Author: royger
Date: Fri Jul 15 09:44:48 2016
New Revision: 302895
URL: https://svnweb.freebsd.org/changeset/base/302895

Log:
  MFC r302635:
  
  xen: automatically disable MSI-X interrupt migration
  
  Approved by:  re (kib)

Modified:
  stable/11/sys/amd64/include/intr_machdep.h
  stable/11/sys/i386/include/intr_machdep.h
  stable/11/sys/x86/x86/msi.c
  stable/11/sys/x86/xen/hvm.c
Directory Properties:
  stable/11/   (props changed)

Modified: stable/11/sys/amd64/include/intr_machdep.h
==============================================================================
--- stable/11/sys/amd64/include/intr_machdep.h  Fri Jul 15 09:28:32 2016        
(r302894)
+++ stable/11/sys/amd64/include/intr_machdep.h  Fri Jul 15 09:44:48 2016        
(r302895)
@@ -149,6 +149,8 @@ extern cpuset_t intr_cpus;
 extern struct mtx icu_lock;
 extern int elcr_found;
 
+extern int msix_disable_migration;
+
 #ifndef DEV_ATPIC
 void   atpic_reset(void);
 #endif

Modified: stable/11/sys/i386/include/intr_machdep.h
==============================================================================
--- stable/11/sys/i386/include/intr_machdep.h   Fri Jul 15 09:28:32 2016        
(r302894)
+++ stable/11/sys/i386/include/intr_machdep.h   Fri Jul 15 09:44:48 2016        
(r302895)
@@ -140,6 +140,8 @@ extern cpuset_t intr_cpus;
 extern struct mtx icu_lock;
 extern int elcr_found;
 
+extern int msix_disable_migration;
+
 #ifndef DEV_ATPIC
 void   atpic_reset(void);
 #endif

Modified: stable/11/sys/x86/x86/msi.c
==============================================================================
--- stable/11/sys/x86/x86/msi.c Fri Jul 15 09:28:32 2016        (r302894)
+++ stable/11/sys/x86/x86/msi.c Fri Jul 15 09:44:48 2016        (r302895)
@@ -149,12 +149,16 @@ struct pic msi_pic = {
        .pic_reprogram_pin = NULL,
 };
 
-/*
+/**
  * Xen hypervisors prior to 4.6.0 do not properly handle updates to
  * enabled MSI-X table entries.  Allow migration of MSI-X interrupts
- * to be disabled via a tunable.
+ * to be disabled via a tunable. Values have the following meaning:
+ *
+ * -1: automatic detection by FreeBSD
+ *  0: enable migration
+ *  1: disable migration
  */
-static int msix_disable_migration = 0;
+int msix_disable_migration = -1;
 SYSCTL_INT(_machdep, OID_AUTO, disable_msix_migration, CTLFLAG_RDTUN,
     &msix_disable_migration, 0,
     "Disable migration of MSI-X interrupts between CPUs");
@@ -312,6 +316,11 @@ msi_init(void)
                return;
        }
 
+       if (msix_disable_migration == -1) {
+               /* The default is to allow migration of MSI-X interrupts. */
+               msix_disable_migration = 0;
+       }
+
        msi_enabled = 1;
        intr_register_pic(&msi_pic);
        mtx_init(&msi_lock, "msi", NULL, MTX_DEF);

Modified: stable/11/sys/x86/xen/hvm.c
==============================================================================
--- stable/11/sys/x86/xen/hvm.c Fri Jul 15 09:28:32 2016        (r302894)
+++ stable/11/sys/x86/xen/hvm.c Fri Jul 15 09:44:48 2016        (r302895)
@@ -134,9 +134,29 @@ xen_hvm_init_hypercall_stubs(enum xen_hv
                return (ENXIO);
 
        if (init_type == XEN_HVM_INIT_COLD) {
+               int major, minor;
+
                do_cpuid(base + 1, regs);
-               printf("XEN: Hypervisor version %d.%d detected.\n",
-                   regs[0] >> 16, regs[0] & 0xffff);
+
+               major = regs[0] >> 16;
+               minor = regs[0] & 0xffff;
+               printf("XEN: Hypervisor version %d.%d detected.\n", major,
+                       minor);
+
+               if (((major < 4) || (major == 4 && minor <= 5)) &&
+                   msix_disable_migration == -1) {
+                       /*
+                        * Xen hypervisors prior to 4.6.0 do not properly
+                        * handle updates to enabled MSI-X table entries,
+                        * so disable MSI-X interrupt migration in that
+                        * case.
+                        */
+                       if (bootverbose)
+                               printf(
+"Disabling MSI-X interrupt migration due to Xen hypervisor bug.\n"
+"Set machdep.msix_disable_migration=0 to forcefully enable it.\n");
+                       msix_disable_migration = 1;
+               }
        }
 
        /*
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