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Re: [PATCH v5 06/13] xen/arm: add support for cache coloring configuration via device-tree
Hi Carlo,
On 02/01/2024 09:51, Carlo Nonato wrote:
This commit adds the "llc-colors" Device Tree attribute that can be used
for DomUs and Dom0less color configurations. The syntax is the same used
for every color config.
Based on original work from: Luca Miccio <lucmiccio@xxxxxxxxx>
Signed-off-by: Carlo Nonato <carlo.nonato@xxxxxxxxxxxxxxx>
Signed-off-by: Marco Solieri <marco.solieri@xxxxxxxxxxxxxxx>
---
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/cache-coloring.rst | 48 ++++++++++++++++++++++++-
docs/misc/arm/device-tree/booting.txt | 4 +++
xen/arch/arm/dom0less-build.c | 13 +++++++
xen/arch/arm/include/asm/llc-coloring.h | 1 +
xen/arch/arm/llc-coloring.c | 17 +++++++++
5 files changed, 82 insertions(+), 1 deletion(-)
diff --git a/docs/misc/arm/cache-coloring.rst b/docs/misc/arm/cache-coloring.rst
index acf82c3df8..ae1dd8f4af 100644
--- a/docs/misc/arm/cache-coloring.rst
+++ b/docs/misc/arm/cache-coloring.rst
@@ -10,7 +10,7 @@ If needed, change the maximum number of colors with
``CONFIG_NR_LLC_COLORS=<n>``.
Compile Xen and the toolstack and then configure it via
-`Command line parameters`_.
+`Command line parameters`_. For DomUs follow `DomUs configuration`_.
Background
**********
@@ -114,6 +114,52 @@ Examples:
| 0 | [0] |
+-------------------+-----------------------------+
+DomUs configuration
+*******************
+
+DomUs colors can be set 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 llc-way-size=64K 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.
Looking at your code, it will use *all* the colors. Some of the colors
might have been assigned to a domain. I am not entirely convinced this
is good idea to allow this as a default setup.
+
Known issues and limitations
****************************
diff --git a/docs/misc/arm/device-tree/booting.txt b/docs/misc/arm/device-tree/booting.txt
index bbd955e9c2..e9f9862e9c 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/arm/cache_coloring.rst" for syntax.
+
- vpl011
An empty property to enable/disable a virtual pl011 for the guest to
diff --git a/xen/arch/arm/dom0less-build.c b/xen/arch/arm/dom0less-build.c
index 1142f7f74a..eb39f5291f 100644
--- a/xen/arch/arm/dom0less-build.c
+++ b/xen/arch/arm/dom0less-build.c
@@ -850,6 +850,7 @@ void __init create_domUs(void)
struct dt_device_node *node;
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)
@@ -993,6 +994,13 @@ 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' is required when LLC coloring is enabled\n");
In the documentation you wrote:
"**Note:** If no color configuration is provided for a domain, the
default one,which corresponds to all available colors, is used instead."
I interpret as you want to continue rather than panic-ing. That said, I
much prefer the panic version.
+ else if ( !llc_coloring_enabled && llc_colors_str)
+ printk(XENLOG_WARNING
+ "'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
@@ -1003,6 +1011,11 @@ 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/arch/arm/include/asm/llc-coloring.h b/xen/arch/arm/include/asm/llc-coloring.h
index ee5551e3cc..5f9b0a8121 100644
--- a/xen/arch/arm/include/asm/llc-coloring.h
+++ b/xen/arch/arm/include/asm/llc-coloring.h
@@ -15,6 +15,7 @@
bool __init llc_coloring_init(void);
int dom0_set_llc_colors(struct domain *d);
+int domain_set_llc_colors_from_str(struct domain *d, const char *str);
#endif /* __ASM_ARM_COLORING_H__ */
diff --git a/xen/arch/arm/llc-coloring.c b/xen/arch/arm/llc-coloring.c
index a08614ec36..d3de5f14cb 100644
--- a/xen/arch/arm/llc-coloring.c
+++ b/xen/arch/arm/llc-coloring.c
@@ -295,6 +295,23 @@ int domain_set_llc_colors_domctl(struct domain *d,
return domain_check_colors(d);
}
+int domain_set_llc_colors_from_str(struct domain *d, const char *str)
+{
+ int err;
+
+ if ( domain_alloc_colors(d, nr_colors) )
This code is somewhat confusing and would deserve some explanation.
AFAICT, you are allocating a large array because parse_color_config()
expects an array of nr_colors.
d->num_llc_colors will also be set to nr_colors but then overriden by
parse_color_config().
It feels to me that maybe set num_llc_colors() in domain_alloc_colors()
is not right.
+ return -ENOMEM;
+
+ err = parse_color_config(str, d->llc_colors, &d->num_llc_colors);
+ if ( err )
+ {
+ printk(XENLOG_ERR "Error parsing LLC color configuration.");
+ return err;
+ }
+
+ return domain_check_colors(d);
+}
+
/*
* Local variables:
* mode: C
Cheers,
--
Julien Grall
|
