[PATCH v4 0/3] arm/efi: Add dom0less support to UEFI boot

[PATCH v4 0/3] arm/efi: Add dom0less support to UEFI boot

[Luca Fancellu]

This serie introduces a way to start a dom0less setup when Xen is booting as EFI
application.
Using the device tree it's now possible to fetch from the disk and load in
memory all the modules needed to start any domU defined in the DT.
Dom0less for now is supported only by the arm architecture.

Luca Fancellu (3):
  arm/efi: Introduce xen,uefi-cfg-load DT property
  arm/efi: Use dom0less configuration when using EFI boot
  arm/efi: load dom0 modules from DT using UEFI

 docs/misc/arm/device-tree/booting.txt |  37 +++
 docs/misc/efi.pandoc                  | 263 ++++++++++++++++++
 xen/arch/arm/efi/efi-boot.h           | 372 +++++++++++++++++++++++++-
 xen/common/efi/boot.c                 |  62 +++--
 4 files changed, 709 insertions(+), 25 deletions(-)

-- 
2.17.1

[PATCH v4 1/3] arm/efi: Introduce xen,uefi-cfg-load DT property

[Luca Fancellu]

Introduce the xen,uefi-cfg-load DT property of /chosen
node for ARM whose presence decide whether to force
the load of the UEFI Xen configuration file.

The logic is that if any multiboot,module is found in
the DT, then the xen,uefi-cfg-load property is used to see
if the UEFI Xen configuration file is needed.

Modify a comment in efi_arch_use_config_file, removing
the part that states "dom0 required" because it's not
true anymore with this commit.

Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
---
v4 changes:
- modify property name to xen,uefi-cfg-load
v3 changes:
- add documentation to misc/arm/device-tree/booting.txt
- Modified variable name and logic from skip_cfg_file to
load_cfg_file
- Add in the commit message that I'm modifying a comment.
v2 changes:
- Introduced uefi,cfg-load property
- Add documentation about the property
---
 docs/misc/arm/device-tree/booting.txt |  8 ++++++++
 docs/misc/efi.pandoc                  |  2 ++
 xen/arch/arm/efi/efi-boot.h           | 28 ++++++++++++++++++++++-----
 3 files changed, 33 insertions(+), 5 deletions(-)

diff --git a/docs/misc/arm/device-tree/booting.txt b/docs/misc/arm/device-tree/booting.txt
index 44cd9e1a9a..352b0ec43a 100644
--- a/docs/misc/arm/device-tree/booting.txt
+++ b/docs/misc/arm/device-tree/booting.txt
@@ -121,6 +121,14 @@ A Xen-aware bootloader would set xen,xen-bootargs for Xen, xen,dom0-bootargs
 for Dom0 and bootargs for native Linux.
 
 
+UEFI boot and DT
+================
+
+When Xen is booted using UEFI, it doesn't read the configuration file if any
+multiboot module is specified. To force Xen to load the configuration file, the
+boolean property xen,uefi-cfg-load must be declared in the /chosen node.
+
+
 Creating Multiple Domains directly from Xen
 ===========================================
 
diff --git a/docs/misc/efi.pandoc b/docs/misc/efi.pandoc
index ac3cd58cae..ed85351541 100644
--- a/docs/misc/efi.pandoc
+++ b/docs/misc/efi.pandoc
@@ -14,6 +14,8 @@ loaded the modules and describes them in the device tree provided to Xen.  If a
 bootloader provides a device tree containing modules then any configuration
 files are ignored, and the bootloader is responsible for populating all
 relevant device tree nodes.
+The property "xen,uefi-cfg-load" can be specified in the /chosen node to force
+Xen to load the configuration file even if multiboot modules are found.
 
 Once built, `make install-xen` will place the resulting binary directly into
 the EFI boot partition, provided `EFI_VENDOR` is set in the environment (and
diff --git a/xen/arch/arm/efi/efi-boot.h b/xen/arch/arm/efi/efi-boot.h
index cf9c37153f..a3e46453d4 100644
--- a/xen/arch/arm/efi/efi-boot.h
+++ b/xen/arch/arm/efi/efi-boot.h
@@ -581,22 +581,40 @@ static void __init efi_arch_load_addr_check(EFI_LOADED_IMAGE *loaded_image)
 
 static bool __init efi_arch_use_config_file(EFI_SYSTEM_TABLE *SystemTable)
 {
+    bool load_cfg_file = true;
     /*
      * For arm, we may get a device tree from GRUB (or other bootloader)
      * that contains modules that have already been loaded into memory.  In
-     * this case, we do not use a configuration file, and rely on the
-     * bootloader to have loaded all required modules and appropriate
-     * options.
+     * this case, we search for the property xen,uefi-cfg-load in the /chosen
+     * node to decide whether to skip the UEFI Xen configuration file or not.
      */
 
     fdt = lookup_fdt_config_table(SystemTable);
     dtbfile.ptr = fdt;
     dtbfile.need_to_free = false; /* Config table memory can't be freed. */
-    if ( !fdt || fdt_node_offset_by_compatible(fdt, 0, "multiboot,module") < 0 )
+
+    if ( fdt_node_offset_by_compatible(fdt, 0, "multiboot,module") > 0 )
+    {
+        /* Locate chosen node */
+        int node = fdt_subnode_offset(fdt, 0, "chosen");
+        const void *cfg_load_prop;
+        int cfg_load_len;
+
+        if ( node > 0 )
+        {
+            /* Check if xen,uefi-cfg-load property exists */
+            cfg_load_prop = fdt_getprop(fdt, node, "xen,uefi-cfg-load",
+                                        &cfg_load_len);
+            if ( !cfg_load_prop )
+                load_cfg_file = false;
+        }
+    }
+
+    if ( !fdt || load_cfg_file )
     {
         /*
          * We either have no FDT, or one without modules, so we must have a
-         * Xen EFI configuration file to specify modules.  (dom0 required)
+         * Xen EFI configuration file to specify modules.
          */
         return true;
     }
-- 
2.17.1

Re: [PATCH v4 1/3] arm/efi: Introduce xen,uefi-cfg-load DT property

[Bertrand Marquis]

Hi Luca,

> On 30 Sep 2021, at 15:28, Luca Fancellu <Luca.Fancellu@arm.com> wrote:
> 
> Introduce the xen,uefi-cfg-load DT property of /chosen
> node for ARM whose presence decide whether to force
> the load of the UEFI Xen configuration file.
> 
> The logic is that if any multiboot,module is found in
> the DT, then the xen,uefi-cfg-load property is used to see
> if the UEFI Xen configuration file is needed.
> 
> Modify a comment in efi_arch_use_config_file, removing
> the part that states "dom0 required" because it's not
> true anymore with this commit.
> 
> Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>
> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Reviewed-by: Bertrand Marquis <bertrand.marquis@arm.com>

Cheers
Bertrand

> ---
> v4 changes:
> - modify property name to xen,uefi-cfg-load
> v3 changes:
> - add documentation to misc/arm/device-tree/booting.txt
> - Modified variable name and logic from skip_cfg_file to
> load_cfg_file
> - Add in the commit message that I'm modifying a comment.
> v2 changes:
> - Introduced uefi,cfg-load property
> - Add documentation about the property
> ---
> docs/misc/arm/device-tree/booting.txt |  8 ++++++++
> docs/misc/efi.pandoc                  |  2 ++
> xen/arch/arm/efi/efi-boot.h           | 28 ++++++++++++++++++++++-----
> 3 files changed, 33 insertions(+), 5 deletions(-)
> 
> diff --git a/docs/misc/arm/device-tree/booting.txt b/docs/misc/arm/device-tree/booting.txt
> index 44cd9e1a9a..352b0ec43a 100644
> --- a/docs/misc/arm/device-tree/booting.txt
> +++ b/docs/misc/arm/device-tree/booting.txt
> @@ -121,6 +121,14 @@ A Xen-aware bootloader would set xen,xen-bootargs for Xen, xen,dom0-bootargs
> for Dom0 and bootargs for native Linux.
> 
> 
> +UEFI boot and DT
> +================
> +
> +When Xen is booted using UEFI, it doesn't read the configuration file if any
> +multiboot module is specified. To force Xen to load the configuration file, the
> +boolean property xen,uefi-cfg-load must be declared in the /chosen node.
> +
> +
> Creating Multiple Domains directly from Xen
> ===========================================
> 
> diff --git a/docs/misc/efi.pandoc b/docs/misc/efi.pandoc
> index ac3cd58cae..ed85351541 100644
> --- a/docs/misc/efi.pandoc
> +++ b/docs/misc/efi.pandoc
> @@ -14,6 +14,8 @@ loaded the modules and describes them in the device tree provided to Xen.  If a
> bootloader provides a device tree containing modules then any configuration
> files are ignored, and the bootloader is responsible for populating all
> relevant device tree nodes.
> +The property "xen,uefi-cfg-load" can be specified in the /chosen node to force
> +Xen to load the configuration file even if multiboot modules are found.
> 
> Once built, `make install-xen` will place the resulting binary directly into
> the EFI boot partition, provided `EFI_VENDOR` is set in the environment (and
> diff --git a/xen/arch/arm/efi/efi-boot.h b/xen/arch/arm/efi/efi-boot.h
> index cf9c37153f..a3e46453d4 100644
> --- a/xen/arch/arm/efi/efi-boot.h
> +++ b/xen/arch/arm/efi/efi-boot.h
> @@ -581,22 +581,40 @@ static void __init efi_arch_load_addr_check(EFI_LOADED_IMAGE *loaded_image)
> 
> static bool __init efi_arch_use_config_file(EFI_SYSTEM_TABLE *SystemTable)
> {
> +    bool load_cfg_file = true;
>     /*
>      * For arm, we may get a device tree from GRUB (or other bootloader)
>      * that contains modules that have already been loaded into memory.  In
> -     * this case, we do not use a configuration file, and rely on the
> -     * bootloader to have loaded all required modules and appropriate
> -     * options.
> +     * this case, we search for the property xen,uefi-cfg-load in the /chosen
> +     * node to decide whether to skip the UEFI Xen configuration file or not.
>      */
> 
>     fdt = lookup_fdt_config_table(SystemTable);
>     dtbfile.ptr = fdt;
>     dtbfile.need_to_free = false; /* Config table memory can't be freed. */
> -    if ( !fdt || fdt_node_offset_by_compatible(fdt, 0, "multiboot,module") < 0 )
> +
> +    if ( fdt_node_offset_by_compatible(fdt, 0, "multiboot,module") > 0 )
> +    {
> +        /* Locate chosen node */
> +        int node = fdt_subnode_offset(fdt, 0, "chosen");
> +        const void *cfg_load_prop;
> +        int cfg_load_len;
> +
> +        if ( node > 0 )
> +        {
> +            /* Check if xen,uefi-cfg-load property exists */
> +            cfg_load_prop = fdt_getprop(fdt, node, "xen,uefi-cfg-load",
> +                                        &cfg_load_len);
> +            if ( !cfg_load_prop )
> +                load_cfg_file = false;
> +        }
> +    }
> +
> +    if ( !fdt || load_cfg_file )
>     {
>         /*
>          * We either have no FDT, or one without modules, so we must have a
> -         * Xen EFI configuration file to specify modules.  (dom0 required)
> +         * Xen EFI configuration file to specify modules.
>          */
>         return true;
>     }
> -- 
> 2.17.1
> 

Re: [PATCH v4 1/3] arm/efi: Introduce xen,uefi-cfg-load DT property

[Stefano Stabellini]

On Thu, 30 Sep 2021, Bertrand Marquis wrote:
> Hi Luca,
> 
> > On 30 Sep 2021, at 15:28, Luca Fancellu <Luca.Fancellu@arm.com> wrote:
> > 
> > Introduce the xen,uefi-cfg-load DT property of /chosen
> > node for ARM whose presence decide whether to force
> > the load of the UEFI Xen configuration file.
> > 
> > The logic is that if any multiboot,module is found in
> > the DT, then the xen,uefi-cfg-load property is used to see
> > if the UEFI Xen configuration file is needed.
> > 
> > Modify a comment in efi_arch_use_config_file, removing
> > the part that states "dom0 required" because it's not
> > true anymore with this commit.
> > 
> > Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>
> > Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
> Reviewed-by: Bertrand Marquis <bertrand.marquis@arm.com>

I committed this patch


> > ---
> > v4 changes:
> > - modify property name to xen,uefi-cfg-load
> > v3 changes:
> > - add documentation to misc/arm/device-tree/booting.txt
> > - Modified variable name and logic from skip_cfg_file to
> > load_cfg_file
> > - Add in the commit message that I'm modifying a comment.
> > v2 changes:
> > - Introduced uefi,cfg-load property
> > - Add documentation about the property
> > ---
> > docs/misc/arm/device-tree/booting.txt |  8 ++++++++
> > docs/misc/efi.pandoc                  |  2 ++
> > xen/arch/arm/efi/efi-boot.h           | 28 ++++++++++++++++++++++-----
> > 3 files changed, 33 insertions(+), 5 deletions(-)
> > 
> > diff --git a/docs/misc/arm/device-tree/booting.txt b/docs/misc/arm/device-tree/booting.txt
> > index 44cd9e1a9a..352b0ec43a 100644
> > --- a/docs/misc/arm/device-tree/booting.txt
> > +++ b/docs/misc/arm/device-tree/booting.txt
> > @@ -121,6 +121,14 @@ A Xen-aware bootloader would set xen,xen-bootargs for Xen, xen,dom0-bootargs
> > for Dom0 and bootargs for native Linux.
> > 
> > 
> > +UEFI boot and DT
> > +================
> > +
> > +When Xen is booted using UEFI, it doesn't read the configuration file if any
> > +multiboot module is specified. To force Xen to load the configuration file, the
> > +boolean property xen,uefi-cfg-load must be declared in the /chosen node.
> > +
> > +
> > Creating Multiple Domains directly from Xen
> > ===========================================
> > 
> > diff --git a/docs/misc/efi.pandoc b/docs/misc/efi.pandoc
> > index ac3cd58cae..ed85351541 100644
> > --- a/docs/misc/efi.pandoc
> > +++ b/docs/misc/efi.pandoc
> > @@ -14,6 +14,8 @@ loaded the modules and describes them in the device tree provided to Xen.  If a
> > bootloader provides a device tree containing modules then any configuration
> > files are ignored, and the bootloader is responsible for populating all
> > relevant device tree nodes.
> > +The property "xen,uefi-cfg-load" can be specified in the /chosen node to force
> > +Xen to load the configuration file even if multiboot modules are found.
> > 
> > Once built, `make install-xen` will place the resulting binary directly into
> > the EFI boot partition, provided `EFI_VENDOR` is set in the environment (and
> > diff --git a/xen/arch/arm/efi/efi-boot.h b/xen/arch/arm/efi/efi-boot.h
> > index cf9c37153f..a3e46453d4 100644
> > --- a/xen/arch/arm/efi/efi-boot.h
> > +++ b/xen/arch/arm/efi/efi-boot.h
> > @@ -581,22 +581,40 @@ static void __init efi_arch_load_addr_check(EFI_LOADED_IMAGE *loaded_image)
> > 
> > static bool __init efi_arch_use_config_file(EFI_SYSTEM_TABLE *SystemTable)
> > {
> > +    bool load_cfg_file = true;
> >     /*
> >      * For arm, we may get a device tree from GRUB (or other bootloader)
> >      * that contains modules that have already been loaded into memory.  In
> > -     * this case, we do not use a configuration file, and rely on the
> > -     * bootloader to have loaded all required modules and appropriate
> > -     * options.
> > +     * this case, we search for the property xen,uefi-cfg-load in the /chosen
> > +     * node to decide whether to skip the UEFI Xen configuration file or not.
> >      */
> > 
> >     fdt = lookup_fdt_config_table(SystemTable);
> >     dtbfile.ptr = fdt;
> >     dtbfile.need_to_free = false; /* Config table memory can't be freed. */
> > -    if ( !fdt || fdt_node_offset_by_compatible(fdt, 0, "multiboot,module") < 0 )
> > +
> > +    if ( fdt_node_offset_by_compatible(fdt, 0, "multiboot,module") > 0 )
> > +    {
> > +        /* Locate chosen node */
> > +        int node = fdt_subnode_offset(fdt, 0, "chosen");
> > +        const void *cfg_load_prop;
> > +        int cfg_load_len;
> > +
> > +        if ( node > 0 )
> > +        {
> > +            /* Check if xen,uefi-cfg-load property exists */
> > +            cfg_load_prop = fdt_getprop(fdt, node, "xen,uefi-cfg-load",
> > +                                        &cfg_load_len);
> > +            if ( !cfg_load_prop )
> > +                load_cfg_file = false;
> > +        }
> > +    }
> > +
> > +    if ( !fdt || load_cfg_file )
> >     {
> >         /*
> >          * We either have no FDT, or one without modules, so we must have a
> > -         * Xen EFI configuration file to specify modules.  (dom0 required)
> > +         * Xen EFI configuration file to specify modules.
> >          */
> >         return true;
> >     }
> > -- 
> > 2.17.1
> > 
> 

Re: [PATCH v4 1/3] arm/efi: Introduce xen,uefi-cfg-load DT property

[Julien Grall]

Hi Luca,

Sorry for jumping late in the conversation. While skimming through what 
has been committed, I noticed one potential issue in this patch and have 
also a question.

On 30/09/2021 16:28, Luca Fancellu wrote:
> Introduce the xen,uefi-cfg-load DT property of /chosen
> node for ARM whose presence decide whether to force
> the load of the UEFI Xen configuration file.
> 
> The logic is that if any multiboot,module is found in
> the DT, then the xen,uefi-cfg-load property is used to see
> if the UEFI Xen configuration file is needed.
> 
> Modify a comment in efi_arch_use_config_file, removing
> the part that states "dom0 required" because it's not
> true anymore with this commit.
> 
> Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>
> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
> ---
> v4 changes:
> - modify property name to xen,uefi-cfg-load
> v3 changes:
> - add documentation to misc/arm/device-tree/booting.txt
> - Modified variable name and logic from skip_cfg_file to
> load_cfg_file
> - Add in the commit message that I'm modifying a comment.
> v2 changes:
> - Introduced uefi,cfg-load property
> - Add documentation about the property
> ---
>   docs/misc/arm/device-tree/booting.txt |  8 ++++++++
>   docs/misc/efi.pandoc                  |  2 ++
>   xen/arch/arm/efi/efi-boot.h           | 28 ++++++++++++++++++++++-----
>   3 files changed, 33 insertions(+), 5 deletions(-)
> 
> diff --git a/docs/misc/arm/device-tree/booting.txt b/docs/misc/arm/device-tree/booting.txt
> index 44cd9e1a9a..352b0ec43a 100644
> --- a/docs/misc/arm/device-tree/booting.txt
> +++ b/docs/misc/arm/device-tree/booting.txt
> @@ -121,6 +121,14 @@ A Xen-aware bootloader would set xen,xen-bootargs for Xen, xen,dom0-bootargs
>   for Dom0 and bootargs for native Linux.
>   
>   
> +UEFI boot and DT
> +================
> +
> +When Xen is booted using UEFI, it doesn't read the configuration file if any
> +multiboot module is specified. To force Xen to load the configuration file, the
> +boolean property xen,uefi-cfg-load must be declared in the /chosen node.
> +
> +
>   Creating Multiple Domains directly from Xen
>   ===========================================
>   
> diff --git a/docs/misc/efi.pandoc b/docs/misc/efi.pandoc
> index ac3cd58cae..ed85351541 100644
> --- a/docs/misc/efi.pandoc
> +++ b/docs/misc/efi.pandoc
> @@ -14,6 +14,8 @@ loaded the modules and describes them in the device tree provided to Xen.  If a
>   bootloader provides a device tree containing modules then any configuration
>   files are ignored, and the bootloader is responsible for populating all
>   relevant device tree nodes.
> +The property "xen,uefi-cfg-load" can be specified in the /chosen node to force
> +Xen to load the configuration file even if multiboot modules are found.

I think this wants to be clarified. Lets imagine both the Device-Tree 
and the cfg provides a kernel. Which one will get used?


>   
>   Once built, `make install-xen` will place the resulting binary directly into
>   the EFI boot partition, provided `EFI_VENDOR` is set in the environment (and
> diff --git a/xen/arch/arm/efi/efi-boot.h b/xen/arch/arm/efi/efi-boot.h
> index cf9c37153f..a3e46453d4 100644
> --- a/xen/arch/arm/efi/efi-boot.h
> +++ b/xen/arch/arm/efi/efi-boot.h
> @@ -581,22 +581,40 @@ static void __init efi_arch_load_addr_check(EFI_LOADED_IMAGE *loaded_image)
>   
>   static bool __init efi_arch_use_config_file(EFI_SYSTEM_TABLE *SystemTable)
>   {
> +    bool load_cfg_file = true;
>       /*
>        * For arm, we may get a device tree from GRUB (or other bootloader)
>        * that contains modules that have already been loaded into memory.  In
> -     * this case, we do not use a configuration file, and rely on the
> -     * bootloader to have loaded all required modules and appropriate
> -     * options.
> +     * this case, we search for the property xen,uefi-cfg-load in the /chosen
> +     * node to decide whether to skip the UEFI Xen configuration file or not.
>        */
>   
>       fdt = lookup_fdt_config_table(SystemTable);
>       dtbfile.ptr = fdt;
>       dtbfile.need_to_free = false; /* Config table memory can't be freed. */
> -    if ( !fdt || fdt_node_offset_by_compatible(fdt, 0, "multiboot,module") < 0 )
> +
> +    if ( fdt_node_offset_by_compatible(fdt, 0, "multiboot,module") > 0 )

AFAICT, fdt_node_offset_by_compatible expects 'fdt' to be non-NULL. 
However, lookup_fdt_config_table() may return NULL on platform with no 
Device-Tree (server tends to be ACPI only). So wouldn't this result to 
dereference NULL and crash?

