[Xen-devel] [PATCH v13 09/23] x86: refactor psr: L3 CAT: 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 gather 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 pick a new COS ID.

This patch implements value array assembling flow.

Signed-off-by: Yi Sun <yi.y.sun@xxxxxxxxxxxxxxx>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
v13:
    - remove an unnecessary blank line.
      (suggested by Jan Beulich)
    - add a new function 'skip_prior_features()' to skip value array according
      to feature type. This function will be used in later patches too.
      (suggested by Jan Beulich)
v12:
    - use 'ARRAY_SIZE' to calculate array boundary.
      (suggested by Jan Beulich)
    - use 'ASSERT_UNREACHABLE()' to record bug and return error code if feat
      exist but props does not exist.
      (suggested by Jan Beulich)
    - return 0 only when value is set in 'insert_val_into_array'.
      (suggested by Jan Beulich)
v11:
    - changes about 'feat_props'.
      (suggested by Jan Beulich)
    - changes about 'get_val'. It is replaced by generic codes.
      (suggested by Jan Beulich)
v10:
    - remove 'get_old_val' to directly call 'get_val' to get needed val.
      (suggested by Jan Beulich)
    - move 'psr_check_cbm' into 'insert_val_to_array'.
      (suggested by Jan Beulich)
    - change type of 'cbm' in 'psr_check_cbm' to 'unsigned long'.
      (suggested by Jan Beulich)
    - remove 'set_new_val' as it can be handled in generic process.
    - changes related to 'feat_props'.
      (suggested by Jan Beulich)
    - adjust flow in 'gather_val_array' to avoid array cross.
      (suggested by Jan Beulich)
    - adjust flow in 'insert_val_to_array' to avoid array cross.
      (suggested by Jan Beulich)
v9:
    - add comments about boundary checking.
      (suggested by Wei Liu)
    - rename 'assemble_val_array' to 'combine_val_array' in pervious patch.
      (suggested by Wei Liu)
    - rename 'l3_cat_get_cos_num' to 'cat_get_cos_num' to cover all L3/L2 CAT
      features.
      (suggested by Roger Pau)
    - rename 'l3_cat_get_old_val' to 'cat_get_old_val' to cover all L3/L2 CAT
      features and reuse cat_get_val in it.
      (suggested by Roger Pau)
    - replace feature list handling to feature array handling.
      (suggested by Roger Pau)
    - modify patch title to indicate 'L3 CAT'.
      (suggested by Jan Beulich)
    - replace 'm' to 'new_val'.
      (suggested by Jan Beulich)
    - move cos check outside callback function.
      (suggested by Jan Beulich)
    - remove 'get_cos_num' callback function.
      (suggested by Jan Beulich)
    - changes about 'uint64_t' to 'uint32_t'.
      (suggested by Jan Beulich)
v6:
    - change 'assemble_val_array' to 'combine_val_array'.
      (suggested by Konrad Rzeszutek Wilk)
    - check return value of 'get_old_val'.
      (suggested by Konrad Rzeszutek Wilk)
    - replace some 'EINVAL' to 'ENOSPC'.
      (suggested by Konrad Rzeszutek Wilk)
v5:
    - modify comments according to changes of codes.
      (suggested by Jan Beulich)
    - change 'bool_t' to 'bool'.
      (suggested by Jan Beulich)
    - modify return value of callback functions because we do not need them
      to return number of entries the feature uses. In caller, we call
      'get_cos_num' to get the number of entries the feature uses.
      (suggested by Jan Beulich)
    - modify variables names to make them better, e.g. 'feat_tmp' to 'feat'.
      (suggested by Jan Beulich)
v4:
    - create this patch to make codes easier to understand.
      (suggested by Jan Beulich)
---
 xen/arch/x86/psr.c | 134 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 132 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/psr.c b/xen/arch/x86/psr.c
index 5aa1bcc..84a8e30 100644
--- a/xen/arch/x86/psr.c
+++ b/xen/arch/x86/psr.c
@@ -210,6 +210,29 @@ 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, unsigned long cbm)
+{
+    unsigned int first_bit, zero_bit;
+
+    /* Set bits should only in the range of [0, cbm_len]. */
+    if ( cbm & (~0ul << 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;
+}
+
 /* CAT common functions implementation. */
 static int cat_init_feature(const struct cpuid_leaf *regs,
                             struct feat_node *feat,
@@ -601,7 +624,14 @@ int psr_get_val(struct domain *d, unsigned int socket,
 /* Set value functions */
 static unsigned int get_cos_num(void)
 {
-    return 0;
+    unsigned int num = 0, i;
+
+    /* Get all features total amount. */
+    for ( i = 0; i < ARRAY_SIZE(feat_props); i++ )
+        if ( feat_props[i] )
+            num += feat_props[i]->cos_num;
+
+    return num;
 }
 
