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Re: [libvirt] [PATCH v3 4/5] qemu: Use predictable file names for memory-backend-file




On 11/07/2017 10:51 AM, Michal Privoznik wrote:
> In some cases management application needs to allocate memory for
> qemu upfront and then just let qemu use that. Since we don't want
> to expose path for memory-backend-file anywhere in the domain
> XML, we can generate predictable paths. In this case:
> 
>   $memoryBackingDir/libvirt/qemu/$shortName/$alias
> 
> where $shortName is result of virDomainObjGetShortName().

Just realized the s/Obj/Def/ from my previous review was missed.

John

> 
> Signed-off-by: Michal Privoznik <mprivozn redhat com>
> ---
>  src/qemu/qemu_command.c                            |  2 +-
>  src/qemu/qemu_conf.c                               | 55 +++++++++++++++++-
>  src/qemu/qemu_conf.h                               |  9 ++-
>  src/qemu/qemu_driver.c                             | 17 ++++++
>  src/qemu/qemu_process.c                            | 65 ++++++++++++++++++----
>  .../qemuxml2argv-cpu-numa-memshared.args           |  6 +-
>  .../qemuxml2argv-fd-memory-numa-topology.args      |  3 +-
>  .../qemuxml2argv-fd-memory-numa-topology2.args     |  6 +-
>  .../qemuxml2argv-fd-memory-numa-topology3.args     |  9 ++-
>  .../qemuxml2argv-hugepages-memaccess2.args         |  9 ++-
>  10 files changed, 155 insertions(+), 26 deletions(-)
> 
> diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
> index c949afe90..c12cfec7a 100644
> --- a/src/qemu/qemu_command.c
> +++ b/src/qemu/qemu_command.c
> @@ -3419,7 +3419,7 @@ qemuBuildMemoryBackendStr(virJSONValuePtr *backendProps,
>          } else {
>              /* We can have both pagesize and mem source. If that's the case,
>               * prefer hugepages as those are more specific. */
> -            if (qemuGetMemoryBackingPath(cfg, &memPath) < 0)
> +            if (qemuGetMemoryBackingPath(def, cfg, mem->info.alias, &memPath) < 0)
>                  goto cleanup;
>          }
>  
> diff --git a/src/qemu/qemu_conf.c b/src/qemu/qemu_conf.c
> index f3cff1503..af503d31c 100644
> --- a/src/qemu/qemu_conf.c
> +++ b/src/qemu/qemu_conf.c
> @@ -1750,9 +1750,41 @@ qemuGetDomainHupageMemPath(const virDomainDef *def,
>  }
>  
>  
> +int
> +qemuGetMemoryBackingBasePath(virQEMUDriverConfigPtr cfg,
> +                             char **path)
> +{
> +    return virAsprintf(path, "%s/libvirt/qemu", cfg->memoryBackingDir);
> +}
> +
> +
> +int
> +qemuGetMemoryBackingDomainPath(const virDomainDef *def,
> +                               virQEMUDriverConfigPtr cfg,
> +                               char **path)
> +{
> +    char *shortName = NULL;
> +    char *base = NULL;
> +    int ret = -1;
> +
> +    if (!(shortName = virDomainDefGetShortName(def)) ||
> +        qemuGetMemoryBackingBasePath(cfg, &base) < 0 ||
> +        virAsprintf(path, "%s/%s", base, shortName) < 0)
> +        goto cleanup;
> +
> +    ret = 0;
> + cleanup:
> +    VIR_FREE(base);
> +    VIR_FREE(shortName);
> +    return ret;
> +}
> +
> +
>  /**
>   * qemuGetMemoryBackingPath:
> + * @def: domain definition
>   * @cfg: the driver config
> + * @alias: memory object alias
>   * @memPath: constructed path
>   *
>   * Constructs path to memory backing dir and stores it at @memPath.
> @@ -1761,8 +1793,27 @@ qemuGetDomainHupageMemPath(const virDomainDef *def,
>   *          -1 otherwise (with error reported).