> +    {
> +        /* Locate chosen node */
> +        int node = fdt_subnode_offset(fdt, 0, "chosen");
> +        const void *cfg_load_prop;
> +        int cfg_load_len;
> +
> +        if ( node > 0 )
> +        {
> +            /* Check if xen,uefi-cfg-load property exists */
> +            cfg_load_prop = fdt_getprop(fdt, node, "xen,uefi-cfg-load",
> +                                        &cfg_load_len);
> +            if ( !cfg_load_prop )
> +                load_cfg_file = false;
> +        }
> +    }
> +
> +    if ( !fdt || load_cfg_file )
>       {
>           /*
>            * We either have no FDT, or one without modules, so we must have a
> -         * Xen EFI configuration file to specify modules.  (dom0 required)
> +         * Xen EFI configuration file to specify modules.
>            */
>           return true;
>       }
> 

Cheers,

-- 
Julien Grall

Re: [PATCH v4 1/3] arm/efi: Introduce xen,uefi-cfg-load DT property

[Luca Fancellu]

> On 6 Oct 2021, at 19:32, Julien Grall <julien@xen.org> wrote:
> 
> Hi Luca,
> 
> Sorry for jumping late in the conversation. While skimming through what has been committed, I noticed one potential issue in this patch and have also a question.
> 
> On 30/09/2021 16:28, Luca Fancellu wrote:
>> Introduce the xen,uefi-cfg-load DT property of /chosen
>> node for ARM whose presence decide whether to force
>> the load of the UEFI Xen configuration file.
>> The logic is that if any multiboot,module is found in
>> the DT, then the xen,uefi-cfg-load property is used to see
>> if the UEFI Xen configuration file is needed.
>> Modify a comment in efi_arch_use_config_file, removing
>> the part that states "dom0 required" because it's not
>> true anymore with this commit.
>> Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>
>> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
>> ---
>> v4 changes:
>> - modify property name to xen,uefi-cfg-load
>> v3 changes:
>> - add documentation to misc/arm/device-tree/booting.txt
>> - Modified variable name and logic from skip_cfg_file to
>> load_cfg_file
>> - Add in the commit message that I'm modifying a comment.
>> v2 changes:
>> - Introduced uefi,cfg-load property
>> - Add documentation about the property
>> ---
>>  docs/misc/arm/device-tree/booting.txt |  8 ++++++++
>>  docs/misc/efi.pandoc                  |  2 ++
>>  xen/arch/arm/efi/efi-boot.h           | 28 ++++++++++++++++++++++-----
>>  3 files changed, 33 insertions(+), 5 deletions(-)
>> diff --git a/docs/misc/arm/device-tree/booting.txt b/docs/misc/arm/device-tree/booting.txt
>> index 44cd9e1a9a..352b0ec43a 100644
>> --- a/docs/misc/arm/device-tree/booting.txt
>> +++ b/docs/misc/arm/device-tree/booting.txt
>> @@ -121,6 +121,14 @@ A Xen-aware bootloader would set xen,xen-bootargs for Xen, xen,dom0-bootargs
>>  for Dom0 and bootargs for native Linux.
>>    +UEFI boot and DT
>> +================
>> +
>> +When Xen is booted using UEFI, it doesn't read the configuration file if any
>> +multiboot module is specified. To force Xen to load the configuration file, the
>> +boolean property xen,uefi-cfg-load must be declared in the /chosen node.
>> +
>> +
>>  Creating Multiple Domains directly from Xen
>>  ===========================================
>>  diff --git a/docs/misc/efi.pandoc b/docs/misc/efi.pandoc
>> index ac3cd58cae..ed85351541 100644
>> --- a/docs/misc/efi.pandoc
>> +++ b/docs/misc/efi.pandoc
>> @@ -14,6 +14,8 @@ loaded the modules and describes them in the device tree provided to Xen.  If a
>>  bootloader provides a device tree containing modules then any configuration
>>  files are ignored, and the bootloader is responsible for populating all
>>  relevant device tree nodes.
>> +The property "xen,uefi-cfg-load" can be specified in the /chosen node to force
>> +Xen to load the configuration file even if multiboot modules are found.
> 

Hi Julien,

> I think this wants to be clarified. Lets imagine both the Device-Tree and the cfg provides a kernel. Which one will get used?

Yes this is will lead to a device tree where there will be two multiboot module for the dom0 kernel, I guess the one really loaded
will be the first multiboot kernel node processed and appended to the boot modules.

I see this is a possible issue and this is handled in the third patch of the serie.


> 
> 
>>    Once built, `make install-xen` will place the resulting binary directly into
>>  the EFI boot partition, provided `EFI_VENDOR` is set in the environment (and
>> diff --git a/xen/arch/arm/efi/efi-boot.h b/xen/arch/arm/efi/efi-boot.h
>> index cf9c37153f..a3e46453d4 100644
>> --- a/xen/arch/arm/efi/efi-boot.h
>> +++ b/xen/arch/arm/efi/efi-boot.h
>> @@ -581,22 +581,40 @@ static void __init efi_arch_load_addr_check(EFI_LOADED_IMAGE *loaded_image)
>>    static bool __init efi_arch_use_config_file(EFI_SYSTEM_TABLE *SystemTable)
>>  {
>> +    bool load_cfg_file = true;
>>      /*
>>       * For arm, we may get a device tree from GRUB (or other bootloader)
>>       * that contains modules that have already been loaded into memory.  In
>> -     * this case, we do not use a configuration file, and rely on the
>> -     * bootloader to have loaded all required modules and appropriate
>> -     * options.
>> +     * this case, we search for the property xen,uefi-cfg-load in the /chosen
>> +     * node to decide whether to skip the UEFI Xen configuration file or not.
>>       */
>>        fdt = lookup_fdt_config_table(SystemTable);
>>      dtbfile.ptr = fdt;
>>      dtbfile.need_to_free = false; /* Config table memory can't be freed. */
>> -    if ( !fdt || fdt_node_offset_by_compatible(fdt, 0, "multiboot,module") < 0 )
>> +
>> +    if ( fdt_node_offset_by_compatible(fdt, 0, "multiboot,module") > 0 )
> 
> AFAICT, fdt_node_offset_by_compatible expects 'fdt' to be non-NULL. However, lookup_fdt_config_table() may return NULL on platform with no Device-Tree (server tends to be ACPI only). So wouldn't this result to dereference NULL and crash?

Thanks for spotting that, I will push a patch to fix it, something like this should be ok:

+    if ( fdt && (fdt_node_offset_by_compatible(fdt, 0, "multiboot,module") > 0) )

Sorry I didn’t spotted earlier.

Cheers,
Luca

> 
>> +    {
>> +        /* Locate chosen node */
>> +        int node = fdt_subnode_offset(fdt, 0, "chosen");
>> +        const void *cfg_load_prop;
>> +        int cfg_load_len;
>> +
>> +        if ( node > 0 )
>> +        {
>> +            /* Check if xen,uefi-cfg-load property exists */
>> +            cfg_load_prop = fdt_getprop(fdt, node, "xen,uefi-cfg-load",
>> +                                        &cfg_load_len);
>> +            if ( !cfg_load_prop )
>> +                load_cfg_file = false;
>> +        }
>> +    }
>> +
>> +    if ( !fdt || load_cfg_file )
>>      {
>>          /*
>>           * We either have no FDT, or one without modules, so we must have a
>> -         * Xen EFI configuration file to specify modules.  (dom0 required)
>> +         * Xen EFI configuration file to specify modules.
>>           */
>>          return true;
>>      }
> 
> Cheers,
> 
> -- 
> Julien Grall

[PATCH v4 2/3] arm/efi: Use dom0less configuration when using EFI boot

[Luca Fancellu]

This patch introduces the support for dom0less configuration
when using UEFI boot on ARM, it permits the EFI boot to
continue if no dom0 kernel is specified but at least one domU
is found.

Introduce the new property "xen,uefi-binary" for device tree boot
module nodes that are subnode of "xen,domain" compatible nodes.
The property holds a string containing the file name of the
binary that shall be loaded by the uefi loader from the filesystem.

Update efi documentation about how to start a dom0less
setup using UEFI

Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>
---
Changes in v4:
- update uefi,cfg-load to xen,uefi-cfg-load in documentation
- fixed comments and code style
- changed variable name from dt_module_found to dt_modules_found
in boot.c
- removed stub efi_arch_check_dt_boot from x86 code because the
architecture does not support DT, protected call with #ifdef
in the common code.
- add comment to explain the result from efi_arch_check_dt_boot
just looking the common code
- Add space before comment in boot.c
- renamed uefi,binary property to xen,uefi-binary
Changes in v3:
- fixed documentation
- fixed name len in strlcpy
- fixed some style issues
- closed filesystem handle before calling blexit
- passed runtime errors up to the stack instead
of calling blexit
- renamed names and function to make them more
general in prevision to load also Dom0 kernel
and ramdisk from DT
Changes in v2:
- remove array of struct file
- fixed some int types
- Made the code use filesystem even when configuration
file is skipped.
- add documentation of uefi,binary in booting.txt
- add documentation on how to boot all configuration
for Xen using UEFI in efi.pandoc
---
 docs/misc/arm/device-tree/booting.txt |  21 ++
 docs/misc/efi.pandoc                  | 203 +++++++++++++++++
 xen/arch/arm/efi/efi-boot.h           | 305 +++++++++++++++++++++++++-
 xen/common/efi/boot.c                 |  46 ++--
 4 files changed, 560 insertions(+), 15 deletions(-)

diff --git a/docs/misc/arm/device-tree/booting.txt b/docs/misc/arm/device-tree/booting.txt
index 352b0ec43a..7258e7e1ec 100644
--- a/docs/misc/arm/device-tree/booting.txt
+++ b/docs/misc/arm/device-tree/booting.txt
@@ -190,6 +190,13 @@ The kernel sub-node has the following properties:
 
     Command line parameters for the guest kernel.
 
+- xen,uefi-binary (UEFI boot only)
+
+    String property that specifies the file name to be loaded by the UEFI boot
+    for this module. If this is specified, there is no need to specify the reg
+    property because it will be created by the UEFI stub on boot.
+    This option is needed only when UEFI boot is used.
+
 The ramdisk sub-node has the following properties:
 
 - compatible
@@ -201,6 +208,13 @@ The ramdisk sub-node has the following properties:
     Specifies the physical address of the ramdisk in RAM and its
     length.
 
+- xen,uefi-binary (UEFI boot only)
+
+    String property that specifies the file name to be loaded by the UEFI boot
+    for this module. If this is specified, there is no need to specify the reg
+    property because it will be created by the UEFI stub on boot.
+    This option is needed only when UEFI boot is used.
+
 
 Example
 =======
@@ -265,6 +279,13 @@ The dtb sub-node should have the following properties:
     Specifies the physical address of the device tree binary fragment
     RAM and its length.
 
+- xen,uefi-binary (UEFI boot only)
+
+    String property that specifies the file name to be loaded by the UEFI boot
+    for this module. If this is specified, there is no need to specify the reg
+    property because it will be created by the UEFI stub on boot.
+    This option is needed only when UEFI boot is used.
+
 As an example:
 
