diff options
| author | Michael Kelley <mhklinux@outlook.com> | 2024-01-22 19:20:28 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-02-01 03:19:06 +0300 |
| commit | 4d53556d87cd335235261765dd91f1563fe45326 (patch) | |
| tree | 1f1159ad4cb91d53b7656cdc5dadb7b892ce82be /drivers/net | |
| parent | b7d2eee1f53899b53f069bba3a59a419fc3d331b (diff) | |
| download | linux-4d53556d87cd335235261765dd91f1563fe45326.tar.xz | |
hv_netvsc: Calculate correct ring size when PAGE_SIZE is not 4 Kbytes
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>
Diffstat (limited to 'drivers/net')
| -rw-r--r-- | drivers/net/hyperv/netvsc_drv.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c index 706ea5263e87..cd15d7b380ab 100644 --- 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); |