From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by smtp.subspace.kernel.org (Postfix) with ESMTP id BE7A642B307; Mon, 6 Jul 2026 16:55:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=13.77.154.182 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783356917; cv=none; b=TrGKFLji3HBM+QCvO2CenBTurRLXtrCOXP0214ywtPCjzGceoae/inyiPw9Rd9C5u0X7MNfs+unJaD0TXU/4LfIzGccGnNUq08eKDvEsXOHOpR+iA38NALtvcSngKanGxvs5I3RrjmNhDJwOdntNIGz+GRL9yLnYjodExF3q7wA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783356917; c=relaxed/simple; bh=V27uU26z+OREAxOjfC3mYvFlmRfHErKF0t40vNkBFcw=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=ts0nudDRhtKpdxZ0IkswkpFS+j+XqiEsgUsd5TXHMdzEjvhIXITOTMFxJ/Us4l+hLVYhZPEkr8ksFlDxlktNQlB9BUATZrY19jVM4wdIk267ApLkkNub7IfMmXSghPhBpkF3521gu/OwyTE1fMQ3mrfe6j82DlQXGdpsCyss5DQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com; spf=pass smtp.mailfrom=linux.microsoft.com; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b=e6MVuqKk; arc=none smtp.client-ip=13.77.154.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="e6MVuqKk" Received: from localhost (unknown [20.236.11.42]) by linux.microsoft.com (Postfix) with ESMTPSA id 8E0BF20B716A; Mon, 6 Jul 2026 09:55:11 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 8E0BF20B716A DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1783356912; bh=HoZoevdHv2yQT0DlpD5qpPEyASfbpumwXGMTTLcX+qw=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=e6MVuqKkQaSr4NlvXcDV/ZTz4kzbCtf9HiZ4CcO444sIzlXx9W6tm9/IqySvh72+U 8gaf3+8hXJUUgIBBNsB+k/sjKVpgqoXacPtkkq5DqYTj1WwU/IUu+3RKyL3FradD3Z lo/CunsxQln6iyAgEt++juRrk+vNQQV/XVE57oCg= Date: Mon, 6 Jul 2026 09:55:10 -0700 From: Jacob Pan To: Yu Zhang Cc: linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org, iommu@lists.linux.dev, linux-pci@vger.kernel.org, linux-arch@vger.kernel.org, wei.liu@kernel.org, kys@microsoft.com, haiyangz@microsoft.com, decui@microsoft.com, longli@microsoft.com, joro@8bytes.org, will@kernel.org, robin.murphy@arm.com, bhelgaas@google.com, kwilczynski@kernel.org, lpieralisi@kernel.org, mani@kernel.org, robh@kernel.org, arnd@arndb.de, jgg@ziepe.ca, mhklinux@outlook.com, tgopinath@linux.microsoft.com, easwar.hariharan@linux.microsoft.com, mrathor@linux.microsoft.com, jacob.pan@linux.microsoft.com Subject: Re: [PATCH v2 3/4] iommu/hyperv: Add para-virtualized IOMMU support for Hyper-V guest Message-ID: <20260706095510.00007ce1@linux.microsoft.com> In-Reply-To: <20260702160518.311234-4-zhangyu1@linux.microsoft.com> References: <20260702160518.311234-1-zhangyu1@linux.microsoft.com> <20260702160518.311234-4-zhangyu1@linux.microsoft.com> Organization: LSG X-Mailer: Claws Mail 3.21.0 (GTK+ 2.24.33; x86_64-w64-mingw32) Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Hi Yu, On Fri, 3 Jul 2026 00:05:17 +0800 Yu Zhang wrote: > +static int hv_iommu_attach_dev(struct iommu_domain *domain, struct > device *dev, > + struct iommu_domain *old) > +{ > + u64 status; > + u32 prefix; > + unsigned long flags; > + struct pci_dev *pdev; > + struct hv_input_attach_device_domain *input; > + struct hv_iommu_endpoint *vdev = dev_iommu_priv_get(dev); > + struct hv_iommu_domain *hv_domain = > to_hv_iommu_domain(domain); > + int ret; > + > + if (vdev->hv_domain == hv_domain) > + return 0; > + Is this needed? seems the core code already skips same domain attach? i.e. static int __iommu_group_set_domain_internal(struct iommu_group *group, struct iommu_domain *new_domain, unsigned int flags) { ... if (group->domain == new_domain) return 0;