         module@0xc000000 {
diff --git a/docs/misc/efi.pandoc b/docs/misc/efi.pandoc
index ed85351541..876cd55005 100644
--- a/docs/misc/efi.pandoc
+++ b/docs/misc/efi.pandoc
@@ -167,3 +167,206 @@ sbsign \
 	--output xen.signed.efi \
 	xen.unified.efi
 ```
+
+## UEFI boot and dom0less on ARM
+
+Dom0less feature is supported by ARM and it is possible to use it when Xen is
+started as an EFI application.
+The way to specify the domU domains is by Device Tree as specified in the
+[dom0less](dom0less.html) documentation page under the "Device Tree
+configuration" section, but instead of declaring the reg property in the boot
+module, the user must specify the "xen,uefi-binary" property containing the name
+of the binary file that has to be loaded in memory.
+The UEFI stub will load the binary in memory and it will add the reg property
+accordingly.
+
+An example here:
+
+domU1 {
+	#address-cells = <1>;
+	#size-cells = <1>;
+	compatible = "xen,domain";
+	memory = <0 0x20000>;
+	cpus = <1>;
+	vpl011;
+
+	module@1 {
+		compatible = "multiboot,kernel", "multiboot,module";
+		xen,uefi-binary = "vmlinuz-3.0.31-0.4-xen";
+		bootargs = "console=ttyAMA0";
+	};
+	module@2 {
+		compatible = "multiboot,ramdisk", "multiboot,module";
+		xen,uefi-binary = "initrd-3.0.31-0.4-xen";
+	};
+	module@3 {
+		compatible = "multiboot,ramdisk", "multiboot,module";
+		xen,uefi-binary = "passthrough.dtb";
+	};
+};
+
+## How to boot different Xen setup using UEFI
+
+These are the different ways to boot a Xen system from UEFI:
+
+ - Boot Xen and Dom0 (minimum required)
+ - Boot Xen and DomU(s) (true dom0less, only on ARM)
+ - Boot Xen, Dom0 and DomU(s) (only on ARM)
+
+### Boot Xen and Dom0
+
+This configuration can be started using the Xen configuration file in the
+example above.
+
+### Boot Xen and DomU(s)
+
+This configuration needs the domU domain(s) specified in the /chosen node,
+examples of how to do that are provided by the documentation about dom0less
+and the example above shows how to use the "xen,uefi-binary" property to use the
+UEFI stub for module loading.
+When adding DomU modules to device tree, also add the property
+xen,uefi-cfg-load under chosen for Xen to load the Xen config file.
+Otherwise, Xen will skip the config file and rely on device tree alone.
+
+Example 1 of how to boot a true dom0less configuration:
+
+Xen configuration file: skipped.
+
+Device tree:
+
+```
+chosen {
+	#size-cells = <0x1>;
+	#address-cells = <0x1>;
+	xen,xen-bootargs = "<Xen command line>"
+
+	domU1 {
+		#size-cells = <0x1>;
+		#address-cells = <0x1>;
+		compatible = "xen,domain";
+		cpus = <0x1>;
+		memory = <0x0 0xc0000>;
+		vpl011;
+
+		module@1 {
+			compatible = "multiboot,kernel", "multiboot,module";
+			xen,uefi-binary = "Image-domu1.bin";
+			bootargs = "console=ttyAMA0 root=/dev/ram0 rw";
+		};
+	};
+	domU2 {
+		#size-cells = <0x1>;
+		#address-cells = <0x1>;
+		compatible = "xen,domain";
+		cpus = <0x1>;
+		memory = <0x0 0x100000>;
+		vpl011;
+
+		module@2 {
+			compatible = "multiboot,kernel", "multiboot,module";
+			xen,uefi-binary = "Image-domu2.bin";
+			bootargs = "console=ttyAMA0 root=/dev/ram0 rw";
+		};
+	};
+};
+```
+
+Example 2 of how to boot a true dom0less configuration:
+
+Xen configuration file:
+
+```
+[global]
+default=xen
+
+[xen]
+options=<Xen command line>
+dtb=<optional DTB>
+```
+
+Device tree:
+
+```
+chosen {
+	#size-cells = <0x1>;
+	#address-cells = <0x1>;
+	xen,uefi-cfg-load;
+
+	domU1 {
+		#size-cells = <0x1>;
+		#address-cells = <0x1>;
+		compatible = "xen,domain";
+		cpus = <0x1>;
+		memory = <0x0 0xc0000>;
+		vpl011;
+
+		module@1 {
+			compatible = "multiboot,kernel", "multiboot,module";
+			xen,uefi-binary = "Image-domu1.bin";
+			bootargs = "console=ttyAMA0 root=/dev/ram0 rw";
+		};
+	};
+	domU2 {
+		#size-cells = <0x1>;
+		#address-cells = <0x1>;
+		compatible = "xen,domain";
+		cpus = <0x1>;
+		memory = <0x0 0x100000>;
+		vpl011;
+
+		module@2 {
+			compatible = "multiboot,kernel", "multiboot,module";
+			xen,uefi-binary = "Image-domu2.bin";
+			bootargs = "console=ttyAMA0 root=/dev/ram0 rw";
+		};
+	};
+};
+```
+
+### Boot Xen, Dom0 and DomU(s)
+
+This configuration is a mix of the two configuration above, to boot this one
+the configuration file must be processed so the /chosen node must have the
+"xen,uefi-cfg-load" property.
+
+Here an example:
+
+Xen configuration file:
+
+```
+[global]
+default=xen
+
+[xen]
+options=<Xen command line>
+kernel=vmlinuz-3.0.31-0.4-xen [domain 0 command line options]
+ramdisk=initrd-3.0.31-0.4-xen
+dtb=<optional DTB>
+```
+
+Device tree:
+
+```
+chosen {
+	#size-cells = <0x1>;
+	#address-cells = <0x1>;
+	xen,uefi-cfg-load;
+
+	domU1 {
+		#size-cells = <0x1>;
+		#address-cells = <0x1>;
+		compatible = "xen,domain";
+		cpus = <0x1>;
+		memory = <0x0 0xc0000>;
+		vpl011;
+
+		module@1 {
+			compatible = "multiboot,kernel", "multiboot,module";
+			xen,uefi-binary = "Image-domu1.bin";
+			bootargs = "console=ttyAMA0 root=/dev/ram0 rw";
+		};
+	};
+};
+```
+
+
diff --git a/xen/arch/arm/efi/efi-boot.h b/xen/arch/arm/efi/efi-boot.h
index a3e46453d4..50b3829ae0 100644
--- a/xen/arch/arm/efi/efi-boot.h
+++ b/xen/arch/arm/efi/efi-boot.h
@@ -8,9 +8,49 @@
 #include <asm/setup.h>
 #include <asm/smp.h>
 
+typedef struct {
+    char *name;
+    unsigned int name_len;
+    EFI_PHYSICAL_ADDRESS addr;
+    UINTN size;
+} module_name;
+
+/*
+ * Binaries will be translated into bootmodules, the maximum number for them is
+ * MAX_MODULES where we should remove a unit for Xen and one for Xen DTB
+ */
+#define MAX_UEFI_MODULES (MAX_MODULES - 2)
+static struct file __initdata module_binary;
+static module_name __initdata modules[MAX_UEFI_MODULES];
+static unsigned int __initdata modules_available = MAX_UEFI_MODULES;
+static unsigned int __initdata modules_idx;
+
+#define ERROR_BINARY_FILE_NOT_FOUND (-1)
+#define ERROR_ALLOC_MODULE_NO_SPACE (-1)
+#define ERROR_ALLOC_MODULE_NAME     (-2)
+#define ERROR_MISSING_DT_PROPERTY   (-3)
+#define ERROR_RENAME_MODULE_NAME    (-4)
+#define ERROR_SET_REG_PROPERTY      (-5)
+#define ERROR_DT_MODULE_DOMU        (-1)
+#define ERROR_DT_CHOSEN_NODE        (-2)
+
 void noreturn efi_xen_start(void *fdt_ptr, uint32_t fdt_size);
 void __flush_dcache_area(const void *vaddr, unsigned long size);
 
+static int get_module_file_index(const char *name, unsigned int name_len);
+static void PrintMessage(const CHAR16 *s);
+static int allocate_module_file(EFI_FILE_HANDLE dir_handle,
+                                const char *name,
+                                unsigned int name_len);
+static int handle_module_node(EFI_FILE_HANDLE dir_handle,
+                              int module_node_offset,
+                              int reg_addr_cells,
+                              int reg_size_cells);
+static bool is_boot_module(int dt_module_offset);
+static int handle_dom0less_domain_node(EFI_FILE_HANDLE dir_handle,
+                                       int domain_node);
+static int efi_arch_check_dt_boot(EFI_FILE_HANDLE dir_handle);
+
 #define DEVICE_TREE_GUID \
 {0xb1b621d5, 0xf19c, 0x41a5, {0x83, 0x0b, 0xd9, 0x15, 0x2c, 0x69, 0xaa, 0xe0}}
 
@@ -552,8 +592,260 @@ static void __init efi_arch_handle_module(const struct file *file,
                          kernel.size) < 0 )
             blexit(L"Unable to set reg property.");
     }
-    else
+    else if ( file != &module_binary )
+        /*
+         * If file is not a dom0 module file and it's not a domU module,
+         * stop here.
+         */
         blexit(L"Unknown module type");
+
+    /*
+     * modules_available is decremented here because for each dom0 file added
+     * from the configuration file, there will be an additional bootmodule,
+     * so the number of available slots will be decremented because there is a
+     * maximum amount of bootmodules that can be loaded.
+     */
+    modules_available--;
+}
+
+/*
+ * This function checks for a binary previously loaded with a give name, it
+ * returns the index of the file in the modules array or a negative number if no
+ * file with that name is found.
+ */
+static int __init get_module_file_index(const char *name,
+                                        unsigned int name_len)
+{
+    unsigned int i;
+    int ret = ERROR_BINARY_FILE_NOT_FOUND;
+
+    for ( i = 0; i < modules_idx; i++ )
+    {
+        module_name *mod = &modules[i];
+        if ( (mod->name_len == name_len) &&
+             (strncmp(mod->name, name, name_len) == 0) )
+        {
+            ret = i;
+            break;
+        }
+    }
+    return ret;
+}
+
+static void __init PrintMessage(const CHAR16 *s)
+{
+    PrintStr(s);
+    PrintStr(newline);
+}
+
+/*
+ * This function allocates a binary and keeps track of its name, it returns the
+ * index of the file in the modules array or a negative number on error.
+ */
+static int __init allocate_module_file(EFI_FILE_HANDLE dir_handle,
+                                       const char *name,
+                                       unsigned int name_len)
+{
+    module_name *file_name;
+    union string module_name;
+    int ret;
+
+    /*
+     * Check if there is any space left for a module, the variable
+     * modules_available is updated each time we use read_file(...)
+     * successfully.
+     */
+    if ( !modules_available )
+    {
+        PrintMessage(L"No space left for modules");
+        return ERROR_ALLOC_MODULE_NO_SPACE;
+    }
+
+    module_name.cs = name;
+    ret = modules_idx;
+
+    /* Save at this index the name of this binary */
+    file_name = &modules[ret];
+
+    if ( efi_bs->AllocatePool(EfiLoaderData, (name_len + 1) * sizeof(char),
+                              (void**)&file_name->name) != EFI_SUCCESS )
+    {
+        PrintMessage(L"Error allocating memory for module binary name");
+        return ERROR_ALLOC_MODULE_NAME;
+    }
+
+    /* Save name and length of the binary in the data structure */
+    strlcpy(file_name->name, name, name_len + 1);
+    file_name->name_len = name_len;
+
+    /* Load the binary in memory */
+    read_file(dir_handle, s2w(&module_name), &module_binary, NULL);
+
+    /* Save address and size */
+    file_name->addr = module_binary.addr;
+    file_name->size = module_binary.size;
+
+    /* s2w(...) allocates some memory, free it */
+    efi_bs->FreePool(module_name.w);
+
+    modules_idx++;
+
+    return ret;
+}
+
+/*
+ * This function checks for the presence of the xen,uefi-binary property in the
+ * module, if found it loads the binary as module and sets the right address
+ * for the reg property into the module DT node.
+ */
+static int __init handle_module_node(EFI_FILE_HANDLE dir_handle,
+                                     int module_node_offset,
+                                     int reg_addr_cells,
+                                     int reg_size_cells)
+{
+    const void *uefi_name_prop;
+    char mod_string[24]; /* Placeholder for module@ + a 64-bit number + \0 */
+    int uefi_name_len, file_idx;
+    module_name *file;
+
+    /* Read xen,uefi-binary property to get the file name. */
+    uefi_name_prop = fdt_getprop(fdt, module_node_offset, "xen,uefi-binary",
+                                 &uefi_name_len);
+
+    if ( !uefi_name_prop )
+        /* Property not found */
+        return 0;
+
+    file_idx = get_module_file_index(uefi_name_prop, uefi_name_len);
+    if ( file_idx < 0 )
+    {
+        file_idx = allocate_module_file(dir_handle, uefi_name_prop,
+                                        uefi_name_len);
+        if ( file_idx < 0 )
+            return file_idx;
+    }
+
+    file = &modules[file_idx];
+
+    snprintf(mod_string, sizeof(mod_string), "module@%"PRIx64, file->addr);
+
+    /* Rename the module to be module@{address} */
+    if ( fdt_set_name(fdt, module_node_offset, mod_string) < 0 )
+    {
+        PrintMessage(L"Unable to modify module node name.");
+        return ERROR_RENAME_MODULE_NAME;
+    }
+
+    if ( fdt_set_reg(fdt, module_node_offset, reg_addr_cells, reg_size_cells,
+                     file->addr, file->size) < 0 )
+    {
+        PrintMessage(L"Unable to set module reg property.");
+        return ERROR_SET_REG_PROPERTY;
+    }
+
+    return 0;
+}
+
+static bool __init is_boot_module(int dt_module_offset)
+{
+    if ( (fdt_node_check_compatible(fdt, dt_module_offset,
+                                    "multiboot,kernel") == 0) ||
+         (fdt_node_check_compatible(fdt, dt_module_offset,
+                                    "multiboot,ramdisk") == 0) ||
+         (fdt_node_check_compatible(fdt, dt_module_offset,
+                                    "multiboot,device-tree") == 0) )
+        return true;
+
+    return false;
+}
+
+/*
+ * This function checks for boot modules under the domU guest domain node
+ * in the DT.
+ * Returns 0 on success, negative number on error.
+ */
+static int __init handle_dom0less_domain_node(EFI_FILE_HANDLE dir_handle,
+                                              int domain_node)
+{
+    int module_node, addr_cells, size_cells, len;
+    const struct fdt_property *prop;
+
+    /* Get #address-cells and #size-cells from domain node */
+    prop = fdt_get_property(fdt, domain_node, "#address-cells", &len);
+    if ( !prop )
+    {
+        PrintMessage(L"#address-cells not found in domain node.");
+        return ERROR_MISSING_DT_PROPERTY;
+    }
+
+    addr_cells = fdt32_to_cpu(*((uint32_t *)prop->data));
+
+    prop = fdt_get_property(fdt, domain_node, "#size-cells", &len);
+    if ( !prop )
+    {
+        PrintMessage(L"#size-cells not found in domain node.");
+        return ERROR_MISSING_DT_PROPERTY;
+    }
+
+    size_cells = fdt32_to_cpu(*((uint32_t *)prop->data));
+
+    /*
+     * Check for nodes compatible with multiboot,{kernel,ramdisk,device-tree}
+     * inside this node
+     */
+    for ( module_node = fdt_first_subnode(fdt, domain_node);
+          module_node > 0;
+          module_node = fdt_next_subnode(fdt, module_node) )
+        if ( is_boot_module(module_node) )
+        {
+            int ret = handle_module_node(dir_handle, module_node, addr_cells,
+                                         size_cells);
+            if ( ret < 0 )
+                return ret;
+        }
+
+    return 0;
+}
+
+/*
+ * This function checks for xen domain nodes under the /chosen node for possible
+ * domU guests to be loaded.
+ * Returns the number of modules loaded or a negative number for error.
+ */
+static int __init efi_arch_check_dt_boot(EFI_FILE_HANDLE dir_handle)
+{
+    int chosen, node, addr_len, size_len;
+    unsigned int i = 0;
+
+    /* Check for the chosen node in the current DTB */
+    chosen = setup_chosen_node(fdt, &addr_len, &size_len);
+    if ( chosen < 0 )
+    {
+        PrintMessage(L"Unable to setup chosen node");
+        return ERROR_DT_CHOSEN_NODE;
+    }
+
+    /* Check for nodes compatible with xen,domain under the chosen node */
+    for ( node = fdt_first_subnode(fdt, chosen);
+          node > 0;
+          node = fdt_next_subnode(fdt, node) )
+    {
+        if ( !fdt_node_check_compatible(fdt, node, "xen,domain") )
+        {
+            /* Found a node with compatible xen,domain; handle this node. */
+            if ( handle_dom0less_domain_node(dir_handle, node) < 0 )
+                return ERROR_DT_MODULE_DOMU;
+        }
+    }
+
+    /* Free boot modules file names if any */
+    for ( ; i < modules_idx; i++ )
+    {
+        /* Free boot modules binary names */
+        efi_bs->FreePool(modules[i].name);
+    }
+
+    return modules_idx;
 }
 
 static void __init efi_arch_cpu(void)
@@ -562,8 +854,19 @@ static void __init efi_arch_cpu(void)
 
 static void __init efi_arch_blexit(void)
 {
+    unsigned int i = 0;
+
     if ( dtbfile.need_to_free )
         efi_bs->FreePages(dtbfile.addr, PFN_UP(dtbfile.size));
+    /* Free boot modules file names if any */
+    for ( ; i < modules_idx; i++ )
+    {
+        /* Free boot modules binary names */
+        efi_bs->FreePool(modules[i].name);
+        /* Free modules binaries */
+        efi_bs->FreePages(modules[i].addr,
+                          PFN_UP(modules[i].size));
+    }
     if ( memmap )
         efi_bs->FreePool(memmap);
 }
diff --git a/xen/common/efi/boot.c b/xen/common/efi/boot.c
index 758f9d74d2..daf7c26099 100644
--- a/xen/common/efi/boot.c
+++ b/xen/common/efi/boot.c
@@ -1127,15 +1127,17 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
     static EFI_GUID __initdata shim_lock_guid = SHIM_LOCK_PROTOCOL_GUID;
     EFI_LOADED_IMAGE *loaded_image;
     EFI_STATUS status;
-    unsigned int i, argc;
-    CHAR16 **argv, *file_name, *cfg_file_name = NULL, *options = NULL;
+    unsigned int i, argc = 0;
+    CHAR16 **argv, *file_name = NULL, *cfg_file_name = NULL, *options = NULL;
     UINTN gop_mode = ~0;
     EFI_SHIM_LOCK_PROTOCOL *shim_lock;
     EFI_GRAPHICS_OUTPUT_PROTOCOL *gop = NULL;
     union string section = { NULL }, name;
     bool base_video = false;
-    const char *option_str;
+    const char *option_str = NULL;
     bool use_cfg_file;
+    int dt_modules_found = 0;
+    EFI_FILE_HANDLE dir_handle;
 
     __set_bit(EFI_BOOT, &efi_flags);
     __set_bit(EFI_LOADER, &efi_flags);
@@ -1216,9 +1218,11 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
 
     efi_arch_relocate_image(0);
 
+    /* Get the file system interface. */
+    dir_handle = get_parent_handle(loaded_image, &file_name);
+
     if ( use_cfg_file )
     {
-        EFI_FILE_HANDLE dir_handle;
         UINTN depth, cols, rows, size;
 
         size = cols = rows = depth = 0;
@@ -1229,9 +1233,6 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
 
         gop = efi_get_gop();
 
-        /* Get the file system interface. */
-        dir_handle = get_parent_handle(loaded_image, &file_name);
-
         /* Read and parse the config file. */
         if ( read_section(loaded_image, L"config", &cfg, NULL) )
             PrintStr(L"Using builtin config file\r\n");
@@ -1285,14 +1286,13 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
             efi_bs->FreePool(name.w);
         }
 
-        if ( !name.s )
-            blexit(L"No Dom0 kernel image specified.");
-
         efi_arch_cfg_file_early(loaded_image, dir_handle, section.s);
 
-        option_str = split_string(name.s);
+        if ( name.s )
+            option_str = split_string(name.s);
 
-        if ( !read_section(loaded_image, L"kernel", &kernel, option_str) )
+        if ( !read_section(loaded_image, L"kernel", &kernel, option_str) &&
+             name.s )
         {
             read_file(dir_handle, s2w(&name), &kernel, option_str);
             efi_bs->FreePool(name.w);
@@ -1361,12 +1361,30 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
         efi_bs->FreePages(cfg.addr, PFN_UP(cfg.size));
         cfg.addr = 0;
 
-        dir_handle->Close(dir_handle);
-
         if ( gop && !base_video )
             gop_mode = efi_find_gop_mode(gop, cols, rows, depth);
     }
 
+#ifdef CONFIG_HAS_DEVICE_TREE
+    /* Get the number of boot modules specified on the DT or an error (<0) */
+    dt_modules_found = efi_arch_check_dt_boot(dir_handle);
+#endif
+
+    dir_handle->Close(dir_handle);
+
+    if ( dt_modules_found < 0 )
+        /* efi_arch_check_dt_boot throws some error */
+        blexit(L"Error processing boot modules on DT.");
+
+    /*
+     * Check if a proper configuration is provided to start Xen:
+     *  - Dom0 specified (minimum required)
+     *  - Dom0 and DomU(s) specified
+     *  - DomU(s) specified
+     */
+    if ( !dt_modules_found && !kernel.addr )
+        blexit(L"No Dom0 kernel image specified.");
+
     efi_arch_edd();
 
     /* XXX Collect EDID info. */
-- 
2.17.1

Re: [PATCH v4 2/3] arm/efi: Use dom0less configuration when using EFI boot

[Bertrand Marquis]

Hi Luca,

> On 30 Sep 2021, at 15:28, Luca Fancellu <Luca.Fancellu@arm.com> wrote:
> 
> This patch introduces the support for dom0less configuration
> when using UEFI boot on ARM, it permits the EFI boot to
> continue if no dom0 kernel is specified but at least one domU
> is found.
> 
> Introduce the new property "xen,uefi-binary" for device tree boot
> module nodes that are subnode of "xen,domain" compatible nodes.
> The property holds a string containing the file name of the
> binary that shall be loaded by the uefi loader from the filesystem.
> 
> Update efi documentation about how to start a dom0less
> setup using UEFI
> 
> Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>
Reviewed-by: Bertrand Marquis <bertrand.marquis@arm.com>

Cheers
Bertrand

> ---
> Changes in v4:
> - update uefi,cfg-load to xen,uefi-cfg-load in documentation
> - fixed comments and code style
> - changed variable name from dt_module_found to dt_modules_found
> in boot.c
> - removed stub efi_arch_check_dt_boot from x86 code because the
> architecture does not support DT, protected call with #ifdef
> in the common code.
> - add comment to explain the result from efi_arch_check_dt_boot
> just looking the common code
> - Add space before comment in boot.c
> - renamed uefi,binary property to xen,uefi-binary
> Changes in v3:
> - fixed documentation
> - fixed name len in strlcpy
> - fixed some style issues
> - closed filesystem handle before calling blexit
> - passed runtime errors up to the stack instead
> of calling blexit
> - renamed names and function to make them more
> general in prevision to load also Dom0 kernel
> and ramdisk from DT
> Changes in v2:
> - remove array of struct file
> - fixed some int types
> - Made the code use filesystem even when configuration
> file is skipped.
> - add documentation of uefi,binary in booting.txt
> - add documentation on how to boot all configuration
> for Xen using UEFI in efi.pandoc
> ---
> docs/misc/arm/device-tree/booting.txt |  21 ++
> docs/misc/efi.pandoc                  | 203 +++++++++++++++++
> xen/arch/arm/efi/efi-boot.h           | 305 +++++++++++++++++++++++++-
> xen/common/efi/boot.c                 |  46 ++--
> 4 files changed, 560 insertions(+), 15 deletions(-)
> 
> diff --git a/docs/misc/arm/device-tree/booting.txt b/docs/misc/arm/device-tree/booting.txt
> index 352b0ec43a..7258e7e1ec 100644
> --- a/docs/misc/arm/device-tree/booting.txt
> +++ b/docs/misc/arm/device-tree/booting.txt
> @@ -190,6 +190,13 @@ The kernel sub-node has the following properties:
> 
>     Command line parameters for the guest kernel.
> 
> +- xen,uefi-binary (UEFI boot only)
> +
> +    String property that specifies the file name to be loaded by the UEFI boot
> +    for this module. If this is specified, there is no need to specify the reg
> +    property because it will be created by the UEFI stub on boot.
> +    This option is needed only when UEFI boot is used.
> +
> The ramdisk sub-node has the following properties:
> 
> - compatible
> @@ -201,6 +208,13 @@ The ramdisk sub-node has the following properties:
>     Specifies the physical address of the ramdisk in RAM and its
>     length.
> 
> +- xen,uefi-binary (UEFI boot only)
> +
> +    String property that specifies the file name to be loaded by the UEFI boot
> +    for this module. If this is specified, there is no need to specify the reg
> +    property because it will be created by the UEFI stub on boot.
