linux-kernel - Re: [PATCH] Drivers: hv: Do not free synic pages when they were not allocated

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Date:   Tue, 4 Apr 2023 16:09:12 +0530
From:   Jinank Jain <jinankjain@...ux.microsoft.com>
To:     Nuno Das Neves <nunodasneves@...ux.microsoft.com>,
        linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     mikelley@...rosoft.com, kys@...rosoft.com, wei.liu@...nel.org,
        haiyangz@...rosoft.com, decui@...rosoft.com
Subject: Re: [PATCH] Drivers: hv: Do not free synic pages when they were not
 allocated

Reviewed-by: Jinank Jain <jinankjain@...ux.microsoft.com>

On 4/4/2023 4:52 AM, Nuno Das Neves wrote:
> In case of root partition or snp, the synic pages are allocated by the
> hypervisor instead of the kernel, so they should not be freed.
>
> Signed-off-by: Nuno Das Neves <nunodasneves@...ux.microsoft.com>
> ---
>   drivers/hv/hv.c | 6 ++++--
>   1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
> index c7f7652932ca..a10cf642c9ad 100644
> --- a/drivers/hv/hv.c
> +++ b/drivers/hv/hv.c
> @@ -193,8 +193,10 @@ void hv_synic_free(void)
>   		struct hv_per_cpu_context *hv_cpu
>   			= per_cpu_ptr(hv_context.cpu_context, cpu);
>   
> -		free_page((unsigned long)hv_cpu->synic_event_page);
> -		free_page((unsigned long)hv_cpu->synic_message_page);
> +		if (!hv_isolation_type_snp() && !hv_root_partition) {
> +			free_page((unsigned long)hv_cpu->synic_event_page);
> +			free_page((unsigned long)hv_cpu->synic_message_page);
> +		}
>   		free_page((unsigned long)hv_cpu->post_msg_page);
>   	}
>