Re: [libvirt] [PATCH 2/2] Add support for preallocated memory - xml2argv

Add conversion from xml to argv for subelements source,access and allocation of <memoryBacking> This change introduces support for preallocated shared file descriptor based memory backing. It allows vhost-user to be used without hugepages. Configured by these elements: <memoryBacking> <source type="file|anonymous"/> <access Mode="shared|private"/> <allocation mode="immediate|ondemand"/> </memoryBacking> --- src/qemu/qemu_command.c | 56 ++++++++++++++++++++++ src/qemu/qemu_command.h | 4 ++ .../qemuxml2argv-memorybacking-set.args | 6 ++- tests/qemuxml2argvtest.c | 3 ++ 4 files changed, 68 insertions(+), 1 deletion(-) diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c index 6944129..321e71f 100644 --- a/src/qemu/qemu_command.c +++ b/src/qemu/qemu_command.c @@ -9328,6 +9328,9 @@ qemuBuildCommandLine(virQEMUDriverPtr driver, if (qemuBuildNVRAMCommandLine(cmd, def, qemuCaps) < 0) goto error; + if (qemuBuildMemoryBackendCommandLine(cmd, def, qemuCaps) < 0) + goto error; + if (snapshot) virCommandAddArgList(cmd, "-loadvm", snapshot->def->name, NULL); @@ -9592,3 +9595,56 @@ qemuBuildChrDeviceStr(char **deviceStr, return ret; } + +static char * +qemuBuildMemoryBackendFileStr(const virDomainDef *def) +{ + virBuffer buf = VIR_BUFFER_INITIALIZER; + const char template[] = "memory-backend-file,id=mem,size=1024M,mem-path=/var/lib/libvirt/qemu";

+ + if (VIR_DOMAIN_MEMORY_ACCESS_SHARED == def->mem.access) { + // add ",share=on" to -object memory-backend-file + virBufferAsprintf(&buf, "%s,share=on", template); + } else { + virBufferAsprintf(&buf, "%s", template); + } + + + if (virBufferCheckError(&buf) < 0) + goto error; + + return virBufferContentAndReset(&buf); + + error: + virBufferFreeAndReset(&buf); + return NULL; +} + + +int +qemuBuildMemoryBackendCommandLine(virCommandPtr cmd, + const virDomainDef *def, + virQEMUCapsPtr qemuCaps __attribute__((unused))) +{ + char *optstr = NULL; + + if (VIR_DOMAIN_MEMORY_ALLOCATION_IMMEDIATE == def->mem.allocation) { + // add '-mem-prealloc' + virCommandAddArg(cmd, "-mem-prealloc"); + } +

+ if (VIR_DOMAIN_MEMORY_SOURCE_FILE == def->mem.source) { + optstr = qemuBuildMemoryBackendFileStr(def); + if (optstr) { + virCommandAddArg(cmd, "-object"); + virCommandAddArg(cmd, optstr); + VIR_FREE(optstr); + }

+ + // add '-object memory-backend-file,id=mem,size=1024M,mem-path=/var/lib/libvirt/qemu' + // add '-numa node,memdev=mem' + virCommandAddArgList(cmd, "-numa", "node,memdev=mem", NULL); + }