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Re: [PATCH] machine/memory encryption: Disable mem merge

From: Philippe Mathieu-Daudé
Subject: Re: [PATCH] machine/memory encryption: Disable mem merge
Date: Thu, 30 Jan 2020 20:33:35 +0100
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2

On 1/30/20 6:50 PM, Dr. David Alan Gilbert (git) wrote:
From: "Dr. David Alan Gilbert" <address@hidden>

When a host is running with memory encryption, the memory isn't visible
to the host kernel; attempts to merge that memory are futile because
what it's really comparing is encrypted memory, usually encrypted
with different keys.

Automatically turn mem-merge off when memory encryption is specified.


Signed-off-by: Dr. David Alan Gilbert <address@hidden>
  hw/core/machine.c | 8 ++++++++
  1 file changed, 8 insertions(+)

diff --git a/hw/core/machine.c b/hw/core/machine.c
index 3e288bfceb..029e1f85b8 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -419,6 +419,14 @@ static void machine_set_memory_encryption(Object *obj, 
const char *value,
      ms->memory_encryption = g_strdup(value);
+    /*
+     * With memory encryption, the host can't see the real contents of RAM,
+     * so there's no point in it trying to merge areas.
+     */
+    if (value) {
+        machine_set_mem_merge(obj, false, errp);

Using the helper is cleaner than accessing ms->mem_merge.
Reviewed-by: Philippe Mathieu-Daudé <address@hidden>

+    }
static bool machine_get_nvdimm(Object *obj, Error **errp)

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