* [PATCH] machine/memory encryption: Disable mem merge
@ 2020-01-30 17:50 Dr. David Alan Gilbert (git)
2020-01-30 19:33 ` Philippe Mathieu-Daudé
2020-03-09 20:47 ` Eduardo Habkost
0 siblings, 2 replies; 3+ messages in thread
From: Dr. David Alan Gilbert (git) @ 2020-01-30 17:50 UTC (permalink / raw)
To: qemu-devel, ehabkost, marcel.apfelbaum, brijesh.singh; +Cc: aarcange
From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
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.
https://bugzilla.redhat.com/show_bug.cgi?id=1796356
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
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,
g_free(ms->memory_encryption);
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);
+ }
}
static bool machine_get_nvdimm(Object *obj, Error **errp)
--
2.24.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] machine/memory encryption: Disable mem merge
2020-01-30 17:50 [PATCH] machine/memory encryption: Disable mem merge Dr. David Alan Gilbert (git)
@ 2020-01-30 19:33 ` Philippe Mathieu-Daudé
2020-03-09 20:47 ` Eduardo Habkost
1 sibling, 0 replies; 3+ messages in thread
From: Philippe Mathieu-Daudé @ 2020-01-30 19:33 UTC (permalink / raw)
To: Dr. David Alan Gilbert (git),
qemu-devel, ehabkost, marcel.apfelbaum, brijesh.singh
Cc: aarcange
On 1/30/20 6:50 PM, Dr. David Alan Gilbert (git) wrote:
> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
>
> 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.
>
> https://bugzilla.redhat.com/show_bug.cgi?id=1796356
>
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> ---
> 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,
>
> g_free(ms->memory_encryption);
> 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 <philmd@redhat.com>
> + }
> }
>
> static bool machine_get_nvdimm(Object *obj, Error **errp)
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] machine/memory encryption: Disable mem merge
2020-01-30 17:50 [PATCH] machine/memory encryption: Disable mem merge Dr. David Alan Gilbert (git)
2020-01-30 19:33 ` Philippe Mathieu-Daudé
@ 2020-03-09 20:47 ` Eduardo Habkost
1 sibling, 0 replies; 3+ messages in thread
From: Eduardo Habkost @ 2020-03-09 20:47 UTC (permalink / raw)
To: Dr. David Alan Gilbert (git); +Cc: aarcange, brijesh.singh, qemu-devel
On Thu, Jan 30, 2020 at 05:50:46PM +0000, Dr. David Alan Gilbert (git) wrote:
> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
>
> 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.
>
> https://bugzilla.redhat.com/show_bug.cgi?id=1796356
>
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Queued, thanks.
--
Eduardo
^ permalink raw reply [flat|nested] 3+ messages in thread
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2020-01-30 17:50 [PATCH] machine/memory encryption: Disable mem merge Dr. David Alan Gilbert (git)
2020-01-30 19:33 ` Philippe Mathieu-Daudé
2020-03-09 20:47 ` Eduardo Habkost
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