From: sashiko-bot@kernel.org
To: "Zhiping Zhang" <zhipingz@meta.com>
Cc: dri-devel@lists.freedesktop.org, linux-pci@vger.kernel.org,
kvm@vger.kernel.org
Subject: Re: [PATCH v13 1/5] PCI/TPH: treat reserved 0b10 completer encoding as unsupported
Date: Fri, 31 Jul 2026 21:38:03 +0000 [thread overview]
Message-ID: <20260731213804.39BEE1F00AC4@smtp.kernel.org> (raw)
In-Reply-To: <20260731211601.3033906-2-zhipingz@meta.com>
> get_rp_completer_type() returns the Root Port's "TPH Completer
> Supported" field (bits 13:12 of Device Capabilities 2) verbatim. The
> 0b10 encoding is reserved, but pcie_enable_tph() feeds the raw value
> into the requester type:
>
> pdev->tph_req_type = min(pdev->tph_req_type, rp_req_type);
>
> and later writes tph_req_type to the TPH Requester Enable field, which
> only defines 0b00 (disable), 0b01 (TPH only) and 0b11 (extended TPH).
>
> No known hardware presents the reserved 0b10 in this field, so this is
> defensive hardening rather than a fix for observed silicon: fold the
> reserved encoding into "not supported" so only the three architected
> values can ever reach the Requester Enable field.
>
> Signed-off-by: Zhiping Zhang <zhipingz@meta.com>
Sashiko has reviewed this patch and found no issues. It looks great!
--
Sashiko AI review · https://sashiko.dev/#/patchset/20260731211601.3033906-1-zhipingz@meta.com?part=1
next prev parent reply other threads:[~2026-07-31 21:38 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-31 21:15 [PATCH v13 0/5] vfio/dma-buf: add TPH support for peer-to-peer access Zhiping Zhang
2026-07-31 21:15 ` [PATCH v13 1/5] PCI/TPH: treat reserved 0b10 completer encoding as unsupported Zhiping Zhang
2026-07-31 21:38 ` sashiko-bot [this message]
2026-07-31 21:15 ` [PATCH v13 2/5] PCI/TPH: Add requester/completer type helpers Zhiping Zhang
2026-07-31 21:40 ` sashiko-bot
2026-07-31 21:15 ` [PATCH v13 3/5] dma-buf: add optional get_pci_tph() callback Zhiping Zhang
2026-07-31 21:37 ` sashiko-bot
2026-07-31 21:15 ` [PATCH v13 4/5] vfio/pci: implement get_pci_tph and DMA_BUF_TPH feature Zhiping Zhang
2026-07-31 21:38 ` sashiko-bot
2026-07-31 21:15 ` [PATCH v13 5/5] RDMA/mlx5: get tph for p2p access when registering dma-buf mr Zhiping Zhang
2026-07-31 21:48 ` sashiko-bot
2026-07-31 22:59 ` Zhiping Zhang
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