>   */
>  int
> -qemuGetMemoryBackingPath(virQEMUDriverConfigPtr cfg,
> +qemuGetMemoryBackingPath(const virDomainDef *def,
> +                         virQEMUDriverConfigPtr cfg,
> +                         const char *alias,
>                           char **memPath)
>  {
> -    return VIR_STRDUP(*memPath, cfg->memoryBackingDir);
> +    char *domainPath = NULL;
> +    int ret = -1;
> +
> +    if (!alias) {
> +        /* This should never happen (TM) */
> +        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> +                       _("memory device alias is not assigned"));
> +        goto cleanup;
> +    }
> +
> +    if (qemuGetMemoryBackingDomainPath(def, cfg, &domainPath) < 0 ||
> +        virAsprintf(memPath, "%s/%s", domainPath, alias) < 0)
> +        goto cleanup;
> +
> +    ret = 0;
> + cleanup:
> +    VIR_FREE(domainPath);
> +    return ret;
>  }
> diff --git a/src/qemu/qemu_conf.h b/src/qemu/qemu_conf.h
> index 9d6866816..a553e30e2 100644
> --- a/src/qemu/qemu_conf.h
> +++ b/src/qemu/qemu_conf.h
> @@ -364,6 +364,13 @@ int qemuGetDomainHupageMemPath(const virDomainDef *def,
>                                 unsigned long long pagesize,
>                                 char **memPath);
>  
> -int qemuGetMemoryBackingPath(virQEMUDriverConfigPtr cfg,
> +int qemuGetMemoryBackingBasePath(virQEMUDriverConfigPtr cfg,
> +                                 char **path);
> +int qemuGetMemoryBackingDomainPath(const virDomainDef *def,
> +                                   virQEMUDriverConfigPtr cfg,
> +                                   char **path);
> +int qemuGetMemoryBackingPath(const virDomainDef *def,
> +                             virQEMUDriverConfigPtr cfg,
> +                             const char *alias,
>                               char **memPath);
>  #endif /* __QEMUD_CONF_H */
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index bb53d78ea..47f85b9bf 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -631,6 +631,7 @@ qemuStateInitialize(bool privileged,
>      uid_t run_uid = -1;
>      gid_t run_gid = -1;
>      char *hugepagePath = NULL;
> +    char *memoryBackingPath = NULL;
>      size_t i;
>  
>      if (VIR_ALLOC(qemu_driver) < 0)
> @@ -889,6 +890,21 @@ qemuStateInitialize(bool privileged,
>          VIR_FREE(hugepagePath);
>      }
>  
> +    if (qemuGetMemoryBackingBasePath(cfg, &memoryBackingPath) < 0)
> +        goto error;
> +
> +    if (virFileMakePath(memoryBackingPath) < 0) {
> +        virReportSystemError(errno,
> +                             _("unable to create memory backing path %s"),
> +                             memoryBackingPath);
> +        goto error;
> +    }
> +
> +    if (privileged &&
> +        virFileUpdatePerm(memoryBackingPath,
> +                          0, S_IXGRP | S_IXOTH) < 0)
> +        goto error;
> +
>      if (!(qemu_driver->closeCallbacks = virCloseCallbacksNew()))
>          goto error;
>  
> @@ -946,6 +962,7 @@ qemuStateInitialize(bool privileged,
>      virObjectUnref(conn);
>      VIR_FREE(driverConf);
>      VIR_FREE(hugepagePath);
> +    VIR_FREE(memoryBackingPath);
>      qemuStateCleanup();
