From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.10]) (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 A154226E6F0 for ; Mon, 17 Nov 2025 02:38:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.10 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763347117; cv=none; b=BHs1s6utwNXPGbJBjXfxi+Q+wYY7CUizE75FT1Q9Ht4twBbkJTEGqHsD88KfZR+Cxt4Kw/Vg3V58Jin0+LOGp8GJLoTgiLKXD9q/l7Z5ZorleMOwmdpV2cksJqzEyywrffpc2c2FDUcLGtL29wmgnOL9ZztX9MO0Cu5GrfNciTs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763347117; c=relaxed/simple; bh=GXluFpReQE+Xxdq2pkCoFp5c4SwUoYGgLpfSR7eyUsM=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=Yj5zahuB1XqmWjdMjRrm0ykvi+GgnJJoKoPcwawiWGrBqtPPX4DhKsdVn7qED5ywgWPNG8g5T9a74rOi7kSKy1+cqTpNqH2C4oDavtdfzPcAKFwS2nqBHb5xE0OCMw17BBuETy7KP2Rq7dzIayD9kaSCGZhmrE6K9pm6JAlZllE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=pass smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=bf1IbFRt; arc=none smtp.client-ip=198.175.65.10 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="bf1IbFRt" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1763347116; x=1794883116; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=GXluFpReQE+Xxdq2pkCoFp5c4SwUoYGgLpfSR7eyUsM=; b=bf1IbFRtRE0pbboWDgXHKMzuAuaC7RSFHAmgLZAq/8lx1t/iASn/n4a8 uQGt93XJrDFx2gS+KLfvq1FU1HmzAkBEGAc0aDoCOkzu1Xgg4y1zxRMKu lmeSaj8I8X+Mdlp9jMb3zyTWADdbpZqyoiaKeHAKNFQjG8ZFa5rzyrJTd Rk0pJYJp3rcc0IQZaVdZ1KyPuhL8Qr14c0hPj9wOPm8Oo5M4soun53OQT dhdUjaM7gnOnFkjx/cHaogzZAdK6gfnk0y4S3DP9YsCMsq5vBJC7hL4YF tCCivnfxxZmZeS4p+MOacJMa3O0VbfkztFeXl0WIusSVpXqf+tovjtdAy Q==; X-CSE-ConnectionGUID: CUm8x8QCSymE5T/nhPuNUw== X-CSE-MsgGUID: SOYqiw0PS0a/Ztm8ntn+Kg== X-IronPort-AV: E=McAfee;i="6800,10657,11615"; a="82729541" X-IronPort-AV: E=Sophos;i="6.19,310,1754982000"; d="scan'208";a="82729541" Received: from orviesa001.jf.intel.com ([10.64.159.141]) by orvoesa102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Nov 2025 18:38:36 -0800 X-CSE-ConnectionGUID: KBsaphOKSKCrEL5PuAldTQ== X-CSE-MsgGUID: 1YC+Zx/bTnas3qHdXf/7EQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.19,310,1754982000"; d="scan'208";a="227658276" Received: from yilunxu-optiplex-7050.sh.intel.com ([10.239.159.165]) by orviesa001.jf.intel.com with ESMTP; 16 Nov 2025 18:38:32 -0800 From: Xu Yilun To: linux-coco@lists.linux.dev, linux-pci@vger.kernel.org Cc: chao.gao@intel.com, dave.jiang@intel.com, baolu.lu@linux.intel.com, yilun.xu@linux.intel.com, yilun.xu@intel.com, zhenzhong.duan@intel.com, kvm@vger.kernel.org, rick.p.edgecombe@intel.com, dave.hansen@linux.intel.com, dan.j.williams@intel.com, kas@kernel.org, x86@kernel.org Subject: [PATCH v1 11/26] iommu/vt-d: Cache max domain ID to avoid redundant calculation Date: Mon, 17 Nov 2025 10:22:55 +0800 Message-Id: <20251117022311.2443900-12-yilun.xu@linux.intel.