[Xen-devel] [PATCH v9 11/25] x86: refactor psr: L3 CAT: set value: implement cos finding flow.

[Yi Sun <yi.y.sun@xxxxxxxxxxxxxxx>]

Continue from patch:
'x86: refactor psr: L3 CAT: set value: assemble features value array'

We can try to find if there is a COS ID on which all features' COS registers
values are same as the array assembled before.

Signed-off-by: Yi Sun <yi.y.sun@xxxxxxxxxxxxxxx>
---
v9:
    - modify comments of 'compare_val' to be same as current implementation.
      (suggested by Wei Liu)
    - fix indentation issue.
      (suggested by Wei Liu)
    - rename 'l3_cat_compare_val' to 'cat_compare_val' to cover all L3/L2 CAT
      features.
      (suggested by Roger Pau)
    - remove parameter 'found' from 'cat_compare_val' and modify the return
      values to let caller know if the id is found or not.
      (suggested by Roger Pau)
    - replace feature list handling to feature array handling.
      (suggested by Roger Pau)
    - replace 'get_cos_num' to 'feat->cos_num'.
      (suggested by Jan Beulich)
    - directly use 'cos_reg_val[0]' as default value.
      (suggested by Jan Beulich)
    - modify patch title to indicate 'L3 CAT'.
      (suggested by Jan Beulich)
    - changes about 'uint64_t' to 'uint32_t'.
      (suggested by Jan Beulich)
v5:
    - modify commit message to provide exact patch name to continue from.
      (suggested by Jan Beulich)
    - remove 'get_cos_max_from_type' because it can be replaced by
      'get_cos_max'.
    - move type check out from callback functions to caller.
      (suggested by Jan Beulich)
    - modify variables names to make them better, e.g. 'feat_tmp' to 'feat'.
      (suggested by Jan Beulich)
    - modify comments according to changes of codes.
      (suggested by Jan Beulich)
v4:
    - create this patch to make codes easier to understand.
      (suggested by Jan Beulich)
---
 xen/arch/x86/psr.c | 95 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 95 insertions(+)

diff --git a/xen/arch/x86/psr.c b/xen/arch/x86/psr.c
index 18aad8e..f2c2614 100644
--- a/xen/arch/x86/psr.c
+++ b/xen/arch/x86/psr.c
@@ -123,6 +123,19 @@ struct feat_node {
                            const struct feat_node *feat,
                            enum cbm_type type,
                            uint32_t new_val);
+
+        /*
+         * compare_val is used in set value process to compare if the
+         * input value array can match all the features' COS registers values
+         * according to input cos id.
+         *
+         * The return value is:
+         * 1 - find the entry in value array.
+         * 0 - not find the entry in value array.
+         * negative - error.
+         */
+        int (*compare_val)(const uint32_t val[], const struct feat_node *feat,
+                           unsigned int cos);
     } ops;
 
     /* Encapsulate feature specific HW info here. */
@@ -352,6 +365,33 @@ static int cat_set_new_val(uint32_t val[],
     return 0;
 }
 
+static int cat_compare_val(const uint32_t val[],
+                           const struct feat_node *feat,
+                           unsigned int cos)
+{
+    /*
+     * Different features' cos_max are different. If cos id of the feature
+     * being set exceeds other feature's cos_max, the val of other feature
+     * must be default value. HW supports such case.
+     */
+    if ( cos > feat->info.cat_info.cos_max )
+    {
+        /* cos_reg_val[0] is the default value. */
+        if ( val[0] != feat->cos_reg_val[0] )
+            return -EINVAL;
+
+        /* Find */
+        return 1;
+    }
+
+    if ( val[0] == feat->cos_reg_val[cos] )
+        /* Find */
+        return 1;
+
+    /* Not find */
+    return 0;
+}
+
 /* L3 CAT ops */
 static const struct feat_ops l3_cat_ops = {
     .get_cos_max = cat_get_cos_max,
@@ -359,6 +399,7 @@ static const struct feat_ops l3_cat_ops = {
     .get_val = cat_get_val,
     .get_old_val = cat_get_old_val,
     .set_new_val = cat_set_new_val,
+    .compare_val = cat_compare_val,
 };
 
 static void __init parse_psr_bool(char *s, char *value, char *feature,
@@ -752,7 +793,61 @@ static int find_cos(const uint32_t val[], uint32_t 
array_len,
                     enum psr_feat_type feat_type,
                     const struct psr_socket_info *info)
 {
+    unsigned int cos, i;
+    const unsigned int *ref = info->cos_ref;
+    const struct feat_node *feat;
+    const uint32_t *val_array = val;
+    int find = 0;
+    unsigned int cos_max;
+
     ASSERT(spin_is_locked((spinlock_t *)(&info->ref_lock)));
+
+    /* cos_max is the one of the feature which is being set. */
+    feat = info->features[feat_type];
+    if ( !feat )
+        return -ENOENT;
+
+    cos_max = feat->ops.get_cos_max(feat);
+
+    for ( cos = 0; cos <= cos_max; cos++ )
+    {
+        if ( cos && !ref[cos] )
+            continue;
+
+        /*
+         * If fail to find cos in below loop, need find whole feature array
+         * again from beginning.
+         */
+        val_array = val;
+        for ( i = 0; i < PSR_SOCKET_MAX_FEAT; i++ )
+        {
+            if ( !info->features[i] )
+                continue;
+
+            feat = info->features[i];
+            /*
+             * Compare value according to feature array order.
+             * We must follow this order because value array is assembled
+             * as this order.
+             */
+            find = feat->ops.compare_val(val_array, feat, cos);
+            if ( find < 0 )
+                return find;
+
+            /* If fail to match, go to next cos to compare. */
+            if ( !find )
+                break;
+
+            val_array += feat->cos_num;
+            if ( val_array - val > array_len )
+                return -ENOSPC;
+        }
+
+        /* For this COS ID all entries in the values array did match. Use it. 
*/
+        if ( find )
+            return cos;
+    }
+
     return -ENOENT;
 }
 
-- 
1.9.1


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