 static int gather_val_array(uint32_t val[],
@@ -609,7 +639,69 @@ static int gather_val_array(uint32_t val[],
                             const struct psr_socket_info *info,
                             unsigned int old_cos)
 {
-    return -EINVAL;
+    unsigned int i;
+
+    if ( !val )
+        return -EINVAL;
+
+    /* Get all features current values according to old_cos. */
+    for ( i = 0; i < ARRAY_SIZE(info->features); i++ )
+    {
+        unsigned int cos = old_cos, j;
+        const struct feat_node *feat = info->features[i];
+        const struct feat_props *props = feat_props[i];
+
+        if ( !feat )
+            continue;
+
+        if ( !props )
+        {
+            ASSERT_UNREACHABLE();
+            return -ENOENT;
+        }
+
+        if ( array_len < props->cos_num )
+            return -ENOSPC;
+
+        /*
+         * If old_cos exceeds current feature's cos_max, we should get
+         * default value. So assign cos to 0 which stores default value.
+         */
+        if ( cos > feat->cos_max )
+            cos = 0;
+
+        /* Value getting order is same as feature array. */
+        for ( j = 0; j < props->cos_num; j++ )
+            val[j] = feat->cos_reg_val[cos * props->cos_num + j];
+
+        array_len -= props->cos_num;
+        val += props->cos_num;
+    }
+
+    return 0;
+}
+
+static int skip_prior_features(uint32_t **val,
+                               unsigned int *array_len,
+                               enum psr_feat_type feat_type)
+{
+    unsigned int i;
+
+    for ( i = 0; i < feat_type; i++ )
+    {
+        const struct feat_props * props = feat_props[i];
+
+        if ( !props )
+            continue;
+
+        if ( *array_len <= props->cos_num )
+            return -ENOSPC;
+
+        *array_len -= props->cos_num;
+        *val += props->cos_num;
+    }
+
+    return 0;
 }
 
 static int insert_val_into_array(uint32_t val[],
@@ -619,6 +711,44 @@ static int insert_val_into_array(uint32_t val[],
                                  enum cbm_type type,
                                  uint32_t new_val)
 {
+    const struct feat_node *feat;
+    const struct feat_props *props;
+    unsigned int i;
+    int ret;
+
+    ASSERT(feat_type < FEAT_TYPE_NUM);
+
+    ret = skip_prior_features(&val, &array_len, feat_type);
+    if ( ret )
+        return ret;
+
+    feat = info->features[feat_type];
+    if ( !feat )
+        return -ENOENT;
+
+    props = feat_props[feat_type];
+    if ( !props )
+    {
+        ASSERT_UNREACHABLE();
+        return -ENOENT;
+    }
+
+    if ( array_len < props->cos_num )
+        return -ENOSPC;
+
+    if ( !psr_check_cbm(feat->cbm_len, new_val) )
+        return -EINVAL;
+
+    /* Value setting position is same as feature array. */
+    for ( i = 0; i < props->cos_num; i++ )
+    {
+        if ( type == props->type[i] )
+        {
+            val[i] = new_val;
+            return 0;
+        }
+    }
+
     return -EINVAL;
 }
 
-- 
1.9.1


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