[PATCH v2 4/5] common/domain: add a domain context record for shared_info...

[Paul Durrant <paul@xxxxxxx>]

... and update xen-domctx to dump some information describing the record.

Signed-off-by: Paul Durrant <pdurrant@xxxxxxxxxx>
---
Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Cc: Wei Liu <wl@xxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Cc: George Dunlap <george.dunlap@xxxxxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Julien Grall <julien@xxxxxxx>
Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>

v2:
 - Drop the header change to define a 'Xen' page size and instead use a
   variable length struct now that the framework makes this is feasible
 - Guard use of 'has_32bit_shinfo' in common code with CONFIG_COMPAT
---
 tools/misc/xen-domctx.c   | 11 ++++++
 xen/common/domain.c       | 81 +++++++++++++++++++++++++++++++++++++++
 xen/include/public/save.h | 10 ++++-
 3 files changed, 101 insertions(+), 1 deletion(-)

diff --git a/tools/misc/xen-domctx.c b/tools/misc/xen-domctx.c
index d663522a8b..a8d3922321 100644
--- a/tools/misc/xen-domctx.c
+++ b/tools/misc/xen-domctx.c
@@ -59,6 +59,16 @@ static void dump_header(struct domain_save_descriptor *desc)
     off += desc->length;
 }
 
+static void dump_shared_info(struct domain_save_descriptor *desc)
+{
+    DOMAIN_SAVE_TYPE(SHARED_INFO) s;
+    READ(s);
+    printf("    SHARED_INFO: field_width %u buffer size: %lu\n",
+           s.field_width, desc->length - sizeof(s));
+
+    off += desc->length;
+}
+
 static void dump_end(struct domain_save_descriptor *desc)
 {
     DOMAIN_SAVE_TYPE(END) e;
@@ -125,6 +135,7 @@ int main(int argc, char **argv)
         switch (desc.typecode)
         {
         case DOMAIN_SAVE_CODE(HEADER): dump_header(&desc); break;
+        case DOMAIN_SAVE_CODE(SHARED_INFO): dump_shared_info(&desc); break;
         case DOMAIN_SAVE_CODE(END): dump_end(&desc); return 0;
         default:
             printf("Unknown type %u: skipping\n", desc.typecode);
diff --git a/xen/common/domain.c b/xen/common/domain.c
index 3dcd73f67c..8b72462e07 100644
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -33,6 +33,7 @@
 #include <xen/xenoprof.h>
 #include <xen/irq.h>
 #include <xen/argo.h>
+#include <xen/save.h>
 #include <asm/debugger.h>
 #include <asm/p2m.h>
 #include <asm/processor.h>
@@ -1646,6 +1647,86 @@ int continue_hypercall_on_cpu(
     return 0;
 }
 
+static int save_shared_info(const struct vcpu *v, struct domain_context *c,
+                            bool dry_run)
+{
+    struct domain *d = v->domain;
+    struct domain_shared_info_context ctxt = {};
+    size_t hdr_size = offsetof(typeof(ctxt), buffer);
+    size_t size = hdr_size + PAGE_SIZE;
+    int rc;
+
+    rc = DOMAIN_SAVE_BEGIN(SHARED_INFO, c, v, size);
+    if ( rc )
+        return rc;
+
+    if ( !dry_run )
+        ctxt.field_width =
+#ifdef CONFIG_COMPAT
+            has_32bit_shinfo(d) ? 4 :
+#endif
+            8;
+
+    rc = domain_save_data(c, &ctxt, hdr_size);
+    if ( rc )
+        return rc;
+
+    rc = domain_save_data(c, d->shared_info, PAGE_SIZE);
+    if ( rc )
+        return rc;
+
+    return domain_save_end(c);
+}
+
+static int load_shared_info(struct vcpu *v, struct domain_context *c)
+{
+    struct domain *d = v->domain;
+    struct domain_shared_info_context ctxt = {};
+    size_t hdr_size = offsetof(typeof(ctxt), buffer);
+    size_t size = hdr_size + PAGE_SIZE;
+    unsigned int i;
+    int rc;
+
+    rc = DOMAIN_LOAD_BEGIN(SHARED_INFO, c, v, size, true);
+    if ( rc )
+        return rc;
+
+    rc = domain_load_data(c, &ctxt, hdr_size);
+    if ( rc )
+        return rc;
+
+    for ( i = 0; i < ARRAY_SIZE(ctxt.pad); i++ )
+        if ( ctxt.pad[i] )
+            return -EINVAL;
+
+    switch ( ctxt.field_width )
+    {
+#ifdef CONFIG_COMPAT
+    case 4:
+        d->arch.has_32bit_shinfo = 1;
+        break;
+#endif
+    case 8:
+#ifdef CONFIG_COMPAT
+        d->arch.has_32bit_shinfo = 0;
+#endif
+        break;
+
+    default:
+        rc = -EINVAL;
+        break;
+    }
+
+    rc = domain_load_data(c, d->shared_info, PAGE_SIZE);
+    if ( rc )
+        return rc;
+
+    return domain_load_end(c);
+}
+
+DOMAIN_REGISTER_SAVE_RESTORE(SHARED_INFO, false, save_shared_info,
+                             load_shared_info);
+
 /*
  * Local variables:
  * mode: C
diff --git a/xen/include/public/save.h b/xen/include/public/save.h
index 7e5f8752bd..ed994a8765 100644
--- a/xen/include/public/save.h
+++ b/xen/include/public/save.h
@@ -79,6 +79,14 @@ struct domain_save_header {
 };
 DECLARE_DOMAIN_SAVE_TYPE(HEADER, 1, struct domain_save_header);
 
-#define DOMAIN_SAVE_CODE_MAX 1
+struct domain_shared_info_context {
+    uint8_t field_width;
+    uint8_t pad[7];
+    uint8_t buffer[]; /* Implementation specific size */
+};
+
+DECLARE_DOMAIN_SAVE_TYPE(SHARED_INFO, 2, struct domain_shared_info_context);
+
+#define DOMAIN_SAVE_CODE_MAX 2
 
 #endif /* __XEN_PUBLIC_SAVE_H__ */
-- 
2.20.1