Use new memory layout for pVM firmware.

Moved data memory to just above pVM firmware image, rather than an
arbitrary location higher in RAM.

Bug: 223166344
Test: ran with patched crosvm
Change-Id: I4fc92edf7752352bc962169b009d052ddd07479d
diff --git a/pvmfw/idmap.S b/pvmfw/idmap.S
index 62555f9..ec3ceaf 100644
--- a/pvmfw/idmap.S
+++ b/pvmfw/idmap.S
@@ -44,9 +44,9 @@
 	.fill		509, 8, 0x0			// 509 GB of remaining VA space
 
 	/* level 2 */
-0:	.fill		511, 8, 0x0
-	.quad		.L_BLOCK_MEM_XIP | 0x7fe00000	// pVM firmware image
+0:	.fill		510, 8, 0x0
+	.quad		.L_BLOCK_MEM_XIP | 0x7fc00000	// pVM firmware image
+	.quad		.L_BLOCK_MEM	 | 0x7fe00000	// Writable memory for stack, heap &c.
 1:	.quad		.L_BLOCK_RO	 | 0x80000000	// DT provided by VMM
 	.quad		.L_BLOCK_RO	 | 0x80200000	// 2 MB of DRAM containing payload image
-	.quad		.L_BLOCK_MEM	 | 0x80400000	// Writable memory for stack, heap &c.
-	.fill		509, 8, 0x0
+	.fill		510, 8, 0x0