Re: [kvm-unit-tests PATCH v3 1/6] lib: s390x: introduce bitfield for PSW mask

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On 6/1/23 09:01, Nico Boehr wrote:
Changing the PSW mask is currently little clumsy, since there is only the
PSW_MASK_* defines. This makes it hard to change e.g. only the address
space in the current PSW without a lot of bit fiddling.

Introduce a bitfield for the PSW mask. This makes this kind of
modifications much simpler and easier to read.

Signed-off-by: Nico Boehr <nrb@xxxxxxxxxxxxx>
---
  lib/s390x/asm/arch_def.h | 25 ++++++++++++++++++++++++-
  s390x/selftest.c         | 40 ++++++++++++++++++++++++++++++++++++++++
  2 files changed, 64 insertions(+), 1 deletion(-)

diff --git a/lib/s390x/asm/arch_def.h b/lib/s390x/asm/arch_def.h
index bb26e008cc68..84f6996c4d8c 100644
--- a/lib/s390x/asm/arch_def.h
+++ b/lib/s390x/asm/arch_def.h
@@ -37,12 +37,35 @@ struct stack_frame_int {
  };
struct psw {
-	uint64_t	mask;
+	union {
+		uint64_t	mask;
+		struct {
+			uint8_t reserved00:1;
+			uint8_t per:1;
+			uint8_t reserved02:3;
+			uint8_t dat:1;
+			uint8_t io:1;
+			uint8_t ext:1;
+			uint8_t key:4;
+			uint8_t reserved12:1;
+			uint8_t mchk:1;
+			uint8_t wait:1;
+			uint8_t pstate:1;
+			uint8_t as:2;
+			uint8_t cc:2;
+			uint8_t prg_mask:4;
+			uint8_t reserved24:7;
+			uint8_t ea:1;
+			uint8_t ba:1;
+			uint32_t reserved33:31;

Hrm, since I already made the mistake of introducing bitfields with and without spaces between the ":" I'm in no position to complain here.

I'm also not sure what the consensus is.

+		};
+	};
  	uint64_t	addr;
  };

I've come to like static asserts for huge structs and bitfields since they can safe you from a *lot* of headaches.

#define PSW(m, a) ((struct psw){ .mask = (m), .addr = (uint64_t)(a) }) +

Whitespace damage

  struct short_psw {
  	uint32_t	mask;
  	uint32_t	addr;
diff --git a/s390x/selftest.c b/s390x/selftest.c
index 13fd36bc06f8..8d81ba312279 100644
--- a/s390x/selftest.c
+++ b/s390x/selftest.c
@@ -74,6 +74,45 @@ static void test_malloc(void)
  	report_prefix_pop();
  }
+static void test_psw_mask(void)
+{
+	uint64_t expected_key = 0xF;

We're using lowercase chars for hex constants

+	struct psw test_psw = PSW(0, 0);
+
+	report_prefix_push("PSW mask");
+	test_psw.dat = 1;
+	report(test_psw.mask == PSW_MASK_DAT, "DAT matches expected=0x%016lx actual=0x%016lx", PSW_MASK_DAT, test_psw.mask);
+
+	test_psw.mask = 0;
+	test_psw.io = 1;
+	report(test_psw.mask == PSW_MASK_IO, "IO matches expected=0x%016lx actual=0x%016lx", PSW_MASK_IO, test_psw.mask);
+
+	test_psw.mask = 0;
+	test_psw.ext = 1;
+	report(test_psw.mask == PSW_MASK_EXT, "EXT matches expected=0x%016lx actual=0x%016lx", PSW_MASK_EXT, test_psw.mask);
+
+	test_psw.mask = expected_key << (63 - 11);
+	report(test_psw.key == expected_key, "PSW Key matches expected=0x%lx actual=0x%x", expected_key, test_psw.key);
+
+	test_psw.mask = 1UL << (63 - 13);
+	report(test_psw.mchk, "MCHK matches");
+
+	test_psw.mask = 0;
+	test_psw.wait = 1;
+	report(test_psw.mask == PSW_MASK_WAIT, "Wait matches expected=0x%016lx actual=0x%016lx", PSW_MASK_WAIT, test_psw.mask);
+
+	test_psw.mask = 0;
+	test_psw.pstate = 1;
+	report(test_psw.mask == PSW_MASK_PSTATE, "Pstate matches expected=0x%016lx actual=0x%016lx", PSW_MASK_PSTATE, test_psw.mask);
+
+	test_psw.mask = 0;
+	test_psw.ea = 1;
+	test_psw.ba = 1;
+	report(test_psw.mask == PSW_MASK_64, "BA/EA matches expected=0x%016lx actual=0x%016lx", PSW_MASK_64, test_psw.mask);
+
+	report_prefix_pop();
+}
+
  int main(int argc, char**argv)
  {
  	report_prefix_push("selftest");
@@ -89,6 +128,7 @@ int main(int argc, char**argv)
  	test_fp();
  	test_pgm_int();
  	test_malloc();
+	test_psw_mask();
return report_summary();
  }




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