From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=198.175.65.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792517861; b=imTqnD7sGFgLtVMe3NzdcYdFrKOvBeIIPvjhQjx/VOOt8dKHbQOx7tRsG9MM2AMq4bbQ H8ZV3EFbEAfNl3tTPIOEUSFCmt1eLEld2Q1EOAIrvYcRLa7lO2ygU17330MdFYzY1iFit KNEDoAksw2++1lB3BO5xHO9CSH/s/k0Cdav6vUoaiDOHp+EBzzHfN6/Lw0AGYVKKp8NPo iSsC14CAURX7sHegIiMkI4YAhq3Uy5C2q4QFMn3wMtmLBorZhIBxHV8asz/arRXI/tbDo 5G2ZQBZBO6qpolXbH8iER+/WNM7Zg2zR3KpGw5oerxfIeekiyJDqRoFY61N7Ti0LVdA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792517861; h=DMARC-Filter:DKIM-Signature:X-CSE-ConnectionGUID:X-CSE-MsgGUID: X-IronPort-AV:X-IronPort-AV:Received:X-CSE-ConnectionGUID: X-CSE-MsgGUID:X-ExtLoop1:X-IronPort-AV:Received:From:To:Cc:Subject: Date:Message-ID:X-Mailer:In-Reply-To:References:MIME-Version: Content-Transfer-Encoding; bh=PCz/m/c0hrv+w+UfpzDjo15sDLKbVAPCRpnlY8c/hao=; b=HYTerl+L6wCdraVacrvUrPUVl9zbZ9aFoaF/ohLNIZnMlTVWC+9lnfTeNiv5RDpVn/qq TcduY9/w3Pb6JX1WOOn2rzvh8CWri2FhiigAa7HyC0A66WfUc0/81QEGO7c2lfaTeUnJh BRp8Z/gJadLqMNlFJpQ1VSSkfl/l32ojj1vA0KMMXemR0HdPtHzS+QC+p01QmKJY4OG92 ghiBJPDLHBe+FKaDViicJQCfiwz8YZCitQi8aZeXb3ZJXlZeLXIHMfyFvYPUpuF3xj8Mr 92bY/K/HACYqVxWbEoHaOxpx3hqzHYxrITupMEgQ9oihoD4q57/84nOfug4ygNQWUTA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass header.d=intel.com header.i=@intel.com header.a=rsa-sha256 header.s=Intel header.b=AhdF1xZu; arc=none smtp.remote-ip=198.175.65.18 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.18]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AD7DE60A382A for ; Tue, 20 Oct 2026 17:37:40 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org AD7DE60A382A Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=intel.com header.i=@intel.com header.a=rsa-sha256 header.s=Intel header.b=AhdF1xZu DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1792517860; x=1824053860; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=RUyd6kZ+YfWyuoa7IgqAcMEVhKzI1d/tst80lIZ4YJ8=; b=AhdF1xZuaTO6iGp/vgt5QQwP8653qp2gE9jJ7/FA6r23lJcgiEfi28Xu 2HwIwouiyla9rz0HDtAjsTWl1pgGwjjzfeTxqYKKXsx3UpS7VFRz+4YEQ CjNAPSlIo1xL3AjfeNpNDDsmLCP04zmgs8W+dlxfQgWKxJKm3JaoYWEKH UBltv/09ws3Avv4NxEDksPMA+cNqMPl8pyBC3zswguBUODrDJHhzz95+R 25thtlgjlKw7ByMYKi3tdAdMoabnETXmDxZvSIWwEsNToPmYjc8No8t6B gxiIFkUlJxHxroPjRZhd815zniPAzYC/K9UTH7DJA05O/4epZiQUj0J0Y w==; X-CSE-ConnectionGUID: w2fzHZtYT2SkxyLn39pw3Q== X-CSE-MsgGUID: F+TS35J6SveOmnL5jbVJzA== X-IronPort-AV: E=McAfee;i="6800,10657,11941"; a="1240987" X-IronPort-AV: E=Sophos;i="6.27,168,1787036400"; d="scan'208";a="1240987" Received: from orviesa009.jf.intel.com ([10.64.159.149]) by orvoesa110.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Oct 2026 10:37:39 -0700 X-CSE-ConnectionGUID: HxxsQgfXS4Kbw/wpKlkfsw== X-CSE-MsgGUID: 4G7+9sKVSiqsPwilTyfZng== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.27,168,1787036400"; d="scan'208";a="2875821" Received: from pavel-dev.sc.intel.com (HELO pepopov-mobl2.amr.corp.intel.com) ([10.3.206.11]) by orviesa009.jf.intel.com with ESMTP; 20 Oct 2026 10:37:39 -0700 From: Pavel Popov To: Bjorn Helgaas , Logan Gunthorpe Cc: Pavel Popov , Leon Romanovsky , Lukas Wunner , Jim Chow , Radu Rugina , Alexey Makhalov , Wei Liu , Michael Kelley , Nathan Ciobanu , bcm-kernel-feedback-list@broadcom.com, virtualization@lists.linux.dev, linux-hyperv@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v4 2/2] PCI/P2PDMA: Allow P2PDMA on Intel Xeon server CPUs Date: Tue, 20 Oct 2026 10:37:36 -0700 Message-ID: <20261020173736.81755-3-pavel.e.popov@intel.