From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=209.85.210.71 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794425065; b=M8rdbDc6nFgFVtb5jxGd3XdiYoQtdeRYpYMx9csUNMROVvs9zFusVcTqEYGTdSX4DWId /4Wl3mnlEgt9+GZ1Wc1hBhhTgTpnH5er7vggnmUcHkbGM7iVgc7qrrQv2sjbJOnHZHh8O qz4DzA1kFpgC9SP1QNMpl0HevZX7mhQY1l+WbocHv4rItDzUrRRKEIsV7Gr8oFGZaqq54 W3Ha6hT1VkZzua8px5oeP1RITSLpSSlGiXBujmMArmL9syvDnYgE4q+a64JIHXJW9x5VB S418hoP25z0wShsHP0Nxc9XdLVWE6UQqK0kpq8PoRvA/e5j84TG2ungcR3W1X0eJnhA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794425065; h=DMARC-Filter:Received:DKIM-Signature:X-Google-DKIM-Signature: X-Forwarded-Encrypted:X-Gm-Message-State:X-Received:Date:In-Reply-To: Mime-Version:References:X-Mailer:Message-ID:Subject:From:To:Cc: Content-Type; bh=S4+DQ/5hS2/5UfXO0mi1ZgFeMRsr05x8y1FYZlBsi/k=; b=L+tCvsDxmktP3H3b1JAz+vx/nTLT/aVjnoexLgsD7ohx0CVKGXJQHtvsfu2/f9NNvxuw boBoc/iX19lIqYd0k+fG5JpzyweaosZfwszjNPAhzDAN6xnAOGO52X3RCBYLhExHuw1u/ GbD8JU5nMQrHKzOCI+LLnYnJR9ghBUFWX+AhheZ1cqCAh44Pv02+1brLOIf+nSvUnn3ZA tBpmn9tC1rx6bu/3vTtGrhQP05A5dDQXlcRKHLE7rBRAvnIRhRRNxltWHQlCnVKvEssmt YEo7RKPrygz6oDycR+vULqcKqKM6WPzsxVRcYLn4nfVyd36LIzzBSgBOa61T4GTTLuQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=google.com; spf=pass smtp.mailfrom=flex--dmatlack.bounces.google.com; dkim=pass header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20260707 header.b="lM/CPmgi"; arc=none smtp.remote-ip=209.85.210.71 Received: from mail-ot1-f71.google.com (mail-ot1-f71.google.com [209.85.210.71]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 90812606F381 for ; Wed, 11 Nov 2026 19:24:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 90812606F381 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--dmatlack.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20260707 header.b=lM/CPmgi Received: by mail-ot1-f71.google.com with SMTP id 46e09a7af769-83c2311eb1dso5148435a34.1 for ; Wed, 11 Nov 2026 11:24:24 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20260707; t=1794425063; x=1795029863; darn=vger.kernel.org; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:from:to:cc:subject:date:message-id:reply-to :content-type; bh=S4+DQ/5hS2/5UfXO0mi1ZgFeMRsr05x8y1FYZlBsi/k=; b=lM/CPmgi2MxnhCIljbY1J6j5HJCMMekv0//LIx4rqPP+rmTASzEwn/BZTlI+Fvfwof f5lzQB0rVXFPhPx5zlOmCXnEZsPPgqwyajdOHm2HucaXGcohS4WqmpNnnr0r28fxAkpE lg/UcKD+gr2bXmw6OtsYfNTumii+2oGuZptwjhXEy2C8uOHAWNG0YYDFtvZLbBscAarT KRjZxsb4x9C8/ukL2U6mxnyYxFXQQR0ZKVLlW4ebshXJs56UjXEXgV5bCqzi520CgmbZ ytScVeEa8/BkQ5DOx6FUZPGNcU6+g53Tsl0ljpXVfOyoViGc3s7rFDA5dCAACnp88HpA e5IA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1794425063; x=1795029863; h=content-type: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:content-type; bh=S4+DQ/5hS2/5UfXO0mi1ZgFeMRsr05x8y1FYZlBsi/k=; b=Xn68LOMyxWNhuS05PSpIKf0T+HQuGb4t8bRA6tgyhccpXEpLYPKXxjIxOIh+mJJAlv pIAWIjrvc7n/4eh5sLqTyVrDHqOXITG+npJ4Xf/1A6AD0NKJ23+mN+FFtT/2PLxytjzs 0gbmgfSHHatWL75xu+w6M0mV8dH/7MZz8wrHZEE4QEzPUgBXRMd6Dmdf4uI9M9pF8o+H tzuYNv6ozD8MPmdiDZGozSPNzOFCrnI1oXx1tBTPIl5W7hMfw11i634m66M3W+ARULKp lM2bnITKYvYNi/ItnTI1hOl9tTQge+00o2EUagtK7uD4uy6awwTA61odbVjSxH9YUNUe 1fzA== X-Forwarded-Encrypted: i=1; AL+hErF4LKBikFuJjMWC4DYIy6JMQZouEqb1QswBGAJBQIrhvDMXhWBTjE/VblqyF+1BQbi5XDiNZMdwDdp0PQ==@vger.kernel.org X-Gm-Message-State: APuU4Z/iNqdHP6bEVmbqMxVWSmLFCxHLYmttgmShAgTfA/BlzTMKj8Sr R0Loqg/X4Cg0LW2PMe06Dfcwk2Hv8zsyIO/TRsALJ8nkUEAbgd19HzmXnL2kcDRYXqldcDNR+uD /BMo8TIJIjMg96w== X-Received: from jabll4.prod.google.com ([2002:a05:6638:9804:b0:61f:e4cd:8716]) (user=dmatlack job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6808:318a:b0:4af:5d69:1cb4 with SMTP id 5614622812f47-56b96ad0615mr3028788b6e.15.1794425063307; Wed, 11 Nov 2026 11:24:23 -0800 (PST) Date: Wed, 11 Nov 2026 19:24:10 +0000 In-Reply-To: <20261111192411.4133780-1-dmatlack@google.com> X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list Mime-Version: 1.0 References: <20261111192411.4133780-1-dmatlack@google.com> X-Mailer: git-send-email 2.56.0.567.gdb80ae8cd5-goog Message-ID: <20261111192411.4133780-7-dmatlack@google.com> Subject: [RFC PATCH 6/7] vfio: selftests: Add vfio_pci_find_p2p_pair() helper From: David Matlack To: dri-devel@lists.freedesktop.org, iommu@lists.linux.dev, kvm@vger.kernel.org, linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-media@vger.kernel.org, linux-pci@vger.kernel.org Cc: Alex Mastro , Alex Williamson , Bjorn Helgaas , "=?UTF-8?q?Christian=20K=C3=B6nig?