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20251117022311.2443900-1-yilun.xu@linux.intel.com> References: <20251117022311.2443900-1-yilun.xu@linux.intel.com> Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Lu Baolu The cap_ndoms() helper calculates the maximum available domain ID from the value of capability register, which can be inefficient if called repeatedly. Cache the maximum supported domain ID in max_domain_id field during initialization to avoid redundant calls to cap_ndoms() throughout the IOMMU driver. No functionality change. Signed-off-by: Lu Baolu Signed-off-by: Dan Williams --- drivers/iommu/intel/iommu.h | 1 + drivers/iommu/intel/dmar.c | 1 + drivers/iommu/intel/iommu.c | 10 +++++----- 3 files changed, 7 insertions(+), 5 deletions(-) diff --git a/drivers/iommu/intel/iommu.h b/drivers/iommu/intel/iommu.h index 3056583d7f56..66c3aa549fd4 100644 --- a/drivers/iommu/intel/iommu.h +++ b/drivers/iommu/intel/iommu.h @@ -724,6 +724,7 @@ struct intel_iommu { /* mutex to protect domain_ida */ struct mutex did_lock; struct ida domain_ida; /* domain id allocator */ + unsigned long max_domain_id; unsigned long *copied_tables; /* bitmap of copied tables */ spinlock_t lock; /* protect context, domain ids */ struct root_entry *root_entry; /* virtual address */ diff --git a/drivers/iommu/intel/dmar.c b/drivers/iommu/intel/dmar.c index ec975c73cfe6..a54934c0536f 100644 --- a/drivers/iommu/intel/dmar.c +++ b/drivers/iommu/intel/dmar.c @@ -1099,6 +1099,7 @@ static int alloc_iommu(struct dmar_drhd_unit *drhd) spin_lock_init(&iommu->lock); ida_init(&iommu->domain_ida); mutex_init(&iommu->did_lock); + iommu->max_domain_id = cap_ndoms(iommu->cap); ver = readl(iommu->reg + DMAR_VER_REG); pr_info("%s: reg_base_addr %llx ver %d:%d cap %llx ecap %llx\n", diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c index e236c7ec221f..848b300da63e 100644 --- a/drivers/iommu/intel/iommu.c +++ b/drivers/iommu/intel/iommu.c @@ -1356,7 +1356,7 @@ int domain_attach_iommu(struct dmar_domain *domain, struct intel_iommu *iommu) } num = ida_alloc_range(&iommu->domain_ida, IDA_START_DID, - cap_ndoms(iommu->cap) - 1, GFP_KERNEL); + iommu->max_domain_id - 1, GFP_KERNEL); if (num < 0) { pr_err("%s: No free domain ids\n", iommu->name); goto err_unlock; @@ -1420,7 +1420,7 @@ static void copied_context_tear_down(struct intel_iommu *iommu, did_old = context_domain_id(context); context_clear_entry(context); - if (did_old < cap_ndoms(iommu->cap)) { + if (did_old < iommu->max_domain_id) { iommu->flush.flush_context(iommu, did_old, PCI_DEVID(bus, devfn), DMA_CCMD_MASK_NOBIT, @@ -1986,7 +1986,7 @@ static int copy_context_table(struct intel_iommu *iommu, continue; did = context_domain_id(&ce); - if (did >= 0 && did < cap_ndoms(iommu->cap)) + if (did >= 0 && did < iommu->max_domain_id) ida_alloc_range(&iommu->domain_ida, did, did, GFP_KERNEL); set_context_copied(iommu, bus, devfn); @@ -2902,7 +2902,7 @@ static ssize_t domains_supported_show(struct device *dev, struct device_attribute *attr, char *buf) { struct intel_iommu *iommu = dev_to_intel_iommu(dev); - return sysfs_emit(buf, "%ld\n", cap_ndoms(iommu->cap)); + return sysfs_emit(buf, "%ld\n", iommu->max_domain_id); } static DEVICE_ATTR_RO(domains_supported); @@ -2913,7 +2913,7 @@ static ssize_t domains_used_show(struct device *dev, unsigned int count = 0; int id; - for (id = 0; id < cap_ndoms(iommu->cap); id++) + for (id = 0; id < iommu->max_domain_id; id++) if (ida_exists(&iommu->domain_ida, id)) count++; -- 2.25.1