Commit 96298232 authored by Christian Borntraeger's avatar Christian Borntraeger Committed by Cornelia Huck
Browse files

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



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: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: default avatarJens Freimann <jfrei@linux.vnet.ibm.com>
Reviewed-by: default avatarAlexander Graf <agraf@suse.de>
Signed-off-by: default avatarCornelia Huck <cornelia.huck@de.ibm.com>
parent 554f8089

pc-bios/s390-ccw/bootmap.c

+47 −8
Original line number Diff line number Diff line
@@ -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;