From: Lukas Wunner <lukas@wunner.de>
To: Vidya Sagar <vidyas@nvidia.com>
Cc: bhelgaas@google.com, alex.williamson@redhat.com,
treding@nvidia.com, jonathanh@nvidia.com,
linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
vsethi@nvidia.com, kthota@nvidia.com, mmaddireddy@nvidia.com,
sagar.tv@gmail.com
Subject: Re: [PATCH V3] PCI: pciehp: Disable ACS Source Validation during hot-remove
Date: Sun, 30 Jul 2023 21:40:26 +0200 [thread overview]
Message-ID: <20230730194026.GA19962@wunner.de> (raw)
In-Reply-To: <20230730191519.3124390-1-vidyas@nvidia.com>
On Mon, Jul 31, 2023 at 12:45:19AM +0530, Vidya Sagar wrote:
> PCIe 6.0, 6.12.1.1 specifies that downstream devices are permitted to
> send upstream messages before they have been assigned a bus number and
> such messages have a Requester ID with Bus number set to 00h.
> If the Downstream port has ACS Source Validation enabled, these messages
> will be detected as ACS violation error.
>
> Hence, disable ACS Source Validation in the bridge device during
> hot-remove operation and re-enable it after enumeration of the
> downstream hierarchy but before binding the respective device drivers.
What are these messages that are sent before assignment of a bus number?
What's the user-visible issue that occurs when they're blocked?
Doesn't disabling Source Validation introduce a security hole because the
device may spoof messages before Source Validation is re-enabled?
PCIe r6.1 sec 6.12.1.1 does indeed point out that the downstream device
is *permitted* to send these messages but the Implementation Note
does *not* prescribe that Source Validation shall be disabled to let them
through. It merely points out that the messages may be filtered if
Source Validation is enabled.
Thanks,
Lukas
next prev parent reply other threads:[~2023-07-30 19:46 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-11 14:52 [PATCH V1] PCI: pciehp: Disable ACS Source Validation during hot-remove Vidya Sagar
2023-01-11 17:11 ` kernel test robot
2023-01-11 17:11 ` kernel test robot
2023-01-11 19:05 ` [PATCH V2] " Vidya Sagar
2023-02-14 23:30 ` Bjorn Helgaas
2023-07-30 19:14 ` Vidya Sagar
2023-07-30 19:15 ` [PATCH V3] " Vidya Sagar
2023-07-30 19:40 ` Lukas Wunner [this message]
2023-07-30 20:02 ` Vidya Sagar
2023-07-31 19:59 ` Lukas Wunner
2023-08-02 0:19 ` Dan Williams
2024-01-04 14:31 ` Vidya Sagar
2024-01-08 14:19 ` Lukas Wunner
2024-01-11 13:44 ` Vidya Sagar
2024-01-18 2:27 ` Vidya Sagar
2024-01-18 10:33 ` Lukas Wunner
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