Add the "llc-colors" Device Tree attribute to express DomUs and Dom0less
color configurations.

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> # non-Arm
---
v10:
- no changes
v9:
- use best-effort allocation in domain_set_llc_colors_from_str()
v8:
- fixed memory leak on error path of domain_set_llc_colors_from_str()
- realloc colors array after parsing from string to reduce memory usage
v7:
- removed alloc_colors() helper usage from domain_set_llc_colors_from_str()
v6:
- rewrote domain_set_llc_colors_from_str() to be more explicit
v5:
- static-mem check has been moved in a previous patch
- added domain_set_llc_colors_from_str() to set colors after domain creation
---
 docs/misc/arm/device-tree/booting.txt |  4 +++
 docs/misc/cache-coloring.rst          | 48 +++++++++++++++++++++++++++
 xen/arch/arm/dom0less-build.c         | 10 ++++++
 xen/common/llc-coloring.c             | 41 +++++++++++++++++++++++
 xen/include/xen/llc-coloring.h        |  1 +
 xen/include/xen/xmalloc.h             | 12 +++++++
 6 files changed, 116 insertions(+)

diff --git a/docs/misc/arm/device-tree/booting.txt b/docs/misc/arm/device-tree/booting.txt
index 3a04f5c57f..9085645433 100644
--- a/docs/misc/arm/device-tree/booting.txt
+++ b/docs/misc/arm/device-tree/booting.txt
@@ -162,6 +162,10 @@ with the following properties:
 
     An integer specifying the number of vcpus to allocate to the guest.
 
+- llc-colors
+    A string specifying the LLC color configuration for the guest.
+    Refer to docs/misc/cache_coloring.rst for syntax.
+
 - vpl011
 
     An empty property to enable/disable a virtual pl011 for the guest to
diff --git a/docs/misc/cache-coloring.rst b/docs/misc/cache-coloring.rst
index c5fb33996c..c14b6ee2f4 100644
--- a/docs/misc/cache-coloring.rst
+++ b/docs/misc/cache-coloring.rst
@@ -12,6 +12,7 @@ If needed, change the maximum number of colors with
 ``CONFIG_LLC_COLORS_ORDER=<n>``.
 
 Runtime configuration is done via `Command line parameters`_.
+For DomUs follow `DomUs configuration`_.
 
 Background
 **********
@@ -147,6 +148,53 @@ LLC specs can be manually set via the above command line parameters. This
 bypasses any auto-probing and it's used to overcome failing situations, such as
 flawed probing logic, or for debugging/testing purposes.
 
+DomUs configuration
+*******************
+
+DomUs colors can be set either in the ``xl`` configuration file (documentation
+at `docs/man/xl.cfg.pod.5.in`) or via Device Tree, also for Dom0less
+configurations (documentation at `docs/misc/arm/device-tree/booting.txt`) using
+the ``llc-colors`` option. For example:
+
+::
+
+    xen,xen-bootargs = "console=dtuart dtuart=serial0 dom0_mem=1G dom0_max_vcpus=1 sched=null llc-coloring=on dom0-llc-colors=2-6";
+    xen,dom0-bootargs "console=hvc0 earlycon=xen earlyprintk=xen root=/dev/ram0"
+
+    dom0 {
+        compatible = "xen,linux-zimage" "xen,multiboot-module";
+        reg = <0x0 0x1000000 0x0 15858176>;
+    };
+
+    dom0-ramdisk {
+        compatible = "xen,linux-initrd" "xen,multiboot-module";
+        reg = <0x0 0x2000000 0x0 20638062>;
+    };
+
+    domU0 {
+        #address-cells = <0x1>;
+        #size-cells = <0x1>;
+        compatible = "xen,domain";
+        memory = <0x0 0x40000>;
+        llc-colors = "4-8,10,11,12";
+        cpus = <0x1>;
+        vpl011 = <0x1>;
+
+        module@2000000 {
+            compatible = "multiboot,kernel", "multiboot,module";
+            reg = <0x2000000 0xffffff>;
+            bootargs = "console=ttyAMA0";
+        };
+
+        module@30000000 {
+            compatible = "multiboot,ramdisk", "multiboot,module";
+            reg = <0x3000000 0xffffff>;
+        };
+    };
+
+**Note:** If no color configuration is provided for a domain, the default one,
+which corresponds to all available colors is used instead.
+
 Known issues and limitations
 ****************************
 
diff --git a/xen/arch/arm/dom0less-build.c b/xen/arch/arm/dom0less-build.c
index 67b1503647..49d1f14d65 100644
--- a/xen/arch/arm/dom0less-build.c
+++ b/xen/arch/arm/dom0less-build.c
@@ -817,6 +817,7 @@ void __init create_domUs(void)
     bool iommu = false;
     const struct dt_device_node *cpupool_node,
                                 *chosen = dt_find_node_by_path("/chosen");
+    const char *llc_colors_str = NULL;
 
