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Re: [PATCH v4 08/19] pc-bios/s390-ccw: Remove panics from ECKD IPL path


From: Thomas Huth
Subject: Re: [PATCH v4 08/19] pc-bios/s390-ccw: Remove panics from ECKD IPL path
Date: Thu, 17 Oct 2024 10:01:27 +0200
User-agent: Mozilla Thunderbird

On 17/10/2024 03.47, jrossi@linux.ibm.com wrote:
From: Jared Rossi <jrossi@linux.ibm.com>

Remove panic-on-error from ECKD block device IPL specific functions so that
error recovery may be possible in the future.

Functions that would previously panic now provide a return code.

Signed-off-by: Jared Rossi <jrossi@linux.ibm.com>
---
  pc-bios/s390-ccw/bootmap.h |   1 +
  pc-bios/s390-ccw/bootmap.c | 193 +++++++++++++++++++++++++------------
  2 files changed, 135 insertions(+), 59 deletions(-)

diff --git a/pc-bios/s390-ccw/bootmap.h b/pc-bios/s390-ccw/bootmap.h
index 09f4e6fb40..271dbabbc3 100644
--- a/pc-bios/s390-ccw/bootmap.h
+++ b/pc-bios/s390-ccw/bootmap.h
@@ -16,6 +16,7 @@
typedef uint64_t block_number_t;
  #define NULL_BLOCK_NR 0xffffffffffffffffULL
+#define ERROR_BLOCK_NR 0xfffffffffffffffeULL
#define FREE_SPACE_FILLER '\xAA' diff --git a/pc-bios/s390-ccw/bootmap.c b/pc-bios/s390-ccw/bootmap.c
index 5477cfe228..dd04bb3384 100644
--- a/pc-bios/s390-ccw/bootmap.c
+++ b/pc-bios/s390-ccw/bootmap.c
@@ -145,14 +145,17 @@ static block_number_t load_eckd_segments(block_number_t 
blk, bool ldipl,
      bool more_data;
memset(_bprs, FREE_SPACE_FILLER, sizeof(_bprs));
-    read_block(blk, bprs, "BPRS read failed");
+    if (virtio_read(blk, bprs)) {
+        puts("BPRS read failed");
+        return ERROR_BLOCK_NR;
+    }
do {
          more_data = false;
          for (j = 0;; j++) {
              block_nr = gen_eckd_block_num(&bprs[j].xeckd, ldipl);
              if (is_null_block_number(block_nr)) { /* end of chunk */
-                break;
+                return NULL_BLOCK_NR;
              }
/* we need the updated blockno for the next indirect entry
@@ -163,15 +166,20 @@ static block_number_t load_eckd_segments(block_number_t 
blk, bool ldipl,
              }
/* List directed pointer does not store block size */
-            IPL_assert(ldipl || block_size_ok(bprs[j].xeckd.bptr.size),
-                       "bad chunk block size");
+            if (!ldipl && !block_size_ok(bprs[j].xeckd.bptr.size)) {
+                puts("Bad chunk block size");
+                return NULL_BLOCK_NR;

Shouldn't that be a "return ERROR_BLOCK_NR" instead?

