[boot-wrapper v5] aarch64: Start Xen on Armv8-R at EL2

[boot-wrapper v5] aarch64: Start Xen on Armv8-R at EL2

[Luca Fancellu]

When bootwrapper is compiled with Xen support and it is started
at EL2 on Armv8-R AArch64, keep the current EL and jump to the
Xen image using the SPSR_KERNEL as spsr_el2 value.

The only available boot method on Armv8-R AArch64 when starting
Xen is spin table at the moment, reflect this in the build
configuration.

Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>
---
v5 changes:
 - Don't allow AArch64-r + Xen + PSCI from the build system, update the commit
   message.
v4 changes:
 - no changes
---
 Makefile.am         | 1 +
 arch/aarch64/boot.S | 2 +-
 configure.ac        | 5 +++++
 3 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/Makefile.am b/Makefile.am
index aecda694fd6c..a8d5c1b96822 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -127,6 +127,7 @@ XEN_CHOSEN	:= xen,xen-bootargs = \"$(XEN_CMDLINE)\";		\
 			compatible = \"xen,linux-zimage\", \"xen,multiboot-module\"; \
 			reg = <0x0 $(DOM0_OFFSET) 0x0 $(KERNEL_SIZE)>;	\
 		   };
+DEFINES		+= -DXEN
 endif
 
 if INITRD
diff --git a/arch/aarch64/boot.S b/arch/aarch64/boot.S
index 565397823cb4..3fcc63bf2437 100644
--- a/arch/aarch64/boot.S
+++ b/arch/aarch64/boot.S
@@ -100,7 +100,7 @@ ASM_FUNC(jump_kernel)
 	mov	x1, x21
 	mov	x2, x22
 	mov	x3, x23
-#if defined(BOOTWRAPPER_64R)
+#if defined(BOOTWRAPPER_64R) && !defined(XEN)
 	// On Armv8-R Linux needs to be booted at EL1
 	mov	x4, #SPSR_KERNEL_EL1
 #else
diff --git a/configure.ac b/configure.ac
index a433c89bd2ae..a16bc25508f3 100644
--- a/configure.ac
+++ b/configure.ac
@@ -115,6 +115,11 @@ AS_IF([test "x$USE_PSCI" != "xyes" -a "x$KERNEL_ES" = "x32"],
 	[AC_MSG_ERROR([With an AArch32 kernel, boot method must be PSCI.])]
 )
 
+# Don't allow PSCI + Xen + aarch64-r
+AS_IF([test "x$USE_PSCI" = "xyes" -a "x$USE_ARCH" = "xaarch64-r" -a "x$X_IMAGE" != "x"],
+	[AC_MSG_ERROR([With aarch64-r and Xen, PSCI must be disabled.])]
+)
+
 # Allow a user to pass --with-initrd
 AC_ARG_WITH([initrd],
 	AS_HELP_STRING([--with-initrd], [embed an initrd in the kernel image]),
-- 
2.34.1

Re: [boot-wrapper v5] aarch64: Start Xen on Armv8-R at EL2

[Mark Rutland]