> +    This option is needed only when UEFI boot is used.
> +
> 
> Example
> =======
> @@ -265,6 +279,13 @@ The dtb sub-node should have the following properties:
>     Specifies the physical address of the device tree binary fragment
>     RAM and its length.
> 
> +- xen,uefi-binary (UEFI boot only)
> +
> +    String property that specifies the file name to be loaded by the UEFI boot
> +    for this module. If this is specified, there is no need to specify the reg
> +    property because it will be created by the UEFI stub on boot.
> +    This option is needed only when UEFI boot is used.
> +
> As an example:
> 
>         module@0xc000000 {
> diff --git a/docs/misc/efi.pandoc b/docs/misc/efi.pandoc
> index ed85351541..876cd55005 100644
> --- a/docs/misc/efi.pandoc
> +++ b/docs/misc/efi.pandoc
> @@ -167,3 +167,206 @@ sbsign \
> 	--output xen.signed.efi \
> 	xen.unified.efi
> ```
> +
> +## UEFI boot and dom0less on ARM
> +
> +Dom0less feature is supported by ARM and it is possible to use it when Xen is
> +started as an EFI application.
> +The way to specify the domU domains is by Device Tree as specified in the
> +[dom0less](dom0less.html) documentation page under the "Device Tree
> +configuration" section, but instead of declaring the reg property in the boot
> +module, the user must specify the "xen,uefi-binary" property containing the name
> +of the binary file that has to be loaded in memory.
> +The UEFI stub will load the binary in memory and it will add the reg property
> +accordingly.
> +
> +An example here:
> +
> +domU1 {
> +	#address-cells = <1>;
> +	#size-cells = <1>;
> +	compatible = "xen,domain";
> +	memory = <0 0x20000>;
> +	cpus = <1>;
> +	vpl011;
> +
> +	module@1 {
> +		compatible = "multiboot,kernel", "multiboot,module";
> +		xen,uefi-binary = "vmlinuz-3.0.31-0.4-xen";
> +		bootargs = "console=ttyAMA0";
> +	};
> +	module@2 {
> +		compatible = "multiboot,ramdisk", "multiboot,module";
> +		xen,uefi-binary = "initrd-3.0.31-0.4-xen";
> +	};
> +	module@3 {
> +		compatible = "multiboot,ramdisk", "multiboot,module";
> +		xen,uefi-binary = "passthrough.dtb";
> +	};
> +};
> +
> +## How to boot different Xen setup using UEFI
> +
> +These are the different ways to boot a Xen system from UEFI:
> +
> + - Boot Xen and Dom0 (minimum required)
> + - Boot Xen and DomU(s) (true dom0less, only on ARM)
> + - Boot Xen, Dom0 and DomU(s) (only on ARM)
> +
> +### Boot Xen and Dom0
> +
> +This configuration can be started using the Xen configuration file in the
> +example above.
> +
> +### Boot Xen and DomU(s)
> +
> +This configuration needs the domU domain(s) specified in the /chosen node,
> +examples of how to do that are provided by the documentation about dom0less
> +and the example above shows how to use the "xen,uefi-binary" property to use the
> +UEFI stub for module loading.
> +When adding DomU modules to device tree, also add the property
> +xen,uefi-cfg-load under chosen for Xen to load the Xen config file.
> +Otherwise, Xen will skip the config file and rely on device tree alone.
> +
> +Example 1 of how to boot a true dom0less configuration:
> +
> +Xen configuration file: skipped.
> +
> +Device tree:
> +
> +```
> +chosen {
> +	#size-cells = <0x1>;
> +	#address-cells = <0x1>;
> +	xen,xen-bootargs = "<Xen command line>"
> +
> +	domU1 {
> +		#size-cells = <0x1>;
> +		#address-cells = <0x1>;
> +		compatible = "xen,domain";
> +		cpus = <0x1>;
> +		memory = <0x0 0xc0000>;
> +		vpl011;
> +
> +		module@1 {
> +			compatible = "multiboot,kernel", "multiboot,module";
> +			xen,uefi-binary = "Image-domu1.bin";
> +			bootargs = "console=ttyAMA0 root=/dev/ram0 rw";
> +		};
> +	};
> +	domU2 {
> +		#size-cells = <0x1>;
> +		#address-cells = <0x1>;
> +		compatible = "xen,domain";
> +		cpus = <0x1>;
> +		memory = <0x0 0x100000>;
> +		vpl011;
> +
> +		module@2 {
> +			compatible = "multiboot,kernel", "multiboot,module";
> +			xen,uefi-binary = "Image-domu2.bin";
> +			bootargs = "console=ttyAMA0 root=/dev/ram0 rw";
> +		};
> +	};
> +};
> +```
> +
> +Example 2 of how to boot a true dom0less configuration:
> +
> +Xen configuration file:
> +
> +```
> +[global]
> +default=xen
> +
> +[xen]
> +options=<Xen command line>
> +dtb=<optional DTB>
> +```
> +
> +Device tree:
> +
> +```
> +chosen {
> +	#size-cells = <0x1>;
> +	#address-cells = <0x1>;
> +	xen,uefi-cfg-load;
> +
> +	domU1 {
> +		#size-cells = <0x1>;
> +		#address-cells = <0x1>;
> +		compatible = "xen,domain";
> +		cpus = <0x1>;
> +		memory = <0x0 0xc0000>;
> +		vpl011;
> +
> +		module@1 {
> +			compatible = "multiboot,kernel", "multiboot,module";
> +			xen,uefi-binary = "Image-domu1.bin";
> +			bootargs = "console=ttyAMA0 root=/dev/ram0 rw";
> +		};
> +	};
> +	domU2 {
> +		#size-cells = <0x1>;
> +		#address-cells = <0x1>;
> +		compatible = "xen,domain";
> +		cpus = <0x1>;
> +		memory = <0x0 0x100000>;
> +		vpl011;
> +
> +		module@2 {
> +			compatible = "multiboot,kernel", "multiboot,module";
> +			xen,uefi-binary = "Image-domu2.bin";
> +			bootargs = "console=ttyAMA0 root=/dev/ram0 rw";
> +		};
> +	};
> +};
> +```
> +
> +### Boot Xen, Dom0 and DomU(s)
> +
> +This configuration is a mix of the two configuration above, to boot this one
> +the configuration file must be processed so the /chosen node must have the
> +"xen,uefi-cfg-load" property.
> +
> +Here an example:
> +
> +Xen configuration file:
> +
> +```
> +[global]
> +default=xen
> +
> +[xen]
> +options=<Xen command line>
> +kernel=vmlinuz-3.0.31-0.4-xen [domain 0 command line options]
> +ramdisk=initrd-3.0.31-0.4-xen
> +dtb=<optional DTB>
> +```
> +
> +Device tree:
> +
> +```
> +chosen {
> +	#size-cells = <0x1>;
> +	#address-cells = <0x1>;
> +	xen,uefi-cfg-load;
> +
> +	domU1 {
> +		#size-cells = <0x1>;
> +		#address-cells = <0x1>;
> +		compatible = "xen,domain";
> +		cpus = <0x1>;
> +		memory = <0x0 0xc0000>;
> +		vpl011;
> +
> +		module@1 {
> +			compatible = "multiboot,kernel", "multiboot,module";
> +			xen,uefi-binary = "Image-domu1.bin";
> +			bootargs = "console=ttyAMA0 root=/dev/ram0 rw";
> +		};
> +	};
> +};
> +```
> +
> +
> diff --git a/xen/arch/arm/efi/efi-boot.h b/xen/arch/arm/efi/efi-boot.h
> index a3e46453d4..50b3829ae0 100644
> --- a/xen/arch/arm/efi/efi-boot.h
> +++ b/xen/arch/arm/efi/efi-boot.h
> @@ -8,9 +8,49 @@
> #include <asm/setup.h>
> #include <asm/smp.h>
> 
> +typedef struct {
> +    char *name;
> +    unsigned int name_len;
> +    EFI_PHYSICAL_ADDRESS addr;
> +    UINTN size;
> +} module_name;
> +
> +/*
> + * Binaries will be translated into bootmodules, the maximum number for them is
> + * MAX_MODULES where we should remove a unit for Xen and one for Xen DTB
> + */
> +#define MAX_UEFI_MODULES (MAX_MODULES - 2)
> +static struct file __initdata module_binary;
> +static module_name __initdata modules[MAX_UEFI_MODULES];
> +static unsigned int __initdata modules_available = MAX_UEFI_MODULES;
> +static unsigned int __initdata modules_idx;
> +
> +#define ERROR_BINARY_FILE_NOT_FOUND (-1)
> +#define ERROR_ALLOC_MODULE_NO_SPACE (-1)
> +#define ERROR_ALLOC_MODULE_NAME     (-2)
> +#define ERROR_MISSING_DT_PROPERTY   (-3)
> +#define ERROR_RENAME_MODULE_NAME    (-4)
> +#define ERROR_SET_REG_PROPERTY      (-5)
> +#define ERROR_DT_MODULE_DOMU        (-1)
> +#define ERROR_DT_CHOSEN_NODE        (-2)
> +
> void noreturn efi_xen_start(void *fdt_ptr, uint32_t fdt_size);
> void __flush_dcache_area(const void *vaddr, unsigned long size);
> 
> +static int get_module_file_index(const char *name, unsigned int name_len);
> +static void PrintMessage(const CHAR16 *s);
> +static int allocate_module_file(EFI_FILE_HANDLE dir_handle,
> +                                const char *name,
> +                                unsigned int name_len);
> +static int handle_module_node(EFI_FILE_HANDLE dir_handle,
> +                              int module_node_offset,
> +                              int reg_addr_cells,
> +                              int reg_size_cells);
> +static bool is_boot_module(int dt_module_offset);
> +static int handle_dom0less_domain_node(EFI_FILE_HANDLE dir_handle,
> +                                       int domain_node);
> +static int efi_arch_check_dt_boot(EFI_FILE_HANDLE dir_handle);
> +
> #define DEVICE_TREE_GUID \
> {0xb1b621d5, 0xf19c, 0x41a5, {0x83, 0x0b, 0xd9, 0x15, 0x2c, 0x69, 0xaa, 0xe0}}
> 
> @@ -552,8 +592,260 @@ static void __init efi_arch_handle_module(const struct file *file,
>                          kernel.size) < 0 )
>             blexit(L"Unable to set reg property.");
>     }
> -    else
> +    else if ( file != &module_binary )
> +        /*
> +         * If file is not a dom0 module file and it's not a domU module,
> +         * stop here.
> +         */
>         blexit(L"Unknown module type");
> +
> +    /*
> +     * modules_available is decremented here because for each dom0 file added
> +     * from the configuration file, there will be an additional bootmodule,
> +     * so the number of available slots will be decremented because there is a
> +     * maximum amount of bootmodules that can be loaded.
> +     */
> +    modules_available--;
> +}
> +
> +/*
> + * This function checks for a binary previously loaded with a give name, it
> + * returns the index of the file in the modules array or a negative number if no
> + * file with that name is found.
> + */
> +static int __init get_module_file_index(const char *name,
> +                                        unsigned int name_len)
> +{
> +    unsigned int i;
> +    int ret = ERROR_BINARY_FILE_NOT_FOUND;
> +
> +    for ( i = 0; i < modules_idx; i++ )
> +    {
> +        module_name *mod = &modules[i];
> +        if ( (mod->name_len == name_len) &&
> +             (strncmp(mod->name, name, name_len) == 0) )
> +        {
> +            ret = i;
> +            break;
> +        }
> +    }
> +    return ret;
> +}
> +
> +static void __init PrintMessage(const CHAR16 *s)
> +{
> +    PrintStr(s);
> +    PrintStr(newline);
> +}
> +
> +/*
> + * This function allocates a binary and keeps track of its name, it returns the
> + * index of the file in the modules array or a negative number on error.
> + */
> +static int __init allocate_module_file(EFI_FILE_HANDLE dir_handle,
> +                                       const char *name,
> +                                       unsigned int name_len)
> +{
> +    module_name *file_name;
> +    union string module_name;
> +    int ret;
> +
> +    /*
> +     * Check if there is any space left for a module, the variable
> +     * modules_available is updated each time we use read_file(...)
> +     * successfully.
> +     */
> +    if ( !modules_available )
> +    {
> +        PrintMessage(L"No space left for modules");
> +        return ERROR_ALLOC_MODULE_NO_SPACE;
> +    }
> +
> +    module_name.cs = name;
> +    ret = modules_idx;
> +
> +    /* Save at this index the name of this binary */
> +    file_name = &modules[ret];
> +
> +    if ( efi_bs->AllocatePool(EfiLoaderData, (name_len + 1) * sizeof(char),
> +                              (void**)&file_name->name) != EFI_SUCCESS )
> +    {
> +        PrintMessage(L"Error allocating memory for module binary name");
> +        return ERROR_ALLOC_MODULE_NAME;
> +    }
> +
> +    /* Save name and length of the binary in the data structure */
> +    strlcpy(file_name->name, name, name_len + 1);
> +    file_name->name_len = name_len;
> +
> +    /* Load the binary in memory */
> +    read_file(dir_handle, s2w(&module_name), &module_binary, NULL);
> +
> +    /* Save address and size */
> +    file_name->addr = module_binary.addr;
> +    file_name->size = module_binary.size;
> +
> +    /* s2w(...) allocates some memory, free it */
> +    efi_bs->FreePool(module_name.w);
> +
> +    modules_idx++;
> +
> +    return ret;
> +}
> +
> +/*
> + * This function checks for the presence of the xen,uefi-binary property in the
> + * module, if found it loads the binary as module and sets the right address
> + * for the reg property into the module DT node.
> + */
> +static int __init handle_module_node(EFI_FILE_HANDLE dir_handle,
> +                                     int module_node_offset,
> +                                     int reg_addr_cells,
> +                                     int reg_size_cells)
> +{
> +    const void *uefi_name_prop;
> +    char mod_string[24]; /* Placeholder for module@ + a 64-bit number + \0 */
> +    int uefi_name_len, file_idx;
> +    module_name *file;
> +
> +    /* Read xen,uefi-binary property to get the file name. */
> +    uefi_name_prop = fdt_getprop(fdt, module_node_offset, "xen,uefi-binary",
> +                                 &uefi_name_len);
> +
> +    if ( !uefi_name_prop )
> +        /* Property not found */
> +        return 0;
> +
> +    file_idx = get_module_file_index(uefi_name_prop, uefi_name_len);
> +    if ( file_idx < 0 )
> +    {
> +        file_idx = allocate_module_file(dir_handle, uefi_name_prop,
> +                                        uefi_name_len);
> +        if ( file_idx < 0 )
> +            return file_idx;
> +    }
> +
> +    file = &modules[file_idx];
> +
> +    snprintf(mod_string, sizeof(mod_string), "module@%"PRIx64, file->addr);
> +
> +    /* Rename the module to be module@{address} */
> +    if ( fdt_set_name(fdt, module_node_offset, mod_string) < 0 )
> +    {
> +        PrintMessage(L"Unable to modify module node name.");
> +        return ERROR_RENAME_MODULE_NAME;
> +    }
> +
> +    if ( fdt_set_reg(fdt, module_node_offset, reg_addr_cells, reg_size_cells,
> +                     file->addr, file->size) < 0 )
> +    {
> +        PrintMessage(L"Unable to set module reg property.");
> +        return ERROR_SET_REG_PROPERTY;
> +    }
> +
> +    return 0;
> +}
> +
> +static bool __init is_boot_module(int dt_module_offset)
> +{
> +    if ( (fdt_node_check_compatible(fdt, dt_module_offset,
> +                                    "multiboot,kernel") == 0) ||
> +         (fdt_node_check_compatible(fdt, dt_module_offset,
> +                                    "multiboot,ramdisk") == 0) ||
> +         (fdt_node_check_compatible(fdt, dt_module_offset,
> +                                    "multiboot,device-tree") == 0) )
> +        return true;
> +
> +    return false;
> +}
> +
> +/*
> + * This function checks for boot modules under the domU guest domain node
> + * in the DT.
> + * Returns 0 on success, negative number on error.
> + */
> +static int __init handle_dom0less_domain_node(EFI_FILE_HANDLE dir_handle,
> +                                              int domain_node)
> +{
> +    int module_node, addr_cells, size_cells, len;
> +    const struct fdt_property *prop;
> +
> +    /* Get #address-cells and #size-cells from domain node */
> +    prop = fdt_get_property(fdt, domain_node, "#address-cells", &len);
> +    if ( !prop )
> +    {
> +        PrintMessage(L"#address-cells not found in domain node.");
> +        return ERROR_MISSING_DT_PROPERTY;
> +    }
> +
> +    addr_cells = fdt32_to_cpu(*((uint32_t *)prop->data));
> +
> +    prop = fdt_get_property(fdt, domain_node, "#size-cells", &len);
> +    if ( !prop )
> +    {
> +        PrintMessage(L"#size-cells not found in domain node.");
> +        return ERROR_MISSING_DT_PROPERTY;
> +    }
> +
> +    size_cells = fdt32_to_cpu(*((uint32_t *)prop->data));
> +
> +    /*
> +     * Check for nodes compatible with multiboot,{kernel,ramdisk,device-tree}
> +     * inside this node
> +     */
> +    for ( module_node = fdt_first_subnode(fdt, domain_node);
> +          module_node > 0;
> +          module_node = fdt_next_subnode(fdt, module_node) )
> +        if ( is_boot_module(module_node) )
> +        {
> +            int ret = handle_module_node(dir_handle, module_node, addr_cells,
> +                                         size_cells);
> +            if ( ret < 0 )
> +                return ret;
> +        }
> +
> +    return 0;
> +}
> +
> +/*
> + * This function checks for xen domain nodes under the /chosen node for possible
> + * domU guests to be loaded.
> + * Returns the number of modules loaded or a negative number for error.
> + */
> +static int __init efi_arch_check_dt_boot(EFI_FILE_HANDLE dir_handle)
> +{
> +    int chosen, node, addr_len, size_len;
> +    unsigned int i = 0;
> +
> +    /* Check for the chosen node in the current DTB */
> +    chosen = setup_chosen_node(fdt, &addr_len, &size_len);
> +    if ( chosen < 0 )
> +    {
> +        PrintMessage(L"Unable to setup chosen node");
> +        return ERROR_DT_CHOSEN_NODE;
> +    }
> +
> +    /* Check for nodes compatible with xen,domain under the chosen node */
> +    for ( node = fdt_first_subnode(fdt, chosen);
> +          node > 0;
> +          node = fdt_next_subnode(fdt, node) )
> +    {
> +        if ( !fdt_node_check_compatible(fdt, node, "xen,domain") )
> +        {
> +            /* Found a node with compatible xen,domain; handle this node. */
> +            if ( handle_dom0less_domain_node(dir_handle, node) < 0 )
> +                return ERROR_DT_MODULE_DOMU;
> +        }
> +    }
> +
> +    /* Free boot modules file names if any */
> +    for ( ; i < modules_idx; i++ )
> +    {
> +        /* Free boot modules binary names */
> +        efi_bs->FreePool(modules[i].name);
> +    }
> +
> +    return modules_idx;
> }
> 
> static void __init efi_arch_cpu(void)
> @@ -562,8 +854,19 @@ static void __init efi_arch_cpu(void)
> 
> static void __init efi_arch_blexit(void)
> {
> +    unsigned int i = 0;
> +
>     if ( dtbfile.need_to_free )
>         efi_bs->FreePages(dtbfile.addr, PFN_UP(dtbfile.size));
> +    /* Free boot modules file names if any */
> +    for ( ; i < modules_idx; i++ )
> +    {
> +        /* Free boot modules binary names */
> +        efi_bs->FreePool(modules[i].name);
> +        /* Free modules binaries */
> +        efi_bs->FreePages(modules[i].addr,
> +                          PFN_UP(modules[i].size));
> +    }
>     if ( memmap )
>         efi_bs->FreePool(memmap);
> }
> diff --git a/xen/common/efi/boot.c b/xen/common/efi/boot.c
> index 758f9d74d2..daf7c26099 100644
> --- a/xen/common/efi/boot.c
> +++ b/xen/common/efi/boot.c
> @@ -1127,15 +1127,17 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
>     static EFI_GUID __initdata shim_lock_guid = SHIM_LOCK_PROTOCOL_GUID;
>     EFI_LOADED_IMAGE *loaded_image;
>     EFI_STATUS status;
> -    unsigned int i, argc;
> -    CHAR16 **argv, *file_name, *cfg_file_name = NULL, *options = NULL;
> +    unsigned int i, argc = 0;
> +    CHAR16 **argv, *file_name = NULL, *cfg_file_name = NULL, *options = NULL;
>     UINTN gop_mode = ~0;
>     EFI_SHIM_LOCK_PROTOCOL *shim_lock;
>     EFI_GRAPHICS_OUTPUT_PROTOCOL *gop = NULL;
>     union string section = { NULL }, name;
>     bool base_video = false;
> -    const char *option_str;
> +    const char *option_str = NULL;
>     bool use_cfg_file;
> +    int dt_modules_found = 0;
> +    EFI_FILE_HANDLE dir_handle;
> 
>     __set_bit(EFI_BOOT, &efi_flags);
>     __set_bit(EFI_LOADER, &efi_flags);
> @@ -1216,9 +1218,11 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
> 
>     efi_arch_relocate_image(0);
> 
> +    /* Get the file system interface. */
> +    dir_handle = get_parent_handle(loaded_image, &file_name);
> +
>     if ( use_cfg_file )
>     {
> -        EFI_FILE_HANDLE dir_handle;
>         UINTN depth, cols, rows, size;
> 
>         size = cols = rows = depth = 0;
> @@ -1229,9 +1233,6 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
> 
>         gop = efi_get_gop();
> 
> -        /* Get the file system interface. */
> -        dir_handle = get_parent_handle(loaded_image, &file_name);
> -
>         /* Read and parse the config file. */
>         if ( read_section(loaded_image, L"config", &cfg, NULL) )
>             PrintStr(L"Using builtin config file\r\n");
> @@ -1285,14 +1286,13 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
>             efi_bs->FreePool(name.w);
>         }
> 
> -        if ( !name.s )
> -            blexit(L"No Dom0 kernel image specified.");
> -
>         efi_arch_cfg_file_early(loaded_image, dir_handle, section.s);
> 
> -        option_str = split_string(name.s);
> +        if ( name.s )
> +            option_str = split_string(name.s);
> 
> -        if ( !read_section(loaded_image, L"kernel", &kernel, option_str) )
> +        if ( !read_section(loaded_image, L"kernel", &kernel, option_str) &&
> +             name.s )
>         {
>             read_file(dir_handle, s2w(&name), &kernel, option_str);
>             efi_bs->FreePool(name.w);
> @@ -1361,12 +1361,30 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
>         efi_bs->FreePages(cfg.addr, PFN_UP(cfg.size));
>         cfg.addr = 0;
> 
> -        dir_handle->Close(dir_handle);
> -
>         if ( gop && !base_video )
>             gop_mode = efi_find_gop_mode(gop, cols, rows, depth);
>     }
> 
> +#ifdef CONFIG_HAS_DEVICE_TREE
> +    /* Get the number of boot modules specified on the DT or an error (<0) */
> +    dt_modules_found = efi_arch_check_dt_boot(dir_handle);
> +#endif
> +
> +    dir_handle->Close(dir_handle);
> +
> +    if ( dt_modules_found < 0 )
> +        /* efi_arch_check_dt_boot throws some error */
> +        blexit(L"Error processing boot modules on DT.");
> +
> +    /*
> +     * Check if a proper configuration is provided to start Xen:
> +     *  - Dom0 specified (minimum required)
> +     *  - Dom0 and DomU(s) specified
> +     *  - DomU(s) specified
> +     */
> +    if ( !dt_modules_found && !kernel.addr )
> +        blexit(L"No Dom0 kernel image specified.");
> +
>     efi_arch_edd();
> 
>     /* XXX Collect EDID info. */
> -- 
> 2.17.1
> 

Re: [PATCH v4 2/3] arm/efi: Use dom0less configuration when using EFI boot

[Stefano Stabellini]

On Thu, 30 Sep 2021, Luca Fancellu wrote:
> This patch introduces the support for dom0less configuration
> when using UEFI boot on ARM, it permits the EFI boot to
> continue if no dom0 kernel is specified but at least one domU
> is found.
> 
> Introduce the new property "xen,uefi-binary" for device tree boot
> module nodes that are subnode of "xen,domain" compatible nodes.
> The property holds a string containing the file name of the
> binary that shall be loaded by the uefi loader from the filesystem.
> 
> Update efi documentation about how to start a dom0less
> setup using UEFI
> 
> Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>

Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>


> ---
> Changes in v4:
> - update uefi,cfg-load to xen,uefi-cfg-load in documentation
> - fixed comments and code style
> - changed variable name from dt_module_found to dt_modules_found
> in boot.c
> - removed stub efi_arch_check_dt_boot from x86 code because the
> architecture does not support DT, protected call with #ifdef
> in the common code.
> - add comment to explain the result from efi_arch_check_dt_boot
> just looking the common code
> - Add space before comment in boot.c
> - renamed uefi,binary property to xen,uefi-binary
> Changes in v3:
> - fixed documentation
> - fixed name len in strlcpy
> - fixed some style issues
> - closed filesystem handle before calling blexit
> - passed runtime errors up to the stack instead
> of calling blexit
> - renamed names and function to make them more
