[Xen-devel] [PATCH v15 10/23] 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>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
v13:
    - remove unnecessary blank line.
      (suggested by Jan Beulich)
v12:
    - use 'ARRAY_SIZE' to calculate array boundary.
      (suggested by Jan Beulich)
    - move same type variables declaration to one line.
      (suggested by Jan Beulich)
    - use 'ASSERT_UNREACHABLE()' to record bug and return error code if feat
      exists but props does not exist.
      (suggested by Jan Beulich)
    - move 'i' definition into the loop to limit its scope.
      (suggested by Jan Beulich)
v11:
    - move 'compare_val' implementation from CDP patch to this.
      (suggested by Jan Beulich)
    - remove 'rc' in 'compare_val' to make codes clearer.
      (suggested by Jan Beulich)
    - changes about 'feat_props'.
      (suggested by Jan Beulich)
    - fix bug.
      (suggested by Jan Beulich)
    - remove unnecessary variable initialization.
      (suggested by Jan Beulich)
    - remove unnecessary comment.
      (suggested by Jan Beulich)
    - adjust array check place prior to using the array.
      (suggested by Jan Beulich)
    - add comment.
v10:
    - remove 'compare_val' hook and its CAT implementation. Make its
      functionality be generic in 'find_cos' flow.
      (suggested by Jan Beulich)
    - changes related to 'props'.
      (suggested by Jan Beulich)
    - rename 'val_array' to 'val_ptr'.
      (suggested by Jan Beulich)
    - rename 'find' to 'found'.
      (suggested by Jan Beulich)
    - move some variables declaration and initialization into loop.
      (suggested by Jan Beulich)
    - adjust codes positions.
      (suggested by Jan Beulich)
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 | 100 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 100 insertions(+)

diff --git a/xen/arch/x86/psr.c b/xen/arch/x86/psr.c
index f7ba892..7bfeafb 100644
--- a/xen/arch/x86/psr.c
+++ b/xen/arch/x86/psr.c
@@ -753,10 +753,110 @@ static int insert_val_into_array(uint32_t val[],
     return -EINVAL;
 }
 
+static int compare_val(const uint32_t val[],
+                       const struct feat_node *feat,
+                       const struct feat_props *props,
+                       unsigned int cos)
+{
+    unsigned int i;
+
+    for ( i = 0; i < props->cos_num; i++ )
+    {
+        uint32_t feat_val;
+
+        /* If cos is bigger than cos_max, we need compare default value. */
+        if ( cos > feat->cos_max )
+        {
+            /*
+             * COS ID 0 always stores the default value.
+             * For CDP:
+             * - DATA default value stored in cos_reg_val[0];
+             * - CODE default value stored in cos_reg_val[1].
+             */
+            feat_val = feat->cos_reg_val[i];
+
+            /*
+             * If cos is bigger than feature's cos_max, the val should be
+             * default value. Otherwise, it fails to find a COS ID. So we
+             * have to exit find flow.
+             */
+            if ( val[i] != feat_val )
+                return -EINVAL;
+        }
+        else
+        {
+            feat_val = feat->cos_reg_val[cos * props->cos_num + i];
+            if ( val[i] != feat_val )
+                return 0;
+        }
+    }
+
+    return 1;
+}
+
 static int find_cos(const uint32_t val[], unsigned int array_len,
                     enum psr_feat_type feat_type,
                     const struct psr_socket_info *info)
 {
+    unsigned int cos, cos_max;
+    const unsigned int *ref = info->cos_ref;
+    const struct feat_node *feat;
+
+    /* cos_max is the one of the feature which is being set. */
+    feat = info->features[feat_type];
+    if ( !feat )
+        return -ENOENT;
+
+    cos_max = feat->cos_max;
+
+    for ( cos = 0; cos <= cos_max; cos++ )
+    {
+        const uint32_t *val_ptr = val;
+        unsigned int len = array_len, i;
+        int rc = 0;
+
+        if ( cos && !ref[cos] )
+            continue;
+
+        for ( i = 0; i < ARRAY_SIZE(info->features); i++ )
+        {
+            const struct feat_props *props = feat_props[i];
+
+            feat = info->features[i];
+            if ( !feat )
+                continue;
+
+            if ( !props )
+            {
+                ASSERT_UNREACHABLE();
+                return -ENOENT;
+            }
+
+            if ( len < props->cos_num )
+                return -ENOSPC;
+
+            /*
+             * Compare value according to feature array order.
+             * We must follow this order because value array is assembled
+             * as this order.
+             */
+            rc = compare_val(val_ptr, feat, props, cos);
+            if ( rc < 0 )
+                return rc;
+
+            /* If fail to match, go to next cos to compare. */
+            if ( !rc )
+                break;
+
+            len -= props->cos_num;
+            val_ptr += props->cos_num;
+        }
+
+        /* For this COS ID all entries in the values array do match. Use it. */
+        if ( rc )
+            return cos;
+    }
+
     return -ENOENT;
 }
 
-- 
1.9.1


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