>      return -1;
>  }
> diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
> index 8eef2794e..eca41261a 100644
> --- a/src/qemu/qemu_process.c
> +++ b/src/qemu/qemu_process.c
> @@ -3324,6 +3324,36 @@ qemuProcessNeedHugepagesPath(virDomainDefPtr def,
>  }
>  
>  
> +static bool
> +qemuProcessNeedMemoryBackingPath(virDomainDefPtr def,
> +                                 virDomainMemoryDefPtr mem)
> +{
> +    size_t i;
> +    size_t numaNodes;
> +
> +    if (def->mem.source == VIR_DOMAIN_MEMORY_SOURCE_FILE ||
> +        def->mem.access != VIR_DOMAIN_MEMORY_ACCESS_DEFAULT)
> +        return true;
> +
> +    numaNodes = virDomainNumaGetNodeCount(def->numa);
> +    for (i = 0; i < numaNodes; i++) {
> +        if (virDomainNumaGetNodeMemoryAccessMode(def->numa, i)
> +            != VIR_DOMAIN_MEMORY_ACCESS_DEFAULT)
> +            return true;
> +    }
> +
> +    if (mem &&
> +        mem->model == VIR_DOMAIN_MEMORY_MODEL_DIMM &&
> +        (mem->access != VIR_DOMAIN_MEMORY_ACCESS_DEFAULT ||
> +         (mem->targetNode >= 0 &&
> +          virDomainNumaGetNodeMemoryAccessMode(def->numa, mem->targetNode)
> +          != VIR_DOMAIN_MEMORY_ACCESS_DEFAULT)))
> +        return true;
> +
> +    return false;
> +}
> +
> +
>  static int
>  qemuProcessBuildDestroyMemoryPathsImpl(virQEMUDriverPtr driver,
>                                         virDomainDefPtr def,
> @@ -3365,33 +3395,46 @@ qemuProcessBuildDestroyMemoryPaths(virQEMUDriverPtr driver,
>                                     bool build)
>  {
>      virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver);
> -    char *hugepagePath = NULL;
> +    char *path = NULL;
>      size_t i;
> -    bool shouldBuild = false;
> +    bool shouldBuildHP = false;
> +    bool shouldBuildMB = false;
>      int ret = -1;
>  
> -    if (build)
> -        shouldBuild = qemuProcessNeedHugepagesPath(vm->def, mem);
> +    if (build) {
> +        shouldBuildHP = qemuProcessNeedHugepagesPath(vm->def, mem);
> +        shouldBuildMB = qemuProcessNeedMemoryBackingPath(vm->def, mem);
> +    }
>  
> -    if (!build || shouldBuild) {
> +    if (!build || shouldBuildHP) {
>          for (i = 0; i < cfg->nhugetlbfs; i++) {
> -            VIR_FREE(hugepagePath);
> -            hugepagePath = qemuGetDomainHugepagePath(vm->def, &cfg->hugetlbfs[i]);
> +            path = qemuGetDomainHugepagePath(vm->def, &cfg->hugetlbfs[i]);
>  
> -            if (!hugepagePath)
> +            if (!path)
>                  goto cleanup;
>  
>              if (qemuProcessBuildDestroyMemoryPathsImpl(driver, vm->def,
> -                                                       hugepagePath, build) < 0)
> +                                                       path, build) < 0)
>                  goto cleanup;
>  
> -            VIR_FREE(hugepagePath);
> +            VIR_FREE(path);
>          }
>      }
>  
> +    if (!build || shouldBuildMB) {
> +        if (qemuGetMemoryBackingDomainPath(vm->def, cfg, &path) < 0)
> +            goto cleanup;
> +
> +        if (qemuProcessBuildDestroyMemoryPathsImpl(driver, vm->def,
> +                                                   path, build) < 0)