=" , David Matlack , Jason Gunthorpe , Josh Hilke , Kevin Tian , Leon Romanovsky , Logan Gunthorpe , Matt Evans , Matt Evans , Mina Almasry , Samiullah Khawaja , Shuah Khan , Sumit Semwal , Vipin Sharma Content-Type: text/plain; charset="UTF-8" Add vfio_pci_find_p2p_pair() to locate an initiator device with memcpy driver support and a distinct target device with a memory BAR of at least min_bar_size bytes from an array of VFIO PCI devices. Factor out vfio_pci_has_p2p_path() as the central place to validate PCI topology and P2P DMA reachability between the two devices in the future. Signed-off-by: David Matlack --- .../lib/include/libvfio/vfio_pci_device.h | 8 ++++ .../selftests/vfio/lib/vfio_pci_device.c | 48 +++++++++++++++++++ 2 files changed, 56 insertions(+) diff --git a/tools/testing/selftests/vfio/lib/include/libvfio/vfio_pci_device.h b/tools/testing/selftests/vfio/lib/include/libvfio/vfio_pci_device.h index fd130f680a2d..9bda93712859 100644 --- a/tools/testing/selftests/vfio/lib/include/libvfio/vfio_pci_device.h +++ b/tools/testing/selftests/vfio/lib/include/libvfio/vfio_pci_device.h @@ -42,6 +42,12 @@ struct vfio_pci_device { struct vfio_pci_driver driver; }; +struct vfio_pci_p2p_pair { + struct vfio_pci_device *initiator; + struct vfio_pci_device *target; + struct vfio_pci_mem_bar mem_bar; +}; + #define dev_info(_dev, _fmt, ...) printf("%s: " _fmt, (_dev)->bdf, ##__VA_ARGS__) #define dev_err(_dev, _fmt, ...) fprintf(stderr, "%s: " _fmt, (_dev)->bdf, ##__VA_ARGS__) @@ -171,6 +177,8 @@ static inline bool vfio_pci_device_match(struct vfio_pci_device *device, bool vfio_pci_find_mem_bar(struct vfio_pci_device *device, u64 min_size, struct vfio_pci_mem_bar *mem_bar); +bool vfio_pci_find_p2p_pair(struct vfio_pci_device **devices, int nr_devices, + u64 min_bar_size, struct vfio_pci_p2p_pair *pair); int __vfio_pci_dmabuf_create(struct vfio_pci_device *device, u32 region_index, u64 offset, u64 length, u32 open_flags); diff --git a/tools/testing/selftests/vfio/lib/vfio_pci_device.c b/tools/testing/selftests/vfio/lib/vfio_pci_device.c index eca6eb13d7f0..16fc98ed170b 100644 --- a/tools/testing/selftests/vfio/lib/vfio_pci_device.c +++ b/tools/testing/selftests/vfio/lib/vfio_pci_device.c @@ -378,6 +378,54 @@ bool vfio_pci_find_mem_bar(struct vfio_pci_device *device, u64 min_size, return false; } +static bool vfio_pci_has_p2p_path(struct vfio_pci_device *initiator, + struct vfio_pci_device *target) +{ + /* + * TODO: Check PCI topology / ACS / host bridge support to verify that + * P2P DMA transactions from @initiator can reach @target. + */ + return initiator != target; +} + +bool vfio_pci_find_p2p_pair(struct vfio_pci_device **devices, int nr_devices, + u64 min_bar_size, struct vfio_pci_p2p_pair *pair) +{ + struct vfio_pci_mem_bar mem_bar; + int i, j; + + for (i = 0; i < nr_devices; i++) { + struct vfio_pci_device *initiator = devices[i]; + const struct vfio_pci_driver_ops *ops = initiator->driver.ops; + + if (!ops || !ops->memcpy_start || !ops->memcpy_wait) + continue; + + for (j = 0; j < nr_devices; j++) { + struct vfio_pci_device *target = devices[j]; + + if (i == j) + continue; + + if (!vfio_pci_has_p2p_path(initiator, target)) + continue; + + if (!vfio_pci_find_mem_bar(target, min_bar_size, + &mem_bar)) + continue; + + *pair = (struct vfio_pci_p2p_pair){ + .initiator = initiator, + .target = target, + .mem_bar = mem_bar, + }; + return true; + } + } + + return false; +} + void vfio_pci_config_access(struct vfio_pci_device *device, bool write, size_t config, size_t size, void *data) { -- 2.56.0.567.gdb80ae8cd5-goog