From: Friedrich Weber <f.weber@proxmox.com>
To: Proxmox VE development discussion <pve-devel@lists.proxmox.com>,
Fiona Ebner <f.ebner@proxmox.com>
Subject: Re: [pve-devel] [PATCH qemu-server/manager/docs 0/3] close #5291: support disabling KSM for specific VMs
Date: Tue, 18 Feb 2025 13:39:02 +0100 [thread overview]
Message-ID: <753aa95e-77c3-4df4-9217-2c736703b747@proxmox.com> (raw)
In-Reply-To: <20250217150444.142182-1-f.ebner@proxmox.com>
On 17/02/2025 16:04, Fiona Ebner wrote:
> KSM exposes a guest's virtual memory to side-channel attacks. Add a VM
> configuration option to disable KSM for specific VMs that need to be
> protected against such attacks. This makes it possible to still
> benefit from KSM for other processes on the host rather than needing
> to turn of KSM completely.
As I had a KSM test setup available, I quickly tested this:
- created 4 VMs that, together, exceed 80% host RAM usage
- on one VM, set `allow-ksm=0` (tested via CLI and GUI)
- started VMs, monitored /proc/PID/ksm_stat
- only for the VM with `allow-ksm=0`, ksm_rmap_items/ksm_merging_pages
in ksm_stat stayed at 0. For all other VMs, both started to grow after a
couple of minutes.
So consider this:
Tested-by: Friedrich Weber <f.weber@proxmox.com>
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prev parent reply other threads:[~2025-02-18 12:39 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-17 15:04 Fiona Ebner
2025-02-17 15:04 ` [pve-devel] [PATCH qemu-server 1/3] " Fiona Ebner
2025-02-17 15:04 ` [pve-devel] [PATCH manager 2/3] close #5291: ui: qemu: memory edit: " Fiona Ebner
2025-02-17 15:04 ` [pve-devel] [PATCH docs 3/3] kernel samepage merging: describe how to disable for a specific VM Fiona Ebner
2025-02-18 12:39 ` Friedrich Weber [this message]
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