From patchwork Thu Jun 2 15:58:11 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lennert Buytenhek X-Patchwork-Id: 12867981 X-Patchwork-Delegate: kuba@kernel.org Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 56790C43334 for ; Thu, 2 Jun 2022 16:04:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232749AbiFBQEE (ORCPT ); Thu, 2 Jun 2022 12:04:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52258 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236753AbiFBQED (ORCPT ); Thu, 2 Jun 2022 12:04:03 -0400 X-Greylist: delayed 344 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Thu, 02 Jun 2022 09:03:59 PDT Received: from mail.wantstofly.org (hmm.wantstofly.org [213.239.204.108]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4F21C21FBC5 for ; Thu, 2 Jun 2022 09:03:58 -0700 (PDT) Received: by mail.wantstofly.org (Postfix, from userid 1000) id C70227F546; Thu, 2 Jun 2022 18:58:11 +0300 (EEST) Date: Thu, 2 Jun 2022 18:58:11 +0300 From: Lennert Buytenhek To: intel-wired-lan@lists.osuosl.org, Tony Nguyen , Jesse Brandeburg Cc: netdev@vger.kernel.org, "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Vitaly Lifshits , Sasha Neftin , Aaron Brown , Jeff Kirsher Subject: [PATCH v1] igc: Reinstate IGC_REMOVED logic and implement it properly Message-ID: MIME-Version: 1.0 Content-Disposition: inline Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org The initially merged version of the igc driver code (via commit 146740f9abc4, "igc: Add support for PF") contained the following IGC_REMOVED checks in the igc_rd32/wr32() MMIO accessors: u32 igc_rd32(struct igc_hw *hw, u32 reg) { u8 __iomem *hw_addr = READ_ONCE(hw->hw_addr); u32 value = 0; if (IGC_REMOVED(hw_addr)) return ~value; value = readl(&hw_addr[reg]); /* reads should not return all F's */ if (!(~value) && (!reg || !(~readl(hw_addr)))) hw->hw_addr = NULL; return value; } And: #define wr32(reg, val) \ do { \ u8 __iomem *hw_addr = READ_ONCE((hw)->hw_addr); \ if (!IGC_REMOVED(hw_addr)) \ writel((val), &hw_addr[(reg)]); \ } while (0) E.g. igb has similar checks in its MMIO accessors, and has a similar macro E1000_REMOVED, which is implemented as follows: #define E1000_REMOVED(h) unlikely(!(h)) These checks serve to detect and take note of an 0xffffffff MMIO read return from the device, which can be caused by a PCIe link flap or some other kind of PCI bus error, and to avoid performing MMIO reads and writes from that point onwards. However, the IGC_REMOVED macro was not originally implemented: #ifndef IGC_REMOVED #define IGC_REMOVED(a) (0) #endif /* IGC_REMOVED */ This led to the IGC_REMOVED logic to be removed entirely in a subsequent commit (commit 3c215fb18e70, "igc: remove IGC_REMOVED function"), with the rationale that such checks matter only for virtualization and that igc does not support virtualization -- but a PCIe device can become detached even without virtualization being in use, and without proper checks, a PCIe bus error affecting an igc adapter will lead to various NULL pointer dereferences, as the first access after the error will set hw->hw_addr to NULL, and subsequent accesses will blindly dereference this now-NULL pointer. This patch reinstates the IGC_REMOVED checks in igc_rd32/wr32(), and implements IGC_REMOVED the way it is done for igb, by checking for the unlikely() case of hw_addr being NULL. This change prevents the oopses seen when a PCIe link flap occurs on an igc adapter. Fixes: 146740f9abc4 ("igc: Add support for PF") Signed-off-by: Lennert Buytenhek Tested-by: Naama Meir Acked-by: Sasha Neftin --- As initially reported on intel-wired-lan@ in February: https://lists.osuosl.org/pipermail/intel-wired-lan/Week-of-Mon-20220214/027787.html We're seeing these NULL pointer dereferences hit fairly reproducibly when rebooting, presumably due to the particularities of reset sequencing on the boards we see this hit on. A link flap can be caused by toggling the Secondary Bus Reset bit in the upstream PCIe bridge's Bridge Control register and can reliably reproduce this problem. drivers/net/ethernet/intel/igc/igc_main.c | 3 +++ drivers/net/ethernet/intel/igc/igc_regs.h | 5 ++++- 2 files changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c index 74b2c590ed5d..38e46e9ba8bb 100644 --- a/drivers/net/ethernet/intel/igc/igc_main.c +++ b/drivers/net/ethernet/intel/igc/igc_main.c @@ -6171,6 +6171,9 @@ u32 igc_rd32(struct igc_hw *hw, u32 reg) u8 __iomem *hw_addr = READ_ONCE(hw->hw_addr); u32 value = 0; + if (IGC_REMOVED(hw_addr)) + return ~value; + value = readl(&hw_addr[reg]); /* reads should not return all F's */ diff --git a/drivers/net/ethernet/intel/igc/igc_regs.h b/drivers/net/ethernet/intel/igc/igc_regs.h index e197a33d93a0..026c3b65fc37 100644 --- a/drivers/net/ethernet/intel/igc/igc_regs.h +++ b/drivers/net/ethernet/intel/igc/igc_regs.h @@ -306,7 +306,8 @@ u32 igc_rd32(struct igc_hw *hw, u32 reg); #define wr32(reg, val) \ do { \ u8 __iomem *hw_addr = READ_ONCE((hw)->hw_addr); \ - writel((val), &hw_addr[(reg)]); \ + if (!IGC_REMOVED(hw_addr)) \ + writel((val), &hw_addr[(reg)]); \ } while (0) #define rd32(reg) (igc_rd32(hw, reg)) @@ -318,4 +319,6 @@ do { \ #define array_rd32(reg, offset) (igc_rd32(hw, (reg) + ((offset) << 2))) +#define IGC_REMOVED(h) unlikely(!(h)) + #endif