From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (unknown [192.55.52.136]) (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 70E221847 for ; Thu, 3 Aug 2023 04:05:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1691035545; x=1722571545; h=message-id:date:mime-version:cc:subject:to:references: from:in-reply-to:content-transfer-encoding; bh=WgVb4J59RLF3p1cq5nNgzuJOUGR0j/yT9TP7r6Wj8Zg=; b=RSdXtfy3yB/WtzKwtvg6ArOjIFVbs8cOFaxPCGeRckTWzXs3Jr3EL2si B6fVc/o+TrlylKvKbLaygGT4j9QeT5UB93ctwAgudyfDI27eT7K1HB4at dL+xNnn/atfT0HE21vhlm5VYw/pX6r8JeJHtft5+fd4F+qVRY56Qozgc9 qMKmgBdnMElRg8uSa4f3JwhUZz1fgo+dwm7N8Xl3tmpZ+IpnbvJ854Bi5 e4CdS473Noh2AJZD81K9ovqznTosMQ7VkD2AH1frDHyEygURKBZLIJdtN uO0/COYig1k/Gc3R+wGrWsxyXdv4eGytCTmCXbdOb0sZIpz5EfprRjrFH Q==; X-IronPort-AV: E=McAfee;i="6600,9927,10790"; a="349360924" X-IronPort-AV: E=Sophos;i="6.01,251,1684825200"; d="scan'208";a="349360924" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Aug 2023 21:05:44 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.01,202,1684825200"; d="scan'208";a="872767507" Received: from blu2-mobl.ccr.corp.intel.com (HELO [10.255.31.34]) ([10.255.31.34]) by fmsmga001-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Aug 2023 21:05:41 -0700 Message-ID: <40d9b0fa-4a36-c3b7-53bb-4333ff89dc45@linux.intel.com> Date: Thu, 3 Aug 2023 12:05:37 +0800 Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Cc: baolu.lu@linux.intel.com, "cohuck@redhat.com" , "eric.auger@redhat.com" , "nicolinc@nvidia.com" , "kvm@vger.kernel.org" , "mjrosato@linux.ibm.com" , "chao.p.peng@linux.intel.com" , "yi.y.sun@linux.intel.com" , "peterx@redhat.com" , "jasowang@redhat.com" , "shameerali.kolothum.thodi@huawei.com" , "lulu@redhat.com" , "suravee.suthikulpanit@amd.com" , "iommu@lists.linux.dev" , "linux-kernel@vger.kernel.org" , "linux-kselftest@vger.kernel.org" , "Duan, Zhenzhong" Subject: Re: [PATCH v4 09/12] iommu/vt-d: Add iotlb flush for nested domain Content-Language: en-US To: "Tian, Kevin" , "Liu, Yi L" , "joro@8bytes.org" , "alex.williamson@redhat.com" , "jgg@nvidia.com" , "robin.murphy@arm.com" References: <20230724111335.107427-1-yi.l.liu@intel.com> <20230724111335.107427-10-yi.l.liu@intel.com> <58ae9095-28f2-a44a-b0e5-be82e1eae9d9@linux.intel.com> From: Baolu Lu In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 2023/8/3 12:00, Tian, Kevin wrote: >> From: Baolu Lu >> Sent: Thursday, August 3, 2023 11:25 AM >> >> On 2023/8/2 15:46, Tian, Kevin wrote: >>>> From: Liu, Yi L >>>> Sent: Monday, July 24, 2023 7:14 PM >>>> >>>> + >>>> + spin_lock_irqsave(&dmar_domain->lock, flags); >>>> + list_for_each_entry(info, &dmar_domain->devices, link) >>>> + intel_nested_invalidate(info->dev, dmar_domain, >>>> + req->addr, req->npages); >>>> + spin_unlock_irqrestore(&dmar_domain->lock, flags); >>> >>> Disabling interrupt while invalidating iotlb is certainly unacceptable. >>> >>> Actually there is no need to walk devices. Under dmar_domain there >>> is already a list of attached iommu's. >> >> Walking device is only necessary when invalidating device TLB. For iotlb >> invalidation, it only needs to know the iommu's. >> > > even for device tlb we may think whether there is any better way > to avoid disabling interrupt. It's a slow path, especially in a guest. I ever tried this. But some device drivers call iommu_unmap() in the interrupt critical path. :-( So we have a long way to go. Best regards, baolu