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[80.230.25.21]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-43fe4e46471sm39731110f8f.28.2026.04.21.15.01.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Apr 2026 15:01:55 -0700 (PDT) Date: Tue, 21 Apr 2026 18:01:53 -0400 From: "Michael S. Tsirkin" To: linux-kernel@vger.kernel.org Cc: Andrew Morton , David Hildenbrand , Vlastimil Babka , Brendan Jackman , Michal Hocko , Suren Baghdasaryan , Jason Wang , Andrea Arcangeli , Gregory Price , linux-mm@kvack.org, virtualization@lists.linux.dev, Xuan Zhuo , Eugenio =?utf-8?B?UMOpcmV6?= Subject: [PATCH RFC v3 13/19] virtio_balloon: a hack to enable host-zeroed page optimization Message-ID: <585a71dace8705d604da7d3093c70896eef5b2bc.1776808210.git.mst@redhat.com> References: MIME-Version: 1.0 In-Reply-To: X-Mailer: git-send-email 2.27.0.106.g8ac3dc51b1 X-Mutt-Fcc: =sent X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: HrFMu5972J6mqxFwt4BJfU7ERsjf2ENfZJx4IckafoU_1776808917 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 280CBC001A X-Stat-Signature: 1ndp7gk3dq33uaj8jgcx3anm6rggsod8 X-Rspam-User: X-HE-Tag: 1776808919-549447 X-HE-Meta: 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 hk02kl3n GW2CdgGJRQy0GBVfYmXchnK9xvsNkmb0dHswOHQKqB4lj/i/Gn6hssIZWJ0lmJ0T5e/lIHvD0s+yEjcB1AjqSRJdiHBIU+ir9wGOwqv/gTRY1f17NzHmwCYBZ8oPH6GsXR4gj96l0Z9ALZ82Ifk0yFDa+wJIuwb6DPp2zH9E5whLlLqxMWF43JVAm5LyoNeoyOLGfAviRx7Rnop5v7qlr71ap2acJGGUGeHjRNnwuHOOwKckwVq+3liTNTXW7MlcXB5KuQWeqJwc+jvTnD1lSZiTHub4bHWufqolNK9YxpvTqvFcNUJ3gg3wC6tLUUiy5ECaHgdvYZBxcEph1EOXMo6V66+c2+kt0FSeuthOocOB/jZ8LWMjnia/GAg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Add a module parameter host_zeroes_pages to opt in to the zeroed page optimization. A proper virtio feature flag is needed before this can be merged. insmod virtio_balloon.ko host_zeroes_pages=1 Signed-off-by: Michael S. Tsirkin Assisted-by: Claude:claude-opus-4-6 --- drivers/virtio/virtio_balloon.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index d1fbc8fe8470..165b123caa64 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -19,6 +19,11 @@ #include #include +static bool host_zeroes_pages; +module_param(host_zeroes_pages, bool, 0444); +MODULE_PARM_DESC(host_zeroes_pages, + "Host zeroes reported pages, skip guest re-zeroing"); + /* * Balloon device works in 4K page units. So each page is pointed to by * multiple balloon pages. All memory counters in this driver are in balloon @@ -1039,6 +1044,8 @@ static int virtballoon_probe(struct virtio_device *vdev) vb->pr_dev_info.order = 5; #endif + /* TODO: needs a virtio feature flag */ + vb->pr_dev_info.host_zeroes_pages = host_zeroes_pages; err = page_reporting_register(&vb->pr_dev_info); if (err) goto out_unregister_oom; -- MST