6.7-stable review patch. If anyone has any objections, please let me know.
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From: Michael Kelley mhklinux@outlook.com
commit 6941f67ad37d5465b75b9ffc498fcf6897a3c00e upstream.
Current code in netvsc_drv_init() incorrectly assumes that PAGE_SIZE is 4 Kbytes, which is wrong on ARM64 with 16K or 64K page size. As a result, the default VMBus ring buffer size on ARM64 with 64K page size is 8 Mbytes instead of the expected 512 Kbytes. While this doesn't break anything, a typical VM with 8 vCPUs and 8 netvsc channels wastes 120 Mbytes (8 channels * 2 ring buffers/channel * 7.5 Mbytes/ring buffer).
Unfortunately, the module parameter specifying the ring buffer size is in units of 4 Kbyte pages. Ideally, it should be in units that are independent of PAGE_SIZE, but backwards compatibility prevents changing that now.
Fix this by having netvsc_drv_init() hardcode 4096 instead of using PAGE_SIZE when calculating the ring buffer size in bytes. Also use the VMBUS_RING_SIZE macro to ensure proper alignment when running with page size larger than 4K.
Cc: stable@vger.kernel.org # 5.15.x Fixes: 7aff79e297ee ("Drivers: hv: Enable Hyper-V code to be built on ARM64") Signed-off-by: Michael Kelley mhklinux@outlook.com Link: https://lore.kernel.org/r/20240122162028.348885-1-mhklinux@outlook.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/hyperv/netvsc_drv.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/net/hyperv/netvsc_drv.c +++ b/drivers/net/hyperv/netvsc_drv.c @@ -44,7 +44,7 @@
static unsigned int ring_size __ro_after_init = 128; module_param(ring_size, uint, 0444); -MODULE_PARM_DESC(ring_size, "Ring buffer size (# of pages)"); +MODULE_PARM_DESC(ring_size, "Ring buffer size (# of 4K pages)"); unsigned int netvsc_ring_bytes __ro_after_init;
static const u32 default_msg = NETIF_MSG_DRV | NETIF_MSG_PROBE | @@ -2805,7 +2805,7 @@ static int __init netvsc_drv_init(void) pr_info("Increased ring_size to %u (min allowed)\n", ring_size); } - netvsc_ring_bytes = ring_size * PAGE_SIZE; + netvsc_ring_bytes = VMBUS_RING_SIZE(ring_size * 4096);
register_netdevice_notifier(&netvsc_netdev_notifier);