[PATCH v4 06/21] target/i386: sev: Use ram_block_discard_disable()

[David Hildenbrand <david@xxxxxxxxxx>]

AMD SEV will pin all guest memory, mark discarding of RAM broken. At the
time this is called, we cannot have anyone active that relies on discards
to work properly - let's still implement error handling.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@xxxxxxxxxx>
Cc: "Michael S. Tsirkin" <mst@xxxxxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: Richard Henderson <rth@xxxxxxxxxxx>
Cc: Eduardo Habkost <ehabkost@xxxxxxxxxx>
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
---
 target/i386/sev.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/target/i386/sev.c b/target/i386/sev.c
index 51cdbe5496..4a4863db28 100644
--- a/target/i386/sev.c
+++ b/target/i386/sev.c
@@ -649,6 +649,12 @@ sev_guest_init(const char *id)
     uint32_t host_cbitpos;
     struct sev_user_data_status status = {};
 
+    ret = ram_block_discard_disable(true);
+    if (ret) {
+        error_report("%s: cannot disable RAM discard", __func__);
+        return NULL;
+    }
+
     sev_state = s = g_new0(SEVState, 1);
     s->sev_info = lookup_sev_guest_info(id);
     if (!s->sev_info) {
@@ -724,6 +730,7 @@ sev_guest_init(const char *id)
 err:
     g_free(sev_state);
     sev_state = NULL;
+    ram_block_discard_disable(false);
     return NULL;
 }
 
-- 
2.26.2