[Xen-devel] [PATCH] to fix ACPI slit table access at runtime

["Kamble, Nitin A" <nitin.a.kamble@xxxxxxxxx>]

Hi Keir,

  I was noticing that the current Xen code was not able to access the ACPI SLIT data (node to node distance) at runtime. And I found root cause of it being the acpi_slit pointer not being valid at runtime.

I have fixed the issue by saving the slit table data at boot time, and using the saved data for runtime access as follows.

 

Please accept or comment.

Thanks & Regards,

Nitin

 

Signed-Off-By: Nitin A Kamble <nitin.a.kamble@xxxxxxxxx>

 

diff -r b474725a242b xen/arch/x86/srat.c

--- a/xen/arch/x86/srat.c             Thu Feb 25 07:50:38 2010 -0800

+++ b/xen/arch/x86/srat.c          Thu Feb 25 08:02:36 2010 -0800

@@ -20,13 +20,15 @@

 #include <asm/e820.h>

 #include <asm/page.h>

 

-static struct acpi_table_slit *__read_mostly acpi_slit;

-

 static nodemask_t nodes_parsed __initdata;

 static nodemask_t nodes_found __initdata;

 static struct node nodes[MAX_NUMNODES] __initdata;

 static u8 __read_mostly pxm2node[256] = { [0 ... 255] = 0xff };

 

+static struct {

+             struct acpi_table_slit slit_table;

+             u8 entries[MAX_NUMNODES * MAX_NUMNODES];

+} acpi_slit;

 

 static int num_node_memblks;

 static struct node node_memblk_range[NR_NODE_MEMBLKS];

@@ -144,7 +146,8 @@

                                printk(KERN_INFO "ACPI: SLIT table looks invalid. Not used.\n");

                                return;

                }

-              acpi_slit = slit;

+

+             memcpy(&acpi_slit, slit, slit->header.length);

 }

 

 /* Callback for Proximity Domain -> LAPIC mapping */

@@ -424,10 +427,10 @@

 {

                int index;

 

-              if (!acpi_slit)

+             if (!acpi_slit.slit_table.header.length)

                                return a == b ? 10 : 20;

-              index = acpi_slit->locality_count * node_to_pxm(a);

-              return acpi_slit->entry[index + node_to_pxm(b)];

+             index = acpi_slit.slit_table.locality_count * node_to_pxm(a);

+             return  acpi_slit.slit_table.entry[index + node_to_pxm(b)];

 }

 

 EXPORT_SYMBOL(__node_distance);

diff -r b474725a242b xen/include/acpi/actbl1.h

--- a/xen/include/acpi/actbl1.h Thu Feb 25 07:50:38 2010 -0800

+++ b/xen/include/acpi/actbl1.h              Thu Feb 25 08:02:36 2010 -0800

@@ -573,7 +573,7 @@

 struct acpi_table_slit {

                struct acpi_table_header header;            /* Common ACPI table header */

                u64 locality_count;

-              u8 entry[1];                        /* Real size = localities^2 */

+             u8 entry[0];                        /* Real size = localities^2 */

 };

 

 /*******************************************************************************

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