linux-kernel - Re: [PATCH v2 2/5] bus: mhi: host: pci_generic: Read SUBSYSTEM_VENDOR

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]

Message-ID: <luaoyvwqp3fpvqgybhstnnrutn46ry3tyfxw2launvnxzfvyqo@pdfdpfocfq6k>
Date: Wed, 6 Aug 2025 22:29:57 +0530
From: Manivannan Sadhasivam <mani@...nel.org>
To: Vivek.Pernamitta@...cinc.com
Cc: mhi@...ts.linux.dev, linux-arm-msm@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Vivek Pernamitta <quic_vpernami@...cinc.com>, 
	Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
Subject: Re: [PATCH v2 2/5] bus: mhi: host: pci_generic: Read
 SUBSYSTEM_VENDOR_ID for VF's to check status

On Thu, Jul 10, 2025 at 02:28:33PM GMT, Vivek.Pernamitta@...cinc.com wrote:
> From: Vivek Pernamitta <quic_vpernami@...cinc.com>
> 
> In SRIOV enabled devices, the VF DEVICE/VENDOR ID register returns FFFFh
> when read (PCIe SRIOV spec-3.4.1.1). Therefore, read the PCIe
> SUBSYSTEM_VENDOR_ID to check if the device is active.
> 
> Signed-off-by: Vivek Pernamitta <quic_vpernami@...cinc.com>
> Reviewed-by: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
> ---
>  drivers/bus/mhi/host/pci_generic.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/bus/mhi/host/pci_generic.c b/drivers/bus/mhi/host/pci_generic.c
> index 7d0ac1c34ddf95ace2a85e5f08884f51604d9b0f..4bafe93b56c54e2b091786e7fcd68a36c8247b8e 100644
> --- a/drivers/bus/mhi/host/pci_generic.c
> +++ b/drivers/bus/mhi/host/pci_generic.c
> @@ -1025,8 +1025,10 @@ static bool mhi_pci_is_alive(struct mhi_controller *mhi_cntrl)
>  	struct pci_dev *pdev = to_pci_dev(mhi_cntrl->cntrl_dev);
>  	u16 vendor = 0;
>  
> -	if (pci_read_config_word(pdev, PCI_VENDOR_ID, &vendor))
> -		return false;
> +	if (pdev->is_virtfn)
> +		pci_read_config_word(pdev, PCI_SUBSYSTEM_VENDOR_ID, &vendor);
> +	else
> +		pci_read_config_word(pdev, PCI_VENDOR_ID, &vendor);

You should not read the sub Vendor ID for VF. PCIe spec suggests reading the PF
Vendor ID for VF. So you should just use pci_physfn() API as below:

	pci_read_config_word(pci_physfn(pdev), PCI_VENDOR_ID, &vendor);

This will work for both PF and VF.

- Mani

-- 
மணிவண்ணன் சதாசிவம்