target/i386: sev: Do not unpin ram device memory region

The commit referenced below skipped pinning ram device memory when
ram blocks are added, we need to do the same when they're removed.

Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Fixes: cedc0ad5 ("target/i386: sev: Do not pin the ram device memory region")
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Message-Id: <156320087103.2556.10983987500488190423.stgit@gimli.home>
Reviewed-by: Singh, Brijesh <brijesh.singh@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

target/i386/sev.c

@@ -161,6 +161,17 @@ sev_ram_block_removed(RAMBlockNotifier *n, void *host, size_t size)
 {
     int r;
     struct kvm_enc_region range;
+    ram_addr_t offset;
+    MemoryRegion *mr;
+
+    /*
+     * The RAM device presents a memory region that should be treated
+     * as IO region and should not have been pinned.
+     */
+    mr = memory_region_from_host(host, &offset);
+    if (mr && memory_region_is_ram_device(mr)) {
+        return;
+    }
 
     range.addr = (__u64)(unsigned long)host;
     range.size = size;