From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753440AbdLMCcD (ORCPT ); Tue, 12 Dec 2017 21:32:03 -0500 Received: from omzsmtpe03.verizonbusiness.com ([199.249.25.208]:21144 "EHLO omzsmtpe03.verizonbusiness.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753374AbdLMB7W (ORCPT ); Tue, 12 Dec 2017 20:59:22 -0500 From: alexander.levin@verizon.com Cc: Alex Williamson , alexander.levin@verizon.com X-Host: mariner.tdc.vzwcorp.com To: "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" Subject: [PATCH AUTOSEL for 4.9 093/100] vfio/pci: Virtualize Maximum Payload Size Thread-Topic: [PATCH AUTOSEL for 4.9 093/100] vfio/pci: Virtualize Maximum Payload Size Thread-Index: AQHTc7XFHBbGn8Wo3kyAIzr1ZZ5kCg== Date: Wed, 13 Dec 2017 01:57:45 +0000 Message-ID: <20171213015722.6722-68-alexander.levin@verizon.com> References: <20171213015722.6722-1-alexander.levin@verizon.com> In-Reply-To: <20171213015722.6722-1-alexander.levin@verizon.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-messagesentrepresentingtype: 1 x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.144.60.250] Content-Type: text/plain; charset="iso-8859-1" MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by nfs id vBD2W8MQ019235 From: Alex Williamson [ Upstream commit 523184972b282cd9ca17a76f6ca4742394856818 ] With virtual PCI-Express chipsets, we now see userspace/guest drivers trying to match the physical MPS setting to a virtual downstream port. Of course a lone physical device surrounded by virtual interconnects cannot make a correct decision for a proper MPS setting. Instead, let's virtualize the MPS control register so that writes through to hardware are disallowed. Userspace drivers like QEMU assume they can write anything to the device and we'll filter out anything dangerous. Since mismatched MPS can lead to AER and other faults, let's add it to the kernel side rather than relying on userspace virtualization to handle it. Signed-off-by: Alex Williamson Reviewed-by: Eric Auger Signed-off-by: Sasha Levin --- drivers/vfio/pci/vfio_pci_config.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/vfio/pci/vfio_pci_config.c b/drivers/vfio/pci/vfio_pci_config.c index 65d4a3015542..9f1ec4392209 100644 --- a/drivers/vfio/pci/vfio_pci_config.c +++ b/drivers/vfio/pci/vfio_pci_config.c @@ -851,11 +851,13 @@ static int __init init_pci_cap_exp_perm(struct perm_bits *perm) /* * Allow writes to device control fields, except devctl_phantom, - * which could confuse IOMMU, and the ARI bit in devctl2, which + * which could confuse IOMMU, MPS, which can break communication + * with other physical devices, and the ARI bit in devctl2, which * is set at probe time. FLR gets virtualized via our writefn. */ p_setw(perm, PCI_EXP_DEVCTL, - PCI_EXP_DEVCTL_BCR_FLR, ~PCI_EXP_DEVCTL_PHANTOM); + PCI_EXP_DEVCTL_BCR_FLR | PCI_EXP_DEVCTL_PAYLOAD, + ~PCI_EXP_DEVCTL_PHANTOM); p_setw(perm, PCI_EXP_DEVCTL2, NO_VIRT, ~PCI_EXP_DEVCTL2_ARI); return 0; } -- 2.11.0