[Xen-devel] [PATCH] xen: Re-upload processor PM data to hypervisor after S3 resume (v2)

[Ben Guthro <benjamin.guthro@xxxxxxxxxx>]

Upon resume, it was found that ACPI C-states were missing from non-boot CPUs.
This change registers a syscore_ops handler for this case, and re-uploads the
PM information to the hypervisor to properly reset the C-state on these
processors.

v2:
v1 did not go through the check_acpi_ids() code-path, and missed some cases when
xen was running with the dom0_max_vcpus= command line parameter.

Signed-Off-By: Ben Guthro <benjamin.guthro@xxxxxxxxxx>
---
 drivers/xen/xen-acpi-processor.c |   78 ++++++++++++++++++++++++++------------
 1 file changed, 53 insertions(+), 25 deletions(-)

diff --git a/drivers/xen/xen-acpi-processor.c b/drivers/xen/xen-acpi-processor.c
index 90e34ac..86b6f69 100644
--- a/drivers/xen/xen-acpi-processor.c
+++ b/drivers/xen/xen-acpi-processor.c
@@ -25,6 +25,7 @@
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/types.h>
+#include <linux/syscore_ops.h>
 #include <acpi/acpi_bus.h>
 #include <acpi/acpi_drivers.h>
 #include <acpi/processor.h>
@@ -51,9 +52,9 @@ static DEFINE_MUTEX(acpi_ids_mutex);
 /* Which ACPI ID we have processed from 'struct acpi_processor'. */
 static unsigned long *acpi_ids_done;
 /* Which ACPI ID exist in the SSDT/DSDT processor definitions. */
-static unsigned long __initdata *acpi_id_present;
+static unsigned long *acpi_id_present;
 /* And if there is an _CST definition (or a PBLK) for the ACPI IDs */
-static unsigned long __initdata *acpi_id_cst_present;
+static unsigned long *acpi_id_cst_present;
 
 static int push_cxx_to_hypervisor(struct acpi_processor *_pr)
 {
@@ -390,6 +391,10 @@ static int __init check_acpi_ids(struct acpi_processor 
*pr_backup)
        if (!pr_backup)
                return -ENODEV;
 
+       if (acpi_id_present && acpi_id_cst_present)
+               /* OK, done this once .. skip to uploading */
+               goto upload;
+
        /* All online CPUs have been processed at this stage. Now verify
         * whether in fact "online CPUs" == physical CPUs.
         */
@@ -408,6 +413,7 @@ static int __init check_acpi_ids(struct acpi_processor 
*pr_backup)
                            read_acpi_id, NULL, NULL, NULL);
        acpi_get_devices("ACPI0007", read_acpi_id, NULL, NULL);
 
+upload:
        if (!bitmap_equal(acpi_id_present, acpi_ids_done, nr_acpi_bits)) {
                unsigned int i;
                for_each_set_bit(i, acpi_id_present, nr_acpi_bits) {
@@ -417,10 +423,7 @@ static int __init check_acpi_ids(struct acpi_processor 
*pr_backup)
                        (void)upload_pm_data(pr_backup);
                }
        }
-       kfree(acpi_id_present);
-       acpi_id_present = NULL;
-       kfree(acpi_id_cst_present);
-       acpi_id_cst_present = NULL;
+
        return 0;
 }
 static int __init check_prereq(void)
@@ -467,10 +470,47 @@ static void free_acpi_perf_data(void)
        free_percpu(acpi_perf_data);
 }
 
-static int __init xen_acpi_processor_init(void)
+static int xen_upload_processor_pm_data(void)
 {
        struct acpi_processor *pr_backup = NULL;
        unsigned int i;
+       int rc = 0;
+
+       printk(KERN_INFO "Uploading Xen processor pm info\n");
+
+       for_each_possible_cpu(i) {
+               struct acpi_processor *_pr;
+               _pr = per_cpu(processors, i /* APIC ID */);
+               if (!_pr)
+                       continue;
+
+               if (!pr_backup) {
+                       pr_backup = kzalloc(sizeof(struct acpi_processor), 
GFP_KERNEL);
+                       if (pr_backup)
+                               memcpy(pr_backup, _pr, sizeof(struct 
acpi_processor));
+               }
+               (void)upload_pm_data(_pr);
+       }
+
+       rc = check_acpi_ids(pr_backup);
+       kfree(pr_backup);
+
+       return rc;
+}
+
+static void xen_acpi_processor_resume(void)
+{
+       bitmap_zero(acpi_ids_done, nr_acpi_bits);
+       xen_upload_processor_pm_data();
+}
+
+static struct syscore_ops xap_syscore_ops = {
+       .resume                 = xen_acpi_processor_resume,
+};
+
+static int __init xen_acpi_processor_init(void)
+{
+       unsigned int i;
        int rc = check_prereq();
 
        if (rc)
@@ -514,27 +554,12 @@ static int __init xen_acpi_processor_init(void)
                        goto err_out;
        }
 
-       for_each_possible_cpu(i) {
-               struct acpi_processor *_pr;
-               _pr = per_cpu(processors, i /* APIC ID */);
-               if (!_pr)
-                       continue;
-
-               if (!pr_backup) {
-                       pr_backup = kzalloc(sizeof(struct acpi_processor), 
GFP_KERNEL);
-                       if (pr_backup)
-                               memcpy(pr_backup, _pr, sizeof(struct 
acpi_processor));
-               }
-               (void)upload_pm_data(_pr);
-       }
-       rc = check_acpi_ids(pr_backup);
-
-       kfree(pr_backup);
-       pr_backup = NULL;
-
+       rc = xen_upload_processor_pm_data();
        if (rc)
                goto err_unregister;
 
+       register_syscore_ops(&xap_syscore_ops);
+
        return 0;
 err_unregister:
        for_each_possible_cpu(i) {
@@ -552,7 +577,10 @@ static void __exit xen_acpi_processor_exit(void)
 {
        int i;
 
+       unregister_syscore_ops(&xap_syscore_ops);
        kfree(acpi_ids_done);
+       kfree(acpi_id_present);
+       kfree(acpi_id_cst_present);
        for_each_possible_cpu(i) {
                struct acpi_processor_performance *perf;
                perf = per_cpu_ptr(acpi_perf_data, i);
-- 
1.7.9.5


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