> general in prevision to load also Dom0 kernel
> and ramdisk from DT
> Changes in v2:
> - remove array of struct file
> - fixed some int types
> - Made the code use filesystem even when configuration
> file is skipped.
> - add documentation of uefi,binary in booting.txt
> - add documentation on how to boot all configuration
> for Xen using UEFI in efi.pandoc
> ---
>  docs/misc/arm/device-tree/booting.txt |  21 ++
>  docs/misc/efi.pandoc                  | 203 +++++++++++++++++
>  xen/arch/arm/efi/efi-boot.h           | 305 +++++++++++++++++++++++++-
>  xen/common/efi/boot.c                 |  46 ++--
>  4 files changed, 560 insertions(+), 15 deletions(-)
> 
> diff --git a/docs/misc/arm/device-tree/booting.txt b/docs/misc/arm/device-tree/booting.txt
> index 352b0ec43a..7258e7e1ec 100644
> --- a/docs/misc/arm/device-tree/booting.txt
> +++ b/docs/misc/arm/device-tree/booting.txt
> @@ -190,6 +190,13 @@ The kernel sub-node has the following properties:
>  
>      Command line parameters for the guest kernel.
>  
> +- xen,uefi-binary (UEFI boot only)
> +
> +    String property that specifies the file name to be loaded by the UEFI boot
> +    for this module. If this is specified, there is no need to specify the reg
> +    property because it will be created by the UEFI stub on boot.
> +    This option is needed only when UEFI boot is used.
> +
>  The ramdisk sub-node has the following properties:
>  
>  - compatible
> @@ -201,6 +208,13 @@ The ramdisk sub-node has the following properties:
>      Specifies the physical address of the ramdisk in RAM and its
>      length.
>  
> +- xen,uefi-binary (UEFI boot only)
> +
> +    String property that specifies the file name to be loaded by the UEFI boot
> +    for this module. If this is specified, there is no need to specify the reg
> +    property because it will be created by the UEFI stub on boot.
> +    This option is needed only when UEFI boot is used.
> +
>  
>  Example
>  =======
> @@ -265,6 +279,13 @@ The dtb sub-node should have the following properties:
>      Specifies the physical address of the device tree binary fragment
>      RAM and its length.
>  
> +- xen,uefi-binary (UEFI boot only)
> +
> +    String property that specifies the file name to be loaded by the UEFI boot
> +    for this module. If this is specified, there is no need to specify the reg
> +    property because it will be created by the UEFI stub on boot.
> +    This option is needed only when UEFI boot is used.
> +
>  As an example:
>  
>          module@0xc000000 {
> diff --git a/docs/misc/efi.pandoc b/docs/misc/efi.pandoc
> index ed85351541..876cd55005 100644
> --- a/docs/misc/efi.pandoc
> +++ b/docs/misc/efi.pandoc
> @@ -167,3 +167,206 @@ sbsign \
>  	--output xen.signed.efi \
>  	xen.unified.efi
>  ```
> +
> +## UEFI boot and dom0less on ARM
> +
> +Dom0less feature is supported by ARM and it is possible to use it when Xen is
> +started as an EFI application.
> +The way to specify the domU domains is by Device Tree as specified in the
> +[dom0less](dom0less.html) documentation page under the "Device Tree
> +configuration" section, but instead of declaring the reg property in the boot
> +module, the user must specify the "xen,uefi-binary" property containing the name
> +of the binary file that has to be loaded in memory.
> +The UEFI stub will load the binary in memory and it will add the reg property
> +accordingly.
> +
> +An example here:
> +
> +domU1 {
> +	#address-cells = <1>;
> +	#size-cells = <1>;
> +	compatible = "xen,domain";
> +	memory = <0 0x20000>;
> +	cpus = <1>;
> +	vpl011;
> +
> +	module@1 {
> +		compatible = "multiboot,kernel", "multiboot,module";
> +		xen,uefi-binary = "vmlinuz-3.0.31-0.4-xen";
> +		bootargs = "console=ttyAMA0";
> +	};
> +	module@2 {
> +		compatible = "multiboot,ramdisk", "multiboot,module";
> +		xen,uefi-binary = "initrd-3.0.31-0.4-xen";
> +	};
> +	module@3 {
> +		compatible = "multiboot,ramdisk", "multiboot,module";
> +		xen,uefi-binary = "passthrough.dtb";
> +	};
> +};
> +
> +## How to boot different Xen setup using UEFI
> +
> +These are the different ways to boot a Xen system from UEFI:
> +
> + - Boot Xen and Dom0 (minimum required)
> + - Boot Xen and DomU(s) (true dom0less, only on ARM)
> + - Boot Xen, Dom0 and DomU(s) (only on ARM)
> +
> +### Boot Xen and Dom0
> +
> +This configuration can be started using the Xen configuration file in the
> +example above.
> +
> +### Boot Xen and DomU(s)
> +
> +This configuration needs the domU domain(s) specified in the /chosen node,
> +examples of how to do that are provided by the documentation about dom0less
> +and the example above shows how to use the "xen,uefi-binary" property to use the
> +UEFI stub for module loading.
> +When adding DomU modules to device tree, also add the property
> +xen,uefi-cfg-load under chosen for Xen to load the Xen config file.
> +Otherwise, Xen will skip the config file and rely on device tree alone.
> +
> +Example 1 of how to boot a true dom0less configuration:
> +
> +Xen configuration file: skipped.
> +
> +Device tree:
> +
> +```
> +chosen {
> +	#size-cells = <0x1>;
> +	#address-cells = <0x1>;
> +	xen,xen-bootargs = "<Xen command line>"
> +
> +	domU1 {
> +		#size-cells = <0x1>;
> +		#address-cells = <0x1>;
> +		compatible = "xen,domain";
> +		cpus = <0x1>;
> +		memory = <0x0 0xc0000>;
> +		vpl011;
> +
> +		module@1 {
> +			compatible = "multiboot,kernel", "multiboot,module";
> +			xen,uefi-binary = "Image-domu1.bin";
> +			bootargs = "console=ttyAMA0 root=/dev/ram0 rw";
> +		};
> +	};
> +	domU2 {
> +		#size-cells = <0x1>;
> +		#address-cells = <0x1>;
> +		compatible = "xen,domain";
> +		cpus = <0x1>;
> +		memory = <0x0 0x100000>;
> +		vpl011;
> +
> +		module@2 {
> +			compatible = "multiboot,kernel", "multiboot,module";
> +			xen,uefi-binary = "Image-domu2.bin";
> +			bootargs = "console=ttyAMA0 root=/dev/ram0 rw";
> +		};
> +	};
> +};
> +```
> +
> +Example 2 of how to boot a true dom0less configuration:
> +
> +Xen configuration file:
> +
> +```
> +[global]
> +default=xen
> +
> +[xen]
> +options=<Xen command line>
> +dtb=<optional DTB>
> +```
> +
> +Device tree:
> +
> +```
> +chosen {
> +	#size-cells = <0x1>;
> +	#address-cells = <0x1>;
> +	xen,uefi-cfg-load;
> +
> +	domU1 {
> +		#size-cells = <0x1>;
> +		#address-cells = <0x1>;
> +		compatible = "xen,domain";
> +		cpus = <0x1>;
> +		memory = <0x0 0xc0000>;
> +		vpl011;
> +
> +		module@1 {
> +			compatible = "multiboot,kernel", "multiboot,module";
> +			xen,uefi-binary = "Image-domu1.bin";
> +			bootargs = "console=ttyAMA0 root=/dev/ram0 rw";
> +		};
> +	};
> +	domU2 {
> +		#size-cells = <0x1>;
> +		#address-cells = <0x1>;
> +		compatible = "xen,domain";
> +		cpus = <0x1>;
> +		memory = <0x0 0x100000>;
> +		vpl011;
> +
> +		module@2 {
> +			compatible = "multiboot,kernel", "multiboot,module";
> +			xen,uefi-binary = "Image-domu2.bin";
> +			bootargs = "console=ttyAMA0 root=/dev/ram0 rw";
> +		};
> +	};
> +};
> +```
> +
> +### Boot Xen, Dom0 and DomU(s)
> +
> +This configuration is a mix of the two configuration above, to boot this one
> +the configuration file must be processed so the /chosen node must have the
> +"xen,uefi-cfg-load" property.
> +
> +Here an example:
> +
> +Xen configuration file:
> +
> +```
> +[global]
> +default=xen
> +
> +[xen]
> +options=<Xen command line>
> +kernel=vmlinuz-3.0.31-0.4-xen [domain 0 command line options]
> +ramdisk=initrd-3.0.31-0.4-xen
> +dtb=<optional DTB>
> +```
> +
> +Device tree:
> +
> +```
> +chosen {
> +	#size-cells = <0x1>;
> +	#address-cells = <0x1>;
> +	xen,uefi-cfg-load;
> +
> +	domU1 {
> +		#size-cells = <0x1>;
> +		#address-cells = <0x1>;
> +		compatible = "xen,domain";
> +		cpus = <0x1>;
> +		memory = <0x0 0xc0000>;
> +		vpl011;
> +
> +		module@1 {
> +			compatible = "multiboot,kernel", "multiboot,module";
> +			xen,uefi-binary = "Image-domu1.bin";
> +			bootargs = "console=ttyAMA0 root=/dev/ram0 rw";
> +		};
> +	};
> +};
> +```
> +
> +
> diff --git a/xen/arch/arm/efi/efi-boot.h b/xen/arch/arm/efi/efi-boot.h
> index a3e46453d4..50b3829ae0 100644
> --- a/xen/arch/arm/efi/efi-boot.h
> +++ b/xen/arch/arm/efi/efi-boot.h
> @@ -8,9 +8,49 @@
>  #include <asm/setup.h>
>  #include <asm/smp.h>
>  
> +typedef struct {
> +    char *name;
> +    unsigned int name_len;
> +    EFI_PHYSICAL_ADDRESS addr;
> +    UINTN size;
> +} module_name;
> +
> +/*
> + * Binaries will be translated into bootmodules, the maximum number for them is
> + * MAX_MODULES where we should remove a unit for Xen and one for Xen DTB
> + */
> +#define MAX_UEFI_MODULES (MAX_MODULES - 2)
> +static struct file __initdata module_binary;
> +static module_name __initdata modules[MAX_UEFI_MODULES];
> +static unsigned int __initdata modules_available = MAX_UEFI_MODULES;
> +static unsigned int __initdata modules_idx;
> +
> +#define ERROR_BINARY_FILE_NOT_FOUND (-1)
> +#define ERROR_ALLOC_MODULE_NO_SPACE (-1)
> +#define ERROR_ALLOC_MODULE_NAME     (-2)
> +#define ERROR_MISSING_DT_PROPERTY   (-3)
> +#define ERROR_RENAME_MODULE_NAME    (-4)
> +#define ERROR_SET_REG_PROPERTY      (-5)
> +#define ERROR_DT_MODULE_DOMU        (-1)
> +#define ERROR_DT_CHOSEN_NODE        (-2)
> +
>  void noreturn efi_xen_start(void *fdt_ptr, uint32_t fdt_size);
>  void __flush_dcache_area(const void *vaddr, unsigned long size);
>  
> +static int get_module_file_index(const char *name, unsigned int name_len);
> +static void PrintMessage(const CHAR16 *s);
> +static int allocate_module_file(EFI_FILE_HANDLE dir_handle,
> +                                const char *name,
> +                                unsigned int name_len);
> +static int handle_module_node(EFI_FILE_HANDLE dir_handle,
> +                              int module_node_offset,
> +                              int reg_addr_cells,
> +                              int reg_size_cells);
> +static bool is_boot_module(int dt_module_offset);
> +static int handle_dom0less_domain_node(EFI_FILE_HANDLE dir_handle,
> +                                       int domain_node);
> +static int efi_arch_check_dt_boot(EFI_FILE_HANDLE dir_handle);
> +
>  #define DEVICE_TREE_GUID \
>  {0xb1b621d5, 0xf19c, 0x41a5, {0x83, 0x0b, 0xd9, 0x15, 0x2c, 0x69, 0xaa, 0xe0}}
>  
> @@ -552,8 +592,260 @@ static void __init efi_arch_handle_module(const struct file *file,
>                           kernel.size) < 0 )
>              blexit(L"Unable to set reg property.");
>      }
> -    else
> +    else if ( file != &module_binary )
> +        /*
> +         * If file is not a dom0 module file and it's not a domU module,
> +         * stop here.
> +         */
>          blexit(L"Unknown module type");
> +
> +    /*
> +     * modules_available is decremented here because for each dom0 file added
> +     * from the configuration file, there will be an additional bootmodule,
> +     * so the number of available slots will be decremented because there is a
> +     * maximum amount of bootmodules that can be loaded.
> +     */
> +    modules_available--;
> +}
> +
> +/*
> + * This function checks for a binary previously loaded with a give name, it
> + * returns the index of the file in the modules array or a negative number if no
> + * file with that name is found.
> + */
> +static int __init get_module_file_index(const char *name,
> +                                        unsigned int name_len)
> +{
> +    unsigned int i;
> +    int ret = ERROR_BINARY_FILE_NOT_FOUND;
> +
> +    for ( i = 0; i < modules_idx; i++ )
> +    {
> +        module_name *mod = &modules[i];
> +        if ( (mod->name_len == name_len) &&
> +             (strncmp(mod->name, name, name_len) == 0) )
> +        {
> +            ret = i;
> +            break;
> +        }
> +    }
> +    return ret;
> +}
> +
> +static void __init PrintMessage(const CHAR16 *s)
> +{
> +    PrintStr(s);
> +    PrintStr(newline);
> +}
> +
> +/*
> + * This function allocates a binary and keeps track of its name, it returns the
> + * index of the file in the modules array or a negative number on error.
> + */
> +static int __init allocate_module_file(EFI_FILE_HANDLE dir_handle,
> +                                       const char *name,
> +                                       unsigned int name_len)
> +{
> +    module_name *file_name;
> +    union string module_name;
> +    int ret;
> +
> +    /*
> +     * Check if there is any space left for a module, the variable
> +     * modules_available is updated each time we use read_file(...)
> +     * successfully.
> +     */
> +    if ( !modules_available )
> +    {
> +        PrintMessage(L"No space left for modules");
> +        return ERROR_ALLOC_MODULE_NO_SPACE;
> +    }
> +
> +    module_name.cs = name;
> +    ret = modules_idx;
> +
> +    /* Save at this index the name of this binary */
> +    file_name = &modules[ret];
> +
> +    if ( efi_bs->AllocatePool(EfiLoaderData, (name_len + 1) * sizeof(char),
> +                              (void**)&file_name->name) != EFI_SUCCESS )
> +    {
> +        PrintMessage(L"Error allocating memory for module binary name");
> +        return ERROR_ALLOC_MODULE_NAME;
> +    }
> +
> +    /* Save name and length of the binary in the data structure */
> +    strlcpy(file_name->name, name, name_len + 1);
> +    file_name->name_len = name_len;
> +
> +    /* Load the binary in memory */
> +    read_file(dir_handle, s2w(&module_name), &module_binary, NULL);
> +
> +    /* Save address and size */
> +    file_name->addr = module_binary.addr;
> +    file_name->size = module_binary.size;
> +
> +    /* s2w(...) allocates some memory, free it */
> +    efi_bs->FreePool(module_name.w);
> +
> +    modules_idx++;
> +
> +    return ret;
> +}
> +
> +/*
> + * This function checks for the presence of the xen,uefi-binary property in the
> + * module, if found it loads the binary as module and sets the right address
> + * for the reg property into the module DT node.
> + */
> +static int __init handle_module_node(EFI_FILE_HANDLE dir_handle,
> +                                     int module_node_offset,
> +                                     int reg_addr_cells,
> +                                     int reg_size_cells)
> +{
> +    const void *uefi_name_prop;
> +    char mod_string[24]; /* Placeholder for module@ + a 64-bit number + \0 */
> +    int uefi_name_len, file_idx;
> +    module_name *file;
> +
> +    /* Read xen,uefi-binary property to get the file name. */
> +    uefi_name_prop = fdt_getprop(fdt, module_node_offset, "xen,uefi-binary",
> +                                 &uefi_name_len);
> +
> +    if ( !uefi_name_prop )
> +        /* Property not found */
> +        return 0;
> +
> +    file_idx = get_module_file_index(uefi_name_prop, uefi_name_len);
> +    if ( file_idx < 0 )
> +    {
> +        file_idx = allocate_module_file(dir_handle, uefi_name_prop,
> +                                        uefi_name_len);
> +        if ( file_idx < 0 )
> +            return file_idx;
> +    }
> +
> +    file = &modules[file_idx];
> +
> +    snprintf(mod_string, sizeof(mod_string), "module@%"PRIx64, file->addr);
> +
> +    /* Rename the module to be module@{address} */
> +    if ( fdt_set_name(fdt, module_node_offset, mod_string) < 0 )
> +    {
> +        PrintMessage(L"Unable to modify module node name.");
> +        return ERROR_RENAME_MODULE_NAME;
> +    }
> +
> +    if ( fdt_set_reg(fdt, module_node_offset, reg_addr_cells, reg_size_cells,
> +                     file->addr, file->size) < 0 )
> +    {
> +        PrintMessage(L"Unable to set module reg property.");
> +        return ERROR_SET_REG_PROPERTY;
> +    }
> +
> +    return 0;
> +}
> +
> +static bool __init is_boot_module(int dt_module_offset)
> +{
> +    if ( (fdt_node_check_compatible(fdt, dt_module_offset,
> +                                    "multiboot,kernel") == 0) ||
> +         (fdt_node_check_compatible(fdt, dt_module_offset,
> +                                    "multiboot,ramdisk") == 0) ||
> +         (fdt_node_check_compatible(fdt, dt_module_offset,
> +                                    "multiboot,device-tree") == 0) )
> +        return true;
> +
> +    return false;
> +}
> +
> +/*
> + * This function checks for boot modules under the domU guest domain node
> + * in the DT.
> + * Returns 0 on success, negative number on error.
> + */
> +static int __init handle_dom0less_domain_node(EFI_FILE_HANDLE dir_handle,
> +                                              int domain_node)
> +{
> +    int module_node, addr_cells, size_cells, len;
> +    const struct fdt_property *prop;
> +
> +    /* Get #address-cells and #size-cells from domain node */
> +    prop = fdt_get_property(fdt, domain_node, "#address-cells", &len);
> +    if ( !prop )
> +    {
> +        PrintMessage(L"#address-cells not found in domain node.");
> +        return ERROR_MISSING_DT_PROPERTY;
> +    }
> +
> +    addr_cells = fdt32_to_cpu(*((uint32_t *)prop->data));
> +
> +    prop = fdt_get_property(fdt, domain_node, "#size-cells", &len);
> +    if ( !prop )
> +    {
> +        PrintMessage(L"#size-cells not found in domain node.");
> +        return ERROR_MISSING_DT_PROPERTY;
> +    }
> +
> +    size_cells = fdt32_to_cpu(*((uint32_t *)prop->data));
> +
> +    /*
> +     * Check for nodes compatible with multiboot,{kernel,ramdisk,device-tree}
> +     * inside this node
> +     */
> +    for ( module_node = fdt_first_subnode(fdt, domain_node);
> +          module_node > 0;
> +          module_node = fdt_next_subnode(fdt, module_node) )
> +        if ( is_boot_module(module_node) )
> +        {
> +            int ret = handle_module_node(dir_handle, module_node, addr_cells,
> +                                         size_cells);
> +            if ( ret < 0 )
> +                return ret;
> +        }
> +
> +    return 0;
> +}
> +
> +/*
> + * This function checks for xen domain nodes under the /chosen node for possible
> + * domU guests to be loaded.
> + * Returns the number of modules loaded or a negative number for error.
> + */
> +static int __init efi_arch_check_dt_boot(EFI_FILE_HANDLE dir_handle)
> +{
> +    int chosen, node, addr_len, size_len;
> +    unsigned int i = 0;
> +
> +    /* Check for the chosen node in the current DTB */
> +    chosen = setup_chosen_node(fdt, &addr_len, &size_len);
> +    if ( chosen < 0 )
> +    {
> +        PrintMessage(L"Unable to setup chosen node");
> +        return ERROR_DT_CHOSEN_NODE;
> +    }
> +
> +    /* Check for nodes compatible with xen,domain under the chosen node */
> +    for ( node = fdt_first_subnode(fdt, chosen);
> +          node > 0;
> +          node = fdt_next_subnode(fdt, node) )
> +    {
> +        if ( !fdt_node_check_compatible(fdt, node, "xen,domain") )
> +        {
> +            /* Found a node with compatible xen,domain; handle this node. */
> +            if ( handle_dom0less_domain_node(dir_handle, node) < 0 )
> +                return ERROR_DT_MODULE_DOMU;
> +        }
> +    }
> +
> +    /* Free boot modules file names if any */
> +    for ( ; i < modules_idx; i++ )
> +    {
> +        /* Free boot modules binary names */
> +        efi_bs->FreePool(modules[i].name);
> +    }
> +
> +    return modules_idx;
>  }
>  
>  static void __init efi_arch_cpu(void)
> @@ -562,8 +854,19 @@ static void __init efi_arch_cpu(void)
>  
>  static void __init efi_arch_blexit(void)
>  {
> +    unsigned int i = 0;
> +
>      if ( dtbfile.need_to_free )
>          efi_bs->FreePages(dtbfile.addr, PFN_UP(dtbfile.size));
> +    /* Free boot modules file names if any */
> +    for ( ; i < modules_idx; i++ )
> +    {
> +        /* Free boot modules binary names */
> +        efi_bs->FreePool(modules[i].name);
> +        /* Free modules binaries */
> +        efi_bs->FreePages(modules[i].addr,
> +                          PFN_UP(modules[i].size));
> +    }
>      if ( memmap )
>          efi_bs->FreePool(memmap);
>  }
> diff --git a/xen/common/efi/boot.c b/xen/common/efi/boot.c
> index 758f9d74d2..daf7c26099 100644
> --- a/xen/common/efi/boot.c
> +++ b/xen/common/efi/boot.c
> @@ -1127,15 +1127,17 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
>      static EFI_GUID __initdata shim_lock_guid = SHIM_LOCK_PROTOCOL_GUID;
>      EFI_LOADED_IMAGE *loaded_image;
>      EFI_STATUS status;
> -    unsigned int i, argc;
> -    CHAR16 **argv, *file_name, *cfg_file_name = NULL, *options = NULL;
> +    unsigned int i, argc = 0;
> +    CHAR16 **argv, *file_name = NULL, *cfg_file_name = NULL, *options = NULL;
>      UINTN gop_mode = ~0;
>      EFI_SHIM_LOCK_PROTOCOL *shim_lock;
>      EFI_GRAPHICS_OUTPUT_PROTOCOL *gop = NULL;
>      union string section = { NULL }, name;
>      bool base_video = false;
> -    const char *option_str;
> +    const char *option_str = NULL;
>      bool use_cfg_file;
> +    int dt_modules_found = 0;
> +    EFI_FILE_HANDLE dir_handle;
>  
>      __set_bit(EFI_BOOT, &efi_flags);
>      __set_bit(EFI_LOADER, &efi_flags);
> @@ -1216,9 +1218,11 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
>  
>      efi_arch_relocate_image(0);
>  
> +    /* Get the file system interface. */
> +    dir_handle = get_parent_handle(loaded_image, &file_name);
> +
>      if ( use_cfg_file )
>      {
> -        EFI_FILE_HANDLE dir_handle;
>          UINTN depth, cols, rows, size;
>  
>          size = cols = rows = depth = 0;
> @@ -1229,9 +1233,6 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
>  
>          gop = efi_get_gop();
>  
> -        /* Get the file system interface. */
> -        dir_handle = get_parent_handle(loaded_image, &file_name);
> -
>          /* Read and parse the config file. */
>          if ( read_section(loaded_image, L"config", &cfg, NULL) )
>              PrintStr(L"Using builtin config file\r\n");
> @@ -1285,14 +1286,13 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
>              efi_bs->FreePool(name.w);
>          }
>  
> -        if ( !name.s )
> -            blexit(L"No Dom0 kernel image specified.");
> -
>          efi_arch_cfg_file_early(loaded_image, dir_handle, section.s);
>  
> -        option_str = split_string(name.s);
> +        if ( name.s )
> +            option_str = split_string(name.s);
>  
> -        if ( !read_section(loaded_image, L"kernel", &kernel, option_str) )
> +        if ( !read_section(loaded_image, L"kernel", &kernel, option_str) &&
> +             name.s )
>          {
>              read_file(dir_handle, s2w(&name), &kernel, option_str);
>              efi_bs->FreePool(name.w);
> @@ -1361,12 +1361,30 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
>          efi_bs->FreePages(cfg.addr, PFN_UP(cfg.size));
>          cfg.addr = 0;
>  
> -        dir_handle->Close(dir_handle);
> -
>          if ( gop && !base_video )
>              gop_mode = efi_find_gop_mode(gop, cols, rows, depth);
>      }
>  
> +#ifdef CONFIG_HAS_DEVICE_TREE
> +    /* Get the number of boot modules specified on the DT or an error (<0) */
> +    dt_modules_found = efi_arch_check_dt_boot(dir_handle);
> +#endif
> +
> +    dir_handle->Close(dir_handle);
> +
> +    if ( dt_modules_found < 0 )
> +        /* efi_arch_check_dt_boot throws some error */
> +        blexit(L"Error processing boot modules on DT.");
> +
> +    /*
> +     * Check if a proper configuration is provided to start Xen:
