D1.3: Fix critical bug - add TMEM column offset for P0 in PV GEMM

The softmax warps store P at tmem_p0_offset=32. PV MMA must read from
the same offset. tOrP0 was missing the offset, causing PV to read from
TMEM column 0 (where S is) instead of column 32 (where P is).
This was the root cause of NaN/zeros in D1 tests.

dsv4/kernels/attention/fmha.py

@@ -174,9 +174,16 @@ class FmhaKernel:
         tOrP_base = pv_thr.make_fragment_A(tP if not self.use_smem_p else sP)
         tOrP = tOrP_base[(None,None,None,0)]
         tCrP = pv_mma.make_fragment_A(sP)
-        # tOrP0 always defined as tOrP. The TMEM-P path in the MMA warp applies
-        # the p0 column offset inline when constructing the gemm arguments.
-        tOrP0 = tOrP
+        # tOrP0: apply TMEM column offset for P0 (TMEM-P path only)
+        # The softmax warps store P at tmem_p0_offset columns. PV MMA must read
+        # from the same offset. For SMEM-P, tOrP is bound to sP (not TMEM).
+        if not self.use_smem_p:
+            tOrP0 = cute.make_tensor(
+                tOrP.iterator + self.qk_acc_dtype.width // self.q_dtype.width * self.tmem_p0_offset,
+                tOrP.layout,
+            )
+        else:
+            tOrP0 = tOrP
 
         tCtO_fake = pv_mma.make_fragment_C(cute.append(pv_as, self.num_acc_stage))
         pipeline.pipeline_init_wait(cluster_shape_mn=cl_vmnk)