Re: [libvirt] [PATCH 2/2] libxl: fix dom0 maximum memory setting

On 02/02/2017 10:31 PM, Jim Fehlig wrote: > When the libxl driver is initialized, it creates a virDomainDef > object for dom0 and adds it to the list of domains. Total memory > for dom0 was being set from the max_memkb field of libxl_dominfo > struct retrieved from libxl, but this field can be set to > LIBXL_MEMKB_DEFAULT (~0ULL) if dom0 maximum memory has not been > explicitly set by the user. > > This patch adds some simple parsing of the Xen commandline, > looking for a dom0_mem parameter that also specifies a 'max' value. > If not specified, dom0 maximum memory is effectively all physical > host memory. > > Signed-off-by: Jim Fehlig <jfehlig(a)suse.com&gt; > --- > src/libxl/libxl_conf.c | 75 ++++++++++++++++++++++++++++++++++++++++++++++++ > src/libxl/libxl_conf.h | 3 ++ > src/libxl/libxl_driver.c | 2 +- > 3 files changed, 79 insertions(+), 1 deletion(-) > > diff --git a/src/libxl/libxl_conf.c b/src/libxl/libxl_conf.c > index b5186f2..bfe0e92 100644 > --- a/src/libxl/libxl_conf.c > +++ b/src/libxl/libxl_conf.c > @@ -34,6 +34,7 @@ > #include "internal.h" > #include "virlog.h" > #include "virerror.h" > +#include "c-ctype.h" > #include "datatypes.h" > #include "virconf.h" > #include "virfile.h" > @@ -1530,6 +1531,80 @@ int libxlDriverConfigLoadFile(libxlDriverConfigPtr cfg, > > } > > +/* > + * dom0's maximum memory can be controled by the user with the 'dom0_mem' Xen > + * command line parameter. E.g. to set dom0's initial memory to 4G and max > + * memory to 8G: dom0_mem=4G,max:8G > + * > + * If not constrained by the user, dom0 can effectively use all host memory. > + * This function returns the configured maximum memory for dom0 in kilobytes, > + * either the user-specified value or total physical memory as a default. > + */ > +unsigned long long > +libxlDriverGetDom0MaxmemConf(libxlDriverConfigPtr cfg) > +{ > + char **cmd_tokens = NULL; > + char **mem_tokens = NULL; > + size_t i; > + size_t j; > + unsigned long long ret; > + libxl_physinfo physinfo; > + > + if (cfg->verInfo->commandline == NULL || > + !(cmd_tokens = virStringSplit(cfg->verInfo->commandline, " ", 0))) > + goto physmem; > + > + for (i = 0; cmd_tokens[i] != NULL; i++) { > + if (!STRPREFIX(cmd_tokens[i], "dom0_mem=")) > + continue; > + > + if (!(mem_tokens = virStringSplit(cmd_tokens[i], ",", 0))) > + break; > + for (j = 0; mem_tokens[j] != NULL; j++) { > + if (STRPREFIX(mem_tokens[j], "max:")) { > + char *p = mem_tokens[j] + 4; > + unsigned long long multiplier = 1; > + > + while (c_isdigit(*p)) > + p++; > + if (virStrToLong_ull(mem_tokens[j] + 4, &p, 10, &ret) < 0) > + break; > + if (*p) { > + switch (*p) { > + case 'k': > + case 'K': > + multiplier = 1024; > + break; > + case 'm': > + case 'M': > + multiplier = 1024 * 1024; > + break; > + case 'g': > + case 'G': > + multiplier = 1024 * 1024 * 1024; > + break; > + } > + } > + ret = (ret * multiplier) / 1024; > + goto cleanup; > + } > + } > + } > + > + physmem: > + /* No 'max' specified in dom0_mem, so dom0 can use all physical memory */ > + libxl_physinfo_init(&physinfo); > + libxl_get_physinfo(cfg->ctx, &physinfo); Despite being an unlikely event, libxl_get_physinfo can fail here - I think you need to check the return value here.

> + ret = (physinfo.total_pages * cfg->verInfo->pagesize) / 1024; > + libxl_physinfo_dispose(&physinfo); > + > + cleanup: > + virStringListFree(cmd_tokens); > + virStringListFree(mem_tokens); > + return ret; > +} > + > + > #ifdef LIBXL_HAVE_DEVICE_CHANNEL > static int > libxlPrepareChannel(virDomainChrDefPtr channel, > diff --git a/src/libxl/libxl_conf.h b/src/libxl/libxl_conf.h > index 69d7885..c4ddbfe 100644 > --- a/src/libxl/libxl_conf.h > +++ b/src/libxl/libxl_conf.h > @@ -173,6 +173,9 @@ libxlDriverNodeGetInfo(libxlDriverPrivatePtr driver, > int libxlDriverConfigLoadFile(libxlDriverConfigPtr cfg, > const char *filename); > > +unsigned long long > +libxlDriverGetDom0MaxmemConf(libxlDriverConfigPtr cfg); > + > int > libxlMakeDisk(virDomainDiskDefPtr l_dev, libxl_device_disk *x_dev); > int > diff --git a/src/libxl/libxl_driver.c b/src/libxl/libxl_driver.c > index 921cc93..e54b3b7 100644 > --- a/src/libxl/libxl_driver.c > +++ b/src/libxl/libxl_driver.c > @@ -615,7 +615,7 @@ libxlAddDom0(libxlDriverPrivatePtr driver) > if (virDomainDefSetVcpus(vm->def, d_info.vcpu_online) < 0) > goto cleanup; > vm->def->mem.cur_balloon = d_info.current_memkb; > - virDomainDefSetMemoryTotal(vm->def, d_info.max_memkb); > + virDomainDefSetMemoryTotal(vm->def, libxlDriverGetDom0MaxmemConf(cfg)); And perhaps checking here too on whether "libxlDriverGetDom0MaxmemConf(cfg) < 0" ?