xen/arm: add Dom0 cache coloring support

Add a command line parameter to allow the user to set the coloring
configuration for Dom0.
A common configuration syntax for cache colors is introduced and
documented.
Take the opportunity to also add:
 - default configuration notion.
 - function to check well-formed configurations.

Direct mapping Dom0 isn't possible when coloring is enabled, so
CDF_directmap flag is removed when creating it.

Based on original work from: Luca Miccio <lucmiccio@gmail.com>

Signed-off-by: Carlo Nonato <carlo.nonato@minervasys.tech>
Signed-off-by: Marco Solieri <marco.solieri@minervasys.tech>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Michal Orzel <michal.orzel@amd.com>

docs/misc/cache-coloring.rst

@@ -107,6 +107,35 @@ Specific documentation is available at `docs/misc/xen-command-line.pandoc`.
 +----------------------+-------------------------------+
 | ``llc-nr-ways``      | Set the LLC number of ways    |
 +----------------------+-------------------------------+
+| ``dom0-llc-colors``  | Dom0 color configuration      |
++----------------------+-------------------------------+
+
+Colors selection format
+***********************
+
+Regardless of the memory pool that has to be colored (Xen, Dom0/DomUs),
+the color selection can be expressed using the same syntax. In particular a
+comma-separated list of colors or ranges of colors is used.
+Ranges are hyphen-separated intervals (such as `0-4`) and are inclusive on both
+sides.
+
+Note that:
+
+- no spaces are allowed between values.
+- no overlapping ranges or duplicated colors are allowed.
+- values must be written in ascending order.
+
+Examples:
+
++-------------------+-----------------------------+
+| **Configuration** | **Actual selection**        |
++-------------------+-----------------------------+
+| 1-2,5-8           | [1, 2, 5, 6, 7, 8]          |
++-------------------+-----------------------------+
+| 4-8,10,11,12      | [4, 5, 6, 7, 8, 10, 11, 12] |
++-------------------+-----------------------------+
+| 0                 | [0]                         |
++-------------------+-----------------------------+
 
 Auto-probing of LLC specs
 #########################

docs/misc/xen-command-line.pandoc

@@ -965,6 +965,15 @@ Controls for the dom0 IOMMU setup.
 
 Specify a list of IO ports to be excluded from dom0 access.
 
+### dom0-llc-colors (arm64)
+> `= List of [ <integer> | <integer>-<integer> ]`
+
+> Default: `All available LLC colors`
+
+Specify dom0 LLC color configuration. This option is available only when
+`CONFIG_LLC_COLORING` is enabled. If the parameter is not set, all available
+colors are used.
+
 ### dom0_max_vcpus
 
 Either:

xen/arch/arm/domain_build.c

@@ -2356,6 +2356,7 @@ void __init create_dom0(void)
         .max_maptrack_frames = -1,
         .grant_opts = XEN_DOMCTL_GRANT_version(opt_gnttab_max_version),
     };
+    unsigned int flags = CDF_privileged;
     int rc;
 
     /* The vGIC for DOM0 is exactly emulating the hardware GIC */
@@ -2383,10 +2384,16 @@ void __init create_dom0(void)
             panic("SVE vector length error\n");
     }
 
-    dom0 = domain_create(0, &dom0_cfg, CDF_privileged | CDF_directmap);
+    if ( !llc_coloring_enabled )
+        flags |= CDF_directmap;
+
+    dom0 = domain_create(0, &dom0_cfg, flags);
     if ( IS_ERR(dom0) )
         panic("Error creating domain 0 (rc = %ld)\n", PTR_ERR(dom0));
 
+    if ( llc_coloring_enabled && (rc = dom0_set_llc_colors(dom0)) )
+        panic("Error initializing LLC coloring for domain 0 (rc = %d)\n", rc);
+
     if ( alloc_dom0_vcpu0(dom0) == NULL )
         panic("Error creating domain 0 vcpu0\n");
 

