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Berrange" , Markus Armbruster , Steve Sistare Subject: [PATCH V6 06/24] machine: aux-ram-share option Date: Tue, 14 Jan 2025 09:23:36 -0800 Message-Id: <1736875434-106563-7-git-send-email-steven.sistare@oracle.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1736875434-106563-1-git-send-email-steven.sistare@oracle.com> References: <1736875434-106563-1-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=2025-01-14_05,2025-01-13_02,2024-11-22_01 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 bulkscore=0 adultscore=0 spamscore=0 suspectscore=0 phishscore=0 malwarescore=0 mlxscore=0 mlxlogscore=999 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2411120000 definitions=main-2501140133 X-Proofpoint-GUID: xZqjWWpxUPVL5azvyMoUv94LGN1d7SX0 X-Proofpoint-ORIG-GUID: xZqjWWpxUPVL5azvyMoUv94LGN1d7SX0 Received-SPF: pass client-ip=205.220.177.32; envelope-from=steven.sistare@oracle.com; helo=mx0b-00069f02.pphosted.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_MED=-0.001, 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_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_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 Reviewed-by: Peter Xu --- hw/core/machine.c | 20 ++++++++++++++++++++ include/hw/boards.h | 1 + qemu-options.hx | 11 +++++++++++ system/physmem.c | 3 +++ 4 files changed, 35 insertions(+) diff --git a/hw/core/machine.c b/hw/core/machine.c index c23b399..57188c5 100644 --- a/hw/core/machine.c +++ b/hw/core/machine.c @@ -457,6 +457,20 @@ 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); @@ -1162,6 +1176,12 @@ static void machine_class_init(ObjectClass *oc, void *data) object_class_property_set_description(oc, "mem-merge", "Enable/disable memory merge support"); +#ifdef CONFIG_POSIX + object_class_property_add_bool(oc, "aux-ram-share", + machine_get_aux_ram_share, + machine_set_aux_ram_share); +#endif + 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 2ad711e..e1f41b2 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 7090d59..90fad31 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 +104,14 @@ SRST Enables or disables ACPI Heterogeneous Memory Attribute Table (HMAT) support. The default is off. + ``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. The default is off. + ``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 03fac0a..cb80ce3 100644 --- a/system/physmem.c +++ b/system/physmem.c @@ -2114,6 +2114,9 @@ RAMBlock *qemu_ram_alloc_internal(ram_addr_t size, ram_addr_t max_size, #ifdef CONFIG_POSIX /* ignore RAM_SHARED for Windows */ if (!host) { + if (!share_flags && current_machine->aux_ram_share) { + ram_flags |= RAM_SHARED; + } if (ram_flags & RAM_SHARED) { const char *name = memory_region_name(mr); int fd = qemu_ram_get_shared_fd(name, errp);