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From:   Vitaly Kuznetsov <vkuznets@redhat.com>
To:     Boqun Feng <boqun.feng@gmail.com>, linux-hyperv@vger.kernel.org,
        linux-kernel@vger.kernel.org
Cc:     "K. Y. Srinivasan" <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Stephen Hemminger <sthemmin@microsoft.com>,
        Wei Liu <wei.liu@kernel.org>, Dexuan Cui <decui@microsoft.com>,
        Boqun Feng <boqun.feng@gmail.com>, stable@vger.kernel.org,
        Baihua Lu <baihua.lu@microsoft.com>
Subject: Re: [PATCH] Drivers: hv: balloon: Use VMBUS_RING_SIZE() wrapper for
 dm_ring_size
In-Reply-To: <20211101150026.736124-1-boqun.feng@gmail.com>
References: <20211101150026.736124-1-boqun.feng@gmail.com>
Date:   Tue, 02 Nov 2021 14:03:57 +0100
Message-ID: <87h7cuk8ua.fsf@vitty.brq.redhat.com>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

Boqun Feng <boqun.feng@gmail.com> writes:

> Baihua reported an error when boot an ARM64 guest with PAGE_SIZE=64k and
> BALLOON is enabled:
>
> 	hv_vmbus: registering driver hv_balloon
> 	hv_vmbus: probe failed for device 1eccfd72-4b41-45ef-b73a-4a6e44c12924 (-22)
>
> The cause of this is that the ringbuffer size for hv_balloon is not
> adjusted with VMBUS_RING_SIZE(), which makes the size not large enough
> for ringbuffers on guest with PAGE_SIZE=64k. Therefore use
> VMBUS_RING_SIZE() to calculate the ringbuffer size. Note that the old
> size (20 * 1024) counts a 4k header in the total size, while
> VMBUS_RING_SIZE() expects the parameter as the payload size, so use
> 16 * 1024.
>
> Cc: <stable@vger.kernel.org> # 5.15.x
> Reported-by: Baihua Lu <baihua.lu@microsoft.com>
> Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
> ---
>  drivers/hv/hv_balloon.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c
> index 7f11ea07d698..ca873a3b98db 100644
> --- a/drivers/hv/hv_balloon.c
> +++ b/drivers/hv/hv_balloon.c
> @@ -480,7 +480,7 @@ module_param(pressure_report_delay, uint, (S_IRUGO | S_IWUSR));
>  MODULE_PARM_DESC(pressure_report_delay, "Delay in secs in reporting pressure");
>  static atomic_t trans_id = ATOMIC_INIT(0);
>  
> -static int dm_ring_size = 20 * 1024;
> +static int dm_ring_size = VMBUS_RING_SIZE(16 * 1024);
>  
>  /*
>   * Driver specific state.

Tested-by: Vitaly Kuznetsov <vkuznets@redhat.com>

Thanks!

-- 
Vitaly