diff mbox series

[v2,2/9] dt-bindings: x86: Add a binding for x86 wakeup mailbox

Message ID 20240823232327.2408869-3-yunhong.jiang@linux.intel.com
State New
Headers show
Series x86/hyperv: Support wakeup mailbox for VTL2 TDX guest | expand

Commit Message

Yunhong Jiang Aug. 23, 2024, 11:23 p.m. UTC 
Add the binding to use mailbox wakeup mechanism to bringup APs.

Signed-off-by: Yunhong Jiang <yunhong.jiang@linux.intel.com>
---
 .../devicetree/bindings/x86/wakeup.yaml       | 64 +++++++++++++++++++
 1 file changed, 64 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/x86/wakeup.yaml

Comments

Krzysztof Kozlowski Aug. 25, 2024, 7:10 a.m. UTC | #1 
On Fri, Aug 23, 2024 at 04:23:20PM -0700, Yunhong Jiang wrote:
> Add the binding to use mailbox wakeup mechanism to bringup APs.
> 
> Signed-off-by: Yunhong Jiang <yunhong.jiang@linux.intel.com>
> ---
>  .../devicetree/bindings/x86/wakeup.yaml       | 64 +++++++++++++++++++
>  1 file changed, 64 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/x86/wakeup.yaml
> 
> diff --git a/Documentation/devicetree/bindings/x86/wakeup.yaml b/Documentation/devicetree/bindings/x86/wakeup.yaml
> new file mode 100644
> index 000000000000..cb84e2756bca
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/x86/wakeup.yaml
> @@ -0,0 +1,64 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +# Copyright (C) 2024 Intel Corporation
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/x86/wakeup.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: x86 mailbox wakeup
> +maintainers:
> +  - Yunhong Jiang <yunhong.jiang@linux.intel.com>
> +
> +description: |
> +  The x86 mailbox wakeup mechanism defines a mechanism to let the bootstrap
> +  processor (BSP) to wake up application processors (APs) through a wakeup
> +  mailbox.
> +
> +  The "wakeup-mailbox-addr" property specifies the wakeup mailbox address. The
> +  wakeup mailbox is a 4K-aligned 4K-size memory block allocated in the reserved
> +  memory.
> +
> +  The wakeup mailbox structure is defined as follows.
> +
> +    uint16_t command;
> +    uint16_t reserved;
> +    uint32_t apic_id;
> +    uint64_t wakeup_vector;
> +    uint8_t  reservedForOs[2032];
> +
> +  The memory after reservedForOs field is reserved and OS should not touch it.
> +
> +  To wakes up a AP, the BSP prepares the wakeup routine, fills the wakeup
> +  routine's address into the wakeup_vector field, fill the apic_id field with
> +  the target AP's APIC_ID, and write 1 to the command field. After receiving the
> +  wakeup command, the target AP will jump to the wakeup routine.
> +
> +  For each AP, the mailbox can be used only once for the wakeup command. After
> +  the AP jumps to the wakeup routine, the mailbox will no longer be checked by
> +  this AP.
> +
> +  The wakeup mailbox structure and the wakeup process is the same as
> +  the Multiprocessor Wakeup Mailbox Structure defined in ACPI spec version 6.5,
> +  section 5.2.12.19 [1].
> +
> +  References:
> +
> +  [1] https://uefi.org/specs/ACPI/6.5/05_ACPI_Software_Programming_Model.html
> +
> +select: false

This schema is still a no-op because of this false.

What is the point of defining one property if it is not placed anywhere?
Every device node can have it? Seems wrong...

You need to come with proper schema. Lack of an example is another thing
- this cannot be even validated by the tools. 

