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Mon, 13 Jul 2026 14:40:56 -0700 (PDT) Received: from twshared10463.03.snb2.facebook.com (2620:10d:c085:108::4) by mail.thefacebook.com (2620:10d:c08b:78::c78f) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.2.2562.41; Mon, 13 Jul 2026 21:40:54 +0000 Received: by devbig259.ftw1.facebook.com (Postfix, from userid 664516) id 54AC441FE14FD; Mon, 13 Jul 2026 14:40:30 -0700 (PDT) From: Zhiping Zhang To: Bjorn Helgaas , CC: Christian Konig , Alex Williamson , , , Zhiping Zhang Subject: [PATCH v1] PCI/TPH: fold reserved completer encoding in get_rp_completer_type() Date: Mon, 13 Jul 2026 14:40:25 -0700 Message-ID: <20260713214026.793795-1-zhipingz@meta.com> X-Mailer: git-send-email 2.52.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-FB-Internal: Safe X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzEzMDIyMiBTYWx0ZWRfXzSD8SlV7UU9B 52aD29W6ZJ/mwn8iDiNe26lvy9dpJZk3/kyhScfW7tf6KmzEAGMYseYEbfctLa7K1NF7mmuO1nr lX3JOnG8G2OhFMb8Yinz9GGaAjIRnCtyVmGyYvlEZszXtCQmRbAVCBfoYEKAAaw7kzu7BYbN0c3 EfvvAWDuMhlgH9OOouwRTQZRjld0VTCeL/nSQOypSc2vTiiO/VLL7tdx84CkPIQFEyfjZfFc907 nVk1vy4+Ot7uzdBi8Wuwp/HmBP8NPkyX7HEeUt7SGyXksGcUcH0oSRzUZqtsYeXUiZiwjuD6QVG CmLmAbxCVdNT0+8ja02Z8P5Cq52YIRDMnoFf6oQ6MZaKIKO/fpxSRpS2c54MiDjYTzJdCXYsfig BKy0MF8I2g1ry033AJQHEZ3CZEUCU9svAwp0lFDyVpAXBS7qovyP1kQG/u4YfBtuvHb/8AdLkx6 lOBD/1AUhzXjESlinLA== X-Authority-Analysis: v=2.4 cv=I4VVgtgg c=1 sm=1 tr=0 ts=6a555b68 cx=c_pps a=CB4LiSf2rd0gKozIdrpkBw==:117 a=CB4LiSf2rd0gKozIdrpkBw==:17 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=7x6HtfJdh03M6CCDgxCd:22 a=8elwO82fXORLTBIkMd32:22 a=VabnemYjAAAA:8 a=SdC2vBNBQt3qShdCGKMA:9 a=gKebqoRLp9LExxC7YDUY:22 X-Proofpoint-GUID: CCumrSTWsJM93uqECi8GZ2V-lpEQlm3s X-Proofpoint-ORIG-GUID: CCumrSTWsJM93uqECi8GZ2V-lpEQlm3s X-Proofpoint-Spam-Info: AW1haW4tMjYwNzEzMDIyMiBTYWx0ZWRfX/xD+e1+l6to4 SZRpPD3DbkCjipJWmMyPhXiNqbMXkg9vidd3B6Pqs1vmqnPIhuDolwSBDg3yGpOH+a2ImKYI4vW U/ZlviwKfBuTSi6SXyoIRhy6Z0yHKn0= X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-07-13_05,2026-07-10_01,2025-10-01_01 Content-Type: text/plain; charset="utf-8" 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 =3D 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). If a Root Port ever presents the reserved 0b10, that value could be written back to hardware, risking undefined behavior. Fold the reserved encoding into "not supported" so only the three defined values can propagate. Fixes: f69767a1ada3 ("PCI: Add TLP Processing Hints (TPH) support") Signed-off-by: Zhiping Zhang --- drivers/pci/tph.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/drivers/pci/tph.c b/drivers/pci/tph.c index 655ffd60e62f..28c8d6676fc2 100644 --- a/drivers/pci/tph.c +++ b/drivers/pci/tph.c @@ -196,7 +196,14 @@ u16 pcie_tph_get_st_table_size(struct pci_dev *pdev) } EXPORT_SYMBOL(pcie_tph_get_st_table_size); =20 -/* Return device's Root Port completer capability */ +/* + * Return device's Root Port completer capability. + * + * The "TPH Completer Supported" field (bits 13:12 of Device Capabilities = 2) + * has a reserved 0b10 encoding. Fold it into "not supported" so only the + * three defined values can propagate into pdev->tph_req_type via the min() + * in pcie_enable_tph(). + */ static u8 get_rp_completer_type(struct pci_dev *pdev) { struct pci_dev *rp; @@ -211,7 +218,14 @@ static u8 get_rp_completer_type(struct pci_dev *pdev) if (ret) return 0; =20 - return FIELD_GET(PCI_EXP_DEVCAP2_TPH_COMP_MASK, reg); + switch (FIELD_GET(PCI_EXP_DEVCAP2_TPH_COMP_MASK, reg)) { + case PCI_EXP_DEVCAP2_TPH_COMP_TPH_ONLY: + return PCI_EXP_DEVCAP2_TPH_COMP_TPH_ONLY; + case PCI_EXP_DEVCAP2_TPH_COMP_EXT_TPH: + return PCI_EXP_DEVCAP2_TPH_COMP_EXT_TPH; + default: + return PCI_EXP_DEVCAP2_TPH_COMP_NONE; + } } =20 /* Write tag to ST table - Return 0 if OK, otherwise -errno */ --=20 2.53.0-Meta