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Wed, 17 Jun 2026 04:19:47 -0700 (PDT) X-Received: by 2002:a05:6000:2683:b0:45e:de42:6e90 with SMTP id ffacd0b85a97d-462386f3fbemr6237015f8f.37.1781695187208; Wed, 17 Jun 2026 04:19:47 -0700 (PDT) Received: from imammedo ([213.175.37.14]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-461eaa0d1c7sm9798088f8f.7.2026.06.17.04.19.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Jun 2026 04:19:46 -0700 (PDT) Date: Wed, 17 Jun 2026 13:19:45 +0200 From: Igor Mammedov To: fanhuang Cc: , , , , , Subject: Re: [PATCH v12 0/4] hw/mem: add sp-mem device for Specific Purpose Memory Message-ID: <20260617131945.5d7cbc5f@imammedo> In-Reply-To: <20260616090808.3047939-1-FangSheng.Huang@amd.com> References: <20260616090808.3047939-1-FangSheng.Huang@amd.com> X-Mailer: Claws Mail 4.4.0 (GTK 3.24.52; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=imammedo@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -24 X-Spam_score: -2.5 X-Spam_bar: -- X-Spam_report: (-2.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.445, 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_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Tue, 16 Jun 2026 17:08:04 +0800 fanhuang wrote: > This series adds a TYPE_MEMORY_DEVICE subclass `sp-mem` for boot-time > SOFT_RESERVED guest memory, following the direction from the v7 > thread [1] and the v8 / v9 / v10 / v11 reviews [2][3][4][5]. review is done, modulo cosmetic patch restructuring and missing tests LGTM. as for adding duplication, I'm expecting cleanup/consolidation refactoring on top, that I've asked for in earlier reviews. > > Background > ---------- > > This series targets coherent CPU + accelerator shared-address-space > systems, where the accelerator's HBM is not a device-private > framebuffer behind a PCIe BAR but a tier of host system memory: > visible to the CPU in the platform physical address space, shared > coherently with the accelerator over the platform fabric, and bound > to a NUMA proximity domain set by platform firmware at boot fabric > training. > > For such a region to function correctly in the guest, two things > must hold simultaneously: the CPU memory subsystem has to see it in > the system memory map (so the CPU side can address it), and it has > to be reserved exclusively for the accelerator's driver (so the > kernel's general allocator does not hand SPM pages to unrelated > workloads). The SOFT_RESERVED memory type in E820 plus a matching > SRAT memory-affinity entry is the mechanism that delivers both: a > firmware-produced topology that the CPU memory subsystem honors and > the accelerator's driver consumes for its own range. > > Approach > -------- > > The series introduces a new TYPE_MEMORY_DEVICE subclass `sp-mem`. > Each instance binds one host memory backend to a single NUMA > proximity domain and is boot-time only; placement, mapped-state > enforcement, and QMP introspection come from the existing > memory-device framework. > > Testing > ------- > > Verified end-to-end on q35 + KVM, with both SeaBIOS and OVMF, for: > > - single sp-mem instance > - two sp-mem instances on different NUMA nodes > > Guest observations: /proc/iomem shows one SOFT_RESERVED entry per > sp-mem device, dmesg SRAT parsing reports the matching > memory_affinity entries with correct PXM, and the umbrella > HOTPLUGGABLE entry covers the remaining hotplug-memory window > without overlapping the sp-mem ranges. > > Changes since v11 > ----------------- > > - Drop the unneeded memory-device.h and system/hostmem.h includes > from sp-mem.h (HostMemoryBackend is forward-declared). > - Use SP_MEM_MEMDEV_PROP in sp_mem_get_memory_region()'s error > message, matching realize(). > - Move the .unmigratable comment next to the field it documents. > > All v11 patch-1 review comments from Philippe; patches 2-4 unchanged. > Patch 4 (MAINTAINERS) retains the Acked-by from Igor and David. > > Previous versions > ----------------- > > v1: https://lore.kernel.org/qemu-devel/20250924103324.2074819-1-FangSheng.Huang@amd.com/ > v2: https://lore.kernel.org/qemu-devel/20251020090701.4036748-1-FangSheng.Huang@amd.com/ > v3: https://lore.kernel.org/qemu-devel/20251208105137.2058928-1-FangSheng.Huang@amd.com/ > v4: https://lore.kernel.org/qemu-devel/20251209093841.2250527-1-FangSheng.Huang@amd.com/ > v5: https://lore.kernel.org/qemu-devel/20260123024312.1601732-1-FangSheng.Huang@amd.com/ > v6: https://lore.kernel.org/qemu-devel/20260226105023.256568-1-FangSheng.Huang@amd.com/ > v7: https://lore.kernel.org/qemu-devel/20260306082735.1106690-1-FangSheng.Huang@amd.com/ > v8: https://lore.kernel.org/qemu-devel/20260527074215.229119-1-FangSheng.Huang@amd.com/ > v9: https://lore.kernel.org/qemu-devel/20260602084447.1100554-1-FangSheng.Huang@amd.com/ > v10: https://lore.kernel.org/qemu-devel/20260605104609.1739911-1-FangSheng.Huang@amd.com/ > v11: https://lore.kernel.org/qemu-devel/20260611100637.2460507-1-FangSheng.Huang@amd.com/ > > [1] v7 thread closeout: > https://lore.kernel.org/qemu-devel/666a7ba1-5d3a-4732-b872-0d9fb2fe8461@amd.com/ > [2] v8 review: > https://lore.kernel.org/qemu-devel/20260601105057.2d764e55@imammedo/ > [3] v9 review: > https://lore.kernel.org/qemu-devel/20260602084447.1100554-1-FangSheng.Huang@amd.com/T/ > [4] v10 review: > https://lore.kernel.org/qemu-devel/20260605104609.1739911-1-FangSheng.Huang@amd.com/T/ > [5] v11 review: > https://lore.kernel.org/qemu-devel/20260611100637.2460507-1-FangSheng.Huang@amd.com/T/ > > fanhuang (4): > hw/mem: add sp-mem device for Specific Purpose Memory > i386/acpi-build: partition device_memory SRAT umbrella for sp-mem > hw/i386: hook sp-mem into the pc machine plug path > MAINTAINERS: cover sp-mem under Memory devices, add R: tag > > MAINTAINERS | 3 + > qapi/machine.json | 43 ++++++++++- > hw/i386/e820_memory_layout.h | 11 +-- > include/hw/mem/sp-mem.h | 33 +++++++++ > hw/core/machine-hmp-cmds.c | 11 +++ > hw/i386/acpi-build.c | 96 +++++++++++++++++++++++-- > hw/i386/pc.c | 36 ++++++++++ > hw/mem/sp-mem.c | 136 +++++++++++++++++++++++++++++++++++ > hw/i386/Kconfig | 2 + > hw/mem/Kconfig | 4 ++ > hw/mem/meson.build | 1 + > 11 files changed, 365 insertions(+), 11 deletions(-) > create mode 100644 include/hw/mem/sp-mem.h > create mode 100644 hw/mem/sp-mem.c > > > base-commit: 2f28d34ea0aead9830478cd1d3d0dd9d9191d82e > -- > 2.34.1 >