Fix save/restore for HVM domains with viridian=1

xc_domain_save/restore currently pay no attention to
HVM_PARAM_VIRIDIAN which results in an HVM domain running a recent
version on Windows (post-Vista) locking up on a domain restore due to
EOIs (done via a viridian MSR write) being silently dropped.  This
patch adds an extra save entry for the viridian parameter and also
adds code in the viridian kernel module to catch attempted use of
viridian functionality when the HVM parameter has not been set.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Committed-by: Keir Fraser <keir@xen.org>

1 files changed, 12 insertions, 2 deletions

diff --git a/xen/arch/x86/hvm/viridian.c b/xen/arch/x86/hvm/viridian.c
index 6d3b899d2e..6a7067c835 100644
--- a/xen/arch/x86/hvm/viridian.c
+++ b/xen/arch/x86/hvm/viridian.c
@@ -206,8 +206,11 @@ int wrmsr_viridian_regs(uint32_t idx, uint64_t val)
     struct vcpu *v = current;
     struct domain *d = v->domain;
 
-    if ( !is_viridian_domain(d) )
+    if ( !is_viridian_domain(d) ) {
+        gdprintk(XENLOG_WARNING, "%s: %d not a viridian domain\n", __func__,
+                 d->domain_id);
         return 0;
+    }
 
     switch ( idx )
     {
@@ -271,8 +274,11 @@ int rdmsr_viridian_regs(uint32_t idx, uint64_t *val)
     struct vcpu *v = current;
     struct domain *d = v->domain;
     
-    if ( !is_viridian_domain(d) )
+    if ( !is_viridian_domain(d) ) {
+        gdprintk(XENLOG_WARNING, "%s: %d not a viridian domain\n", __func__,
+                 d->domain_id);
         return 0;
+    }
 
     switch ( idx )
     {
@@ -411,6 +417,8 @@ static int viridian_load_domain_ctxt(struct domain *d, hvm_domain_context_t *h)
     if ( hvm_load_entry(VIRIDIAN_DOMAIN, h, &ctxt) != 0 )
         return -EINVAL;
 
+    ASSERT(is_viridian_domain(d));
+
     d->arch.hvm_domain.viridian.hypercall_gpa.raw = ctxt.hypercall_gpa;
     d->arch.hvm_domain.viridian.guest_os_id.raw   = ctxt.guest_os_id;
 
@@ -455,6 +463,8 @@ static int viridian_load_vcpu_ctxt(struct domain *d, hvm_domain_context_t *h)
     if ( hvm_load_entry(VIRIDIAN_VCPU, h, &ctxt) != 0 )
         return -EINVAL;
 
+    ASSERT(is_viridian_domain(d));
+
     v->arch.hvm_vcpu.viridian.apic_assist.raw = ctxt.apic_assist;
 
     return 0;