On Wed, Nov 27, 2024 at 10:23:00AM +0000, Luca Fancellu wrote:
> When bootwrapper is compiled with Xen support and it is started
> at EL2 on Armv8-R AArch64, keep the current EL and jump to the
> Xen image using the SPSR_KERNEL as spsr_el2 value.
> 
> The only available boot method on Armv8-R AArch64 when starting
> Xen is spin table at the moment, reflect this in the build
> configuration.
> 
> Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>
> ---
> v5 changes:
>  - Don't allow AArch64-r + Xen + PSCI from the build system, update the commit
>    message.
> v4 changes:
>  - no changes
> ---
>  Makefile.am         | 1 +
>  arch/aarch64/boot.S | 2 +-
>  configure.ac        | 5 +++++
>  3 files changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/Makefile.am b/Makefile.am
> index aecda694fd6c..a8d5c1b96822 100644
> --- a/Makefile.am
> +++ b/Makefile.am
> @@ -127,6 +127,7 @@ XEN_CHOSEN	:= xen,xen-bootargs = \"$(XEN_CMDLINE)\";		\
>  			compatible = \"xen,linux-zimage\", \"xen,multiboot-module\"; \
>  			reg = <0x0 $(DOM0_OFFSET) 0x0 $(KERNEL_SIZE)>;	\
>  		   };
> +DEFINES		+= -DXEN
>  endif
>  
>  if INITRD
> diff --git a/arch/aarch64/boot.S b/arch/aarch64/boot.S
> index 565397823cb4..3fcc63bf2437 100644
> --- a/arch/aarch64/boot.S
> +++ b/arch/aarch64/boot.S
> @@ -100,7 +100,7 @@ ASM_FUNC(jump_kernel)
>  	mov	x1, x21
>  	mov	x2, x22
>  	mov	x3, x23
> -#if defined(BOOTWRAPPER_64R)
> +#if defined(BOOTWRAPPER_64R) && !defined(XEN)
>  	// On Armv8-R Linux needs to be booted at EL1
>  	mov	x4, #SPSR_KERNEL_EL1
>  #else
> diff --git a/configure.ac b/configure.ac
> index a433c89bd2ae..a16bc25508f3 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -115,6 +115,11 @@ AS_IF([test "x$USE_PSCI" != "xyes" -a "x$KERNEL_ES" = "x32"],
>  	[AC_MSG_ERROR([With an AArch32 kernel, boot method must be PSCI.])]
>  )
>  
> +# Don't allow PSCI + Xen + aarch64-r
> +AS_IF([test "x$USE_PSCI" = "xyes" -a "x$USE_ARCH" = "xaarch64-r" -a "x$X_IMAGE" != "x"],
> +	[AC_MSG_ERROR([With aarch64-r and Xen, PSCI must be disabled.])]
> +)

I'll delete the comment and change the message here to:

	With an AArch64-R Xen, boot method must be spin-table.

... since that's consistent with the other message above:

	With an AArch32 kernel, boot method must be PSCI.

... and it's slightly nicer to tell the user what will work rather than
what won't work.

Otherwise this looks fine to me, and I will apply this shortly (with
those changes) if no-one objects.

Mark.

Re: [boot-wrapper v5] aarch64: Start Xen on Armv8-R at EL2

[Luca Fancellu]

