selftests: kvm: s390: Add debug print functions

Add functions to simply print some basic state information in selftests.

The output can be enabled by setting:

#define TH_LOG_ENABLED 1
#define DEBUG 1

* print_psw: current SIE state description and VM run state
* print_hex_bytes: print memory with some counting markers
* print_hex: PRINT_HEX with 512 bytes
* print_run: use print_psw and print_hex to print contents of VM run
state and SIE state description
* print_regs: print content of general and control registers

All prints use pr_debug for the output and can be configured using
DEBUG.

Signed-off-by: Christoph Schlameuss <[e-mail]>
Acked-by: Janosch Frank <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Janosch Frank <[e-mail]>
Message-ID: <[e-mail]>

tools/testing/selftests/kvm/include/s390x/debug_print.h

···
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Definition for kernel virtual machines on s390x
+ *
+ * Copyright IBM Corp. 2024
+ *
+ * Authors:
+ *  Christoph Schlameuss <[e-mail]>
+ */
+
+#ifndef SELFTEST_KVM_DEBUG_PRINT_H
+#define SELFTEST_KVM_DEBUG_PRINT_H
+
+#include "asm/ptrace.h"
+#include "kvm_util.h"
+#include "sie.h"
+
+static inline void print_hex_bytes(const char *name, u64 addr, size_t len)
+{
+	u64 pos;
+
+	pr_debug("%s (%p)\n", name, (void *)addr);
+	pr_debug("            0/0x00---------|");
+	if (len > 8)
+		pr_debug(" 8/0x08---------|");
+	if (len > 16)
+		pr_debug(" 16/0x10--------|");
+	if (len > 24)
+		pr_debug(" 24/0x18--------|");
+	for (pos = 0; pos < len; pos += 8) {
+		if ((pos % 32) == 0)
+			pr_debug("\n %3lu 0x%.3lx ", pos, pos);
+		pr_debug(" %16lx", *((u64 *)(addr + pos)));
+	}
+	pr_debug("\n");
+}
+
+static inline void print_hex(const char *name, u64 addr)
+{
+	print_hex_bytes(name, addr, 512);
+}
+
+static inline void print_psw(struct kvm_run *run, struct kvm_s390_sie_block *sie_block)
+{
+	pr_debug("flags:0x%x psw:0x%.16llx:0x%.16llx exit:%u %s\n",
+		 run->flags,
+		 run->psw_mask, run->psw_addr,
+		 run->exit_reason, exit_reason_str(run->exit_reason));
+	pr_debug("sie_block psw:0x%.16llx:0x%.16llx\n",
+		 sie_block->psw_mask, sie_block->psw_addr);
+}
+
+static inline void print_run(struct kvm_run *run, struct kvm_s390_sie_block *sie_block)
+{
+	print_hex_bytes("run", (u64)run, 0x150);
+	print_hex("sie_block", (u64)sie_block);
+	print_psw(run, sie_block);
+}
+
+static inline void print_regs(struct kvm_run *run)
+{
+	struct kvm_sync_regs *sync_regs = &run->s.regs;
+
+	print_hex_bytes("GPRS", (u64)sync_regs->gprs, 8 * NUM_GPRS);
+	print_hex_bytes("ACRS", (u64)sync_regs->acrs, 4 * NUM_ACRS);
+	print_hex_bytes("CRS", (u64)sync_regs->crs, 8 * NUM_CRS);
+}
+
+#endif /* SELFTEST_KVM_DEBUG_PRINT_H */