+            }
if (!eckd_valid_address(&bprs[j].xeckd, ldipl)) {
                  /*
                   * If an invalid address is found during LD-IPL then break and
-                 * retry as CCW
+                 * retry as CCW-IPL, otherwise abort on error
                   */
-                IPL_assert(ldipl, "bad chunk ECKD addr");
+                if (!ldipl) {
+                    puts("Bad chunk ECKD address");
+                    return ERROR_BLOCK_NR;
+                }
                  break;
              }
@@ -189,7 +197,10 @@ static block_number_t load_eckd_segments(block_number_t blk, bool ldipl,
                   * I.e. the next ptr must point to the unused memory area
                   */
                  memset(_bprs, FREE_SPACE_FILLER, sizeof(_bprs));
-                read_block(block_nr, bprs, "BPRS continuation read failed");
+                if (virtio_read(block_nr, bprs)) {
+                    puts("BPRS continuation read failed");
+                    return ERROR_BLOCK_NR;
+                }
                  more_data = true;
                  break;
              }
@@ -198,7 +209,10 @@ static block_number_t load_eckd_segments(block_number_t 
blk, bool ldipl,
               * to memory (address).
               */
              rc = virtio_read_many(block_nr, (void *)(*address), count + 1);
-            IPL_assert(rc == 0, "code chunk read failed");
+            if (rc != 0) {
+                puts("Code chunk read failed");
+                return ERROR_BLOCK_NR;
+            }
*address += (count + 1) * virtio_get_block_size();
          }
@@ -232,7 +246,10 @@ static int eckd_get_boot_menu_index(block_number_t 
s1b_block_nr)
/* Get Stage1b data */
      memset(sec, FREE_SPACE_FILLER, sizeof(sec));
-    read_block(s1b_block_nr, s1b, "Cannot read stage1b boot loader");
+    if (virtio_read(s1b_block_nr, s1b)) {
+        puts("Cannot read stage1b boot loader");
+        return -EIO;
+    }
memset(_s2, FREE_SPACE_FILLER, sizeof(_s2)); @@ -244,7 +261,10 @@ static int eckd_get_boot_menu_index(block_number_t s1b_block_nr)
              break;
          }
- read_block(cur_block_nr, s2_cur_blk, "Cannot read stage2 boot loader");
+        if (virtio_read(cur_block_nr, s2_cur_blk)) {
+            puts("Cannot read stage2 boot loader");
+            return -EIO;
+        }
if (find_zipl_boot_menu_banner(&banner_offset)) {
              /*
@@ -252,8 +272,10 @@ static int eckd_get_boot_menu_index(block_number_t 
s1b_block_nr)
               * possibility of menu data spanning multiple blocks.
               */
              if (prev_block_nr) {
-                read_block(prev_block_nr, s2_prev_blk,
-                           "Cannot read stage2 boot loader");
+                if (virtio_read(prev_block_nr, s2_prev_blk)) {
+                    puts("Cannot read stage2 boot loader");
+                    return -EIO;
+                }
              }
if (i + 1 < STAGE2_BLK_CNT_MAX) {
@@ -261,8 +283,10 @@ static int eckd_get_boot_menu_index(block_number_t 
s1b_block_nr)
              }
if (next_block_nr && !is_null_block_number(next_block_nr)) {
-                read_block(next_block_nr, s2_next_blk,
-                           "Cannot read stage2 boot loader");
+                if (virtio_read(next_block_nr, s2_next_blk)) {
+                    puts("Cannot read stage2 boot loader");
+                    return -EIO;
+                }
              }
return menu_get_zipl_boot_index(s2_cur_blk + banner_offset);
@@ -275,7 +299,7 @@ static int eckd_get_boot_menu_index(block_number_t 
s1b_block_nr)
      return 0;
  }
-static void run_eckd_boot_script(block_number_t bmt_block_nr,
+static int run_eckd_boot_script(block_number_t bmt_block_nr,
                                   block_number_t s1b_block_nr)
  {
      int i;
@@ -292,17 +316,28 @@ static void run_eckd_boot_script(block_number_t 
bmt_block_nr,
      }
debug_print_int("loadparm", loadparm);
-    IPL_assert(loadparm < MAX_BOOT_ENTRIES, "loadparm value greater than"
-               " maximum number of boot entries allowed");
+    if (loadparm >= MAX_BOOT_ENTRIES) {
+        puts("loadparm value greater than max number of boot entries allowed");
+        return -EINVAL;
+    }
memset(sec, FREE_SPACE_FILLER, sizeof(sec));
-    read_block(bmt_block_nr, sec, "Cannot read Boot Map Table");
+    if (virtio_read(bmt_block_nr, sec)) {
+        puts("Cannot read Boot Map Table");
+        return -EIO;
+    }
block_nr = gen_eckd_block_num(&bmt->entry[loadparm].xeckd, ldipl);
-    IPL_assert(block_nr != -1, "Cannot find Boot Map Table Entry");
+    if (block_nr == NULL_BLOCK_NR) {
+        puts("Cannot find Boot Map Table Entry");
+        return -EIO;
+    }
memset(sec, FREE_SPACE_FILLER, sizeof(sec));
-    read_block(block_nr, sec, "Cannot read Boot Map Script");
+    if (virtio_read(block_nr, sec)) {
+        puts("Cannot read Boot Map Script");
+        return -EIO;
+    }
for (i = 0; bms->entry[i].type == BOOT_SCRIPT_LOAD ||
                  bms->entry[i].type == BOOT_SCRIPT_SIGNATURE; i++) {
@@ -317,21 +352,28 @@ static void run_eckd_boot_script(block_number_t 
bmt_block_nr,
do {
              block_nr = load_eckd_segments(block_nr, ldipl, &address);
-        } while (block_nr != -1);
+        } while (block_nr != ERROR_BLOCK_NR && block_nr != NULL_BLOCK_NR);
+
+        if (block_nr == ERROR_BLOCK_NR) {
+            return ldipl ? 0 : -EIO;
+        }

Mostly a matter of style, but if you move the if-statement into the while loop, you don't have to check for ERROR_BLOCK_NR in the while condition again.

      }
if (ldipl && bms->entry[i].type != BOOT_SCRIPT_EXEC) {
          /* Abort LD-IPL and retry as CCW-IPL */
-        return;
+        return 0;
      }
- IPL_assert(bms->entry[i].type == BOOT_SCRIPT_EXEC,
-               "Unknown script entry type");
+    if (bms->entry[i].type != BOOT_SCRIPT_EXEC) {
+        puts("Unknown script entry type");
+        return -EINVAL;
+    }
      write_reset_psw(bms->entry[i].address.load_address); /* no return */
      jump_to_IPL_code(0); /* no return */
+    return 1;
  }
...
@@ -787,12 +859,15 @@ static void load_iso_bc_entry(IsoBcSection *load)
      uint32_t blks_to_load = bswap16(s.sector_count) >> ET_SECTOR_SHIFT;
      long real_size = iso_get_file_size(bswap32(s.load_rba));
- if (real_size) {
+    if (real_size > 0) {
          /* Round up blocks to load */
          blks_to_load = (real_size + ISO_SECTOR_SIZE - 1) / ISO_SECTOR_SIZE;
          puts("ISO boot image size verified");
      } else {
          puts("ISO boot image size could not be verified");
+        if (real_size < 0) {
+            return;
+        }
      }

Ah, here's the fix for the problem that I complained about in the previous patch :-) ... looks like you've squashed it into the wrong patch.

 Thomas





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