Hi Mark,

> On 28 Nov 2024, at 11:03, Mark Rutland <mark.rutland@arm.com> wrote:
> 
> On Wed, Nov 27, 2024 at 10:23:00AM +0000, Luca Fancellu wrote:
>> When bootwrapper is compiled with Xen support and it is started
>> at EL2 on Armv8-R AArch64, keep the current EL and jump to the
>> Xen image using the SPSR_KERNEL as spsr_el2 value.
>> 
>> The only available boot method on Armv8-R AArch64 when starting
>> Xen is spin table at the moment, reflect this in the build
>> configuration.
>> 
>> Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>
>> ---
>> v5 changes:
>> - Don't allow AArch64-r + Xen + PSCI from the build system, update the commit
>>   message.
>> v4 changes:
>> - no changes
>> ---
>> Makefile.am         | 1 +
>> arch/aarch64/boot.S | 2 +-
>> configure.ac        | 5 +++++
>> 3 files changed, 7 insertions(+), 1 deletion(-)
>> 
>> diff --git a/Makefile.am b/Makefile.am
>> index aecda694fd6c..a8d5c1b96822 100644
>> --- a/Makefile.am
>> +++ b/Makefile.am
>> @@ -127,6 +127,7 @@ XEN_CHOSEN := xen,xen-bootargs = \"$(XEN_CMDLINE)\"; \
>> compatible = \"xen,linux-zimage\", \"xen,multiboot-module\"; \
>> reg = <0x0 $(DOM0_OFFSET) 0x0 $(KERNEL_SIZE)>; \
>>   };
>> +DEFINES += -DXEN
>> endif
>> 
>> if INITRD
>> diff --git a/arch/aarch64/boot.S b/arch/aarch64/boot.S
>> index 565397823cb4..3fcc63bf2437 100644
>> --- a/arch/aarch64/boot.S
>> +++ b/arch/aarch64/boot.S
>> @@ -100,7 +100,7 @@ ASM_FUNC(jump_kernel)
>> mov x1, x21
>> mov x2, x22
>> mov x3, x23
>> -#if defined(BOOTWRAPPER_64R)
>> +#if defined(BOOTWRAPPER_64R) && !defined(XEN)
>> // On Armv8-R Linux needs to be booted at EL1
>> mov x4, #SPSR_KERNEL_EL1
>> #else
>> diff --git a/configure.ac b/configure.ac
>> index a433c89bd2ae..a16bc25508f3 100644
>> --- a/configure.ac
>> +++ b/configure.ac
>> @@ -115,6 +115,11 @@ AS_IF([test "x$USE_PSCI" != "xyes" -a "x$KERNEL_ES" = "x32"],
>> [AC_MSG_ERROR([With an AArch32 kernel, boot method must be PSCI.])]
>> )
>> 
>> +# Don't allow PSCI + Xen + aarch64-r
>> +AS_IF([test "x$USE_PSCI" = "xyes" -a "x$USE_ARCH" = "xaarch64-r" -a "x$X_IMAGE" != "x"],
>> + [AC_MSG_ERROR([With aarch64-r and Xen, PSCI must be disabled.])]
>> +)
> 
> I'll delete the comment and change the message here to:
> 
> With an AArch64-R Xen, boot method must be spin-table.
> 
> ... since that's consistent with the other message above:
> 
> With an AArch32 kernel, boot method must be PSCI.
> 
> ... and it's slightly nicer to tell the user what will work rather than
> what won't work.
> 
> Otherwise this looks fine to me, and I will apply this shortly (with
> those changes) if no-one objects.

Sounds good to me! Thanks!

> 
> Mark.

Re: [boot-wrapper v5] aarch64: Start Xen on Armv8-R at EL2

[Mark Rutland]

On Thu, Nov 28, 2024 at 11:06:14AM +0000, Luca Fancellu wrote:
> > On 28 Nov 2024, at 11:03, Mark Rutland <mark.rutland@arm.com> wrote:
> > On Wed, Nov 27, 2024 at 10:23:00AM +0000, Luca Fancellu wrote:
> >> When bootwrapper is compiled with Xen support and it is started
> >> at EL2 on Armv8-R AArch64, keep the current EL and jump to the
> >> Xen image using the SPSR_KERNEL as spsr_el2 value.
> >>
> >> The only available boot method on Armv8-R AArch64 when starting
> >> Xen is spin table at the moment, reflect this in the build
> >> configuration.
> >>
> >> Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>

> >> +# Don't allow PSCI + Xen + aarch64-r
> >> +AS_IF([test "x$USE_PSCI" = "xyes" -a "x$USE_ARCH" = "xaarch64-r" -a "x$X_IMAGE" != "x"],
> >> + [AC_MSG_ERROR([With aarch64-r and Xen, PSCI must be disabled.])]
> >> +)
> >
> > I'll delete the comment and change the message here to:
> >
> > With an AArch64-R Xen, boot method must be spin-table.
> >
> > ... since that's consistent with the other message above:
> >
> > With an AArch32 kernel, boot method must be PSCI.
> >
> > ... and it's slightly nicer to tell the user what will work rather than
> > what won't work.
> >
> > Otherwise this looks fine to me, and I will apply this shortly (with
> > those changes) if no-one objects.
> 
> Sounds good to me! Thanks!

Thanks; applied (with those fixups).

Mark.