On 06.04.2018 11:28, Thomas Huth wrote: > On 05.04.2018 17:07, Viktor Mihajlovski wrote: >> IPL over a virtio-scsi device requires special handling not >> available in the real architecture. For this purpose the IPL >> type 0xFF has been chosen as means of communication between >> QEMU and the pc-bios. However, a guest OS could be confused >> by seeing an unknown IPL type. >> >> This change sets the IPL parameter type to 0x02 (CCW) to prevent >> this. Pre-existing Linux has looked up the IPL parameters only in >> the case of FCP IPL. This means that the behavior should stay >> the same even if Linux checks for the IPL type unconditionally. >> >> Signed-off-by: Viktor Mihajlovski <mihaj...@linux.vnet.ibm.com> >> --- >> pc-bios/s390-ccw/bootmap.c | 7 +++++++ >> pc-bios/s390-ccw/iplb.h | 15 +++++++++++++-- >> 2 files changed, 20 insertions(+), 2 deletions(-) >> >> diff --git a/pc-bios/s390-ccw/bootmap.c b/pc-bios/s390-ccw/bootmap.c >> index fc2a9fe..9287b7a 100644 >> --- a/pc-bios/s390-ccw/bootmap.c >> +++ b/pc-bios/s390-ccw/bootmap.c >> @@ -70,6 +70,13 @@ static void jump_to_IPL_code(uint64_t address) >> { >> /* store the subsystem information _after_ the bootmap was loaded */ >> write_subsystem_identification(); >> + >> + /* prevent unknown IPL types in the guest */ >> + if (iplb.pbt == S390_IPL_TYPE_QEMU_SCSI) { >> + iplb.pbt = S390_IPL_TYPE_CCW; >> + set_iplb(&iplb); >> + } >> + >> /* >> * 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 >> diff --git a/pc-bios/s390-ccw/iplb.h b/pc-bios/s390-ccw/iplb.h >> index 7dfce4f..5357a36 100644 >> --- a/pc-bios/s390-ccw/iplb.h >> +++ b/pc-bios/s390-ccw/iplb.h >> @@ -97,16 +97,27 @@ extern QemuIplParameters qipl; >> #define S390_IPL_TYPE_CCW 0x02 >> #define S390_IPL_TYPE_QEMU_SCSI 0xff >> >> -static inline bool store_iplb(IplParameterBlock *iplb) >> +static inline bool manage_iplb(IplParameterBlock *iplb, bool store) >> { >> register unsigned long addr asm("0") = (unsigned long) iplb; >> register unsigned long rc asm("1") = 0; >> >> asm volatile ("diag %0,%2,0x308\n" >> : "+d" (addr), "+d" (rc) >> - : "d" (6) >> + : "d" (store ? 6 : 5) >> : "memory", "cc"); > > I can't find a proper public specification for diag 308, so no clue how > to review this properly. Christian, could you please have a look? > > Thomas >
If it helps, here's the respective Linux implementation: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/s390/kernel/ipl.c#n182 -- Regards, Viktor Mihajlovski