| Message ID | 1461045570-6138-1-git-send-email-dirk.behme@de.bosch.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
(CC REST maintainers) Hello Dirk, Please CC the relevant maintainers for this patch. You can use scripts/get_maintainers.pl for this purpose. On 19/04/16 06:59, Dirk Behme wrote: > On ARM64 Linux the HVC instruction is used to trap into Xen. As this > can be set only at EL3, i.e. outside from Xen, document this boot > requirement. > > Signed-off-by: Dirk Behme <dirk.behme@de.bosch.com> > --- > docs/misc/arm/booting.txt | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/docs/misc/arm/booting.txt b/docs/misc/arm/booting.txt > index 9802e5e..ffc9029 100644 > --- a/docs/misc/arm/booting.txt > +++ b/docs/misc/arm/booting.txt > @@ -23,6 +23,10 @@ The exceptions to this on 32-bit ARM are as follows: > > There are no exception on 64-bit ARM. > > +On ARM64 Linux it has to be ensured that the Secure Configuration > +Register has the HVC instructions enabled at EL1 and above > +(SCR_EL3.HCE == 1). The requirement is the same for ARM32 (SCR.HCE == 1). I would create a specific section in this documentation to list what the firmware should do in EL3 before starting Xen. In addition to this patch, I would add a check in Xen to make sure the Hyp calls have been enabled by the firmware. Regards, > + > [1] linux/Documentation/arm/Booting > Latest version: http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/arm/Booting > >
On 20.04.2016 15:21, Julien Grall wrote: > (CC REST maintainers) > > Hello Dirk, > > Please CC the relevant maintainers for this patch. You can use > scripts/get_maintainers.pl for this purpose. > > On 19/04/16 06:59, Dirk Behme wrote: >> On ARM64 Linux the HVC instruction is used to trap into Xen. As this >> can be set only at EL3, i.e. outside from Xen, document this boot >> requirement. >> >> Signed-off-by: Dirk Behme <dirk.behme@de.bosch.com> >> --- >> docs/misc/arm/booting.txt | 4 ++++ >> 1 file changed, 4 insertions(+) >> >> diff --git a/docs/misc/arm/booting.txt b/docs/misc/arm/booting.txt >> index 9802e5e..ffc9029 100644 >> --- a/docs/misc/arm/booting.txt >> +++ b/docs/misc/arm/booting.txt >> @@ -23,6 +23,10 @@ The exceptions to this on 32-bit ARM are as follows: >> >> There are no exception on 64-bit ARM. >> >> +On ARM64 Linux it has to be ensured that the Secure Configuration >> +Register has the HVC instructions enabled at EL1 and above >> +(SCR_EL3.HCE == 1). > > The requirement is the same for ARM32 (SCR.HCE == 1). > > I would create a specific section in this documentation to list what the > firmware should do in EL3 before starting Xen. Done: http://lists.xen.org/archives/html/xen-devel/2016-04/msg02687.html > In addition to this patch, I would add a check in Xen to make sure the > Hyp calls have been enabled by the firmware. Hmm, I have to re-read the documentation how to do this in EL2. We can't read SCR_EL3 in EL2? Best regards Dirk
Hi Dirk, On 22/04/2016 07:23, Dirk Behme wrote: > On 20.04.2016 15:21, Julien Grall wrote: >> I would create a specific section in this documentation to list what the >> firmware should do in EL3 before starting Xen. > > > Done: > > http://lists.xen.org/archives/html/xen-devel/2016-04/msg02687.html Thank you, I will look at it soon. > >> In addition to this patch, I would add a check in Xen to make sure the >> Hyp calls have been enabled by the firmware. > > > Hmm, I have to re-read the documentation how to do this in EL2. We can't > read SCR_EL3 in EL2? Oh yes. sorry I would have thought the register would be exposed RO to EL2. Regards,
diff --git a/docs/misc/arm/booting.txt b/docs/misc/arm/booting.txt index 9802e5e..ffc9029 100644 --- a/docs/misc/arm/booting.txt +++ b/docs/misc/arm/booting.txt @@ -23,6 +23,10 @@ The exceptions to this on 32-bit ARM are as follows: There are no exception on 64-bit ARM. +On ARM64 Linux it has to be ensured that the Secure Configuration +Register has the HVC instructions enabled at EL1 and above +(SCR_EL3.HCE == 1). + [1] linux/Documentation/arm/Booting Latest version: http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/arm/Booting
On ARM64 Linux the HVC instruction is used to trap into Xen. As this can be set only at EL3, i.e. outside from Xen, document this boot requirement. Signed-off-by: Dirk Behme <dirk.behme@de.bosch.com> --- docs/misc/arm/booting.txt | 4 ++++ 1 file changed, 4 insertions(+)