Best regards,
Krzysztof
Yunhong Jiang Aug. 27, 2024, 8:45 p.m. UTC | #2 
On Sun, Aug 25, 2024 at 09:10:01AM +0200, Krzysztof Kozlowski wrote:
> On Fri, Aug 23, 2024 at 04:23:20PM -0700, Yunhong Jiang wrote:
> > Add the binding to use mailbox wakeup mechanism to bringup APs.
> > 
> > Signed-off-by: Yunhong Jiang <yunhong.jiang@linux.intel.com>
> > ---
> >  .../devicetree/bindings/x86/wakeup.yaml       | 64 +++++++++++++++++++
> >  1 file changed, 64 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/x86/wakeup.yaml
> > 
> > diff --git a/Documentation/devicetree/bindings/x86/wakeup.yaml b/Documentation/devicetree/bindings/x86/wakeup.yaml
> > new file mode 100644
> > index 000000000000..cb84e2756bca
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/x86/wakeup.yaml
> > @@ -0,0 +1,64 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +# Copyright (C) 2024 Intel Corporation
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/x86/wakeup.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: x86 mailbox wakeup
> > +maintainers:
> > +  - Yunhong Jiang <yunhong.jiang@linux.intel.com>
> > +
> > +description: |
> > +  The x86 mailbox wakeup mechanism defines a mechanism to let the bootstrap
> > +  processor (BSP) to wake up application processors (APs) through a wakeup
> > +  mailbox.
> > +
> > +  The "wakeup-mailbox-addr" property specifies the wakeup mailbox address. The
> > +  wakeup mailbox is a 4K-aligned 4K-size memory block allocated in the reserved
> > +  memory.
> > +
> > +  The wakeup mailbox structure is defined as follows.
> > +
> > +    uint16_t command;
> > +    uint16_t reserved;
> > +    uint32_t apic_id;
> > +    uint64_t wakeup_vector;
> > +    uint8_t  reservedForOs[2032];
> > +
> > +  The memory after reservedForOs field is reserved and OS should not touch it.
> > +
> > +  To wakes up a AP, the BSP prepares the wakeup routine, fills the wakeup
> > +  routine's address into the wakeup_vector field, fill the apic_id field with
> > +  the target AP's APIC_ID, and write 1 to the command field. After receiving the
> > +  wakeup command, the target AP will jump to the wakeup routine.
> > +
> > +  For each AP, the mailbox can be used only once for the wakeup command. After
> > +  the AP jumps to the wakeup routine, the mailbox will no longer be checked by
> > +  this AP.
> > +
> > +  The wakeup mailbox structure and the wakeup process is the same as
> > +  the Multiprocessor Wakeup Mailbox Structure defined in ACPI spec version 6.5,
> > +  section 5.2.12.19 [1].
> > +
> > +  References:
> > +
> > +  [1] https://uefi.org/specs/ACPI/6.5/05_ACPI_Software_Programming_Model.html
> > +
> > +select: false
> 
> This schema is still a no-op because of this false.
> 
> What is the point of defining one property if it is not placed anywhere?
> Every device node can have it? Seems wrong...
> 
> You need to come with proper schema. Lack of an example is another thing
> - this cannot be even validated by the tools. 
> 
> Best regards,
> Krzysztof

Thank you for the feedback. Will update the schema file on next round
submission.

Thanks
--jyh

>
Yunhong Jiang Sept. 10, 2024, 6:13 a.m. UTC | #3 
On Tue, Aug 27, 2024 at 01:45:49PM -0700, Yunhong Jiang wrote:
> On Sun, Aug 25, 2024 at 09:10:01AM +0200, Krzysztof Kozlowski wrote:
> > On Fri, Aug 23, 2024 at 04:23:20PM -0700, Yunhong Jiang wrote:
> > > Add the binding to use mailbox wakeup mechanism to bringup APs.
> > > 
> > > Signed-off-by: Yunhong Jiang <yunhong.jiang@linux.intel.com>
> > > ---
> > >  .../devicetree/bindings/x86/wakeup.yaml       | 64 +++++++++++++++++++
> > >  1 file changed, 64 insertions(+)
> > >  create mode 100644 Documentation/devicetree/bindings/x86/wakeup.yaml
> > > 
> > > diff --git a/Documentation/devicetree/bindings/x86/wakeup.yaml b/Documentation/devicetree/bindings/x86/wakeup.yaml
> > > new file mode 100644
> > > index 000000000000..cb84e2756bca
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/x86/wakeup.yaml
> > > @@ -0,0 +1,64 @@
> > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > > +# Copyright (C) 2024 Intel Corporation
> > > +%YAML 1.2
> > > +---
> > > +$id: http://devicetree.org/schemas/x86/wakeup.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: x86 mailbox wakeup
> > > +maintainers:
> > > +  - Yunhong Jiang <yunhong.jiang@linux.intel.com>
> > > +
> > > +description: |
> > > +  The x86 mailbox wakeup mechanism defines a mechanism to let the bootstrap
> > > +  processor (BSP) to wake up application processors (APs) through a wakeup
> > > +  mailbox.
> > > +
> > > +  The "wakeup-mailbox-addr" property specifies the wakeup mailbox address. The
> > > +  wakeup mailbox is a 4K-aligned 4K-size memory block allocated in the reserved
> > > +  memory.
> > > +
> > > +  The wakeup mailbox structure is defined as follows.
> > > +
> > > +    uint16_t command;
> > > +    uint16_t reserved;
> > > +    uint32_t apic_id;
> > > +    uint64_t wakeup_vector;
> > > +    uint8_t  reservedForOs[2032];
> > > +
> > > +  The memory after reservedForOs field is reserved and OS should not touch it.
> > > +
> > > +  To wakes up a AP, the BSP prepares the wakeup routine, fills the wakeup
> > > +  routine's address into the wakeup_vector field, fill the apic_id field with
> > > +  the target AP's APIC_ID, and write 1 to the command field. After receiving the
> > > +  wakeup command, the target AP will jump to the wakeup routine.
> > > +
> > > +  For each AP, the mailbox can be used only once for the wakeup command. After
> > > +  the AP jumps to the wakeup routine, the mailbox will no longer be checked by
> > > +  this AP.
> > > +
> > > +  The wakeup mailbox structure and the wakeup process is the same as
> > > +  the Multiprocessor Wakeup Mailbox Structure defined in ACPI spec version 6.5,
> > > +  section 5.2.12.19 [1].
> > > +
> > > +  References:
> > > +
> > > +  [1] https://uefi.org/specs/ACPI/6.5/05_ACPI_Software_Programming_Model.html
> > > +
> > > +select: false
> > 
> > This schema is still a no-op because of this false.
> > 
> > What is the point of defining one property if it is not placed anywhere?
> > Every device node can have it? Seems wrong...
> > 
> > You need to come with proper schema. Lack of an example is another thing
> > - this cannot be even validated by the tools. 
> > 
> > Best regards,
> > Krzysztof

