linux-kernel - Re: [PATCH V2 3/4] misc: vop: simply return the saved dma address instead of virt_to

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Tue, 29 Sep 2020 11:26:43 +0100
From:   Christoph Hellwig <hch@...radead.org>
To:     Sherry Sun <sherry.sun@....com>
Cc:     hch@...radead.org, sudeep.dutt@...el.com, ashutosh.dixit@...el.com,
        arnd@...db.de, gregkh@...uxfoundation.org, kishon@...com,
        lorenzo.pieralisi@....com, linux-kernel@...r.kernel.org,
        linux-pci@...r.kernel.org, linux-imx@....com
Subject: Re: [PATCH V2 3/4] misc: vop: simply return the saved dma address
 instead of virt_to_phys

On Tue, Sep 29, 2020 at 04:44:24PM +0800, Sherry Sun wrote:
> The device page and vring should use consistent memory which are
> allocated by dma_alloc_coherent api, when user space wants to get its
> physical address, virt_to_phys cannot be used, should simply return the
> saved device page dma address by get_dp_dma callback and the vring dma
> address saved in mic_vqconfig.

More importantly you can't just all virt_to_phys on a return value
from dma_alloc_coherent, so this needs to be folded into patch 1.

>  	if (!offset) {
> -		*pa = virt_to_phys(vpdev->hw_ops->get_dp(vpdev));
> +		if (vpdev->hw_ops->get_dp_dma)
> +			*pa = vpdev->hw_ops->get_dp_dma(vpdev);
> +		else {
> +			dev_err(vop_dev(vdev), "can't get device page physical address\n");
> +			return -EINVAL;
> +		}

I don't think we need the NULL check here.  Wouldn't it also make sense
to return the virtual and DMA address from ->get_dp instead of adding
another method?