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Re: [PATCH v4 3/4] pc-bios: s390x: Use reset PSW if avaliable


From: Thomas Huth
Subject: Re: [PATCH v4 3/4] pc-bios: s390x: Use reset PSW if avaliable
Date: Tue, 6 Oct 2020 20:10:51 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0

On 06/10/2020 11.42, Janosch Frank wrote:
If a blob provides a reset PSW then we should use it instead of
branching to the PSW address and using our own mask.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
---
  pc-bios/s390-ccw/bootmap.c  |  6 ++++--
  pc-bios/s390-ccw/jump2ipl.c | 26 +++++++++++++++++++-------
  pc-bios/s390-ccw/s390-ccw.h |  1 +
  3 files changed, 24 insertions(+), 9 deletions(-)

diff --git a/pc-bios/s390-ccw/bootmap.c b/pc-bios/s390-ccw/bootmap.c
index 8747c4ea26..88bd12d5d7 100644
--- a/pc-bios/s390-ccw/bootmap.c
+++ b/pc-bios/s390-ccw/bootmap.c
@@ -273,7 +273,8 @@ static void run_eckd_boot_script(block_number_t 
bmt_block_nr,
IPL_assert(bms->entry[i].type == BOOT_SCRIPT_EXEC,
                 "Unknown script entry type");
-    jump_to_IPL_code(bms->entry[i].address.load_address); /* no return */
+    write_reset_psw(bms->entry[i].address.load_address); /* no return */
+    jump_to_IPL_code(0); /* no return */
  }
static void ipl_eckd_cdl(void)
@@ -515,7 +516,8 @@ static void zipl_run(ScsiBlockPtr *pte)
      IPL_assert(entry->component_type == ZIPL_COMP_ENTRY_EXEC, "No EXEC 
entry");
/* should not return */
-    jump_to_IPL_code(entry->compdat.load_psw & PSW_MASK_SHORT_ADDR);
+    write_reset_psw(entry->compdat.load_psw);
+    jump_to_IPL_code(0);
  }
static void ipl_scsi(void)
diff --git a/pc-bios/s390-ccw/jump2ipl.c b/pc-bios/s390-ccw/jump2ipl.c
index b6aad32def..63afa4a349 100644
--- a/pc-bios/s390-ccw/jump2ipl.c
+++ b/pc-bios/s390-ccw/jump2ipl.c
@@ -12,15 +12,21 @@
#define KERN_IMAGE_START 0x010000UL
  #define RESET_PSW_MASK (PSW_MASK_SHORTPSW | PSW_MASK_64)
+#define RESET_PSW ((uint64_t)&jump_to_IPL_addr | RESET_PSW_MASK)
static uint64_t *reset_psw = 0, save_psw, ipl_continue; +void write_reset_psw(uint64_t psw)
+{
+    *reset_psw = psw;
+}
+
  static void jump_to_IPL_addr(void)
  {
      __attribute__((noreturn)) void (*ipl)(void) = (void *)ipl_continue;
/* Restore reset PSW */
-    *reset_psw = save_psw;
+    write_reset_psw(save_psw);
ipl();
      /* should not return */
@@ -43,11 +49,12 @@ void jump_to_IPL_code(uint64_t address)
       * content of non-BIOS memory after we loaded the guest, so we
       * save the original content and restore it in jump_to_IPL_2.
       */
-    save_psw = *reset_psw;
-    *reset_psw = (uint64_t) &jump_to_IPL_addr;
-    *reset_psw |= RESET_PSW_MASK;
-    ipl_continue = address;
-    debug_print_int("set IPL addr to", ipl_continue);
+    if (address) {
+        save_psw = *reset_psw;
+        write_reset_psw(RESET_PSW);
+        ipl_continue = address;
+    }
+    debug_print_int("set IPL addr to", address ? address : *reset_psw & 
PSW_MASK_SHORT_ADDR);

checkpatch.pl complains about a very long line here...
I'll change this line to use the Elvis operator, so that is a little bit short, ok?

 Thomas




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