From b687773b5046beea17064041e543f91b063b50b6 Mon Sep 17 00:00:00 2001
From: Michal Orzel
Date: Wed, 7 Sep 2022 13:08:52 +0200
Subject: Add support for Xen boot-time cpupools

Introduce support for creating boot-time cpupools in the device tree and
assigning them to dom0less domUs. Add the following options:
 - CPUPOOL[number]="cpu@1,...,cpu@N scheduler" to specify the
   list of cpus' node names and the scheduler to be used to create cpupool
 - NUM_CPUPOOLS to specify the number of cpupools to create
 - DOMU_CPUPOOL[number]="<id>" to specify the id of the cpupool to
   assign to domU

Example usage:
CPUPOOL[0]="cpu@1,cpu@2 null"
DOMU_CPUPOOL[0]=0
NUM_CPUPOOLS=1

The above example will create a boot-time cpupool (id=0) with 2 cpus:
cpu@1, cpu@2 and the null scheduler. It will assign the cpupool with
id=0 to domU0.

Signed-off-by: Michal Orzel <michal.orzel@amd.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Signed-off-by: Stefano Stabellini <stefano.stabellini@amd.com>
---
 README.md                | 10 ++++++
 scripts/uboot-script-gen | 79 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 89 insertions(+)

diff --git a/README.md b/README.md
index bd9dac9..0418183 100644
--- a/README.md
+++ b/README.md
@@ -181,6 +181,9 @@ Where:
   present. If set to 1, the VM can use PV drivers. Older Linux kernels
   might break.
 
+- DOMU_CPUPOOL[number] specifies the id of the cpupool (created using
+  CPUPOOL[number] option, where number == id) that will be assigned to domU.
+
 - LINUX is optional but specifies the Linux kernel for when Xen is NOT
   used.  To enable this set any LINUX\_\* variables and do NOT set the
   XEN variable.
@@ -223,6 +226,13 @@ Where:
   include the public key in.  This can only be used with
   FIT_ENC_KEY_DIR.  See the -u option below for more information.
 
+- CPUPOOL[number]="cpu@1,...,cpu@N scheduler"
+  specifies the list of cpus' node names (separated by commas) and the scheduler
+  to be used to create boot-time cpupool. If no scheduler is set, the Xen
+  default one will be used.
+
+- NUM_CPUPOOLS specifies the number of boot-time cpupools to create.
+
 Then you can invoke uboot-script-gen as follows:
 
 ```
diff --git a/scripts/uboot-script-gen b/scripts/uboot-script-gen
index 18c0ce1..1f8ab5f 100755
--- a/scripts/uboot-script-gen
+++ b/scripts/uboot-script-gen
@@ -176,6 +176,80 @@ function add_device_tree_static_mem()
     dt_set "$path" "xen,static-mem" "hex" "${cells[*]}"
 }
 
+function add_device_tree_cpupools()
+{
+    local cpu
+    local cpus
+    local scheduler
+    local cpu_list
+    local phandle
+    local cpu_phandles
+    local i
+    local j
+
+    i=0
+    while test $i -lt $NUM_CPUPOOLS
+    do
+        cpus=$(echo ${CPUPOOL[$i]} | awk '{print $1}')
+        scheduler=$(echo ${CPUPOOL[$i]} | awk '{print $NF}')
+        cpu_phandles=
+
+        for cpu in ${cpus//,/ }
+        do
+            cpu="/cpus/$cpu"
+
+            # check if cpu exists
+            if ! fdtget "${DEVICE_TREE}" "$cpu" "reg" &> /dev/null
+            then
+                echo "$cpu does not exist"
+                cleanup_and_return_err
+            fi
+
+            # check if cpu is already assigned
+            if [[ "$cpu_list" == *"$cpu"* ]]
+            then
+                echo "$cpu already assigned to another cpupool"
+                cleanup_and_return_err
+            fi
+
+            # set phandle for a cpu if there is none
+            if ! phandle=$(fdtget -t x "${DEVICE_TREE}" "$cpu" "phandle" 2> /dev/null)
+            then
+                get_next_phandle phandle
+            fi
+
+            dt_set "$cpu" "phandle" "hex" "$phandle"
+            cpu_phandles="$cpu_phandles $phandle"
+            cpu_list="$cpu_list $cpu"
+        done
+
+        # create cpupool node
+        get_next_phandle phandle
+        dt_mknode "/chosen" "cpupool_$i"
+        dt_set "/chosen/cpupool_$i" "phandle" "hex" "$phandle"
+        dt_set "/chosen/cpupool_$i" "compatible" "str" "xen,cpupool"
+        dt_set "/chosen/cpupool_$i" "cpupool-cpus" "hex" "$cpu_phandles"
+
+        if test "$scheduler" != "$cpus"
+        then
+            dt_set "/chosen/cpupool_$i" "cpupool-sched" "str" "$scheduler"
+        fi
+
+        j=0
+        while test $j -lt $NUM_DOMUS
+        do
+            # assign cpupool to domU
+            if test "${DOMU_CPUPOOL[$j]}" -eq "$i"
+            then
+                dt_set "/chosen/domU$j" "domain-cpupool" "hex" "$phandle"
+            fi
+            j=$(( $j + 1 ))
+        done
+
+        i=$(( $i + 1 ))
+    done
+}
+
 function xen_device_tree_editing()
 {
     dt_set "/chosen" "#address-cells" "hex" "0x2"
@@ -252,6 +326,11 @@ function xen_device_tree_editing()
         fi
         i=$(( $i + 1 ))
     done
+
+    if test "$NUM_CPUPOOLS" && test "$NUM_CPUPOOLS" -gt 0
+    then
+        add_device_tree_cpupools
+    fi
 }
 
 function linux_device_tree_editing()
-- 
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