> +     *  - Dom0 specified (minimum required)
> +     *  - Dom0 and DomU(s) specified
> +     *  - DomU(s) specified
> +     */
> +    if ( !dt_modules_found && !kernel.addr )
> +        blexit(L"No Dom0 kernel image specified.");
> +
>      efi_arch_edd();
>  
>      /* XXX Collect EDID info. */
> -- 
> 2.17.1
> 

Re: [PATCH v4 2/3] arm/efi: Use dom0less configuration when using EFI boot

[Jan Beulich]

On 30.09.2021 16:28, Luca Fancellu wrote:
> --- a/xen/common/efi/boot.c
> +++ b/xen/common/efi/boot.c
> @@ -1127,15 +1127,17 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
>      static EFI_GUID __initdata shim_lock_guid = SHIM_LOCK_PROTOCOL_GUID;
>      EFI_LOADED_IMAGE *loaded_image;
>      EFI_STATUS status;
> -    unsigned int i, argc;
> -    CHAR16 **argv, *file_name, *cfg_file_name = NULL, *options = NULL;
> +    unsigned int i, argc = 0;
> +    CHAR16 **argv, *file_name = NULL, *cfg_file_name = NULL, *options = NULL;

Are these two changes really still needed?

> @@ -1285,14 +1286,13 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
>              efi_bs->FreePool(name.w);
>          }
>  
> -        if ( !name.s )
> -            blexit(L"No Dom0 kernel image specified.");
> -
>          efi_arch_cfg_file_early(loaded_image, dir_handle, section.s);
>  
> -        option_str = split_string(name.s);
> +        if ( name.s )
> +            option_str = split_string(name.s);

        option_str = name.s ? split_string(name.s) : NULL;

would be the less intrusive change (eliminating the need to add an
initialized for option_str). Or if you really want to stick to your
model, then please at the same time at least move option_str into
the more narrow scope.

> @@ -1361,12 +1361,30 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
>          efi_bs->FreePages(cfg.addr, PFN_UP(cfg.size));
>          cfg.addr = 0;
>  
> -        dir_handle->Close(dir_handle);
> -
>          if ( gop && !base_video )
>              gop_mode = efi_find_gop_mode(gop, cols, rows, depth);
>      }
>  
> +#ifdef CONFIG_HAS_DEVICE_TREE
> +    /* Get the number of boot modules specified on the DT or an error (<0) */
> +    dt_modules_found = efi_arch_check_dt_boot(dir_handle);
> +#endif

So I had asked to add a stub enclosed in such an #ifdef, to avoid the
#ifdef here. I may be willing to let you keep things as you have them
now, but I'd like to understand why you've picked that different
approach despite the prior discussion.

> +    dir_handle->Close(dir_handle);
> +
> +    if ( dt_modules_found < 0 )
> +        /* efi_arch_check_dt_boot throws some error */
> +        blexit(L"Error processing boot modules on DT.");
> +
> +    /*
> +     * Check if a proper configuration is provided to start Xen:
> +     *  - Dom0 specified (minimum required)
> +     *  - Dom0 and DomU(s) specified
> +     *  - DomU(s) specified
> +     */

May I suggest to shorten the three bullet points to "At least one
of Dom0 or DomU(s) specified"?

> +    if ( !dt_modules_found && !kernel.addr )
> +        blexit(L"No Dom0 kernel image specified.");

And may I also ask to alter the text here, to be less confusing to
dom0less folks? E.g. "No initial domain kernel specified"?

Jan

Re: [PATCH v4 2/3] arm/efi: Use dom0less configuration when using EFI boot

[Luca Fancellu]

> On 1 Oct 2021, at 12:02, Jan Beulich <jbeulich@suse.com> wrote:
> 
> On 30.09.2021 16:28, Luca Fancellu wrote:
>> --- a/xen/common/efi/boot.c
>> +++ b/xen/common/efi/boot.c
>> @@ -1127,15 +1127,17 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
>>     static EFI_GUID __initdata shim_lock_guid = SHIM_LOCK_PROTOCOL_GUID;
>>     EFI_LOADED_IMAGE *loaded_image;
>>     EFI_STATUS status;
>> -    unsigned int i, argc;
>> -    CHAR16 **argv, *file_name, *cfg_file_name = NULL, *options = NULL;
>> +    unsigned int i, argc = 0;
>> +    CHAR16 **argv, *file_name = NULL, *cfg_file_name = NULL, *options = NULL;
> 
> Are these two changes really still needed?

Yes you are right, I will revert back them.

> 
>> @@ -1285,14 +1286,13 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
>>             efi_bs->FreePool(name.w);
>>         }
>> 
>> -        if ( !name.s )
>> -            blexit(L"No Dom0 kernel image specified.");
>> -
>>         efi_arch_cfg_file_early(loaded_image, dir_handle, section.s);
>> 
>> -        option_str = split_string(name.s);
>> +        if ( name.s )
>> +            option_str = split_string(name.s);
> 
>        option_str = name.s ? split_string(name.s) : NULL;

I will use your suggestion above so I don’t have to initialise it.

> 
> would be the less intrusive change (eliminating the need to add an
> initialized for option_str). Or if you really want to stick to your
> model, then please at the same time at least move option_str into
> the more narrow scope.
> 
>> @@ -1361,12 +1361,30 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
>>         efi_bs->FreePages(cfg.addr, PFN_UP(cfg.size));
>>         cfg.addr = 0;
>> 
>> -        dir_handle->Close(dir_handle);
>> -
>>         if ( gop && !base_video )
>>             gop_mode = efi_find_gop_mode(gop, cols, rows, depth);
>>     }
>> 
>> +#ifdef CONFIG_HAS_DEVICE_TREE
>> +    /* Get the number of boot modules specified on the DT or an error (<0) */
>> +    dt_modules_found = efi_arch_check_dt_boot(dir_handle);
>> +#endif
> 
> So I had asked to add a stub enclosed in such an #ifdef, to avoid the
> #ifdef here. I may be willing to let you keep things as you have them
> now, but I'd like to understand why you've picked that different
> approach despite the prior discussion.

There must be a misunderstanding, your message in the v3 was:

"Every time I see this addition I'm getting puzzled. As a result I'm
afraid I now need to finally ask you to do something about this (and
I'm sorry for doing so only now). There would better be no notion of
DT in x86 code, and there would better also not be a need for
architectures not supporting DT to each supply such a stub. Instead
I think you want to put this stub in xen/common/efi/boot.c, inside a
suitable #ifdef.”

So I thought you wanted me to remove the stub in x86 (since it doesn’t support DT)
and put this call under #ifdef so it won’t be compiled for arch not supporting DT.


> 
>> +    dir_handle->Close(dir_handle);
>> +
>> +    if ( dt_modules_found < 0 )
>> +        /* efi_arch_check_dt_boot throws some error */
>> +        blexit(L"Error processing boot modules on DT.");
>> +
>> +    /*
>> +     * Check if a proper configuration is provided to start Xen:
>> +     *  - Dom0 specified (minimum required)
>> +     *  - Dom0 and DomU(s) specified
>> +     *  - DomU(s) specified
>> +     */
> 
> May I suggest to shorten the three bullet points to "At least one
> of Dom0 or DomU(s) specified"?

Sure I will change to:

/* Check if at least one of Dom0 or DomU(s) is specified */

> 
>> +    if ( !dt_modules_found && !kernel.addr )
>> +        blexit(L"No Dom0 kernel image specified.");
> 
> And may I also ask to alter the text here, to be less confusing to
> dom0less folks? E.g. "No initial domain kernel specified"?

Yes I will change that.

Cheers,
Luca

> 
> Jan
> 

Re: [PATCH v4 2/3] arm/efi: Use dom0less configuration when using EFI boot

[Jan Beulich]

On 01.10.2021 15:55, Luca Fancellu wrote:
>> On 1 Oct 2021, at 12:02, Jan Beulich <jbeulich@suse.com> wrote:
>> On 30.09.2021 16:28, Luca Fancellu wrote:
>>> @@ -1361,12 +1361,30 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
>>>         efi_bs->FreePages(cfg.addr, PFN_UP(cfg.size));
>>>         cfg.addr = 0;
>>>
>>> -        dir_handle->Close(dir_handle);
>>> -
>>>         if ( gop && !base_video )
>>>             gop_mode = efi_find_gop_mode(gop, cols, rows, depth);
>>>     }
>>>
>>> +#ifdef CONFIG_HAS_DEVICE_TREE
>>> +    /* Get the number of boot modules specified on the DT or an error (<0) */
>>> +    dt_modules_found = efi_arch_check_dt_boot(dir_handle);
>>> +#endif
>>
>> So I had asked to add a stub enclosed in such an #ifdef, to avoid the
>> #ifdef here. I may be willing to let you keep things as you have them
>> now, but I'd like to understand why you've picked that different
>> approach despite the prior discussion.
> 
> There must be a misunderstanding, your message in the v3 was:
> 
> "Every time I see this addition I'm getting puzzled. As a result I'm
> afraid I now need to finally ask you to do something about this (and
> I'm sorry for doing so only now). There would better be no notion of
> DT in x86 code, and there would better also not be a need for
> architectures not supporting DT to each supply such a stub. Instead
> I think you want to put this stub in xen/common/efi/boot.c, inside a
> suitable #ifdef.”
> 
> So I thought you wanted me to remove the stub in x86 (since it doesn’t support DT)
> and put this call under #ifdef so it won’t be compiled for arch not supporting DT.

So FTAOD I'll repeat the crucial part: "I think you want to put this
stub in xen/common/efi/boot.c". There was nothing about removing the
stub altogether.

Jan

Re: [PATCH v4 2/3] arm/efi: Use dom0less configuration when using EFI boot

[Luca Fancellu]

> On 1 Oct 2021, at 15:22, Jan Beulich <jbeulich@suse.com> wrote:
> 
> On 01.10.2021 15:55, Luca Fancellu wrote:
>>> On 1 Oct 2021, at 12:02, Jan Beulich <jbeulich@suse.com> wrote:
>>> On 30.09.2021 16:28, Luca Fancellu wrote:
>>>> @@ -1361,12 +1361,30 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
>>>>        efi_bs->FreePages(cfg.addr, PFN_UP(cfg.size));
>>>>        cfg.addr = 0;
>>>> 
>>>> -        dir_handle->Close(dir_handle);
>>>> -
>>>>        if ( gop && !base_video )
>>>>            gop_mode = efi_find_gop_mode(gop, cols, rows, depth);
>>>>    }
>>>> 
>>>> +#ifdef CONFIG_HAS_DEVICE_TREE
>>>> +    /* Get the number of boot modules specified on the DT or an error (<0) */
>>>> +    dt_modules_found = efi_arch_check_dt_boot(dir_handle);
>>>> +#endif
>>> 
>>> So I had asked to add a stub enclosed in such an #ifdef, to avoid the
>>> #ifdef here. I may be willing to let you keep things as you have them
>>> now, but I'd like to understand why you've picked that different
>>> approach despite the prior discussion.
>> 
>> There must be a misunderstanding, your message in the v3 was:
>> 
>> "Every time I see this addition I'm getting puzzled. As a result I'm
>> afraid I now need to finally ask you to do something about this (and
>> I'm sorry for doing so only now). There would better be no notion of
>> DT in x86 code, and there would better also not be a need for
>> architectures not supporting DT to each supply such a stub. Instead
>> I think you want to put this stub in xen/common/efi/boot.c, inside a
>> suitable #ifdef.”
>> 
>> So I thought you wanted me to remove the stub in x86 (since it doesn’t support DT)
>> and put this call under #ifdef so it won’t be compiled for arch not supporting DT.
> 
> So FTAOD I'll repeat the crucial part: "I think you want to put this
> stub in xen/common/efi/boot.c". There was nothing about removing the
> stub altogether.

Oh ok, now I see, so in your opinion this is a better idea:

#ifndef CONFIG_HAS_DEVICE_TREE
static inline int __init efi_arch_check_dt_boot(EFI_FILE_HANDLE dir_handle)
{
    return 0;
}
#endif

But I would like to understand the advantage respect of my approach, could you
explain me?

Cheers,
Luca


> 
> Jan
> 

Re: [PATCH v4 2/3] arm/efi: Use dom0less configuration when using EFI boot

[Jan Beulich]

On 01.10.2021 17:13, Luca Fancellu wrote:
> 
> 
>> On 1 Oct 2021, at 15:22, Jan Beulich <jbeulich@suse.com> wrote:
>>
>> On 01.10.2021 15:55, Luca Fancellu wrote:
>>>> On 1 Oct 2021, at 12:02, Jan Beulich <jbeulich@suse.com> wrote:
>>>> On 30.09.2021 16:28, Luca Fancellu wrote:
>>>>> @@ -1361,12 +1361,30 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
>>>>>        efi_bs->FreePages(cfg.addr, PFN_UP(cfg.size));
>>>>>        cfg.addr = 0;
>>>>>
>>>>> -        dir_handle->Close(dir_handle);
>>>>> -
>>>>>        if ( gop && !base_video )
>>>>>            gop_mode = efi_find_gop_mode(gop, cols, rows, depth);
>>>>>    }
>>>>>
>>>>> +#ifdef CONFIG_HAS_DEVICE_TREE
>>>>> +    /* Get the number of boot modules specified on the DT or an error (<0) */
>>>>> +    dt_modules_found = efi_arch_check_dt_boot(dir_handle);
>>>>> +#endif
>>>>
>>>> So I had asked to add a stub enclosed in such an #ifdef, to avoid the
>>>> #ifdef here. I may be willing to let you keep things as you have them
>>>> now, but I'd like to understand why you've picked that different
>>>> approach despite the prior discussion.
>>>
>>> There must be a misunderstanding, your message in the v3 was:
>>>
>>> "Every time I see this addition I'm getting puzzled. As a result I'm
>>> afraid I now need to finally ask you to do something about this (and
>>> I'm sorry for doing so only now). There would better be no notion of
>>> DT in x86 code, and there would better also not be a need for
>>> architectures not supporting DT to each supply such a stub. Instead
>>> I think you want to put this stub in xen/common/efi/boot.c, inside a
>>> suitable #ifdef.”
>>>
>>> So I thought you wanted me to remove the stub in x86 (since it doesn’t support DT)
>>> and put this call under #ifdef so it won’t be compiled for arch not supporting DT.
>>
>> So FTAOD I'll repeat the crucial part: "I think you want to put this
>> stub in xen/common/efi/boot.c". There was nothing about removing the
>> stub altogether.
> 
> Oh ok, now I see, so in your opinion this is a better idea:
> 
> #ifndef CONFIG_HAS_DEVICE_TREE
> static inline int __init efi_arch_check_dt_boot(EFI_FILE_HANDLE dir_handle)
> {
>     return 0;
> }
> #endif
> 
> But I would like to understand the advantage respect of my approach, could you
> explain me?

Well, to a degree it's a matter of taste. Your approach may lead to a long
series of various #ifdef sections in a single function, harming readability.
Having stubs instead (usually placed in headers, albeit not in this case)
allows the main bodies of code to remain more tidy.

Jan

Re: [PATCH v4 2/3] arm/efi: Use dom0less configuration when using EFI boot

[Luca Fancellu]

> On 7 Oct 2021, at 08:15, Jan Beulich <jbeulich@suse.com> wrote:
> 
> On 01.10.2021 17:13, Luca Fancellu wrote:
>> 
>> 
>>> On 1 Oct 2021, at 15:22, Jan Beulich <jbeulich@suse.com> wrote:
>>> 
>>> On 01.10.2021 15:55, Luca Fancellu wrote:
>>>>> On 1 Oct 2021, at 12:02, Jan Beulich <jbeulich@suse.com> wrote:
>>>>> On 30.09.2021 16:28, Luca Fancellu wrote:
>>>>>> @@ -1361,12 +1361,30 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
>>>>>>       efi_bs->FreePages(cfg.addr, PFN_UP(cfg.size));
>>>>>>       cfg.addr = 0;
>>>>>> 
>>>>>> -        dir_handle->Close(dir_handle);
>>>>>> -
>>>>>>       if ( gop && !base_video )
>>>>>>           gop_mode = efi_find_gop_mode(gop, cols, rows, depth);
>>>>>>   }
>>>>>> 
>>>>>> +#ifdef CONFIG_HAS_DEVICE_TREE
>>>>>> +    /* Get the number of boot modules specified on the DT or an error (<0) */
>>>>>> +    dt_modules_found = efi_arch_check_dt_boot(dir_handle);
>>>>>> +#endif
>>>>> 
>>>>> So I had asked to add a stub enclosed in such an #ifdef, to avoid the
>>>>> #ifdef here. I may be willing to let you keep things as you have them
>>>>> now, but I'd like to understand why you've picked that different
>>>>> approach despite the prior discussion.
>>>> 
>>>> There must be a misunderstanding, your message in the v3 was:
>>>> 
>>>> "Every time I see this addition I'm getting puzzled. As a result I'm
>>>> afraid I now need to finally ask you to do something about this (and
>>>> I'm sorry for doing so only now). There would better be no notion of
>>>> DT in x86 code, and there would better also not be a need for
>>>> architectures not supporting DT to each supply such a stub. Instead
>>>> I think you want to put this stub in xen/common/efi/boot.c, inside a
>>>> suitable #ifdef.”
>>>> 
>>>> So I thought you wanted me to remove the stub in x86 (since it doesn’t support DT)
>>>> and put this call under #ifdef so it won’t be compiled for arch not supporting DT.
>>> 
>>> So FTAOD I'll repeat the crucial part: "I think you want to put this
>>> stub in xen/common/efi/boot.c". There was nothing about removing the
>>> stub altogether.
>> 
>> Oh ok, now I see, so in your opinion this is a better idea:
>> 
>> #ifndef CONFIG_HAS_DEVICE_TREE
>> static inline int __init efi_arch_check_dt_boot(EFI_FILE_HANDLE dir_handle)
>> {
>>    return 0;
>> }
>> #endif
>> 
>> But I would like to understand the advantage respect of my approach, could you
>> explain me?
> 
> Well, to a degree it's a matter of taste. Your approach may lead to a long
> series of various #ifdef sections in a single function, harming readability.
> Having stubs instead (usually placed in headers, albeit not in this case)
> allows the main bodies of code to remain more tidy.

Yes right, in this case I did in another way because declaring the stub in the .c file
was (in my opinion) not the right thing to do, since also the name (efi_arch_*) recalls
something arch oriented and so not to be put in the common code.

In this way any future architecture supporting DT, can just provide the function (or a 
stub) and we don’t have stubs in architectures that won’t ever support DT.

In your opinion that solution could be acceptable?

Cheers,
Luca

> 
> Jan

Re: [PATCH v4 2/3] arm/efi: Use dom0less configuration when using EFI boot

[Jan Beulich]

On 08.10.2021 15:38, Luca Fancellu wrote:
>> On 7 Oct 2021, at 08:15, Jan Beulich <jbeulich@suse.com> wrote:
>> On 01.10.2021 17:13, Luca Fancellu wrote:
>>>> On 1 Oct 2021, at 15:22, Jan Beulich <jbeulich@suse.com> wrote:
>>>> On 01.10.2021 15:55, Luca Fancellu wrote:
>>>>>> On 1 Oct 2021, at 12:02, Jan Beulich <jbeulich@suse.com> wrote:
>>>>>> On 30.09.2021 16:28, Luca Fancellu wrote:
>>>>>>> @@ -1361,12 +1361,30 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
>>>>>>>       efi_bs->FreePages(cfg.addr, PFN_UP(cfg.size));
>>>>>>>       cfg.addr = 0;
>>>>>>>
>>>>>>> -        dir_handle->Close(dir_handle);
>>>>>>> -
>>>>>>>       if ( gop && !base_video )
>>>>>>>           gop_mode = efi_find_gop_mode(gop, cols, rows, depth);
>>>>>>>   }
>>>>>>>
>>>>>>> +#ifdef CONFIG_HAS_DEVICE_TREE
>>>>>>> +    /* Get the number of boot modules specified on the DT or an error (<0) */
>>>>>>> +    dt_modules_found = efi_arch_check_dt_boot(dir_handle);
>>>>>>> +#endif
>>>>>>
>>>>>> So I had asked to add a stub enclosed in such an #ifdef, to avoid the
>>>>>> #ifdef here. I may be willing to let you keep things as you have them
>>>>>> now, but I'd like to understand why you've picked that different
>>>>>> approach despite the prior discussion.
>>>>>
>>>>> There must be a misunderstanding, your message in the v3 was:
>>>>>
>>>>> "Every time I see this addition I'm getting puzzled. As a result I'm
>>>>> afraid I now need to finally ask you to do something about this (and
>>>>> I'm sorry for doing so only now). There would better be no notion of
>>>>> DT in x86 code, and there would better also not be a need for
>>>>> architectures not supporting DT to each supply such a stub. Instead
>>>>> I think you want to put this stub in xen/common/efi/boot.c, inside a
>>>>> suitable #ifdef.”
>>>>>
>>>>> So I thought you wanted me to remove the stub in x86 (since it doesn’t support DT)
>>>>> and put this call under #ifdef so it won’t be compiled for arch not supporting DT.
>>>>
>>>> So FTAOD I'll repeat the crucial part: "I think you want to put this
>>>> stub in xen/common/efi/boot.c". There was nothing about removing the
>>>> stub altogether.
>>>
>>> Oh ok, now I see, so in your opinion this is a better idea:
>>>
>>> #ifndef CONFIG_HAS_DEVICE_TREE
>>> static inline int __init efi_arch_check_dt_boot(EFI_FILE_HANDLE dir_handle)
>>> {
>>>    return 0;
>>> }
>>> #endif
>>>
>>> But I would like to understand the advantage respect of my approach, could you
>>> explain me?
>>
>> Well, to a degree it's a matter of taste. Your approach may lead to a long
>> series of various #ifdef sections in a single function, harming readability.
>> Having stubs instead (usually placed in headers, albeit not in this case)
>> allows the main bodies of code to remain more tidy.
> 
> Yes right, in this case I did in another way because declaring the stub in the .c file
> was (in my opinion) not the right thing to do, since also the name (efi_arch_*) recalls
> something arch oriented and so not to be put in the common code.

Feel free to drop "arch" from the hook name.

> In this way any future architecture supporting DT, can just provide the function (or a 
> stub) and we don’t have stubs in architectures that won’t ever support DT.
> 
> In your opinion that solution could be acceptable?

Yes, but not preferable.

Jan

[PATCH v4 3/3] arm/efi: load dom0 modules from DT using UEFI

[Luca Fancellu]

Add support to load Dom0 boot modules from
the device tree using the xen,uefi-binary property.

Update documentation about that.

Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>
---
Changes in v4:
- Add check to avoid double definition of Dom0 ramdisk
from cfg file and DT
- Fix if conditions indentation in boot.c
- Moved Dom0 kernel verification code after check for
presence for Dom0 or DomU(s)
- Changed uefi,binary property to xen,uefi-binary
Changes in v3:
- new patch
---
 docs/misc/arm/device-tree/booting.txt |  8 ++++
 docs/misc/efi.pandoc                  | 64 +++++++++++++++++++++++++--
 xen/arch/arm/efi/efi-boot.h           | 47 ++++++++++++++++++--
 xen/common/efi/boot.c                 | 16 ++++---
 4 files changed, 123 insertions(+), 12 deletions(-)

diff --git a/docs/misc/arm/device-tree/booting.txt b/docs/misc/arm/device-tree/booting.txt
index 7258e7e1ec..8e0c327ba4 100644
--- a/docs/misc/arm/device-tree/booting.txt
+++ b/docs/misc/arm/device-tree/booting.txt
@@ -70,6 +70,14 @@ Each node contains the following properties:
 	priority of this field vs. other mechanisms of specifying the
 	bootargs for the kernel.
 
+- uefi,binary (UEFI boot only)
+
+	String property that specifies the file name to be loaded by the UEFI
+	boot for this module. If this is specified, there is no need to specify
+	the reg property because it will be created by the UEFI stub on boot.
+	This option is needed only when UEFI boot is used, the node needs to be
+	compatible with multiboot,kernel or multiboot,ramdisk.
+
 Examples
 ========
 
diff --git a/docs/misc/efi.pandoc b/docs/misc/efi.pandoc
index 876cd55005..4abbb5bb82 100644
--- a/docs/misc/efi.pandoc
+++ b/docs/misc/efi.pandoc
@@ -167,6 +167,28 @@ sbsign \
 	--output xen.signed.efi \
 	xen.unified.efi
 ```
+## UEFI boot and Dom0 modules on ARM
+
+When booting using UEFI on ARM, it is possible to specify the Dom0 modules
+directly from the device tree without using the Xen configuration file, here an
+example:
+
+chosen {
+	#size-cells = <0x1>;
+	#address-cells = <0x1>;
+	xen,xen-bootargs = "[Xen boot arguments]"
+
+	module@1 {
+		compatible = "multiboot,kernel", "multiboot,module";
+		xen,uefi-binary = "vmlinuz-3.0.31-0.4-xen";
+		bootargs = "[domain 0 command line options]";
+	};
+
+	module@2 {
+		compatible = "multiboot,ramdisk", "multiboot,module";
+		xen,uefi-binary = "initrd-3.0.31-0.4-xen";
+	};
+}
 