     BUG_ON(chosen == NULL);
     dt_for_each_child_node(chosen, node)
@@ -965,6 +966,10 @@ void __init create_domUs(void)
 #endif
         }
 
+        dt_property_read_string(node, "llc-colors", &llc_colors_str);
+        if ( !llc_coloring_enabled && llc_colors_str )
+            panic("'llc-colors' found, but LLC coloring is disabled\n");
+
         /*
          * The variable max_init_domid is initialized with zero, so here it's
          * very important to use the pre-increment operator to call
@@ -975,6 +980,11 @@ void __init create_domUs(void)
             panic("Error creating domain %s (rc = %ld)\n",
                   dt_node_name(node), PTR_ERR(d));
 
+        if ( llc_coloring_enabled &&
+             (rc = domain_set_llc_colors_from_str(d, llc_colors_str)) )
+            panic("Error initializing LLC coloring for domain %s (rc = %d)\n",
+                  dt_node_name(node), rc);
+
         d->is_console = true;
         dt_device_set_used_by(node, d->domain_id);
 
diff --git a/xen/common/llc-coloring.c b/xen/common/llc-coloring.c
index 3cfd0ce78c..14e056fb10 100644
--- a/xen/common/llc-coloring.c
+++ b/xen/common/llc-coloring.c
@@ -5,6 +5,7 @@
  * Copyright (C) 2024, Advanced Micro Devices, Inc.
  * Copyright (C) 2024, Minerva Systems SRL
  */
+#include "xen/xmalloc.h"
 #include <xen/guest_access.h>
 #include <xen/keyhandler.h>
 #include <xen/llc-coloring.h>
@@ -270,6 +271,46 @@ void domain_llc_coloring_free(struct domain *d)
     xfree(__va(__pa(d->llc_colors)));
 }
 
+int __init domain_set_llc_colors_from_str(struct domain *d, const char *str)
+{
+    int err;
+    unsigned int *colors, num_colors;
+
+    if ( !str )
+    {
+        domain_set_default_colors(d);
+        return 0;
+    }
+
+    colors = xmalloc_array(unsigned int, max_nr_colors);
+    if ( !colors )
+        return -ENOMEM;
+
+    err = parse_color_config(str, colors, max_nr_colors, &num_colors);
+    if ( err )
+    {
+        printk(XENLOG_ERR "Error parsing LLC color configuration");
+        xfree(colors);
+        return err;
+    }
+
+    if ( !check_colors(colors, num_colors) )
+    {
+        printk(XENLOG_ERR "%pd: bad LLC color config\n", d);
+        xfree(colors);
+        return -EINVAL;
+    }
+
+    /* Adjust the size cause it was initially set to max_nr_colors */
+    d->llc_colors = xrealloc_array(colors, num_colors);
+    if ( !d->llc_colors )
+        d->llc_colors = colors;
+
+    d->num_llc_colors = num_colors;
+
+    return 0;
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/xen/include/xen/llc-coloring.h b/xen/include/xen/llc-coloring.h
index 657f4d0a10..76d3cbae0e 100644
--- a/xen/include/xen/llc-coloring.h
+++ b/xen/include/xen/llc-coloring.h
@@ -32,6 +32,7 @@ void arch_llc_coloring_init(void);
 int dom0_set_llc_colors(struct domain *d);
 int domain_set_llc_colors(struct domain *d,
                           const struct xen_domctl_set_llc_colors *config);
+int domain_set_llc_colors_from_str(struct domain *d, const char *str);
 
 #endif /* __COLORING_H__ */
 
diff --git a/xen/include/xen/xmalloc.h b/xen/include/xen/xmalloc.h
index b903fa2e26..f0412fb4e0 100644
--- a/xen/include/xen/xmalloc.h
+++ b/xen/include/xen/xmalloc.h
@@ -37,6 +37,9 @@
     ((_type *)_xmalloc_array(sizeof(_type), __alignof__(_type), _num))
 #define xzalloc_array(_type, _num) \
     ((_type *)_xzalloc_array(sizeof(_type), __alignof__(_type), _num))
+#define xrealloc_array(_ptr, _num)                                  \
+    ((typeof(_ptr))_xrealloc_array(_ptr, sizeof(typeof(*(_ptr))),   \
+                                   __alignof__(typeof(*(_ptr))), _num))
 
