Yes, with second patch is magically works, meaning the patch description 
is not correct because the problem for powerpc it not at all related to 
memory alignment but to endianness. And endianness should have been 
fixed by patch 1, but instead of it, patch 1 just hides the problem by 
forcing casts.

The real fix for endianness which should be your patch 1 is the 
following change. With that change it works perfectly well without any 
forced cast:

diff --git a/lib/checksum_kunit.c b/lib/checksum_kunit.c
index 225bb7701460..bf70850035c7 100644
--- a/lib/checksum_kunit.c
+++ b/lib/checksum_kunit.c

@@ -215,7 +215,7 @@ static const u32 init_sums_no_overflow[] = {
  	0xffff0000, 0xfffffffb,
  };

-static const __sum16 expected_csum_ipv6_magic[] = {
+static const u16 expected_csum_ipv6_magic[] = {
  	0x18d4, 0x3085, 0x2e4b, 0xd9f4, 0xbdc8, 0x78f,	0x1034, 0x8422, 0x6fc0,
  	0xd2f6, 0xbeb5, 0x9d3,	0x7e2a, 0x312e, 0x778e, 0xc1bb, 0x7cf2, 0x9d1e,
  	0xca21, 0xf3ff, 0x7569, 0xb02e, 0xca86, 0x7e76, 0x4539, 0x45e3, 0xf28d,

@@ -241,7 +241,7 @@ static const __sum16 expected_csum_ipv6_magic[] = {
  	0x3845, 0x1014
  };

-static const __sum16 expected_fast_csum[] = {
+static const u16 expected_fast_csum[] = {
  	0xda83, 0x45da, 0x4f46, 0x4e4f, 0x34e,	0xe902, 0xa5e9, 0x87a5, 0x7187,
  	0x5671, 0xf556, 0x6df5, 0x816d, 0x8f81, 0xbb8f, 0xfbba, 0x5afb, 0xbe5a,
  	0xedbe, 0xabee, 0x6aac, 0xe6b,	0xea0d, 0x67ea, 0x7e68, 0x8a7e, 0x6f8a,

@@ -577,7 +577,8 @@ static void test_csum_no_carry_inputs(struct kunit 

*test)

  static void test_ip_fast_csum(struct kunit *test)
  {
-	__sum16 csum_result, expected;
+	__sum16 csum_result;
+	u16 expected;

  	for (int len = IPv4_MIN_WORDS; len < IPv4_MAX_WORDS; len++) {
  		for (int index = 0; index < NUM_IP_FAST_CSUM_TESTS; index++) {

@@ -586,7 +587,7 @@ static void test_ip_fast_csum(struct kunit *test)
  				expected_fast_csum[(len - IPv4_MIN_WORDS) *
  						   NUM_IP_FAST_CSUM_TESTS +
  						   index];
-			CHECK_EQ(expected, csum_result);
+			CHECK_EQ(to_sum16(expected), csum_result);
  		}
  	}
  }

@@ -598,7 +599,7 @@ static void test_csum_ipv6_magic(struct kunit *test)
  	const struct in6_addr *daddr;
  	unsigned int len;
  	unsigned char proto;
-	unsigned int csum;
+	__wsum csum;

  	const int daddr_offset = sizeof(struct in6_addr);
  	const int len_offset = sizeof(struct in6_addr) + sizeof(struct in6_addr);

@@ -611,10 +612,10 @@ static void test_csum_ipv6_magic(struct kunit *test)
  		saddr = (const struct in6_addr *)(random_buf + i);
  		daddr = (const struct in6_addr *)(random_buf + i +
  						  daddr_offset);
-		len = *(unsigned int *)(random_buf + i + len_offset);
+		len = le32_to_cpu(*(__le32 *)(random_buf + i + len_offset));
  		proto = *(random_buf + i + proto_offset);
-		csum = *(unsigned int *)(random_buf + i + csum_offset);
-		CHECK_EQ(expected_csum_ipv6_magic[i],
+		csum = *(__wsum *)(random_buf + i + csum_offset);
+		CHECK_EQ(to_sum16(expected_csum_ipv6_magic[i]),
  			 csum_ipv6_magic(saddr, daddr, len, proto, csum));
  	}
  #endif /* !CONFIG_NET */
---

Christophe