From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f202.google.com (mail-pg1-f202.google.com [209.85.215.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8442B3D1719 for ; Fri, 29 May 2026 11:12:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780053142; cv=none; b=uCIIAHx2pnAKYaRusH9NEBbveNWq05X3a214zNSmcPlMhKSGiMSl2Wa2o5bghpmuKUoL8pNMkcJX5TU5MlcVwNmDARDyBRMOtjx1pBbKzBFox8n6ym0lQ+v9XilCdjwZw+jUeeOAYtxH/PrSFtLhqvD3gZtb4j8LWhJMmVqAS38= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780053142; c=relaxed/simple; bh=utNKQCvUkPmBqehTN/p5pEe6fKwGdjlepuYbZLj1XUc=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=kr1XjJo2bmPhUUDPRKiPO5u7CvJBd24/qIdqM8ZiN3GzraJrP5etCUPcSp5M28pdsIB1eCTDW6DlYs2U2FGfGUf7nJvqG0tRhxNEhtZXghgdpgq3+Y8GWRVT4ntAc/pCYhyl+6+JzmovqLs++ber8snkOBzHc1V6MDUljqZK6dY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--praan.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=dUfGjDGa; arc=none smtp.client-ip=209.85.215.202 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--praan.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="dUfGjDGa" Received: by mail-pg1-f202.google.com with SMTP id 41be03b00d2f7-c8576bc9254so609715a12.1 for ; Fri, 29 May 2026 04:12:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1780053139; x=1780657939; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=KwPPE5/66gX8tYQEwBiFqJ6gT9Mjq1jN4WhTwmvmXVQ=; b=dUfGjDGaauOsq9z3Q9ltvS3ODxPjCyjr2Tm4j4bk+2N3iZfqqI6x5T5zmwcH0S8D3O qyCkLT3C9nf5xuYQfsdD8vFXHgRFYQVIp4Ume7XSD3yJxHYYiNQYcnHm9vF15OD2GsXi OWG6ehFqzbZq5zhqa3I7sdcB+gS7ADitd+lhOV4ijn2zGQA4FErvN9w6Ysb7jDLWd/OC OvHxNuD5OpDQ9ZPFMnSAc/P2bnmrdgoSFdPiNLJNLTJWbmNa187Z6SyZwfuv7nJhi5jR obmj0+gUYC2dqO+oOOlkn1lcUpcuioUAtNBg5YUc83Lp7WTPDjg27F+kIyfo5VI5MKU2 yqAw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1780053139; x=1780657939; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=KwPPE5/66gX8tYQEwBiFqJ6gT9Mjq1jN4WhTwmvmXVQ=; b=ULgzIEwvN4m+Lt4OL5YXTbEKfVEK204jzv7PzY1lrScr/OYyzssr+rG8BJVFV0kUln XQ7WQj27YDr+JgLjfvRyQvepy0XrzbT0ywHMnJmPDNFEL2o0VBrHKjiny2M4bgEc78Tt Vw0IrcjH2r4z4P7MTM55zW2mhLinzYEtfvH5Y1KD8FAznvUyx0y4Qg//h5qGhuNc2tTk XW9Ea+l0KDyU1M8vnusXATCd+ggsGyI/lLVSROsqcmdBztnBkyf+0p19g6fzh8gJnSc4 hBzTd+dxkv+YvEi1GwGW1m/YCjYi+W269N+k8Kp8pq5UJZZskgOwLKbBxJEk+9d0bAGb 3ihg== X-Forwarded-Encrypted: i=1; AFNElJ9tTXyWB3xl8ysppdXeCfLtOGPBEunHiy/f+SwjcCMuf6evw1ES9T/SeID90WFyN3ymVQVtnumbjbkZIcA=@vger.kernel.org X-Gm-Message-State: AOJu0YwsoFjT9FnswkXemv3oociSeyvFiXxlDrjagOFhCmYMFxiL/e6r RH6+8xiwdhhStquAq/P++8TChxDrIXy1/lOVVADXl3dFF+Sv0GDcDv8Zn9nqAQVH1d6QNUH0f3R lbw== X-Received: from pfbky33.prod.google.com ([2002:a05:6a00:6f61:b0:82f:b6a3:3dbc]) (user=praan job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:14d3:b0:842:994:93a7 with SMTP id d2e1a72fcca58-84212a7f6a0mr2674296b3a.5.1780053138377; Fri, 29 May 2026 04:12:18 -0700 (PDT) Date: Fri, 29 May 2026 11:12:05 +0000 In-Reply-To: <20260529111208.387412-1-praan@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260529111208.387412-1-praan@google.com> X-Mailer: git-send-email 2.54.0.823.g6e5bcc1fc9-goog Message-ID: <20260529111208.387412-4-praan@google.com> Subject: [PATCH v6 3/6] PCI/ATS: Mandate checking pci_ats_supported() before pci_prepare_ats() From: Pranjal Shrivastava To: iommu@lists.linux.dev, linux-pci@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Cc: Joerg Roedel , Will Deacon , Bjorn Helgaas , David Woodhouse , Lu Baolu , Robin Murphy , Suravee Suthikulpanit , Jason Gunthorpe , Nicolin Chen , David Matlack , Samiullah Khawaja , Daniel Mentz , Pasha Tatashin , Mostafa Saleh , Pranjal Shrivastava Content-Type: text/plain; charset="UTF-8" Currently, pci_prepare_ats() internally calls pci_ats_supported() and returns -EINVAL if the device does not support ATS. While this provides a silent safety check, it conflates support detection with configuration. Update pci_prepare_ats() to wrap the internal pci_ats_supported check in a WARN_ON(). This mandates all callers to call pci_prepare_ats() only if the function supports ATS. Update the function documentation to mention that callers must verify ATS support (via pci_ats_supported()) before calling pci_prepare_ats(). Suggested-by: Baolu Lu Signed-off-by: Pranjal Shrivastava --- drivers/pci/ats.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c index 9cb23780093d..f1434f86ac40 100644 --- a/drivers/pci/ats.c +++ b/drivers/pci/ats.c @@ -56,7 +56,9 @@ EXPORT_SYMBOL_GPL(pci_ats_supported); * @ps: the IOMMU page shift * * This must be done by the IOMMU driver on the PF before any VFs are created to - * ensure that the VF can have ATS enabled. + * ensure that the VF can have ATS enabled. Callers must verify that ATS is + * supported by the device (e.g. via pci_ats_supported()) before calling this + * function. * * Returns 0 on success, or negative on failure. */ @@ -64,7 +66,7 @@ int pci_prepare_ats(struct pci_dev *dev, int ps) { u16 ctrl; - if (!pci_ats_supported(dev)) + if (WARN_ON(!pci_ats_supported(dev))) return -EINVAL; if (WARN_ON(dev->ats_enabled)) -- 2.54.0.823.g6e5bcc1fc9-goog