Re: [libvirt] [PATCH 1/2] qemuBuildMemoryBackendStr: Fix hugepages lookup process

https://bugzilla.redhat.com/show_bug.cgi?id=1196644 So this function is called to construct the guest NUMA part of the qemu command line. At the beginning, the configured hugepages

are searched to find the best match for given guest NUMA node. Configured hugepages can have a @nodeset attribute to specify on which guest NUMA nodes should be the hugepages backing used. There is, however, one 'corner case'. Users may just tell 'use hugepages to back all the nodes'. In other words: <memoryBacking> <hugepages/> </memoryBacking> <cpu> <numa> <cell id='0' cpus='0-1' memory='1024000' unit='KiB'/> </numa> </cpu> Our code fails in this case. Well, since there's no @nodeset (nor any <page/> child element to <hugepages/>) we fail to lookup the default hugepage size to use. Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com&gt; --- src/qemu/qemu_command.c | 41 ++++---- .../qemuxml2argv-hugepages-numa.args | 46 +++++++++ .../qemuxml2argv-hugepages-numa.xml | 107 +++++++++++++++++++++ tests/qemuxml2argvtest.c | 8 ++ 4 files changed, 183 insertions(+), 19 deletions(-) create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-hugepages-numa.args create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-hugepages-numa.xml diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c index 99755f1..cb31fac 100644 --- a/src/qemu/qemu_command.c +++ b/src/qemu/qemu_command.c @@ -4760,9 +4760,6 @@ qemuBuildMemoryBackendStr(unsigned long long size, hugepage = master_hugepage; } - if (hugepage) - pagesize = hugepage->size; -

if (hugepage && hugepage->size == system_page_size) { /* However, if user specified to use "huge" page * of regular system page size, it's as if they @@ -4778,23 +4775,29 @@ qemuBuildMemoryBackendStr(unsigned long long size, goto cleanup; } - /* Now lets see, if the huge page we want to use is even mounted - * and ready to use */ - for (i = 0; i < cfg->nhugetlbfs; i++) { - if (cfg->hugetlbfs[i].size == hugepage->size) - break; - } - - if (i == cfg->nhugetlbfs) { - virReportError(VIR_ERR_INTERNAL_ERROR, - _("Unable to find any usable hugetlbfs mount for %llu KiB"), - pagesize); - goto cleanup; - } - VIR_FREE(mem_path);

- if (!(mem_path = qemuGetHugepagePath(&cfg->hugetlbfs[i]))) - goto cleanup; + if (hugepage->size) { + /* Now lets see, if the huge page we want to use is even mounted + * and ready to use */ + for (i = 0; i < cfg->nhugetlbfs; i++) { + if (cfg->hugetlbfs[i].size == hugepage->size) + break; + } + + if (i == cfg->nhugetlbfs) { + virReportError(VIR_ERR_INTERNAL_ERROR, + _("Unable to find any usable hugetlbfs mount for %llu KiB"), + hugepage->size); + goto cleanup; + } + + if (!(mem_path = qemuGetHugepagePath(&cfg->hugetlbfs[i]))) + goto cleanup; + } else { + if (!(mem_path = qemuGetDefaultHugepath(cfg->hugetlbfs, + cfg->nhugetlbfs))) + goto cleanup; + } *backendType = "memory-backend-file";