[src/trunk]: src/sys/arch/xen/xen Workarounds for amazon's Xen 4.2 version, s...

[bouyer <bouyer%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/0b88e64edb18
branches:  trunk
changeset: 938506:0b88e64edb18
user:      bouyer <bouyer%NetBSD.org@localhost>
date:      Wed Sep 09 16:46:06 2020 +0000

description:
Workarounds for amazon's Xen 4.2 version, still present on some instances:
- It doens't provides an xencons, so allow HVM_PARAM_CONSOLE_PFN to fail
- the xen clock is not fully functionnal, so don't try to use it if
  HVM_PARAM_CONSOLE_PFN failed.
- it doesn't have XEN_HVM_CPUID_VCPU_ID_PRESENT so fall back to ci_acpiid
  as ci_vcpuid in this case.

It also doesn't support the per-CPU event callback; so fix the fallback
to global vector (don't try to register more per-cpu vector)
Should fix port-amd64/55543

diffstat:

 sys/arch/xen/xen/hypervisor.c |  76 +++++++++++++++++++++++++-----------------
 1 files changed, 45 insertions(+), 31 deletions(-)

diffs (125 lines):

diff -r a63a5af743bf -r 0b88e64edb18 sys/arch/xen/xen/hypervisor.c
--- a/sys/arch/xen/xen/hypervisor.c     Wed Sep 09 16:29:59 2020 +0000
+++ b/sys/arch/xen/xen/hypervisor.c     Wed Sep 09 16:46:06 2020 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: hypervisor.c,v 1.87 2020/07/14 00:45:53 yamaguchi Exp $ */
+/* $NetBSD: hypervisor.c,v 1.88 2020/09/09 16:46:06 bouyer Exp $ */
 
 /*
  * Copyright (c) 2005 Manuel Bouyer.
@@ -53,7 +53,7 @@
 
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: hypervisor.c,v 1.87 2020/07/14 00:45:53 yamaguchi Exp $");
+__KERNEL_RCSID(0, "$NetBSD: hypervisor.c,v 1.88 2020/09/09 16:46:06 bouyer Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -413,32 +413,42 @@
        xen_hvm_param.index = HVM_PARAM_CONSOLE_PFN;
        
        if ( HYPERVISOR_hvm_op(HVMOP_get_param, &xen_hvm_param) < 0) {
-               aprint_error(
+               aprint_debug(
                    "Xen HVM: Unable to obtain xencons page address\n");
-               return 0;
+               xen_start_info.console.domU.mfn = 0;
+               xen_start_info.console.domU.evtchn = -1;
+               xencons_interface = 0;
+       } else {
+               /* Re-use PV field */
+               xen_start_info.console.domU.mfn = xen_hvm_param.value;
+
+               pmap_kenter_pa((vaddr_t) xencons_interface,
+                   ptoa(xen_start_info.console.domU.mfn),
+                   VM_PROT_READ|VM_PROT_WRITE, 0);
+
+               xen_hvm_param.domid = DOMID_SELF;
+               xen_hvm_param.index = HVM_PARAM_CONSOLE_EVTCHN;
+
+               if ( HYPERVISOR_hvm_op(HVMOP_get_param, &xen_hvm_param) < 0) {
+                       aprint_error(
+                          "Xen HVM: Unable to obtain xencons event channel\n");
+                       return 0;
+               }
+
+               xen_start_info.console.domU.evtchn = xen_hvm_param.value;
        }
 
-       /* Re-use PV field */
-       xen_start_info.console.domU.mfn = xen_hvm_param.value;
-
-       pmap_kenter_pa((vaddr_t) xencons_interface, ptoa(xen_start_info.console.domU.mfn),
-           VM_PROT_READ|VM_PROT_WRITE, 0);
-
-       xen_hvm_param.domid = DOMID_SELF;
-       xen_hvm_param.index = HVM_PARAM_CONSOLE_EVTCHN;
-
-       if ( HYPERVISOR_hvm_op(HVMOP_get_param, &xen_hvm_param) < 0) {
-               aprint_error(
-                   "Xen HVM: Unable to obtain xencons event channel\n");
-               return 0;
+       /*
+        * PR port-amd64/55543
+        * workround for amazon's Xen 4.2: it looks like the Xen clock is not
+        * fully funtionnal here. This version also doesn't support
+        * HVM_PARAM_CONSOLE_PFN. 
+        */
+       if (xencons_interface != 0) {
+               delay_func = x86_delay = xen_delay;
+               x86_initclock_func = xen_initclocks;
        }
 
-       xen_start_info.console.domU.evtchn = xen_hvm_param.value;
-
-
-       delay_func = x86_delay = xen_delay;
-       x86_initclock_func = xen_initclocks;
-
        vm_guest = VM_GUEST_XENPVHVM; /* Be more specific */
        return 1;
 }
@@ -458,13 +468,14 @@
 
        descs[0] = 0;
        x86_cpuid(XEN_CPUID_LEAF(4), descs);
-       if (!(descs[0] & XEN_HVM_CPUID_VCPU_ID_PRESENT)) {
-               aprint_error_dev(ci->ci_dev, "Xen HVM: can't get VCPU id\n");
-               vm_guest = VM_GUEST_XENHVM;
-               return 0;
+       if (descs[0] & XEN_HVM_CPUID_VCPU_ID_PRESENT) {
+               ci->ci_vcpuid = descs[1];
+       } else {
+               aprint_debug_dev(ci->ci_dev,
+                   "Xen HVM: can't get VCPU id, falling back to ci_acpiid\n");
+               ci->ci_vcpuid = ci->ci_acpiid;
        }
 
-       ci->ci_vcpuid = descs[1];
        ci->ci_vcpu = &HYPERVISOR_shared_info->vcpu_info[ci->ci_vcpuid];
 
        /* Register event callback handler. */
@@ -491,6 +502,7 @@
                                panic("event upcall vector");
                        aprint_error_dev(ci->ci_dev,
                            "falling back to global vector\n");
+                       xenhvm_use_percpu_callback = 0;
                } else {
                        /*
                         * From FreeBSD:
@@ -664,9 +676,11 @@
        config_found_ia(self, "xendevbus", &hac.hac_xenbus, hypervisor_print);
 #endif
 #if NXENCONS > 0
-       memset(&hac, 0, sizeof(hac));
-       hac.hac_xencons.xa_device = "xencons";
-       config_found_ia(self, "xendevbus", &hac.hac_xencons, hypervisor_print);
+       if (xencons_interface != 0) {
+               memset(&hac, 0, sizeof(hac));
+               hac.hac_xencons.xa_device = "xencons";
+               config_found_ia(self, "xendevbus", &hac.hac_xencons, hypervisor_print);
+       }
 #endif
 #if defined(XENPV) && defined(DOM0OPS)
 #if NPCI > 0