[Xen-devel] [PATCH v7 09/24] x86: refactor psr: set value: assemble features value array.

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

Only can one COS ID be used by one domain at one time. That means all enabled
features' COS registers at this COS ID are valid for this domain at that time.

When user updates a feature's value, we need make sure all other features'
values are not affected. So, we firstly need assemble an array which contains
all features current values and replace the setting feature's value in array
to new value.

Then, we can try to find if there is a COS ID on which all features' COS
registers values are same as the array. If we can find, we just use this COS
ID. If fail to find, we need allocate a new COS ID.

This patch implements value array assembling flow.

Signed-off-by: Yi Sun <yi.y.sun@xxxxxxxxxxxxxxx>
---
 xen/arch/x86/psr.c | 151 +++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 146 insertions(+), 5 deletions(-)

diff --git a/xen/arch/x86/psr.c b/xen/arch/x86/psr.c
index 7d6d3fe..66792e9 100644
--- a/xen/arch/x86/psr.c
+++ b/xen/arch/x86/psr.c
@@ -119,6 +119,32 @@ struct feat_ops {
     /* get_val is used to get feature COS register value. */
     bool (*get_val)(const struct feat_node *feat, unsigned int cos,
                     enum cbm_type type, uint64_t *val);
+    /*
+     * get_cos_num is used to get the COS registers amount used by the
+     * feature for one setting, e.g. CDP uses 2 COSs but CAT uses 1.
+     */
+    unsigned int (*get_cos_num)(const struct feat_node *feat);
+    /*
+     * get_old_val and set_new_val are a pair of functions called in order.
+     * The caller will traverse all features in the list and call both
+     * functions for every feature to do below two things:
+     * 1. get old_cos register value of all supported features and
+     * 2. set the new value for the feature.
+     *
+     * All the values are set into value array according the traversal order,
+     * meaning the same order of feature list members.
+     *
+     * The return value meaning:
+     * 0 - success.
+     * negative - error.
+     */
+    int (*get_old_val)(uint64_t val[],
+                       const struct feat_node *feat,
+                       unsigned int old_cos);
+    int (*set_new_val)(uint64_t val[],
+                       const struct feat_node *feat,
+                       enum cbm_type type,
+                       uint64_t m);
 };
 
 /*
@@ -204,6 +230,29 @@ static enum psr_feat_type psr_cbm_type_to_feat_type(enum 
cbm_type type)
     return feat_type;
 }
 
+static bool psr_check_cbm(unsigned int cbm_len, uint64_t cbm)
+{
+    unsigned int first_bit, zero_bit;
+
+    /* Set bits should only in the range of [0, cbm_len). */
+    if ( cbm & (~0ull << cbm_len) )
+        return false;
+
+    /* At least one bit need to be set. */
+    if ( cbm == 0 )
+        return false;
+
+    first_bit = find_first_bit(&cbm, cbm_len);
+    zero_bit = find_next_zero_bit(&cbm, cbm_len, first_bit);
+
+    /* Set bits should be contiguous. */
+    if ( zero_bit < cbm_len &&
+         find_next_bit(&cbm, cbm_len, zero_bit) < cbm_len )
+        return false;
+
+    return true;
+}
+
 /* L3 CAT functions implementation. */
 static void l3_cat_init_feature(struct cpuid_leaf regs,
                                 struct feat_node *feat,
@@ -272,10 +321,45 @@ static bool l3_cat_get_val(const struct feat_node *feat, 
unsigned int cos,
     return true;
 }
 