 ## UEFI boot and dom0less on ARM
 
@@ -326,10 +348,10 @@ chosen {
 ### Boot Xen, Dom0 and DomU(s)
 
 This configuration is a mix of the two configuration above, to boot this one
-the configuration file must be processed so the /chosen node must have the
-"xen,uefi-cfg-load" property.
+the configuration file can be processed or the Dom0 modules can be read from
+the device tree.
 
-Here an example:
+Here the first example:
 
 Xen configuration file:
 
@@ -369,4 +391,40 @@ chosen {
 };
 ```
 
+Here the second example:
+
+Device tree:
+
+```
+chosen {
+	#size-cells = <0x1>;
+	#address-cells = <0x1>;
+	xen,xen-bootargs = "[Xen boot arguments]"
+
+	module@1 {
+		compatible = "multiboot,kernel", "multiboot,module";
+		xen,uefi-binary = "vmlinuz-3.0.31-0.4-xen";
+		bootargs = "[domain 0 command line options]";
+	};
+
+	module@2 {
+		compatible = "multiboot,ramdisk", "multiboot,module";
+		xen,uefi-binary = "initrd-3.0.31-0.4-xen";
+	};
+
+	domU1 {
+		#size-cells = <0x1>;
+		#address-cells = <0x1>;
+		compatible = "xen,domain";
+		cpus = <0x1>;
+		memory = <0x0 0xc0000>;
+		vpl011;
 
+		module@1 {
+			compatible = "multiboot,kernel", "multiboot,module";
+			xen,uefi-binary = "Image-domu1.bin";
+			bootargs = "console=ttyAMA0 root=/dev/ram0 rw";
+		};
+	};
+};
+```
diff --git a/xen/arch/arm/efi/efi-boot.h b/xen/arch/arm/efi/efi-boot.h
index 50b3829ae0..b122e2846a 100644
--- a/xen/arch/arm/efi/efi-boot.h
+++ b/xen/arch/arm/efi/efi-boot.h
@@ -31,8 +31,11 @@ static unsigned int __initdata modules_idx;
 #define ERROR_MISSING_DT_PROPERTY   (-3)
 #define ERROR_RENAME_MODULE_NAME    (-4)
 #define ERROR_SET_REG_PROPERTY      (-5)
+#define ERROR_DOM0_ALREADY_FOUND    (-6)
+#define ERROR_DOM0_RAMDISK_FOUND    (-7)
 #define ERROR_DT_MODULE_DOMU        (-1)
 #define ERROR_DT_CHOSEN_NODE        (-2)
+#define ERROR_DT_MODULE_DOM0        (-3)
 
 void noreturn efi_xen_start(void *fdt_ptr, uint32_t fdt_size);
 void __flush_dcache_area(const void *vaddr, unsigned long size);
@@ -45,7 +48,8 @@ static int allocate_module_file(EFI_FILE_HANDLE dir_handle,
 static int handle_module_node(EFI_FILE_HANDLE dir_handle,
                               int module_node_offset,
                               int reg_addr_cells,
-                              int reg_size_cells);
+                              int reg_size_cells,
+                              bool is_domu_module);
 static bool is_boot_module(int dt_module_offset);
 static int handle_dom0less_domain_node(EFI_FILE_HANDLE dir_handle,
                                        int domain_node);
@@ -701,7 +705,8 @@ static int __init allocate_module_file(EFI_FILE_HANDLE dir_handle,
 static int __init handle_module_node(EFI_FILE_HANDLE dir_handle,
                                      int module_node_offset,
                                      int reg_addr_cells,
-                                     int reg_size_cells)
+                                     int reg_size_cells,
+                                     bool is_domu_module)
 {
     const void *uefi_name_prop;
     char mod_string[24]; /* Placeholder for module@ + a 64-bit number + \0 */
@@ -743,6 +748,34 @@ static int __init handle_module_node(EFI_FILE_HANDLE dir_handle,
         return ERROR_SET_REG_PROPERTY;
     }
 
+    if ( !is_domu_module )
+    {
+        if ( (fdt_node_check_compatible(fdt, module_node_offset,
+                                    "multiboot,kernel") == 0) )
+        {
+            /*
+            * This is the Dom0 kernel, wire it to the kernel variable because it
+            * will be verified by the shim lock protocol later in the common
+            * code.
+            */
+            if ( kernel.addr )
+            {
+                PrintMessage(L"Dom0 kernel already found in cfg file.");
+                return ERROR_DOM0_ALREADY_FOUND;
+            }
+            kernel.need_to_free = false; /* Freed using the module array */
+            kernel.addr = file->addr;
+            kernel.size = file->size;
+        }
+        else if ( ramdisk.addr &&
+                  (fdt_node_check_compatible(fdt, module_node_offset,
+                                             "multiboot,ramdisk") == 0) )
+        {
+            PrintMessage(L"Dom0 ramdisk already found in cfg file.");
+            return ERROR_DOM0_RAMDISK_FOUND;
+        }
+    }
+
     return 0;
 }
 
@@ -799,7 +832,7 @@ static int __init handle_dom0less_domain_node(EFI_FILE_HANDLE dir_handle,
         if ( is_boot_module(module_node) )
         {
             int ret = handle_module_node(dir_handle, module_node, addr_cells,
-                                         size_cells);
+                                         size_cells, true);
             if ( ret < 0 )
                 return ret;
         }
@@ -809,7 +842,7 @@ static int __init handle_dom0less_domain_node(EFI_FILE_HANDLE dir_handle,
 
 /*
  * This function checks for xen domain nodes under the /chosen node for possible
- * domU guests to be loaded.
+ * dom0 and domU guests to be loaded.
  * Returns the number of modules loaded or a negative number for error.
  */
 static int __init efi_arch_check_dt_boot(EFI_FILE_HANDLE dir_handle)
@@ -836,6 +869,12 @@ static int __init efi_arch_check_dt_boot(EFI_FILE_HANDLE dir_handle)
             if ( handle_dom0less_domain_node(dir_handle, node) < 0 )
                 return ERROR_DT_MODULE_DOMU;
         }
+        else if ( is_boot_module(node) )
+        {
+            if ( handle_module_node(dir_handle, node, addr_len, size_len,
+                                    false) < 0 )
+                return ERROR_DT_MODULE_DOM0;
+        }
     }
 
     /* Free boot modules file names if any */
diff --git a/xen/common/efi/boot.c b/xen/common/efi/boot.c
index daf7c26099..e4295dbe34 100644
--- a/xen/common/efi/boot.c
+++ b/xen/common/efi/boot.c
@@ -1296,11 +1296,6 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
         {
             read_file(dir_handle, s2w(&name), &kernel, option_str);
             efi_bs->FreePool(name.w);
-
-            if ( !EFI_ERROR(efi_bs->LocateProtocol(&shim_lock_guid, NULL,
-                            (void **)&shim_lock)) &&
-                 (status = shim_lock->Verify(kernel.ptr, kernel.size)) != EFI_SUCCESS )
-                PrintErrMesg(L"Dom0 kernel image could not be verified", status);
         }
 
         if ( !read_section(loaded_image, L"ramdisk", &ramdisk, NULL) )
@@ -1385,6 +1380,17 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
     if ( !dt_modules_found && !kernel.addr )
         blexit(L"No Dom0 kernel image specified.");
 
+    /*
+     * The Dom0 kernel can be loaded from the configuration file or by the
+     * device tree through the efi_arch_check_dt_boot function, in this stage
+     * verify it.
+     */
+    if ( kernel.addr &&
+         !EFI_ERROR(efi_bs->LocateProtocol(&shim_lock_guid, NULL,
+                                           (void **)&shim_lock)) &&
+         (status = shim_lock->Verify(kernel.ptr, kernel.size)) != EFI_SUCCESS )
+        PrintErrMesg(L"Dom0 kernel image could not be verified", status);
+
     efi_arch_edd();
 
     /* XXX Collect EDID info. */
-- 
2.17.1

Re: [PATCH v4 3/3] arm/efi: load dom0 modules from DT using UEFI

[Bertrand Marquis]

Hi Luca,

> On 30 Sep 2021, at 15:28, Luca Fancellu <Luca.Fancellu@arm.com> wrote:
> 
> Add support to load Dom0 boot modules from
> the device tree using the xen,uefi-binary property.
> 
> Update documentation about that.
> 
> Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>
Reviewed-by: Bertrand Marquis <bertrand.marquis@arm.com>

Cheers
Bertrand

> ---
> Changes in v4:
> - Add check to avoid double definition of Dom0 ramdisk
> from cfg file and DT
> - Fix if conditions indentation in boot.c
> - Moved Dom0 kernel verification code after check for
> presence for Dom0 or DomU(s)
> - Changed uefi,binary property to xen,uefi-binary
> Changes in v3:
> - new patch
> ---
> docs/misc/arm/device-tree/booting.txt |  8 ++++
> docs/misc/efi.pandoc                  | 64 +++++++++++++++++++++++++--
> xen/arch/arm/efi/efi-boot.h           | 47 ++++++++++++++++++--
> xen/common/efi/boot.c                 | 16 ++++---
> 4 files changed, 123 insertions(+), 12 deletions(-)
> 
> diff --git a/docs/misc/arm/device-tree/booting.txt b/docs/misc/arm/device-tree/booting.txt
> index 7258e7e1ec..8e0c327ba4 100644
> --- a/docs/misc/arm/device-tree/booting.txt
> +++ b/docs/misc/arm/device-tree/booting.txt
> @@ -70,6 +70,14 @@ Each node contains the following properties:
> 	priority of this field vs. other mechanisms of specifying the
> 	bootargs for the kernel.
> 
> +- uefi,binary (UEFI boot only)
> +
> +	String property that specifies the file name to be loaded by the UEFI
> +	boot for this module. If this is specified, there is no need to specify
> +	the reg property because it will be created by the UEFI stub on boot.
> +	This option is needed only when UEFI boot is used, the node needs to be
> +	compatible with multiboot,kernel or multiboot,ramdisk.
> +
> Examples
> ========
> 
> diff --git a/docs/misc/efi.pandoc b/docs/misc/efi.pandoc
> index 876cd55005..4abbb5bb82 100644
> --- a/docs/misc/efi.pandoc
> +++ b/docs/misc/efi.pandoc
> @@ -167,6 +167,28 @@ sbsign \
> 	--output xen.signed.efi \
> 	xen.unified.efi
> ```
> +## UEFI boot and Dom0 modules on ARM
> +
> +When booting using UEFI on ARM, it is possible to specify the Dom0 modules
> +directly from the device tree without using the Xen configuration file, here an
> +example:
> +
> +chosen {
> +	#size-cells = <0x1>;
> +	#address-cells = <0x1>;
> +	xen,xen-bootargs = "[Xen boot arguments]"
> +
> +	module@1 {
> +		compatible = "multiboot,kernel", "multiboot,module";
> +		xen,uefi-binary = "vmlinuz-3.0.31-0.4-xen";
> +		bootargs = "[domain 0 command line options]";
> +	};
> +
> +	module@2 {
> +		compatible = "multiboot,ramdisk", "multiboot,module";
> +		xen,uefi-binary = "initrd-3.0.31-0.4-xen";
> +	};
> +}
> 
> ## UEFI boot and dom0less on ARM
> 
> @@ -326,10 +348,10 @@ chosen {
> ### Boot Xen, Dom0 and DomU(s)
> 
> This configuration is a mix of the two configuration above, to boot this one
> -the configuration file must be processed so the /chosen node must have the
> -"xen,uefi-cfg-load" property.
> +the configuration file can be processed or the Dom0 modules can be read from
> +the device tree.
> 
> -Here an example:
> +Here the first example:
> 
> Xen configuration file:
> 
> @@ -369,4 +391,40 @@ chosen {
> };
> ```
> 
> +Here the second example:
> +
> +Device tree:
> +
> +```
> +chosen {
> +	#size-cells = <0x1>;
> +	#address-cells = <0x1>;
> +	xen,xen-bootargs = "[Xen boot arguments]"
> +
> +	module@1 {
> +		compatible = "multiboot,kernel", "multiboot,module";
> +		xen,uefi-binary = "vmlinuz-3.0.31-0.4-xen";
> +		bootargs = "[domain 0 command line options]";
> +	};
> +
> +	module@2 {
> +		compatible = "multiboot,ramdisk", "multiboot,module";
> +		xen,uefi-binary = "initrd-3.0.31-0.4-xen";
> +	};
> +
> +	domU1 {
> +		#size-cells = <0x1>;
> +		#address-cells = <0x1>;
> +		compatible = "xen,domain";
> +		cpus = <0x1>;
> +		memory = <0x0 0xc0000>;
> +		vpl011;
> 
> +		module@1 {
> +			compatible = "multiboot,kernel", "multiboot,module";
> +			xen,uefi-binary = "Image-domu1.bin";
> +			bootargs = "console=ttyAMA0 root=/dev/ram0 rw";
> +		};
> +	};
> +};
> +```
> diff --git a/xen/arch/arm/efi/efi-boot.h b/xen/arch/arm/efi/efi-boot.h
> index 50b3829ae0..b122e2846a 100644
> --- a/xen/arch/arm/efi/efi-boot.h
> +++ b/xen/arch/arm/efi/efi-boot.h
> @@ -31,8 +31,11 @@ static unsigned int __initdata modules_idx;
> #define ERROR_MISSING_DT_PROPERTY   (-3)
> #define ERROR_RENAME_MODULE_NAME    (-4)
> #define ERROR_SET_REG_PROPERTY      (-5)
> +#define ERROR_DOM0_ALREADY_FOUND    (-6)
> +#define ERROR_DOM0_RAMDISK_FOUND    (-7)
> #define ERROR_DT_MODULE_DOMU        (-1)
> #define ERROR_DT_CHOSEN_NODE        (-2)
> +#define ERROR_DT_MODULE_DOM0        (-3)
> 
> void noreturn efi_xen_start(void *fdt_ptr, uint32_t fdt_size);
> void __flush_dcache_area(const void *vaddr, unsigned long size);
> @@ -45,7 +48,8 @@ static int allocate_module_file(EFI_FILE_HANDLE dir_handle,
> static int handle_module_node(EFI_FILE_HANDLE dir_handle,
>                               int module_node_offset,
>                               int reg_addr_cells,
> -                              int reg_size_cells);
> +                              int reg_size_cells,
> +                              bool is_domu_module);
> static bool is_boot_module(int dt_module_offset);
> static int handle_dom0less_domain_node(EFI_FILE_HANDLE dir_handle,
>                                        int domain_node);
> @@ -701,7 +705,8 @@ static int __init allocate_module_file(EFI_FILE_HANDLE dir_handle,
> static int __init handle_module_node(EFI_FILE_HANDLE dir_handle,
>                                      int module_node_offset,
>                                      int reg_addr_cells,
> -                                     int reg_size_cells)
> +                                     int reg_size_cells,
> +                                     bool is_domu_module)
> {
>     const void *uefi_name_prop;
>     char mod_string[24]; /* Placeholder for module@ + a 64-bit number + \0 */
> @@ -743,6 +748,34 @@ static int __init handle_module_node(EFI_FILE_HANDLE dir_handle,
>         return ERROR_SET_REG_PROPERTY;
>     }
> 
> +    if ( !is_domu_module )
> +    {
> +        if ( (fdt_node_check_compatible(fdt, module_node_offset,
> +                                    "multiboot,kernel") == 0) )
> +        {
> +            /*
> +            * This is the Dom0 kernel, wire it to the kernel variable because it
> +            * will be verified by the shim lock protocol later in the common
> +            * code.
> +            */
> +            if ( kernel.addr )
> +            {
> +                PrintMessage(L"Dom0 kernel already found in cfg file.");
> +                return ERROR_DOM0_ALREADY_FOUND;
> +            }
> +            kernel.need_to_free = false; /* Freed using the module array */
> +            kernel.addr = file->addr;
> +            kernel.size = file->size;
> +        }
> +        else if ( ramdisk.addr &&
> +                  (fdt_node_check_compatible(fdt, module_node_offset,
> +                                             "multiboot,ramdisk") == 0) )
> +        {
> +            PrintMessage(L"Dom0 ramdisk already found in cfg file.");
> +            return ERROR_DOM0_RAMDISK_FOUND;
> +        }
> +    }
> +
>     return 0;
> }
> 
> @@ -799,7 +832,7 @@ static int __init handle_dom0less_domain_node(EFI_FILE_HANDLE dir_handle,
>         if ( is_boot_module(module_node) )
>         {
>             int ret = handle_module_node(dir_handle, module_node, addr_cells,
> -                                         size_cells);
> +                                         size_cells, true);
>             if ( ret < 0 )
>                 return ret;
>         }
> @@ -809,7 +842,7 @@ static int __init handle_dom0less_domain_node(EFI_FILE_HANDLE dir_handle,
> 
> /*
>  * This function checks for xen domain nodes under the /chosen node for possible
> - * domU guests to be loaded.
> + * dom0 and domU guests to be loaded.
>  * Returns the number of modules loaded or a negative number for error.
>  */
> static int __init efi_arch_check_dt_boot(EFI_FILE_HANDLE dir_handle)
> @@ -836,6 +869,12 @@ static int __init efi_arch_check_dt_boot(EFI_FILE_HANDLE dir_handle)
>             if ( handle_dom0less_domain_node(dir_handle, node) < 0 )
>                 return ERROR_DT_MODULE_DOMU;
>         }
> +        else if ( is_boot_module(node) )
> +        {
> +            if ( handle_module_node(dir_handle, node, addr_len, size_len,
> +                                    false) < 0 )
> +                return ERROR_DT_MODULE_DOM0;
> +        }
>     }
> 
>     /* Free boot modules file names if any */
> diff --git a/xen/common/efi/boot.c b/xen/common/efi/boot.c
> index daf7c26099..e4295dbe34 100644
> --- a/xen/common/efi/boot.c
> +++ b/xen/common/efi/boot.c
> @@ -1296,11 +1296,6 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
>         {
>             read_file(dir_handle, s2w(&name), &kernel, option_str);
>             efi_bs->FreePool(name.w);
> -
> -            if ( !EFI_ERROR(efi_bs->LocateProtocol(&shim_lock_guid, NULL,
> -                            (void **)&shim_lock)) &&
> -                 (status = shim_lock->Verify(kernel.ptr, kernel.size)) != EFI_SUCCESS )
> -                PrintErrMesg(L"Dom0 kernel image could not be verified", status);
>         }
> 
>         if ( !read_section(loaded_image, L"ramdisk", &ramdisk, NULL) )
> @@ -1385,6 +1380,17 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
>     if ( !dt_modules_found && !kernel.addr )
>         blexit(L"No Dom0 kernel image specified.");
> 
> +    /*
> +     * The Dom0 kernel can be loaded from the configuration file or by the
> +     * device tree through the efi_arch_check_dt_boot function, in this stage
> +     * verify it.
> +     */
> +    if ( kernel.addr &&
