From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 BA9AF431488; Thu, 30 Jul 2026 14:35:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785422143; cv=none; b=msRem1aN4SldtKNPFquVNCDxeVSp0HGSxIFnYPMi+pxvStHAGDXqSZn7vPKk1rwkSQB9W+xBxwxEBeYuKQ42xske6Evfc6f1sgyIjOFXPll/pQeWaERHPTaGixtAq+qqUjyC+PxXlCNlQ2SZafddSsdC4iIeFUAnvIPiNYkpJYQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785422143; c=relaxed/simple; bh=x/9SbpoT2Sjb3L08QlAbE7BAiVK0RE0gRVEMSz4smVs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=E0eMkBs9dftw1Fgp/ei849tgF6jyYTVx9mUZ/fNUUWUbiMt3+AT44kO5mF7AxoSdS4NOMuefHVSv50ZoSfqA6ig6pzif7wVgO6yRMrcSfqiHse2kTClDnNNdh9ZkEkKulLpxoDWlapyPhnBtnKNDQ4/KSUAo+Ff2a0bLOgcWLfE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=VO6E3kB4; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="VO6E3kB4" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1A4FE1F000E9; Thu, 30 Jul 2026 14:35:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1785422142; bh=+QqaXLIVL42cWXS/GUxLtXOrRrSm2HzeGV7xgN3xe8Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=VO6E3kB4LIcx7DCZDcYTKLWK8zwJaFIOMblN10RCxzIldS/YLSAN7Y+VAwKZrE9gX 8pskP7dtkFmzLgFI3t2d315wtxNgrlOV24u7WraUbDDzaQ9iWsIn+I3QhWXQn+KNKD TNcPVnMS0C8KVxfnomzLIISgKeIYzEoGi7WMT9jI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Hariprasad Kelam , Nitin Shetty J , Jakub Kicinski , Sasha Levin Subject: [PATCH 7.1 339/744] octeontx2-pf: tc: fix egress ratelimiting Date: Thu, 30 Jul 2026 16:10:12 +0200 Message-ID: <20260730141451.487700415@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260730141444.267951807@linuxfoundation.org> References: <20260730141444.267951807@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Hariprasad Kelam [ Upstream commit bb0d96ebe5f4d1acccf4dc36ca7f01f9a8fa1ba1 ] The egress rate calculation computes an incorrect mantissa and exponent, causing up to ~50% deviation from the configured rate at lower speeds. Rework the computation to follow the hardware rate formula: rate = 2 * (1 + mantissa/256) * 2^exp / (1 << div_exp) Keep div_exp = 0 and derive exp and mantissa from half of the requested rate. Rates below 2 Mbps are floored to the smallest encodable step (exp = 0, mantissa = 0). Fixes: e638a83f167e ("octeontx2-pf: TC_MATCHALL egress ratelimiting offload") Signed-off-by: Hariprasad Kelam Signed-off-by: Nitin Shetty J Link: https://patch.msgid.link/20260717084349.2227796-1-nshettyj@marvell.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- .../ethernet/marvell/octeontx2/nic/otx2_tc.c | 29 ++++++++++--------- 1 file changed, 16 insertions(+), 13 deletions(-) diff --git a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_tc.c b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_tc.c index 40162b08014dd6..0b46ec29e64eaa 100644 --- a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_tc.c +++ b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_tc.c @@ -30,6 +30,7 @@ #define OTX2_UNSUPP_LSE_DEPTH GENMASK(6, 4) #define MCAST_INVALID_GRP (-1U) +#define RATE_MANTISSA_BITS 8 static void otx2_get_egress_burst_cfg(struct otx2_nic *nic, u32 burst, u32 *burst_exp, u32 *burst_mantissa) @@ -66,28 +67,30 @@ static void otx2_get_egress_burst_cfg(struct otx2_nic *nic, u32 burst, static void otx2_get_egress_rate_cfg(u64 maxrate, u32 *exp, u32 *mantissa, u32 *div_exp) { - u64 tmp; - /* Rate calculation by hardware * * PIR_ADD = ((256 + mantissa) << exp) / 256 * rate = (2 * PIR_ADD) / ( 1 << div_exp) * The resultant rate is in Mbps. + * + * Use div_exp = 0 and compute exp/mantissa for maxrate / 2; the + * leading factor of two yields the full rate. Rates below 2 Mbps + * are floored to the smallest step (exp = 0, mantissa = 0). */ - /* 2Mbps to 100Gbps can be expressed with div_exp = 0. - * Setting this to '0' will ease the calculation of - * exponent and mantissa. - */ *div_exp = 0; - if (maxrate) { - *exp = ilog2(maxrate) ? ilog2(maxrate) - 1 : 0; - tmp = maxrate - rounddown_pow_of_two(maxrate); - if (maxrate < MAX_RATE_MANTISSA) - *mantissa = tmp * 2; - else - *mantissa = tmp / (1ULL << (*exp - 7)); + maxrate = maxrate / 2; + if (!maxrate) { + /* Rates below 2 Mbps map to the smallest step */ + *exp = 0; + *mantissa = 0; + } else { + *exp = ilog2(maxrate); + /* Clear MSB and derive fractional bits */ + maxrate &= ~BIT(*exp); + *mantissa = (maxrate << RATE_MANTISSA_BITS) >> *exp; + } } else { /* Instead of disabling rate limiting, set all values to max */ *exp = MAX_RATE_EXPONENT; -- 2.53.0