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| author | Michael Kelley <mhklinux@outlook.com> | 2024-01-22 08:20:28 -0800 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2024-01-23 17:19:42 -0800 |
| commit | 6941f67ad37d5465b75b9ffc498fcf6897a3c00e (patch) | |
| tree | 22ec9831af657ba80389af56119a7a7f02d84819 /drivers/net/hyperv | |
| parent | 3222bc997a24821ea4f96d1a9108dafeadc00cfb (diff) | |
| download | linux-6941f67ad37d5465b75b9ffc498fcf6897a3c00e.tar.gz linux-6941f67ad37d5465b75b9ffc498fcf6897a3c00e.tar.bz2 linux-6941f67ad37d5465b75b9ffc498fcf6897a3c00e.zip | |
hv_netvsc: Calculate correct ring size when PAGE_SIZE is not 4 Kbytes
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>
Diffstat (limited to 'drivers/net/hyperv')
| -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 4406427d4617..273bd8a20122 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 | @@ -2807,7 +2807,7 @@ 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); |