; i += blockDim.x) {
-    out[token_idx * hidden_size + i] = float_to_int8_rn(
-        static_cast<float>(input[token_idx * hidden_size + i]) * tmp_scale);
+    out[i] = float_to_int8_rn(static_cast<float>(input[i]) * tmp_scale);
   }
 }
 
 template <typename scalar_t, typename scale_type, typename azp_type>
 __global__ void dynamic_scaled_int8_azp_quant_kernel(
     scalar_t const* __restrict__ input, int8_t* __restrict__ out,
     scale_type* scale, azp_type* azp, const int hidden_size) {
-  int const token_idx = blockIdx.x;
+  int64_t const token_idx = blockIdx.x;
+
+  // Must be performed using 64-bit math to avoid integer overflow.
+  out += token_idx * hidden_size;
+  input += token_idx * hidden_size;
 
   // Scan for the min and max value for this token
   float max_val = std::numeric_limits<float>::min();
   float min_val = std::numeric_limits<float>::max();
   for (int i = threadIdx.x; i < hidden_size; i += blockDim.x) {
-    auto val = static_cast<float>(input[token_idx * hidden_size + i]);
+    auto val = static_cast<float>(input[i]);
     max_val = std::max(max_val, val);
     min_val = std::min(min_val, val);
   }
@@ -200,10 +214,10 @@ __global__ void dynamic_scaled_int8_azp_quant_kernel(
 
   // Quantize the values
   for (int i = threadIdx.x; i < hidden_size; i += blockDim.x) {
-    auto const val = static_cast<float>(input[token_idx * hidden_size + i]);
+    auto const val = static_cast<float>(input[i]);
     auto const quant_val =
         int32_to_int8(float_to_int32_rn(val / scale_val) + azp_val);
-    out[token_idx * hidden_size + i] = quant_val;
+    out[i] = quant_val;
   }
 }