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pc-bios/s390-ccw: do a subsystem reset before running the guest

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The loader BIOS has already activated several devices. Let's do a
subsystem reset before jumping into the guest. As there is no direct
way of doing so, we use diagnose 308 to bring the system in a
defined state. This is similar to what kdump on s390 uses. We have
to define a small trampoline function that restores the low bytes
to whatever the bootmap has written there.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Jens Freimann <jfrei@linux.vnet.ibm.com>
Reviewed-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
This commit is contained in:
Christian Borntraeger 2014-06-18 14:16:45 +02:00 committed by Cornelia Huck
parent 554f80896d
commit 9629823290
1 changed files with 47 additions and 8 deletions
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55
pc-bios/s390-ccw/bootmap.c
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@ -58,6 +58,52 @@ struct mbr {
/* Scratch space */
static uint8_t sec[SECTOR_SIZE] __attribute__((__aligned__(SECTOR_SIZE)));
typedef struct ResetInfo {
uint32_t ipl_mask;
uint32_t ipl_addr;
uint32_t ipl_continue;
} ResetInfo;
ResetInfo save;
static void jump_to_IPL_2(void)
{
ResetInfo *current = 0;
void (*ipl)(void) = (void *) (uint64_t) current->ipl_continue;
debug_print_addr("set IPL addr to", ipl);
/* Ensure the guest output starts fresh */
sclp_print("\n");
*current = save;
ipl(); /* should not return */
}
static void jump_to_IPL_code(uint64_t address)
{
/*
* The IPL PSW is at address 0. We also must not overwrite the
* content of non-BIOS memory after we loaded the guest, so we
* save the original content and restore it in jump_to_IPL_2.
*/
ResetInfo *current = 0;
save = *current;
current->ipl_addr = (uint32_t) (uint64_t) &jump_to_IPL_2;
current->ipl_continue = address & 0x7fffffff;
/*
* HACK ALERT.
* We use the load normal reset to keep r15 unchanged. jump_to_IPL_2
* can then use r15 as its stack pointer.
*/
asm volatile("lghi 1,1\n\t"
"diag 1,1,0x308\n\t"
: : : "1", "memory");
virtio_panic("\n! IPL returns !\n");
}
/* Check for ZIPL magic. Returns 0 if not matched. */
static int zipl_magic(uint8_t *ptr)
{
@ -123,7 +169,6 @@ static int zipl_run(struct scsi_blockptr *pte)
{
struct component_header *header;
struct component_entry *entry;
void (*ipl)(void);
uint8_t tmp_sec[SECTOR_SIZE];
virtio_read(pte->blockno, tmp_sec);
@ -157,14 +202,8 @@ static int zipl_run(struct scsi_blockptr *pte)
goto fail;
}
/* Ensure the guest output starts fresh */
sclp_print("\n");
/* And run the OS! */
ipl = (void*)(entry->load_address & 0x7fffffff);
debug_print_addr("set IPL addr to", ipl);
/* should not return */
ipl();
jump_to_IPL_code(entry->load_address);
return 0;