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>

4 files changed, 39 insertions, 2 deletions

diff --git a/tools/libxc/xc_domain_restore.c b/tools/libxc/xc_domain_restore.c
index 5cf099c92e..882678a9c5 100644
--- a/tools/libxc/xc_domain_restore.c
+++ b/tools/libxc/xc_domain_restore.c
@@ -675,6 +675,7 @@ typedef struct {
     uint64_t vm86_tss;
     uint64_t console_pfn;
     uint64_t acpi_ioport_location;
+    uint64_t viridian;
 } pagebuf_t;
 
 static int pagebuf_init(pagebuf_t* buf)
@@ -809,6 +810,16 @@ static int pagebuf_get_one(xc_interface *xch, struct restore_ctx *ctx,
         }
         return pagebuf_get_one(xch, ctx, buf, fd, dom);
 
+    case XC_SAVE_ID_HVM_VIRIDIAN:
+        /* Skip padding 4 bytes then read the acpi ioport location. */
+        if ( RDEXACT(fd, &buf->viridian, sizeof(uint32_t)) ||
+             RDEXACT(fd, &buf->viridian, sizeof(uint64_t)) )
+        {
+            PERROR("error read the viridian flag");
+            return -1;
+        }
+        return pagebuf_get_one(xch, ctx, buf, fd, dom);
+
     default:
         if ( (count > MAX_BATCH_SIZE) || (count < 0) ) {
             ERROR("Max batch size exceeded (%d). Giving up.", count);
@@ -1440,6 +1451,9 @@ int xc_domain_restore(xc_interface *xch, int io_fd, uint32_t dom,
             fcntl(io_fd, F_SETFL, orig_io_fd_flags | O_NONBLOCK);
     }
 
+    if (pagebuf.viridian != 0)
+        xc_set_hvm_param(xch, dom, HVM_PARAM_VIRIDIAN, 1);
+
     if (pagebuf.acpi_ioport_location == 1) {
         DBGPRINTF("Use new firmware ioport from the checkpoint\n");
         xc_set_hvm_param(xch, dom, HVM_PARAM_ACPI_IOPORTS_LOCATION, 1);
diff --git a/tools/libxc/xc_domain_save.c b/tools/libxc/xc_domain_save.c
index 76a377acd4..88edd37fe0 100644
--- a/tools/libxc/xc_domain_save.c
+++ b/tools/libxc/xc_domain_save.c
@@ -1506,6 +1506,18 @@ int xc_domain_save(xc_interface *xch, int io_fd, uint32_t dom, uint32_t max_iter
             PERROR("Error when writing the firmware ioport version");
             goto out;
         }
+
+        chunk.id = XC_SAVE_ID_HVM_VIRIDIAN;
+        chunk.data = 0;
+        xc_get_hvm_param(xch, dom, HVM_PARAM_VIRIDIAN,
+                         (unsigned long *)&chunk.data);
+
+        if ( (chunk.data != 0) &&
+             wrexact(io_fd, &chunk, sizeof(chunk)) )
+        {
+            PERROR("Error when writing the viridian flag");
+            goto out;
+        }
     }
 
     if ( !callbacks->checkpoint )
diff --git a/tools/libxc/xg_save_restore.h b/tools/libxc/xg_save_restore.h
index 02116012e2..9648e80c3a 100644
--- a/tools/libxc/xg_save_restore.h
+++ b/tools/libxc/xg_save_restore.h
@@ -134,6 +134,7 @@
 #define XC_SAVE_ID_HVM_CONSOLE_PFN    -8 /* (HVM-only) */
 #define XC_SAVE_ID_LAST_CHECKPOINT    -9 /* Commit to restoring after completion of current iteration. */
 #define XC_SAVE_ID_HVM_ACPI_IOPORTS_LOCATION -10
+#define XC_SAVE_ID_HVM_VIRIDIAN       -11
 
 /*
 ** We process save/restore/migrate in batches of pages; the below
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;