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Mon, 29 Sep 2025 08:57:24 -0700 (PDT) Received: from ziepe.ca ([130.41.10.202]) by smtp.gmail.com with ESMTPSA id af79cd13be357-85c307acfb2sm830379085a.39.2025.09.29.08.57.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 29 Sep 2025 08:57:24 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1v3GFf-0000000CM69-2XTb; Mon, 29 Sep 2025 12:57:23 -0300 Date: Mon, 29 Sep 2025 12:57:23 -0300 From: Jason Gunthorpe To: Samiullah Khawaja Cc: David Woodhouse , Lu Baolu , Joerg Roedel , Will Deacon , Pasha Tatashin , iommu@lists.linux.dev, Robin Murphy , Pratyush Yadav , Kevin Tian , linux-kernel@vger.kernel.org, Saeed Mahameed , Adithya Jayachandran , Parav Pandit , Leon Romanovsky , William Tu , Vipin Sharma , dmatlack@google.com, zhuyifei@google.com, Chris Li , praan@google.com Subject: Re: [RFC PATCH 08/15] iommu/vt-d: Implement live update preserve_iommu_context Message-ID: <20250929155723.GE2695987@ziepe.ca> References: <20250928190624.3735830-1-skhawaja@google.com> <20250928190624.3735830-9-skhawaja@google.com> Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250928190624.3735830-9-skhawaja@google.com> On Sun, Sep 28, 2025 at 07:06:16PM +0000, Samiullah Khawaja wrote: > +static int unpreserve_iommu_context(struct intel_iommu *iommu, int end) > +{ > + struct context_entry *context; > + int i; > + > + if (end < 0) > + end = ROOT_ENTRY_NR; > + > + for (i = 0; i < end; i++) { > + context = iommu_context_addr(iommu, i, 0, 0); > + if (context) > + WARN_ON_ONCE(kho_unpreserve_folio(virt_to_folio(context))); Wrong function. IIRC all of these allocations came from iommu-pages.c and have struct page metadata. iommu-pages needs to participate in restoring them and put back it's struct page information. > static int preserve_iommu_state(struct intel_iommu *iommu, > struct iommu_unit_ser *ser) > { > - pr_warn("Not implemented\n"); > - return 0; > + int ret; > + > + spin_lock(&iommu->lock); > + ret = preserve_iommu_context(iommu); > + if (ret) > + goto error; > + > + ret = kho_preserve_folio(virt_to_folio(iommu->root_entry)); > + if (ret) { > + unpreserve_iommu_context(iommu, -1); > + goto error; > + } > + > + ser->phys_addr = iommu->reg_phys; > + ser->root_table = __pa(iommu->root_entry); > + atomic_set(&iommu->preserved, 1); Why all these atomics?? Also most probably this should all be flowing through the core code as I think the core code has to genericall prevent attach/detach/probe from happing once serialization has started. Jason