> +            goto cleanup;
> +
> +        VIR_FREE(path);
> +    }
> +
>      ret = 0;
>   cleanup:
> -    VIR_FREE(hugepagePath);
> +    VIR_FREE(path);
>      virObjectUnref(cfg);
>      return ret;
>  }
> diff --git a/tests/qemuxml2argvdata/qemuxml2argv-cpu-numa-memshared.args b/tests/qemuxml2argvdata/qemuxml2argv-cpu-numa-memshared.args
> index 5700c3413..352819429 100644
> --- a/tests/qemuxml2argvdata/qemuxml2argv-cpu-numa-memshared.args
> +++ b/tests/qemuxml2argvdata/qemuxml2argv-cpu-numa-memshared.args
> @@ -10,10 +10,12 @@ QEMU_AUDIO_DRV=none \
>  -M pc \
>  -m 214 \
>  -smp 16,sockets=2,cores=4,threads=2 \
> --object memory-backend-file,id=ram-node0,mem-path=/var/lib/libvirt/qemu/ram,\
> +-object memory-backend-file,id=ram-node0,\
> +mem-path=/var/lib/libvirt/qemu/ram/libvirt/qemu/-1-QEMUGuest1/ram-node0,\
>  share=yes,size=112197632 \
>  -numa node,nodeid=0,cpus=0-7,memdev=ram-node0 \
> --object memory-backend-file,id=ram-node1,mem-path=/var/lib/libvirt/qemu/ram,\
> +-object memory-backend-file,id=ram-node1,\
> +mem-path=/var/lib/libvirt/qemu/ram/libvirt/qemu/-1-QEMUGuest1/ram-node1,\
>  share=no,size=112197632 \
>  -numa node,nodeid=1,cpus=8-15,memdev=ram-node1 \
>  -uuid c7a5fdbd-edaf-9455-926a-d65c16db1809 \
> diff --git a/tests/qemuxml2argvdata/qemuxml2argv-fd-memory-numa-topology.args b/tests/qemuxml2argvdata/qemuxml2argv-fd-memory-numa-topology.args
> index 12f3d8ab8..fa1353259 100644
> --- a/tests/qemuxml2argvdata/qemuxml2argv-fd-memory-numa-topology.args
> +++ b/tests/qemuxml2argvdata/qemuxml2argv-fd-memory-numa-topology.args
> @@ -11,7 +11,8 @@ QEMU_AUDIO_DRV=none \
>  -m 14336 \
>  -mem-prealloc \
>  -smp 8,sockets=1,cores=8,threads=1 \
> --object memory-backend-file,id=ram-node0,mem-path=/var/lib/libvirt/qemu/ram,\
> +-object memory-backend-file,id=ram-node0,\
> +mem-path=/var/lib/libvirt/qemu/ram/libvirt/qemu/-1-instance-00000092/ram-node0,\
>  share=yes,size=15032385536 \
>  -numa node,nodeid=0,cpus=0-7,memdev=ram-node0 \
>  -uuid 126f2720-6f8e-45ab-a886-ec9277079a67 \
> diff --git a/tests/qemuxml2argvdata/qemuxml2argv-fd-memory-numa-topology2.args b/tests/qemuxml2argvdata/qemuxml2argv-fd-memory-numa-topology2.args
> index 585e4d506..6f73a1b99 100644
> --- a/tests/qemuxml2argvdata/qemuxml2argv-fd-memory-numa-topology2.args
> +++ b/tests/qemuxml2argvdata/qemuxml2argv-fd-memory-numa-topology2.args
> @@ -11,10 +11,12 @@ QEMU_AUDIO_DRV=none \
>  -m 28672 \
>  -mem-prealloc \
>  -smp 20,sockets=1,cores=8,threads=1 \
> --object memory-backend-file,id=ram-node0,mem-path=/var/lib/libvirt/qemu/ram,\
> +-object memory-backend-file,id=ram-node0,\
> +mem-path=/var/lib/libvirt/qemu/ram/libvirt/qemu/-1-instance-00000092/ram-node0,\
>  share=no,size=15032385536 \
>  -numa node,nodeid=0,cpus=0-7,memdev=ram-node0 \
> --object memory-backend-file,id=ram-node1,mem-path=/var/lib/libvirt/qemu/ram,\
> +-object memory-backend-file,id=ram-node1,\
> +mem-path=/var/lib/libvirt/qemu/ram/libvirt/qemu/-1-instance-00000092/ram-node1,\
>  share=yes,size=15032385536 \
>  -numa node,nodeid=1,cpus=8-15,memdev=ram-node1 \
>  -uuid 126f2720-6f8e-45ab-a886-ec9277079a67 \
