Re: [Qemu-devel] [PATCH 3/3] s390: Do not pass inofficial IPL type to the guest
On 04/05/2018 05:07 PM, 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
Reviewed-by: Christian Borntraeger
I will do some testing on the whole series and answer to the cover letter.
Just in case.
> ---
> 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");
> return rc == 0x01;
> }
>
> +
> +static inline bool store_iplb(IplParameterBlock *iplb)
> +{
> +return manage_iplb(iplb, true);
> +}
> +
> +static inline bool set_iplb(IplParameterBlock *iplb)
> +{
> +return manage_iplb(iplb, false);
> +}
> +
> #endif /* IPLB_H */
>
Re: [Qemu-devel] [PATCH 3/3] s390: Do not pass inofficial IPL type to the guest
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
>> ---
>> 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
Re: [Qemu-devel] [PATCH 3/3] s390: Do not pass inofficial IPL type to the guest
On Fri, 6 Apr 2018 11:28:31 +0200
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
> > ---
> > 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?
It does match the diag 308 store/load implementation in
target/s390x/diag.c... but a pointer to an official spec (if public)
would still be appreciated :)
Re: [Qemu-devel] [PATCH 3/3] s390: Do not pass inofficial IPL type to the guest
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
> ---
> 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
Re: [Qemu-devel] [PATCH 3/3] s390: Do not pass inofficial IPL type to the guest
On 05.04.2018 17:11, David Hildenbrand 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
>> ---
>> 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);
>> +}
>
> Confused, doesn't this imply that a system reset immediately after this
> instruction will result in something different getting booted?
>
Not if the other (QEMU) patches of this series are applied. Without
them, the behavior is the same as with an re-ipl (Today's Linux will
always request a CCW re-ipl).
[...]
--
Regards,
Viktor Mihajlovski
Re: [Qemu-devel] [PATCH 3/3] s390: Do not pass inofficial IPL type to the guest
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
> ---
> 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);
> +}
Confused, doesn't this imply that a system reset immediately after this
instruction will result in something different getting booted?
> +
> /*
> * 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");
> return rc == 0x01;
> }
>
> +
> +static inline bool store_iplb(IplParameterBlock *iplb)
> +{
> +return manage_iplb(iplb, true);
> +}
> +
> +static inline bool set_iplb(IplParameterBlock *iplb)
> +{
> +return manage_iplb(iplb, false);
> +}
> +
> #endif /* IPLB_H */
>
--
Thanks,
David / dhildenb
