xive: Fix xive reset corrupting EQ allocation bitmap

This causes us to hand out the physical processor EQs again to
VPs when KVM uses the XIVE, thus causing loss of host interrupts.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>

hw/xive.c

@@ -3649,6 +3649,7 @@ static void xive_cleanup_cpu_cam(struct cpu_thread *c)
 static void xive_reset_one(struct xive *x)
 {
 	struct cpu_thread *c;
+	bool eq_firmware;
 	int i = 0;
 
 	/* Mask all interrupt sources */
@@ -3666,15 +3667,29 @@ static void xive_reset_one(struct xive *x)
 	bitmap_for_each_one(*x->eq_map, MAX_EQ_COUNT >> 3, i) {
 		struct xive_eq eq0 = {0};
 		struct xive_eq *eq;
+		int j;
 
 		if (i == 0)
 			continue;
-		eq = xive_get_eq(x, i);
-		if (!eq)
-			continue;
-		xive_eqc_cache_update(x, x->block_id,
-				      i, 0, 4, &eq0, false, true);
-		if (!(eq->w0 & EQ_W0_FIRMWARE))
+		eq_firmware = false;
+		for (j = 0; j < 8; j++) {
+			uint32_t idx = (i << 3) | j;
+
+			eq = xive_get_eq(x, idx);
+			if (!eq)
+				continue;
+
+			/* We need to preserve the firmware bit, otherwise
+			 * we will incorrectly free the EQs that are reserved
+			 * for the physical CPUs
+			 */
+			eq0.w0 = eq->w0 & EQ_W0_FIRMWARE;
+			xive_eqc_cache_update(x, x->block_id,
+					      idx, 0, 4, &eq0, false, true);
+			if (eq->w0 & EQ_W0_FIRMWARE)
+				eq_firmware = true;
+		}
+		if (!eq_firmware)
 			bitmap_clr_bit(*x->eq_map, i);
 	}