xen/common/llc-coloring.c

@@ -29,6 +29,66 @@ static unsigned int __initdata llc_nr_ways;
 integer_param("llc-nr-ways", llc_nr_ways);
 /* Number of colors available in the LLC */
 static unsigned int __ro_after_init max_nr_colors;
+/* Default coloring configuration */
+static unsigned int __ro_after_init default_colors[NR_LLC_COLORS];
+
+static unsigned int __initdata dom0_colors[NR_LLC_COLORS];
+static unsigned int __initdata dom0_num_colors;
+
+/*
+ * Parse the coloring configuration given in the buf string, following the
+ * syntax below.
+ *
+ * COLOR_CONFIGURATION ::= COLOR | RANGE,...,COLOR | RANGE
+ * RANGE               ::= COLOR-COLOR
+ *
+ * Example: "0,2-6,15-16" represents the set of colors: 0,2,3,4,5,6,15,16.
+ */
+static int __init parse_color_config(const char *buf, unsigned int colors[],
+                                     unsigned int max_num_colors,
+                                     unsigned int *num_colors)
+{
+    const char *s = buf;
+
+    *num_colors = 0;
+
+    while ( *s != '\0' )
+    {
+        unsigned int color, start, end;
+
+        start = simple_strtoul(s, &s, 0);
+
+        if ( *s == '-' )    /* Range */
+        {
+            s++;
+            end = simple_strtoul(s, &s, 0);
+        }
+        else                /* Single value */
+            end = start;
+
+        if ( start > end || (end - start) > (UINT_MAX - *num_colors) ||
+             (*num_colors + (end - start)) >= max_num_colors )
+            return -EINVAL;
+
+        /* Colors are range checked in check_colors() */
+        for ( color = start; color <= end; color++ )
+            colors[(*num_colors)++] = color;
+
+        if ( *s == ',' )
+            s++;
+        else if ( *s != '\0' )
+            break;
+    }
+
+    return *s ? -EINVAL : 0;
+}
+
+static int __init parse_dom0_colors(const char *s)
+{
+    return parse_color_config(s, dom0_colors, ARRAY_SIZE(dom0_colors),
+                              &dom0_num_colors);
+}
+custom_param("dom0-llc-colors", parse_dom0_colors);
 
 static void print_colors(const unsigned int colors[], unsigned int num_colors)
 {
@@ -53,9 +113,27 @@ static void print_colors(const unsigned int colors[], unsigned int num_colors)
     printk(" }\n");
 }
 
+static bool __init check_colors(const unsigned int colors[],
+                                unsigned int num_colors)
+{
+    unsigned int i;
+
+    for ( i = 0; i < num_colors; i++ )
+    {
+        if ( colors[i] >= max_nr_colors )
+        {
+            printk(XENLOG_ERR "LLC color %u >= %u (max allowed)\n", colors[i],
+                   max_nr_colors);
+            return false;
+        }
+    }
+
+    return true;
+}
+
 void __init llc_coloring_init(void)
 {
-    unsigned int way_size;
+    unsigned int way_size, i;
 
     llc_coloring_enabled = (opt_llc_coloring >= 1);
     if ( (opt_llc_coloring != 0) && llc_size && llc_nr_ways )
@@ -94,6 +172,9 @@ void __init llc_coloring_init(void)
     else if ( max_nr_colors < 2 )
         panic("Number of LLC colors %u < 2\n", max_nr_colors);
 
+    for ( i = 0; i < max_nr_colors; i++ )
+        default_colors[i] = i;
+
     arch_llc_coloring_init();
 }
 
@@ -115,6 +196,43 @@ void domain_dump_llc_colors(const struct domain *d)
     print_colors(d->llc_colors, d->num_llc_colors);
 }
 
+static void __init domain_set_default_colors(struct domain *d)
+{
+    printk(XENLOG_WARNING
+           "LLC color config not found for %pd, using all colors\n", d);
+
+    d->llc_colors = default_colors;
+    d->num_llc_colors = max_nr_colors;
+}
+
+int __init dom0_set_llc_colors(struct domain *d)
+{
+    typeof(*dom0_colors) *colors;
+
+    if ( !dom0_num_colors )
+    {
+        domain_set_default_colors(d);
+        return 0;
+    }
+
+    if ( (dom0_num_colors > max_nr_colors) ||
+         !check_colors(dom0_colors, dom0_num_colors) )
+    {
+        printk(XENLOG_ERR "%pd:  bad LLC color config\n", d);
+        return -EINVAL;
+    }
+
+    colors = xmalloc_array(typeof(*dom0_colors), dom0_num_colors);
+    if ( !colors )
+        return -ENOMEM;
+
+    memcpy(colors, dom0_colors, sizeof(*colors) * dom0_num_colors);
+    d->llc_colors = colors;
+    d->num_llc_colors = dom0_num_colors;
+
+    return 0;
+}
+
 /*
  * Local variables:
  * mode: C

xen/include/xen/llc-coloring.h

@@ -28,6 +28,7 @@ static inline void domain_dump_llc_colors(const struct domain *d) {}
 
 unsigned int get_llc_way_size(void);
 void arch_llc_coloring_init(void);
+int dom0_set_llc_colors(struct domain *d);
 
 #endif /* __XEN_LLC_COLORING_H__ */