From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3EC4426F288; Thu, 12 Mar 2026 20:25:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773347102; cv=none; b=bPJufLtPyrNMmDVZ5eJFrvwFl3C7jPWIvMRkfOSbr1RgrtBihdg76q8iAnLgWAUlh+Zb76XzBn/eoojCdfzJ0RAfnL7sZstVFWslOHRyxvybGn7lGiIF5lHBm9T1aneTp7EW9Cy/B/84ax6ZD+XLhPf5lSJ0LEtr8wDNqRft6vw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773347102; c=relaxed/simple; bh=Mut3VgCeWzm/qusa2pXgf53YaG5pTSFngCc9bHwt1Ps=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=AKSoQRCS5XStjK+nd2YuHYpEqhoXkCY61rAyCjadlmrk/cY4Xy6mxwWClZyu3VhC/QPoja7nJQUoMLxhO1A+/o/wnqwNfa0e2c6QQTUAEPPagjfah4NWXGFYT/jZor9cDGGV6fKdTARQ1yfc9CxOTZvvL7uAxI5JefJ3g2Xwsgs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=QJedRug4; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="QJedRug4" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 83B70C4CEF7; Thu, 12 Mar 2026 20:25:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1773347102; bh=Mut3VgCeWzm/qusa2pXgf53YaG5pTSFngCc9bHwt1Ps=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=QJedRug4BQhc0jygBDgc4uDo6yGjiW6F3OdASY+LiBfrubF8uVFk4sfb2jiSL8nmm DLBIjNp7i3mDtRbaQ6/Ye6znokENFIRxtC1tpy4R80hLnUF4omHAWrWFnNqdIxap4W 3PaFJcI/Ek9WO1oWKC062LxZxLMWuynhHPckJaAQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Sathesh Edara , Shinas Rasheed , Vimlesh Kumar , Paolo Abeni , Sasha Levin Subject: [PATCH 6.12 204/265] octeon_ep_vf: avoid compiler and IQ/OQ reordering Date: Thu, 12 Mar 2026 21:09:51 +0100 Message-ID: <20260312201025.689668839@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260312201018.128816016@linuxfoundation.org> References: <20260312201018.128816016@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Vimlesh Kumar [ Upstream commit 6c73126ecd1080351b468fe43353b2f705487f44 ] Utilize READ_ONCE and WRITE_ONCE APIs for IO queue Tx/Rx variable access to prevent compiler optimization and reordering. Additionally, ensure IO queue OUT/IN_CNT registers are flushed by performing a read-back after writing. The compiler could reorder reads/writes to pkts_pending, last_pkt_count, etc., causing stale values to be used when calculating packets to process or register updates to send to hardware. The Octeon hardware requires a read-back after writing to OUT_CNT/IN_CNT registers to ensure the write has been flushed through any posted write buffers before the interrupt resend bit is set. Without this, we have observed cases where the hardware didn't properly update its internal state. wmb/rmb only provides ordering guarantees but doesn't prevent the compiler from performing optimizations like caching in registers, load tearing etc. Fixes: 1cd3b407977c3 ("octeon_ep_vf: add Tx/Rx processing and interrupt support") Signed-off-by: Sathesh Edara Signed-off-by: Shinas Rasheed Signed-off-by: Vimlesh Kumar Link: https://patch.msgid.link/20260227091402.1773833-5-vimleshk@marvell.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin --- .../marvell/octeon_ep_vf/octep_vf_main.c | 21 ++++++++------ .../marvell/octeon_ep_vf/octep_vf_rx.c | 28 +++++++++++++------ 2 files changed, 33 insertions(+), 16 deletions(-) diff --git a/drivers/net/ethernet/marvell/octeon_ep_vf/octep_vf_main.c b/drivers/net/ethernet/marvell/octeon_ep_vf/octep_vf_main.c index a8332965084b9..72c1e9415efaa 100644 --- a/drivers/net/ethernet/marvell/octeon_ep_vf/octep_vf_main.c +++ b/drivers/net/ethernet/marvell/octeon_ep_vf/octep_vf_main.c @@ -296,17 +296,22 @@ static void octep_vf_clean_irqs(struct octep_vf_device *oct) static void octep_vf_update_pkt(struct octep_vf_iq *iq, struct octep_vf_oq *oq) { - u32 pkts_pend = oq->pkts_pending; + u32 pkts_pend = READ_ONCE(oq->pkts_pending); + u32 last_pkt_count = READ_ONCE(oq->last_pkt_count); + u32 pkts_processed = READ_ONCE(iq->pkts_processed); + u32 pkt_in_done = READ_ONCE(iq->pkt_in_done); netdev_dbg(iq->netdev, "enabling intr for Q-%u\n", iq->q_no); - if (iq->pkts_processed) { - writel(iq->pkts_processed, iq->inst_cnt_reg); - iq->pkt_in_done -= iq->pkts_processed; - iq->pkts_processed = 0; + if (pkts_processed) { + writel(pkts_processed, iq->inst_cnt_reg); + readl(iq->inst_cnt_reg); + WRITE_ONCE(iq->pkt_in_done, (pkt_in_done - pkts_processed)); + WRITE_ONCE(iq->pkts_processed, 0); } - if (oq->last_pkt_count - pkts_pend) { - writel(oq->last_pkt_count - pkts_pend, oq->pkts_sent_reg); - oq->last_pkt_count = pkts_pend; + if (last_pkt_count - pkts_pend) { + writel(last_pkt_count - pkts_pend, oq->pkts_sent_reg); + readl(oq->pkts_sent_reg); + WRITE_ONCE(oq->last_pkt_count, pkts_pend); } /* Flush the previous wrties before writing to RESEND bit */ diff --git a/drivers/net/ethernet/marvell/octeon_ep_vf/octep_vf_rx.c b/drivers/net/ethernet/marvell/octeon_ep_vf/octep_vf_rx.c index 6f865dbbba6c6..b579d5b545c46 100644 --- a/drivers/net/ethernet/marvell/octeon_ep_vf/octep_vf_rx.c +++ b/drivers/net/ethernet/marvell/octeon_ep_vf/octep_vf_rx.c @@ -325,9 +325,16 @@ static int octep_vf_oq_check_hw_for_pkts(struct octep_vf_device *oct, struct octep_vf_oq *oq) { u32 pkt_count, new_pkts; + u32 last_pkt_count, pkts_pending; pkt_count = readl(oq->pkts_sent_reg); - new_pkts = pkt_count - oq->last_pkt_count; + last_pkt_count = READ_ONCE(oq->last_pkt_count); + new_pkts = pkt_count - last_pkt_count; + + if (pkt_count < last_pkt_count) { + dev_err(oq->dev, "OQ-%u pkt_count(%u) < oq->last_pkt_count(%u)\n", + oq->q_no, pkt_count, last_pkt_count); + } /* Clear the hardware packets counter register if the rx queue is * being processed continuously with-in a single interrupt and @@ -339,8 +346,9 @@ static int octep_vf_oq_check_hw_for_pkts(struct octep_vf_device *oct, pkt_count = readl(oq->pkts_sent_reg); new_pkts += pkt_count; } - oq->last_pkt_count = pkt_count; - oq->pkts_pending += new_pkts; + WRITE_ONCE(oq->last_pkt_count, pkt_count); + pkts_pending = READ_ONCE(oq->pkts_pending); + WRITE_ONCE(oq->pkts_pending, (pkts_pending + new_pkts)); return new_pkts; } @@ -369,7 +377,7 @@ static int __octep_vf_oq_process_rx(struct octep_vf_device *oct, struct sk_buff *skb; u32 read_idx; - read_idx = oq->host_read_idx; + read_idx = READ_ONCE(oq->host_read_idx); rx_bytes = 0; desc_used = 0; for (pkt = 0; pkt < pkts_to_process; pkt++) { @@ -463,7 +471,7 @@ static int __octep_vf_oq_process_rx(struct octep_vf_device *oct, napi_gro_receive(oq->napi, skb); } - oq->host_read_idx = read_idx; + WRITE_ONCE(oq->host_read_idx, read_idx); oq->refill_count += desc_used; oq->stats->packets += pkt; oq->stats->bytes += rx_bytes; @@ -486,22 +494,26 @@ int octep_vf_oq_process_rx(struct octep_vf_oq *oq, int budget) { u32 pkts_available, pkts_processed, total_pkts_processed; struct octep_vf_device *oct = oq->octep_vf_dev; + u32 pkts_pending; pkts_available = 0; pkts_processed = 0; total_pkts_processed = 0; while (total_pkts_processed < budget) { /* update pending count only when current one exhausted */ - if (oq->pkts_pending == 0) + pkts_pending = READ_ONCE(oq->pkts_pending); + if (pkts_pending == 0) octep_vf_oq_check_hw_for_pkts(oct, oq); + pkts_pending = READ_ONCE(oq->pkts_pending); pkts_available = min(budget - total_pkts_processed, - oq->pkts_pending); + pkts_pending); if (!pkts_available) break; pkts_processed = __octep_vf_oq_process_rx(oct, oq, pkts_available); - oq->pkts_pending -= pkts_processed; + pkts_pending = READ_ONCE(oq->pkts_pending); + WRITE_ONCE(oq->pkts_pending, (pkts_pending - pkts_processed)); total_pkts_processed += pkts_processed; } -- 2.51.0