Hi,
On 23/05/2023 08:43, Luca Fancellu wrote:
Add a device tree property in the dom0less domU configuration
to enable the guest to use SVE.
Update documentation.
Signed-off-by: Luca Fancellu <luca.fance...@arm.com>
---
Changes from v6:
- Use ifdef in create_domUs and fail if 'sve' is used on systems
with CONFIG_ARM64_SVE not selected (Bertrand, Julien, Jan)
Changes from v5:
- Stop the domain creation if SVE not supported or SVE VL
errors (Julien, Bertrand)
- now sve_sanitize_vl_param is renamed to sve_domctl_vl_param
and returns a boolean, change the affected code.
- Reworded documentation.
Changes from v4:
- Now it is possible to specify the property "sve" for dom0less
device tree node without any value, that means the platform
supported VL will be used.
Changes from v3:
- Now domainconfig_encode_vl is named sve_encode_vl
Changes from v2:
- xen_domctl_createdomain field name has changed into sve_vl
and its value is the VL/128, use domainconfig_encode_vl
to encode a plain VL in bits.
Changes from v1:
- No changes
Changes from RFC:
- Changed documentation
---
docs/misc/arm/device-tree/booting.txt | 16 +++++++++++++++
xen/arch/arm/domain_build.c | 28 +++++++++++++++++++++++++++
2 files changed, 44 insertions(+)
diff --git a/docs/misc/arm/device-tree/booting.txt
b/docs/misc/arm/device-tree/booting.txt
index 3879340b5e0a..32a0e508c471 100644
--- a/docs/misc/arm/device-tree/booting.txt
+++ b/docs/misc/arm/device-tree/booting.txt
@@ -193,6 +193,22 @@ with the following properties:
Optional. Handle to a xen,cpupool device tree node that identifies the
cpupool where the guest will be started at boot.
+- sve
+
+ Optional. The `sve` property enables Arm SVE usage for the domain and sets
+ the maximum SVE vector length, the option is applicable only to AArch64
Depending on the discussion on the other patch, s/aarch64/arm64/. With
the other comments addressed:
Acked-by: Julien Grall <jgr...@amazon.com>
+ guests.
+ A value equal to 0 disables the feature, this is the default value.
+ Specifying this property with no value, means that the SVE vector length
+ will be set equal to the maximum vector length supported by the platform.
+ Values above 0 explicitly set the maximum SVE vector length for the domain,
+ allowed values are from 128 to maximum 2048, being multiple of 128.
+ Please note that when the user explicitly specifies the value, if that
value
+ is above the hardware supported maximum SVE vector length, the domain
+ creation will fail and the system will stop, the same will occur if the
+ option is provided with a non zero value, but the platform doesn't support
+ SVE.
+
- xen,enhanced
A string property. Possible property values are:
diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index 9202a96d9c28..ba4fe9e165ee 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -4008,6 +4008,34 @@ void __init create_domUs(void)
d_cfg.max_maptrack_frames = val;
}
+ if ( dt_get_property(node, "sve", &val) )
+ {
+#ifdef CONFIG_ARM64_SVE
+ unsigned int sve_vl_bits;
+ bool ret = false;
+
+ if ( !val )
+ {
+ /* Property found with no value, means max HW VL supported */
+ ret = sve_domctl_vl_param(-1, &sve_vl_bits);
+ }
+ else
+ {
+ if ( dt_property_read_u32(node, "sve", &val) )
+ ret = sve_domctl_vl_param(val, &sve_vl_bits);
+ else
+ panic("Error reading 'sve' property");
+ }
+
+ if ( ret )
+ d_cfg.arch.sve_vl = sve_encode_vl(sve_vl_bits);
+ else
+ panic("SVE vector length error\n");
+#else
+ panic("'sve' property found, but CONFIG_ARM64_SVE not selected");
+#endif
+ }
+
/*
* The variable max_init_domid is initialized with zero, so here it's
* very important to use the pre-increment operator to call
--
Julien Grall
