netdev - Re: [PATCH V4 00/12] PCIe TPH and cache direct injection support

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: <0d9b0e83-9f54-4471-bdef-5bbe84cc7aec@amd.com>
Date: Thu, 5 Sep 2024 10:45:57 -0500
From: Wei Huang <wei.huang2@....com>
To: Bjorn Helgaas <helgaas@...nel.org>
Cc: linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-doc@...r.kernel.org, netdev@...r.kernel.org,
 Jonathan.Cameron@...wei.com, corbet@....net, davem@...emloft.net,
 edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
 alex.williamson@...hat.com, gospo@...adcom.com, michael.chan@...adcom.com,
 ajit.khaparde@...adcom.com, somnath.kotur@...adcom.com,
 andrew.gospodarek@...adcom.com, manoj.panicker2@....com,
 Eric.VanTassell@....com, vadim.fedorenko@...ux.dev, horms@...nel.org,
 bagasdotme@...il.com, bhelgaas@...gle.com, lukas@...ner.de,
 paul.e.luse@...el.com, jing2.liu@...el.com
Subject: Re: [PATCH V4 00/12] PCIe TPH and cache direct injection support



On 9/4/24 15:20, Bjorn Helgaas wrote:
> To me, this series would make more sense if we squashed these
> together:
> 
>   PCI: Introduce PCIe TPH support framework
>   PCI: Add TPH related register definition
>   PCI/TPH: Add pcie_enable_tph() to enable TPH
>   PCI/TPH: Add pcie_disable_tph() to disable TPH
>   PCI/TPH: Add save/restore support for TPH
> 
> These would add the "minimum viable functionality", e.g., enable TPH
> just for Processing Hints, with no Steering Tag support at all.  Would
> also include "pci=notph".

Will do

> 
>   PCI/TPH: Add pcie_tph_set_st_entry() to set ST tag
>   PCI/TPH: Add pcie_tph_get_cpu_st() to get ST tag
> 
> And squash these also to add Steering Tag support in a single commit,
> including enhancing the save/restore.

Can you elaborate on save/restore enhancement? Assuming that the first
combined patch will have save/restore support as suggested. Are you
talking about the ST entries save/restore as the enhancements (see
below), because the second combined patch deals with ST?

        st_entry = (u16 *)cap;
        offset = PCI_TPH_BASE_SIZEOF;
	num_entries = get_st_table_size(pdev);
        for (i = 0; i < num_entries; i++) {
                pci_write_config_word(pdev, pdev->tph_cap + offset,
 	                              *st_entry++);
                offset += sizeof(u16);
	}

> 
>   PCI/TPH: Add pcie_tph_modes() to query TPH modes
>   PCI/TPH: Add pcie_tph_enabled() to check TPH state
> 
> And maybe we can get away without these altogether.  I mentioned
> pcie_tph_modes() elsewhere; seems possibly unnecessary since drivers
> can just request the mode they want and we'll fail if it's not
> supported.
> 
> Drivers should also be able to remember whether they enabled TPH
> successfully without us having to remind them.