From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f53.google.com (mail-wm1-f53.google.com [209.85.128.53]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 50FCD7FBAC for ; Wed, 22 May 2024 08:27:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.53 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716366457; cv=none; b=UACahKxOEn+a66tCFFXW6I5i3kfiZrfWeoR8PLuvJXWi32wJyiq1iorh/Uweai2p2+siuQrT8N2ebbG157czlCAfYrrMFW9fYLyDpO4paj2ar9v1qvu7WxkvDM3RLJc0hVFiUbCkWwtC1FyhPqsrWc1lWBtm/+JyBXkl4qZZNe0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716366457; c=relaxed/simple; bh=EzbbarVAceIThGcdDJQMoTLX0eccNmtcHB8EGB1fufo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Lu1PMwAqEYTsRzhjlf3UplpaNA9de6DT0bYLocO0zYfP325vKfZp+WtK8In1DScyquCxB2UA0CAdsFWlBwPjp+ugTUqqpuxa97Hq+naP1PtvX9ZCoZWjt3tkyLJ7k84u7fDDo3FjsXdanBJUlfQY7jQP3MATTSeNyC8NW4IgQsQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=N4FKnVoB; arc=none smtp.client-ip=209.85.128.53 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="N4FKnVoB" Received: by mail-wm1-f53.google.com with SMTP id 5b1f17b1804b1-4202ca70270so6544025e9.3 for ; Wed, 22 May 2024 01:27:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1716366454; x=1716971254; darn=lists.linux.dev; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=9tTr2u/xpZoc7xpf88V/G0TB2e+qjtO4Yfevyp6Z/VM=; b=N4FKnVoB6QUy+7rYjO/InXrK/nfTGyOMs2Ad1XJYJlXSroxS2FjOKVXde7gIG2G/Wi +y8xcCqesjEsdJR1uf4li0TpH0Z2DvAmXjj7dpSkeCgxocyUDY/ag/1oPCFKkVpdVVaL ZsX+Z5HWMphwWTYARb3kgi5at4xl00MuaEje5zHDEf9wKqdkAcE/A3/dG8tszmJDJ4Q0 nJ9eBZ0Md8svaCyHxjsa6EaTO6IHb8U19mP6L4Mhjkpyaakzwmdl5bf+tJ9ztFDHeQfA oxfNqthoDwmfKAIECAAaFXZRALWTYT/0MMJkNs/C2HlvpXxADSObVXfUd2R/LsLkOpeM mQbw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1716366454; x=1716971254; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=9tTr2u/xpZoc7xpf88V/G0TB2e+qjtO4Yfevyp6Z/VM=; b=r7KTWmAbFeqMzutDnzL+zV52SEpdhlyw6ooIFj6BatZmqRatouOCeamHHqUx10wOBN PPDeY3kpaGDc90qx4+IhfbOEC7XGbpj6TwmJtglwVWef2312Y440jZ968hxdUHhp1WrV WXS1JSBqwTNOp2ZP43UM+26qdzNJlSjmVzIqLtUKu289QW9oVVULcio/DRY9VzxSqi2Q OtEG+EzVuDCgJ1XSIHWnOqryrAJOel+jS3Op0RkAd0vKSNUla63IvX2aB/NDrqDxGY12 bc642q8fPTLjpYAudWXjhfPbvNFrAwwmWkQYOUd72m64HO9F6wj3eZzZPXT1jnwZRXxY IU9w== X-Gm-Message-State: AOJu0YxHT6Z3Q9ZgWUcvHv3HSrPPl5x3spAnsf53mtMGRqzKwzX9NxCp urOf02L+1SOgXXMeLuhwIdYpCDME/O1KW0OlpP0YQHjtEYFbgb+KFLR4reZuP8M= X-Google-Smtp-Source: AGHT+IG9IJ8rp3fmMs48dAk6Y747OYcyjpxClqnc3kVxDzH+SdddvdkpIdEFObD0FX56tEt3Spe1fQ== X-Received: by 2002:a05:600c:21d5:b0:420:2cbe:7f16 with SMTP id 5b1f17b1804b1-420fd3726d5mr13217935e9.34.1716366453292; Wed, 22 May 2024 01:27:33 -0700 (PDT) Received: from fedora.iskraemeco.si (84-255-245-182.static.t-2.net. [84.255.245.182]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3502b79bc0asm33964495f8f.1.2024.05.22.01.27.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 22 May 2024 01:27:32 -0700 (PDT) From: Uros Bizjak To: iommu@lists.linux.dev, linux-kernel@vger.kernel.org Cc: Uros Bizjak , David Woodhouse , Lu Baolu , Joerg Roedel , Will Deacon , Robin Murphy Subject: [PATCH 2/3] iommu/vt-d: Use try_cmpxchg64() in intel_pasid_get_entry() Date: Wed, 22 May 2024 10:26:48 +0200 Message-ID: <20240522082729.971123-2-ubizjak@gmail.com> X-Mailer: git-send-email 2.45.1 In-Reply-To: <20240522082729.971123-1-ubizjak@gmail.com> References: <20240522082729.971123-1-ubizjak@gmail.com> Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Use try_cmpxchg64() instead of cmpxchg64 (*ptr, old, new) != old in intel_pasid_get_entry(). cmpxchg returns success in ZF flag, so this change saves a compare after cmpxchg (and related move instruction in front of cmpxchg). Signed-off-by: Uros Bizjak Cc: David Woodhouse Cc: Lu Baolu Cc: Joerg Roedel Cc: Will Deacon Cc: Robin Murphy --- drivers/iommu/intel/pasid.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/drivers/iommu/intel/pasid.c b/drivers/iommu/intel/pasid.c index abce19e2ad6f..9bf45bc4b967 100644 --- a/drivers/iommu/intel/pasid.c +++ b/drivers/iommu/intel/pasid.c @@ -146,6 +146,8 @@ static struct pasid_entry *intel_pasid_get_entry(struct device *dev, u32 pasid) retry: entries = get_pasid_table_from_pde(&dir[dir_index]); if (!entries) { + u64 tmp; + entries = iommu_alloc_page_node(info->iommu->node, GFP_ATOMIC); if (!entries) return NULL; @@ -156,8 +158,9 @@ static struct pasid_entry *intel_pasid_get_entry(struct device *dev, u32 pasid) * clear. However, this entry might be populated by others * while we are preparing it. Use theirs with a retry. */ - if (cmpxchg64(&dir[dir_index].val, 0ULL, - (u64)virt_to_phys(entries) | PASID_PTE_PRESENT)) { + tmp = 0ULL; + if (!try_cmpxchg64(&dir[dir_index].val, &tmp, + (u64)virt_to_phys(entries) | PASID_PTE_PRESENT)) { iommu_free_page(entries); goto retry; } -- 2.45.1