Hi, Krzysztof, I'm working to address your comments and have some questions.
Hope to get help/guide from your side.

For the select, the writing-schema.rst describes it as "A json-schema used to
match nodes for applying the schema" but I'm a bit confused. In my case, should
it be "cpus" node? Is there any code/tools that uses this property, so that I
can have a better understanding?

For your "validated by the tools", can you please share the tools you used to
validate the schema? I used "make dt_binding_check" per the
submitting-patches.rst but I think your comments is about another tool.

Sorry for the bothering. I read the DT spec and the
Documentation/devicetree/bindings documents and still not sure.

Than you
--jyh

> 
> Thank you for the feedback. Will update the schema file on next round
> submission.
> 
> Thanks
> --jyh
> 
> > 
>
diff mbox series

Patch

diff --git a/Documentation/devicetree/bindings/x86/wakeup.yaml b/Documentation/devicetree/bindings/x86/wakeup.yaml
new file mode 100644
index 000000000000..cb84e2756bca
--- /dev/null
+++ b/Documentation/devicetree/bindings/x86/wakeup.yaml
@@ -0,0 +1,64 @@ 
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+# Copyright (C) 2024 Intel Corporation
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/x86/wakeup.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: x86 mailbox wakeup
+maintainers:
+  - Yunhong Jiang <yunhong.jiang@linux.intel.com>
+
+description: |
+  The x86 mailbox wakeup mechanism defines a mechanism to let the bootstrap
+  processor (BSP) to wake up application processors (APs) through a wakeup
+  mailbox.
+
+  The "wakeup-mailbox-addr" property specifies the wakeup mailbox address. The
+  wakeup mailbox is a 4K-aligned 4K-size memory block allocated in the reserved
+  memory.
+
+  The wakeup mailbox structure is defined as follows.
+
+    uint16_t command;
+    uint16_t reserved;
+    uint32_t apic_id;
+    uint64_t wakeup_vector;
+    uint8_t  reservedForOs[2032];
+
+  The memory after reservedForOs field is reserved and OS should not touch it.
+
+  To wakes up a AP, the BSP prepares the wakeup routine, fills the wakeup
+  routine's address into the wakeup_vector field, fill the apic_id field with
+  the target AP's APIC_ID, and write 1 to the command field. After receiving the
+  wakeup command, the target AP will jump to the wakeup routine.
+
+  For each AP, the mailbox can be used only once for the wakeup command. After
+  the AP jumps to the wakeup routine, the mailbox will no longer be checked by
+  this AP.
+
+  The wakeup mailbox structure and the wakeup process is the same as
+  the Multiprocessor Wakeup Mailbox Structure defined in ACPI spec version 6.5,
+  section 5.2.12.19 [1].
+
+  References:
+
+  [1] https://uefi.org/specs/ACPI/6.5/05_ACPI_Software_Programming_Model.html
+
+select: false
+
+properties:
+  wakeup-mailbox-addr:
+    $ref: /schemas/types.yaml#/definitions/uint64
+    description: |
+      The physical address of the wakeup mailbox data structure. The address
+      must be 4K bytes aligned 4k-size memory and it should be in the reserved
+      memory.
+
+      This requires the "enable-method" property in the cpus node is set to
+      "acpi-wakeup-mailbox".
+
+required:
+  - wakeup-mailbox-addr
+
+additionalProperties: false