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20261020173736.81755-1-pavel.e.popov@intel.com> References: <20261020173736.81755-1-pavel.e.popov@intel.com> X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Peer-to-Peer DMA (P2PDMA) between two devices requires either a shared upstream bridge or a host bridge matching pci_p2pdma_whitelist[]. In VMware guests, passthrough devices appear directly on virtual root buses without host bridge devices. In Hyper-V guests, each passthrough device appears in a PCI domain of its own without a host bridge device. Consequently, P2PDMA checks evaluate endpoint Device IDs against the host bridge whitelist, causing P2PDMA requests to fail regardless of host support. This affects discrete devices such as GPUs, NICs and NVMe drives. Add an explicit list of the Intel Xeon server generations from Skylake-SP to Diamond Rapids to cpu_supports_p2pdma(). These are the CPUs whose host bridges are in pci_p2pdma_whitelist[] without restrictions. AMD Zen and newer are already covered by cpu_supports_p2pdma(), so only Intel entries are needed. Tested with the Intel Level Zero P2P benchmark (ze_peer) on Arc Pro B60 cards in a Linux guest on VMware ESXi 9.0 (Emerald Rapids host). Signed-off-by: Pavel Popov Reviewed-by: Logan Gunthorpe --- drivers/pci/p2pdma.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c index 6b4f0843b404..cb9084fb0990 100644 --- a/drivers/pci/p2pdma.c +++ b/drivers/pci/p2pdma.c @@ -21,6 +21,11 @@ #include #include +#ifdef CONFIG_X86 +#include +#include +#endif + struct pci_p2pdma { struct gen_pool *pool; bool p2pmem_published; @@ -520,6 +525,21 @@ static void seq_buf_print_bus_devfn(struct seq_buf *buf, struct pci_dev *pdev) } #ifdef CONFIG_X86 +/* Intel Xeon CPUs whose host bridges support p2pdma */ +static const struct x86_cpu_id p2pdma_intel_cpu_ids[] = { + X86_MATCH_VFM(INTEL_SKYLAKE_X, NULL), + X86_MATCH_VFM(INTEL_ICELAKE_X, NULL), + X86_MATCH_VFM(INTEL_ICELAKE_D, NULL), + X86_MATCH_VFM(INTEL_SAPPHIRERAPIDS_X, NULL), + X86_MATCH_VFM(INTEL_EMERALDRAPIDS_X, NULL), + X86_MATCH_VFM(INTEL_GRANITERAPIDS_X, NULL), + X86_MATCH_VFM(INTEL_GRANITERAPIDS_D, NULL), + X86_MATCH_VFM(INTEL_ATOM_CRESTMONT_X, NULL), + X86_MATCH_VFM(INTEL_ATOM_DARKMONT_X, NULL), + X86_MATCH_VFM(INTEL_DIAMONDRAPIDS_X, NULL), + {} +}; + static bool cpu_supports_p2pdma(void) { struct cpuinfo_x86 *c = &cpu_data(0); @@ -528,6 +548,10 @@ static bool cpu_supports_p2pdma(void) if (c->x86_vendor == X86_VENDOR_AMD && c->x86 >= 0x17) return true; + /* Listed Intel Xeon CPUs support p2pdma */ + if (x86_match_cpu(p2pdma_intel_cpu_ids)) + return true; + return false; } #else /* !CONFIG_X86 */ -- 2.53.0