 /* Allocate space for a structure with a flexible array of typed objects. */
 #define xzalloc_flex_struct(type, field, nr) \
@@ -98,6 +101,15 @@ static inline void *_xzalloc_array(
     return _xzalloc(size * num, align);
 }
 
+static inline void *_xrealloc_array(
+    void *ptr, unsigned long size, unsigned long align, unsigned long num)
+{
+    /* Check for overflow. */
+    if ( size && num > UINT_MAX / size )
+        return NULL;
+    return _xrealloc(ptr, size * num, align);
+}
+
 /*
  * Pooled allocator interface.
  */
-- 
2.43.0

On 19/11/2024 15:13, Carlo Nonato wrote:
> 
> 
> Add the "llc-colors" Device Tree attribute to express DomUs and Dom0less
NIT: s/attribute/property/

> color configurations.
> 
> 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> # non-Arm
> ---
> v10:
> - no changes
> v9:
> - use best-effort allocation in domain_set_llc_colors_from_str()
> v8:
> - fixed memory leak on error path of domain_set_llc_colors_from_str()
> - realloc colors array after parsing from string to reduce memory usage
> v7:
> - removed alloc_colors() helper usage from domain_set_llc_colors_from_str()
> v6:
> - rewrote domain_set_llc_colors_from_str() to be more explicit
> v5:
> - static-mem check has been moved in a previous patch
> - added domain_set_llc_colors_from_str() to set colors after domain creation
> ---
>  docs/misc/arm/device-tree/booting.txt |  4 +++
>  docs/misc/cache-coloring.rst          | 48 +++++++++++++++++++++++++++
>  xen/arch/arm/dom0less-build.c         | 10 ++++++
>  xen/common/llc-coloring.c             | 41 +++++++++++++++++++++++
>  xen/include/xen/llc-coloring.h        |  1 +
>  xen/include/xen/xmalloc.h             | 12 +++++++
>  6 files changed, 116 insertions(+)
> 
> diff --git a/docs/misc/arm/device-tree/booting.txt b/docs/misc/arm/device-tree/booting.txt
> index 3a04f5c57f..9085645433 100644
> --- a/docs/misc/arm/device-tree/booting.txt
> +++ b/docs/misc/arm/device-tree/booting.txt
> @@ -162,6 +162,10 @@ with the following properties:
> 
>      An integer specifying the number of vcpus to allocate to the guest.
> 
> +- llc-colors
> +    A string specifying the LLC color configuration for the guest.
> +    Refer to docs/misc/cache_coloring.rst for syntax.
Shouldn't we make it clear that this property is Arm64 only?

> +
>  - vpl011
> 
>      An empty property to enable/disable a virtual pl011 for the guest to
> diff --git a/docs/misc/cache-coloring.rst b/docs/misc/cache-coloring.rst
> index c5fb33996c..c14b6ee2f4 100644
> --- a/docs/misc/cache-coloring.rst
> +++ b/docs/misc/cache-coloring.rst
> @@ -12,6 +12,7 @@ If needed, change the maximum number of colors with
>  ``CONFIG_LLC_COLORS_ORDER=<n>``.
> 
>  Runtime configuration is done via `Command line parameters`_.
> +For DomUs follow `DomUs configuration`_.
> 
>  Background
>  **********
> @@ -147,6 +148,53 @@ LLC specs can be manually set via the above command line parameters. This
>  bypasses any auto-probing and it's used to overcome failing situations, such as
>  flawed probing logic, or for debugging/testing purposes.
> 
> +DomUs configuration
> +*******************
> +
> +DomUs colors can be set either in the ``xl`` configuration file (documentation
> +at `docs/man/xl.cfg.pod.5.in`) or via Device Tree, also for Dom0less
> +configurations (documentation at `docs/misc/arm/device-tree/booting.txt`) using
NIT: I think you can remove the part "also for Dom0less configurations" if you already
mentioned "or via Device Tree".

Other than that:
Reviewed-by: Michal Orzel <michal.orzel@amd.com>

~Michal