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Berrange" , Markus Armbruster , Steve Sistare Subject: [PATCH V4 04/19] machine: aux-ram-share option Date: Mon, 2 Dec 2024 05:19:56 -0800 Message-Id: <1733145611-62315-5-git-send-email-steven.sistare@oracle.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1733145611-62315-1-git-send-email-steven.sistare@oracle.com> References: <1733145611-62315-1-git-send-email-steven.sistare@oracle.com> X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1057,Hydra:6.0.680,FMLib:17.12.68.34 definitions=2024-12-02_09,2024-12-02_01,2024-11-22_01 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 adultscore=0 mlxlogscore=999 spamscore=0 suspectscore=0 malwarescore=0 mlxscore=0 phishscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2411120000 definitions=main-2412020116 X-Proofpoint-ORIG-GUID: _V1EcolF7YMQF8qT4u5Y8zj1wa8s8qDi X-Proofpoint-GUID: _V1EcolF7YMQF8qT4u5Y8zj1wa8s8qDi Received-SPF: pass client-ip=205.220.177.32; envelope-from=steven.sistare@oracle.com; helo=mx0b-00069f02.pphosted.com X-Spam_score_int: -31 X-Spam_score: -3.2 X-Spam_bar: --- X-Spam_report: (-3.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_MED=-0.444, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=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: 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 Allocate auxilliary guest RAM as an anonymous file that is shareable with an external process. This option applies to memory allocated as a side effect of creating various devices. It does not apply to memory-backend-objects, whether explicitly specified on the command line, or implicitly created by the -m command line option. This option is intended to support new migration modes, in which the memory region can be transferred in place to a new QEMU process, by sending the memfd file descriptor to the process. Memory contents are preserved, and if the mode also transfers device descriptors, then pages that are locked in memory for DMA remain locked. This behavior is a pre-requisite for supporting vfio, vdpa, and iommufd devices with the new modes. Signed-off-by: Steve Sistare --- hw/core/machine.c | 18 ++++++++++++++++++ include/hw/boards.h | 1 + qemu-options.hx | 15 +++++++++++++++ system/physmem.c | 3 +++ 4 files changed, 37 insertions(+) diff --git a/hw/core/machine.c b/hw/core/machine.c index a35c4a8..b299b40 100644 --- a/hw/core/machine.c +++ b/hw/core/machine.c @@ -437,6 +437,20 @@ static void machine_set_mem_merge(Object *obj, bool value, Error **errp) ms->mem_merge = value; } +static bool machine_get_aux_ram_share(Object *obj, Error **errp) +{ + MachineState *ms = MACHINE(obj); + + return ms->aux_ram_share; +} + +static void machine_set_aux_ram_share(Object *obj, bool value, Error **errp) +{ + MachineState *ms = MACHINE(obj); + + ms->aux_ram_share = value; +} + static bool machine_get_usb(Object *obj, Error **errp) { MachineState *ms = MACHINE(obj); @@ -1129,6 +1143,10 @@ static void machine_class_init(ObjectClass *oc, void *data) object_class_property_set_description(oc, "mem-merge", "Enable/disable memory merge support"); + object_class_property_add_bool(oc, "aux-ram-share", + machine_get_aux_ram_share, + machine_set_aux_ram_share); + object_class_property_add_bool(oc, "usb", machine_get_usb, machine_set_usb); object_class_property_set_description(oc, "usb", diff --git a/include/hw/boards.h b/include/hw/boards.h index 36fbb9b..922ecd4 100644 --- a/include/hw/boards.h +++ b/include/hw/boards.h @@ -410,6 +410,7 @@ struct MachineState { bool enable_graphics; ConfidentialGuestSupport *cgs; HostMemoryBackend *memdev; + bool aux_ram_share; /* * convenience alias to ram_memdev_id backend memory region * or to numa container memory region diff --git a/qemu-options.hx b/qemu-options.hx index dacc979..02b9118 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -38,6 +38,9 @@ DEF("machine", HAS_ARG, QEMU_OPTION_machine, \ " nvdimm=on|off controls NVDIMM support (default=off)\n" " memory-encryption=@var{} memory encryption object to use (default=none)\n" " hmat=on|off controls ACPI HMAT support (default=off)\n" +#ifdef CONFIG_POSIX + " aux-ram-share=on|off allocate auxiliary guest RAM as shared (default: off)\n" +#endif " memory-backend='backend-id' specifies explicitly provided backend for main RAM (default=none)\n" " cxl-fmw.0.targets.0=firsttarget,cxl-fmw.0.targets.1=secondtarget,cxl-fmw.0.size=size[,cxl-fmw.0.interleave-granularity=granularity]\n", QEMU_ARCH_ALL) @@ -101,6 +104,18 @@ SRST Enables or disables ACPI Heterogeneous Memory Attribute Table (HMAT) support. The default is off. +#ifdef CONFIG_POSIX + ``aux-ram-share=on|off`` + Allocate auxiliary guest RAM as an anonymous file that is + shareable with an external process. This option applies to + memory allocated as a side effect of creating various devices. + It does not apply to memory-backend-objects, whether explicitly + specified on the command line, or implicitly created by the -m + command line option. + + Some migration modes require aux-ram-share=on. +#endif + ``memory-backend='id'`` An alternative to legacy ``-mem-path`` and ``mem-prealloc`` options. Allows to use a memory backend as main RAM. diff --git a/system/physmem.c b/system/physmem.c index 36f0811..0bcb2cc 100644 --- a/system/physmem.c +++ b/system/physmem.c @@ -2164,6 +2164,9 @@ RAMBlock *qemu_ram_alloc_internal(ram_addr_t size, ram_addr_t max_size, new_block->flags = ram_flags; if (!host && !xen_enabled()) { + if (!share_flags && current_machine->aux_ram_share) { + new_block->flags |= RAM_SHARED; + } if ((new_block->flags & RAM_SHARED) && !qemu_ram_alloc_shared(new_block, &local_err)) { goto err;