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([2a01:e0a:f0e:9070:527b:9dff:feef:3874]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-4f0276b4f64sm88063521cf.13.2025.12.08.09.05.50 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 08 Dec 2025 09:05:53 -0800 (PST) Message-ID: Date: Mon, 8 Dec 2025 18:05:49 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 06/33] hw/arm/smmuv3-accel: Initialize shared system address space To: Shameer Kolothum , qemu-arm@nongnu.org, qemu-devel@nongnu.org Cc: peter.maydell@linaro.org, jgg@nvidia.com, nicolinc@nvidia.com, ddutile@redhat.com, berrange@redhat.com, nathanc@nvidia.com, mochs@nvidia.com, smostafa@google.com, wangzhou1@hisilicon.com, jiangkunkun@huawei.com, jonathan.cameron@huawei.com, zhangfei.gao@linaro.org, zhenzhong.duan@intel.com, yi.l.liu@intel.com, kjaju@nvidia.com References: <20251120132213.56581-1-skolothumtho@nvidia.com> <20251120132213.56581-7-skolothumtho@nvidia.com> From: Eric Auger In-Reply-To: <20251120132213.56581-7-skolothumtho@nvidia.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: nG5OffRJuyPxcG-bdUVw0ImMWh_lHkU8UGeFyiQmudM_1765213555 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=170.10.129.124; envelope-from=eric.auger@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-arm@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: eric.auger@redhat.com Errors-To: qemu-arm-bounces+qemu-arm=archiver.kernel.org@nongnu.org Sender: qemu-arm-bounces+qemu-arm=archiver.kernel.org@nongnu.org On 11/20/25 2:21 PM, Shameer Kolothum wrote: > To support accelerated SMMUv3 instances, introduce a shared system-wide > AddressSpace (shared_as_sysmem) that aliases the global system memory. > This shared AddressSpace will be used in a subsequent patch for all > vfio-pci devices behind all accelerated SMMUv3 instances within a VM. > > Sharing a single system AddressSpace ensures that all devices behind > accelerated SMMUv3s use the same system address space pointer. This > allows VFIO/iommufd to reuse a single IOAS ID in iommufd_cdev_attach(), > enabling the Stage-2 page tables to be shared within the VM rather than > duplicated for each SMMUv3 instance. > > Reviewed-by: Nicolin Chen > Reviewed-by: Jonathan Cameron > Signed-off-by: Shameer Kolothum Reviewed-by: Eric Auger Eric > --- > hw/arm/smmuv3-accel.c | 26 ++++++++++++++++++++++++++ > 1 file changed, 26 insertions(+) > > diff --git a/hw/arm/smmuv3-accel.c b/hw/arm/smmuv3-accel.c > index 99ef0db8c4..b2eded743e 100644 > --- a/hw/arm/smmuv3-accel.c > +++ b/hw/arm/smmuv3-accel.c > @@ -11,6 +11,14 @@ > #include "hw/arm/smmuv3.h" > #include "smmuv3-accel.h" > > +/* > + * The root region aliases the global system memory, and shared_as_sysmem > + * provides a shared Address Space referencing it. This Address Space is used > + * by all vfio-pci devices behind all accelerated SMMUv3 instances within a VM. > + */ > +static MemoryRegion root, sysmem; > +static AddressSpace *shared_as_sysmem; > + > static SMMUv3AccelDevice *smmuv3_accel_get_dev(SMMUState *bs, SMMUPciBus *sbus, > PCIBus *bus, int devfn) > { > @@ -51,9 +59,27 @@ static const PCIIOMMUOps smmuv3_accel_ops = { > .get_address_space = smmuv3_accel_find_add_as, > }; > > +static void smmuv3_accel_as_init(SMMUv3State *s) > +{ > + > + if (shared_as_sysmem) { > + return; > + } > + > + memory_region_init(&root, OBJECT(s), "root", UINT64_MAX); > + memory_region_init_alias(&sysmem, OBJECT(s), "smmuv3-accel-sysmem", > + get_system_memory(), 0, > + memory_region_size(get_system_memory())); > + memory_region_add_subregion(&root, 0, &sysmem); > + > + shared_as_sysmem = g_new0(AddressSpace, 1); > + address_space_init(shared_as_sysmem, &root, "smmuv3-accel-as-sysmem"); > +} > + > void smmuv3_accel_init(SMMUv3State *s) > { > SMMUState *bs = ARM_SMMU(s); > > bs->iommu_ops = &smmuv3_accel_ops; > + smmuv3_accel_as_init(s); > }