| Message ID | 025d0bdd5e76b334754c09c445fe621090121da5.1717168113.git.mprivozn@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | backends/hostmem: Report more errors on failures | expand |
On 31/5/24 17:10, Michal Privoznik wrote: > If memory-backend-{file,ram} has a size that's not aligned to > underlying page size it is not only wasteful, but also may lead > to hard to debug behaviour. For instance, in case > memory-backend-file and hugepages, madvise() and mbind() fail. > Rightfully so, page is the smallest unit they can work with. And > even though an error is reported, the root cause it not very > clear: > > qemu-system-x86_64: Couldn't set property 'dump' on 'memory-backend-file': Invalid argument > > After this commit: > > qemu-system-x86_64: backend 'memory-backend-file' memory size must be multiple of 2 MiB Thanks! Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org> > Signed-off-by: Michal Privoznik <mprivozn@redhat.com> > --- > backends/hostmem.c | 10 ++++++++++ > 1 file changed, 10 insertions(+)
diff --git a/backends/hostmem.c b/backends/hostmem.c index 012a8c190f..4d6c69fe4d 100644 --- a/backends/hostmem.c +++ b/backends/hostmem.c @@ -20,6 +20,7 @@ #include "qom/object_interfaces.h" #include "qemu/mmap-alloc.h" #include "qemu/madvise.h" +#include "qemu/cutils.h" #include "hw/qdev-core.h" #ifdef CONFIG_NUMA @@ -337,6 +338,7 @@ host_memory_backend_memory_complete(UserCreatable *uc, Error **errp) HostMemoryBackendClass *bc = MEMORY_BACKEND_GET_CLASS(uc); void *ptr; uint64_t sz; + size_t pagesize; bool async = !phase_check(PHASE_LATE_BACKENDS_CREATED); if (!bc->alloc) { @@ -348,6 +350,14 @@ host_memory_backend_memory_complete(UserCreatable *uc, Error **errp) ptr = memory_region_get_ram_ptr(&backend->mr); sz = memory_region_size(&backend->mr); + pagesize = qemu_ram_pagesize(backend->mr.ram_block); + + if (!QEMU_IS_ALIGNED(sz, pagesize)) { + g_autofree char *pagesize_str = size_to_str(pagesize); + error_setg(errp, "backend '%s' memory size must be multiple of %s", + object_get_typename(OBJECT(uc)), pagesize_str); + return; + } if (backend->merge && qemu_madvise(ptr, sz, QEMU_MADV_MERGEABLE)) {
If memory-backend-{file,ram} has a size that's not aligned to underlying page size it is not only wasteful, but also may lead to hard to debug behaviour. For instance, in case memory-backend-file and hugepages, madvise() and mbind() fail. Rightfully so, page is the smallest unit they can work with. And even though an error is reported, the root cause it not very clear: qemu-system-x86_64: Couldn't set property 'dump' on 'memory-backend-file': Invalid argument After this commit: qemu-system-x86_64: backend 'memory-backend-file' memory size must be multiple of 2 MiB Signed-off-by: Michal Privoznik <mprivozn@redhat.com> --- backends/hostmem.c | 10 ++++++++++ 1 file changed, 10 insertions(+)