> +         !EFI_ERROR(efi_bs->LocateProtocol(&shim_lock_guid, NULL,
> +                                           (void **)&shim_lock)) &&
> +         (status = shim_lock->Verify(kernel.ptr, kernel.size)) != EFI_SUCCESS )
> +        PrintErrMesg(L"Dom0 kernel image could not be verified", status);
> +
>     efi_arch_edd();
> 
>     /* XXX Collect EDID info. */
> -- 
> 2.17.1
> 

Re: [PATCH v4 3/3] arm/efi: load dom0 modules from DT using UEFI

[Stefano Stabellini]

On Thu, 30 Sep 2021, Luca Fancellu wrote:
> Add support to load Dom0 boot modules from
> the device tree using the xen,uefi-binary property.
> 
> Update documentation about that.
> 
> Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>
> ---
> Changes in v4:
> - Add check to avoid double definition of Dom0 ramdisk
> from cfg file and DT
> - Fix if conditions indentation in boot.c
> - Moved Dom0 kernel verification code after check for
> presence for Dom0 or DomU(s)
> - Changed uefi,binary property to xen,uefi-binary
> Changes in v3:
> - new patch
> ---
>  docs/misc/arm/device-tree/booting.txt |  8 ++++
>  docs/misc/efi.pandoc                  | 64 +++++++++++++++++++++++++--
>  xen/arch/arm/efi/efi-boot.h           | 47 ++++++++++++++++++--
>  xen/common/efi/boot.c                 | 16 ++++---
>  4 files changed, 123 insertions(+), 12 deletions(-)
> 
> diff --git a/docs/misc/arm/device-tree/booting.txt b/docs/misc/arm/device-tree/booting.txt
> index 7258e7e1ec..8e0c327ba4 100644
> --- a/docs/misc/arm/device-tree/booting.txt
> +++ b/docs/misc/arm/device-tree/booting.txt
> @@ -70,6 +70,14 @@ Each node contains the following properties:
>  	priority of this field vs. other mechanisms of specifying the
>  	bootargs for the kernel.
>  
> +- uefi,binary (UEFI boot only)

Needs to be renamed, but it could be done on commit:

Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>



> +	String property that specifies the file name to be loaded by the UEFI
> +	boot for this module. If this is specified, there is no need to specify
> +	the reg property because it will be created by the UEFI stub on boot.
> +	This option is needed only when UEFI boot is used, the node needs to be
> +	compatible with multiboot,kernel or multiboot,ramdisk.
> +
>  Examples
>  ========
>  
> diff --git a/docs/misc/efi.pandoc b/docs/misc/efi.pandoc
> index 876cd55005..4abbb5bb82 100644
> --- a/docs/misc/efi.pandoc
> +++ b/docs/misc/efi.pandoc
> @@ -167,6 +167,28 @@ sbsign \
>  	--output xen.signed.efi \
>  	xen.unified.efi
>  ```
> +## UEFI boot and Dom0 modules on ARM
> +
> +When booting using UEFI on ARM, it is possible to specify the Dom0 modules
> +directly from the device tree without using the Xen configuration file, here an
> +example:
> +
> +chosen {
> +	#size-cells = <0x1>;
> +	#address-cells = <0x1>;
> +	xen,xen-bootargs = "[Xen boot arguments]"
> +
> +	module@1 {
> +		compatible = "multiboot,kernel", "multiboot,module";
> +		xen,uefi-binary = "vmlinuz-3.0.31-0.4-xen";
> +		bootargs = "[domain 0 command line options]";
> +	};
> +
> +	module@2 {
> +		compatible = "multiboot,ramdisk", "multiboot,module";
> +		xen,uefi-binary = "initrd-3.0.31-0.4-xen";
> +	};
> +}
>  
>  ## UEFI boot and dom0less on ARM
>  
> @@ -326,10 +348,10 @@ chosen {
>  ### Boot Xen, Dom0 and DomU(s)
>  
>  This configuration is a mix of the two configuration above, to boot this one
> -the configuration file must be processed so the /chosen node must have the
> -"xen,uefi-cfg-load" property.
> +the configuration file can be processed or the Dom0 modules can be read from
> +the device tree.
>  
> -Here an example:
> +Here the first example:
>  
>  Xen configuration file:
>  
> @@ -369,4 +391,40 @@ chosen {
>  };
>  ```
>  
> +Here the second example:
> +
> +Device tree:
> +
> +```
> +chosen {
> +	#size-cells = <0x1>;
> +	#address-cells = <0x1>;
> +	xen,xen-bootargs = "[Xen boot arguments]"
> +
> +	module@1 {
> +		compatible = "multiboot,kernel", "multiboot,module";
> +		xen,uefi-binary = "vmlinuz-3.0.31-0.4-xen";
> +		bootargs = "[domain 0 command line options]";
> +	};
> +
> +	module@2 {
> +		compatible = "multiboot,ramdisk", "multiboot,module";
> +		xen,uefi-binary = "initrd-3.0.31-0.4-xen";
> +	};
> +
> +	domU1 {
> +		#size-cells = <0x1>;
> +		#address-cells = <0x1>;
> +		compatible = "xen,domain";
> +		cpus = <0x1>;
> +		memory = <0x0 0xc0000>;
> +		vpl011;
>  
> +		module@1 {
> +			compatible = "multiboot,kernel", "multiboot,module";
> +			xen,uefi-binary = "Image-domu1.bin";
> +			bootargs = "console=ttyAMA0 root=/dev/ram0 rw";
> +		};
> +	};
> +};
> +```
> diff --git a/xen/arch/arm/efi/efi-boot.h b/xen/arch/arm/efi/efi-boot.h
> index 50b3829ae0..b122e2846a 100644
> --- a/xen/arch/arm/efi/efi-boot.h
> +++ b/xen/arch/arm/efi/efi-boot.h
> @@ -31,8 +31,11 @@ static unsigned int __initdata modules_idx;
>  #define ERROR_MISSING_DT_PROPERTY   (-3)
>  #define ERROR_RENAME_MODULE_NAME    (-4)
>  #define ERROR_SET_REG_PROPERTY      (-5)
> +#define ERROR_DOM0_ALREADY_FOUND    (-6)
> +#define ERROR_DOM0_RAMDISK_FOUND    (-7)
>  #define ERROR_DT_MODULE_DOMU        (-1)
>  #define ERROR_DT_CHOSEN_NODE        (-2)
> +#define ERROR_DT_MODULE_DOM0        (-3)
>  
>  void noreturn efi_xen_start(void *fdt_ptr, uint32_t fdt_size);
>  void __flush_dcache_area(const void *vaddr, unsigned long size);
> @@ -45,7 +48,8 @@ static int allocate_module_file(EFI_FILE_HANDLE dir_handle,
>  static int handle_module_node(EFI_FILE_HANDLE dir_handle,
>                                int module_node_offset,
>                                int reg_addr_cells,
> -                              int reg_size_cells);
> +                              int reg_size_cells,
> +                              bool is_domu_module);
>  static bool is_boot_module(int dt_module_offset);
>  static int handle_dom0less_domain_node(EFI_FILE_HANDLE dir_handle,
>                                         int domain_node);
> @@ -701,7 +705,8 @@ static int __init allocate_module_file(EFI_FILE_HANDLE dir_handle,
>  static int __init handle_module_node(EFI_FILE_HANDLE dir_handle,
>                                       int module_node_offset,
>                                       int reg_addr_cells,
> -                                     int reg_size_cells)
> +                                     int reg_size_cells,
> +                                     bool is_domu_module)
>  {
>      const void *uefi_name_prop;
>      char mod_string[24]; /* Placeholder for module@ + a 64-bit number + \0 */
> @@ -743,6 +748,34 @@ static int __init handle_module_node(EFI_FILE_HANDLE dir_handle,
>          return ERROR_SET_REG_PROPERTY;
>      }
>  
> +    if ( !is_domu_module )
> +    {
> +        if ( (fdt_node_check_compatible(fdt, module_node_offset,
> +                                    "multiboot,kernel") == 0) )
> +        {
> +            /*
> +            * This is the Dom0 kernel, wire it to the kernel variable because it
> +            * will be verified by the shim lock protocol later in the common
> +            * code.
> +            */
> +            if ( kernel.addr )
> +            {
> +                PrintMessage(L"Dom0 kernel already found in cfg file.");
> +                return ERROR_DOM0_ALREADY_FOUND;
> +            }
> +            kernel.need_to_free = false; /* Freed using the module array */
> +            kernel.addr = file->addr;
> +            kernel.size = file->size;
> +        }
> +        else if ( ramdisk.addr &&
> +                  (fdt_node_check_compatible(fdt, module_node_offset,
> +                                             "multiboot,ramdisk") == 0) )
> +        {
> +            PrintMessage(L"Dom0 ramdisk already found in cfg file.");
> +            return ERROR_DOM0_RAMDISK_FOUND;
> +        }
> +    }
> +
>      return 0;
>  }
>  
> @@ -799,7 +832,7 @@ static int __init handle_dom0less_domain_node(EFI_FILE_HANDLE dir_handle,
>          if ( is_boot_module(module_node) )
>          {
>              int ret = handle_module_node(dir_handle, module_node, addr_cells,
> -                                         size_cells);
> +                                         size_cells, true);
>              if ( ret < 0 )
>                  return ret;
>          }
> @@ -809,7 +842,7 @@ static int __init handle_dom0less_domain_node(EFI_FILE_HANDLE dir_handle,
>  
>  /*
>   * This function checks for xen domain nodes under the /chosen node for possible
> - * domU guests to be loaded.
> + * dom0 and domU guests to be loaded.
>   * Returns the number of modules loaded or a negative number for error.
>   */
>  static int __init efi_arch_check_dt_boot(EFI_FILE_HANDLE dir_handle)
> @@ -836,6 +869,12 @@ static int __init efi_arch_check_dt_boot(EFI_FILE_HANDLE dir_handle)
>              if ( handle_dom0less_domain_node(dir_handle, node) < 0 )
>                  return ERROR_DT_MODULE_DOMU;
>          }
> +        else if ( is_boot_module(node) )
> +        {
> +            if ( handle_module_node(dir_handle, node, addr_len, size_len,
> +                                    false) < 0 )
> +                return ERROR_DT_MODULE_DOM0;
> +        }
>      }
>  
>      /* Free boot modules file names if any */
> diff --git a/xen/common/efi/boot.c b/xen/common/efi/boot.c
> index daf7c26099..e4295dbe34 100644
> --- a/xen/common/efi/boot.c
> +++ b/xen/common/efi/boot.c
> @@ -1296,11 +1296,6 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
>          {
>              read_file(dir_handle, s2w(&name), &kernel, option_str);
>              efi_bs->FreePool(name.w);
> -
> -            if ( !EFI_ERROR(efi_bs->LocateProtocol(&shim_lock_guid, NULL,
> -                            (void **)&shim_lock)) &&
> -                 (status = shim_lock->Verify(kernel.ptr, kernel.size)) != EFI_SUCCESS )
> -                PrintErrMesg(L"Dom0 kernel image could not be verified", status);
>          }
>  
>          if ( !read_section(loaded_image, L"ramdisk", &ramdisk, NULL) )
> @@ -1385,6 +1380,17 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
>      if ( !dt_modules_found && !kernel.addr )
>          blexit(L"No Dom0 kernel image specified.");
>  
> +    /*
> +     * The Dom0 kernel can be loaded from the configuration file or by the
> +     * device tree through the efi_arch_check_dt_boot function, in this stage
> +     * verify it.
> +     */
> +    if ( kernel.addr &&
> +         !EFI_ERROR(efi_bs->LocateProtocol(&shim_lock_guid, NULL,
> +                                           (void **)&shim_lock)) &&
> +         (status = shim_lock->Verify(kernel.ptr, kernel.size)) != EFI_SUCCESS )
> +        PrintErrMesg(L"Dom0 kernel image could not be verified", status);
> +
>      efi_arch_edd();
>  
>      /* XXX Collect EDID info. */
> -- 
> 2.17.1
> 

Re: [PATCH v4 3/3] arm/efi: load dom0 modules from DT using UEFI

[Jan Beulich]

On 30.09.2021 16:28, Luca Fancellu wrote:
> Add support to load Dom0 boot modules from
> the device tree using the xen,uefi-binary property.
> 
> Update documentation about that.
> 
> Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>

Acked-by: Jan Beulich <jbeulich@suse.com>
despite ...

> @@ -1385,6 +1380,17 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
>      if ( !dt_modules_found && !kernel.addr )
>          blexit(L"No Dom0 kernel image specified.");
>  
> +    /*
> +     * The Dom0 kernel can be loaded from the configuration file or by the
> +     * device tree through the efi_arch_check_dt_boot function, in this stage
> +     * verify it.
> +     */
> +    if ( kernel.addr &&

... me still being a little unhappy with the inconsistent use of the
union fields so close together: This one is now consistent with the
one visible further up in context, but ...

> +         !EFI_ERROR(efi_bs->LocateProtocol(&shim_lock_guid, NULL,> +                                           (void **)&shim_lock)) &&
> +         (status = shim_lock->Verify(kernel.ptr, kernel.size)) != EFI_SUCCESS )

... is now inconsistent with this use. But yeah - read_file() is
even worse in that sense, except that there the different uses are
for specific reasons, while here the only requirement is to satisfy
shim_lock->Verify().

Please feel free to retain my ack in case you decide to use .ptr in
all three places.

Jan

Re: [PATCH v4 3/3] arm/efi: load dom0 modules from DT using UEFI

[Luca Fancellu]

> On 1 Oct 2021, at 12:16, Jan Beulich <jbeulich@suse.com> wrote:
> 
> On 30.09.2021 16:28, Luca Fancellu wrote:
>> Add support to load Dom0 boot modules from
>> the device tree using the xen,uefi-binary property.
>> 
>> Update documentation about that.
>> 
>> Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>
> 
> Acked-by: Jan Beulich <jbeulich@suse.com>
> despite ...
> 
>> @@ -1385,6 +1380,17 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
>>     if ( !dt_modules_found && !kernel.addr )
>>         blexit(L"No Dom0 kernel image specified.");
>> 
>> +    /*
>> +     * The Dom0 kernel can be loaded from the configuration file or by the
>> +     * device tree through the efi_arch_check_dt_boot function, in this stage
>> +     * verify it.
>> +     */
>> +    if ( kernel.addr &&
> 
> ... me still being a little unhappy with the inconsistent use of the
> union fields so close together: This one is now consistent with the
> one visible further up in context, but ...
> 
>> +         !EFI_ERROR(efi_bs->LocateProtocol(&shim_lock_guid, NULL,> +                                           (void **)&shim_lock)) &&
>> +         (status = shim_lock->Verify(kernel.ptr, kernel.size)) != EFI_SUCCESS )
> 
> ... is now inconsistent with this use. But yeah - read_file() is
> even worse in that sense, except that there the different uses are
> for specific reasons, while here the only requirement is to satisfy
> shim_lock->Verify().
> 
> Please feel free to retain my ack in case you decide to use .ptr in
> all three places.

Hi Jan,

Sure I will do the modification you suggested, I will fix also my silly mistake that
Stefano pointed out.

Just to be sure, I explain what I will do:

In the second patch I will change:

    if ( !dt_modules_found && !kernel.addr )

To 

    if ( !dt_modules_found && !kernel.ptr )


And in this patch I will use:

if ( kernel.ptr &&
         !EFI_ERROR(efi_bs->LocateProtocol(&shim_lock_guid, NULL,
                                           (void **)&shim_lock)) &&
         (status = shim_lock->Verify(kernel.ptr, kernel.size)) != EFI_SUCCESS )
        PrintErrMesg(L"Dom0 kernel image could not be verified", status);

Do you agree on them? Can I retain your ack to this patch doing these changes?

Cheers,
Luca

> 
> Jan
> 

Re: [PATCH v4 3/3] arm/efi: load dom0 modules from DT using UEFI

[Jan Beulich]

On 01.10.2021 16:08, Luca Fancellu wrote:
> 
> 
>> On 1 Oct 2021, at 12:16, Jan Beulich <jbeulich@suse.com> wrote:
>>
>> On 30.09.2021 16:28, Luca Fancellu wrote:
>>> Add support to load Dom0 boot modules from
>>> the device tree using the xen,uefi-binary property.
>>>
>>> Update documentation about that.
>>>
>>> Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>
>>
>> Acked-by: Jan Beulich <jbeulich@suse.com>
>> despite ...
>>
>>> @@ -1385,6 +1380,17 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
>>>     if ( !dt_modules_found && !kernel.addr )
>>>         blexit(L"No Dom0 kernel image specified.");
>>>
>>> +    /*
>>> +     * The Dom0 kernel can be loaded from the configuration file or by the
>>> +     * device tree through the efi_arch_check_dt_boot function, in this stage
>>> +     * verify it.
>>> +     */
>>> +    if ( kernel.addr &&
>>
>> ... me still being a little unhappy with the inconsistent use of the
>> union fields so close together: This one is now consistent with the
>> one visible further up in context, but ...
>>
>>> +         !EFI_ERROR(efi_bs->LocateProtocol(&shim_lock_guid, NULL,> +                                           (void **)&shim_lock)) &&
>>> +         (status = shim_lock->Verify(kernel.ptr, kernel.size)) != EFI_SUCCESS )
>>
>> ... is now inconsistent with this use. But yeah - read_file() is
>> even worse in that sense, except that there the different uses are
>> for specific reasons, while here the only requirement is to satisfy
>> shim_lock->Verify().
>>
>> Please feel free to retain my ack in case you decide to use .ptr in
>> all three places.
> 
> Hi Jan,
> 
> Sure I will do the modification you suggested, I will fix also my silly mistake that
> Stefano pointed out.
> 
> Just to be sure, I explain what I will do:
> 
> In the second patch I will change:
> 
>     if ( !dt_modules_found && !kernel.addr )
> 
> To 
> 
>     if ( !dt_modules_found && !kernel.ptr )
> 
> 
> And in this patch I will use:
> 
> if ( kernel.ptr &&
>          !EFI_ERROR(efi_bs->LocateProtocol(&shim_lock_guid, NULL,
>                                            (void **)&shim_lock)) &&
>          (status = shim_lock->Verify(kernel.ptr, kernel.size)) != EFI_SUCCESS )
>         PrintErrMesg(L"Dom0 kernel image could not be verified", status);
> 
> Do you agree on them?

Yes and ...

> Can I retain your ack to this patch doing these changes?

... as previously said, yes.

Jan