+static unsigned int l3_cat_get_cos_num(const struct feat_node *feat)
+{
+    return 1;
+}
+
+static int l3_cat_get_old_val(uint64_t val[],
+                              const struct feat_node *feat,
+                              unsigned int old_cos)
+{
+    if ( old_cos > feat->info.l3_cat_info.cos_max )
+        /* Use default value. */
+        old_cos = 0;
+
+    /* CAT */
+    val[0] =  feat->cos_reg_val[old_cos];
+
+    return 0;
+}
+
+static int l3_cat_set_new_val(uint64_t val[],
+                              const struct feat_node *feat,
+                              enum cbm_type type,
+                              uint64_t m)
+{
+    if ( !psr_check_cbm(feat->info.l3_cat_info.cbm_len, m) )
+        return -EINVAL;
+
+    val[0] = m;
+
+    return 0;
+}
+
 static const struct feat_ops l3_cat_ops = {
     .get_cos_max = l3_cat_get_cos_max,
     .get_feat_info = l3_cat_get_feat_info,
     .get_val = l3_cat_get_val,
+    .get_cos_num = l3_cat_get_cos_num,
+    .get_old_val = l3_cat_get_old_val,
+    .set_new_val = l3_cat_set_new_val,
 };
 
 static void __init parse_psr_bool(char *s, char *value, char *feature,
@@ -546,15 +630,42 @@ int psr_get_val(struct domain *d, unsigned int socket,
 /* Set value functions */
 static unsigned int get_cos_num(const struct psr_socket_info *info)
 {
-    return 0;
+    const struct feat_node *feat_tmp;
+    unsigned int num = 0;
+
+    /* Get all features total amount. */
+    list_for_each_entry(feat_tmp, &info->feat_list, list)
+        num += feat_tmp->ops.get_cos_num(feat_tmp);
+
+    return num;
 }
 
-static int assemble_val_array(uint64_t *val,
+static int combine_val_array(uint64_t *val,
                               uint32_t array_len,
                               const struct psr_socket_info *info,
                               unsigned int old_cos)
 {
-    return -EINVAL;
+    const struct feat_node *feat;
+    int ret;
+    uint64_t *val_tmp = val;
+
+    if ( !val )
+        return -EINVAL;
+
+    /* Get all features current values according to old_cos. */
+    list_for_each_entry(feat, &info->feat_list, list)
+    {
+        /* value getting order is same as feature list */
+        ret = feat->ops.get_old_val(val_tmp, feat, old_cos);
+        if ( ret )
+            return ret;
+
+        val_tmp += feat->ops.get_cos_num(feat);
+        if ( val_tmp - val > array_len)
+            return -ENOSPC;
+    }
+
+    return 0;
 }
 
 static int set_new_val_to_array(uint64_t *val,
@@ -564,7 +675,37 @@ static int set_new_val_to_array(uint64_t *val,
                                 enum cbm_type type,
                                 uint64_t m)
 {
-    return -EINVAL;
+    const struct feat_node *feat;
+    int ret;
+    uint64_t *val_tmp = val;
+
+    /* Set new value into array according to feature's position in array. */
+    list_for_each_entry(feat, &info->feat_list, list)
+    {
+        if ( feat->feature != feat_type )
+        {
+            val_tmp += feat->ops.get_cos_num(feat);
+            if ( val_tmp - val > array_len)
+                return -ENOSPC;
+
+            continue;
+        }
+
+        /*
+         * Value setting position is same as feature list.
+         * Different features may have different setting behaviors, e.g. CDP
+         * has two values (DATA/CODE) which need us to save input value to
+         * different position in the array according to type, so we have to
+         * maintain a callback function.
+         */
+        ret = feat->ops.set_new_val(val_tmp, feat, type, m);
+        if ( ret )
+            return ret;
+        else
+            break;
+    }
+
+    return 0;
 }
 
 static int find_cos(const uint64_t *val, uint32_t array_len,
@@ -635,7 +776,7 @@ int psr_set_val(struct domain *d, unsigned int socket,
     if ( !val_array )
         return -ENOMEM;
 
-    if ( (ret = assemble_val_array(val_array, array_len, info, old_cos)) != 0 )
+    if ( (ret = combine_val_array(val_array, array_len, info, old_cos)) != 0 )
     {
         xfree(val_array);
         return ret;
-- 
1.9.1


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