> diff --git a/tests/qemuxml2argvdata/qemuxml2argv-fd-memory-numa-topology3.args b/tests/qemuxml2argvdata/qemuxml2argv-fd-memory-numa-topology3.args
> index e9a57a69e..3c352fe03 100644
> --- a/tests/qemuxml2argvdata/qemuxml2argv-fd-memory-numa-topology3.args
> +++ b/tests/qemuxml2argvdata/qemuxml2argv-fd-memory-numa-topology3.args
> @@ -11,13 +11,16 @@ QEMU_AUDIO_DRV=none \
>  -m 43008 \
>  -mem-prealloc \
>  -smp 32,sockets=1,cores=24,threads=1 \
> --object memory-backend-file,id=ram-node0,mem-path=/var/lib/libvirt/qemu/ram,\
> +-object memory-backend-file,id=ram-node0,\
> +mem-path=/var/lib/libvirt/qemu/ram/libvirt/qemu/-1-instance-00000092/ram-node0,\
>  share=yes,size=15032385536 \
>  -numa node,nodeid=0,cpus=0-1,memdev=ram-node0 \
> --object memory-backend-file,id=ram-node1,mem-path=/var/lib/libvirt/qemu/ram,\
> +-object memory-backend-file,id=ram-node1,\
> +mem-path=/var/lib/libvirt/qemu/ram/libvirt/qemu/-1-instance-00000092/ram-node1,\
>  share=yes,size=15032385536 \
>  -numa node,nodeid=1,cpus=2-3,memdev=ram-node1 \
> --object memory-backend-file,id=ram-node2,mem-path=/var/lib/libvirt/qemu/ram,\
> +-object memory-backend-file,id=ram-node2,\
> +mem-path=/var/lib/libvirt/qemu/ram/libvirt/qemu/-1-instance-00000092/ram-node2,\
>  share=no,size=15032385536 \
>  -numa node,nodeid=2,cpus=4-5,memdev=ram-node2 \
>  -uuid 126f2720-6f8e-45ab-a886-ec9277079a67 \
> diff --git a/tests/qemuxml2argvdata/qemuxml2argv-hugepages-memaccess2.args b/tests/qemuxml2argvdata/qemuxml2argv-hugepages-memaccess2.args
> index 55db49171..d8e506c19 100644
> --- a/tests/qemuxml2argvdata/qemuxml2argv-hugepages-memaccess2.args
> +++ b/tests/qemuxml2argvdata/qemuxml2argv-hugepages-memaccess2.args
> @@ -10,17 +10,20 @@ QEMU_AUDIO_DRV=none \
>  -M pc \
>  -m size=4194304k,slots=16,maxmem=8388608k \
>  -smp 4,sockets=4,cores=1,threads=1 \
> --object memory-backend-file,id=ram-node0,mem-path=/var/lib/libvirt/qemu/ram,\
> +-object memory-backend-file,id=ram-node0,\
> +mem-path=/var/lib/libvirt/qemu/ram/libvirt/qemu/-1-QEMUGuest1/ram-node0,\
>  share=no,size=1073741824,host-nodes=0-3,policy=bind \
>  -numa node,nodeid=0,cpus=0,memdev=ram-node0 \
>  -object memory-backend-file,id=ram-node1,prealloc=yes,\
>  mem-path=/dev/hugepages2M/libvirt/qemu/-1-QEMUGuest1,share=yes,size=1073741824,\
>  host-nodes=0-3,policy=bind \
>  -numa node,nodeid=1,cpus=1,memdev=ram-node1 \
> --object memory-backend-file,id=ram-node2,mem-path=/var/lib/libvirt/qemu/ram,\
> +-object memory-backend-file,id=ram-node2,\
> +mem-path=/var/lib/libvirt/qemu/ram/libvirt/qemu/-1-QEMUGuest1/ram-node2,\
>  share=no,size=1073741824,host-nodes=0-3,policy=bind \
>  -numa node,nodeid=2,cpus=2,memdev=ram-node2 \
> --object memory-backend-file,id=ram-node3,mem-path=/var/lib/libvirt/qemu/ram,\
> +-object memory-backend-file,id=ram-node3,\
> +mem-path=/var/lib/libvirt/qemu/ram/libvirt/qemu/-1-QEMUGuest1/ram-node3,\
>  share=no,size=1073741824,host-nodes=3,policy=bind \
>  -numa node,nodeid=3,cpus=3,memdev=ram-node3 \
>  -object memory-backend-file,id=memdimm0,prealloc=yes,\
> 


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