From 4ebc74dbbf7ad50e4101629f3f5da5fdc1544051 Mon Sep 17 00:00:00 2001 From: Igor Mammedov Date: Wed, 19 Feb 2020 11:09:51 -0500 Subject: [PATCH] hostmem: fix strict bind policy When option -mem-prealloc is used with one or more memory-backend objects, created backends may not obey configured bind policy or creation may fail after kernel attempts to move pages according to bind policy. Reason is in file_ram_alloc(), which will pre-allocate any descriptor based RAM if global mem_prealloc != 0 and that happens way before bind policy is applied to memory range. One way to fix it would be to extend memory_region_foo() API and add more invariants that could broken later due implicit dependencies that's hard to track. Another approach is to drop adhoc main RAM allocation and consolidate it around memory-backend. That allows to have single place that allocates guest RAM (main and memdev) in the same way and then global mem_prealloc could be replaced by backend's property[s] that will affect created memory-backend objects but only in correct order this time. With main RAM now converted to hostmem backends, there is no point in keeping global mem_prealloc around, so alias -mem-prealloc to "memory-backend.prealloc=on" machine compat[*] property and make mem_prealloc a local variable to only stir registration of compat property. *) currently user accessible -global works only with DEVICE based objects and extra work is needed to make it work with hostmem backends. But that is convenience option and out of scope of this already huge refactoring. Hence machine compat properties were used. Signed-off-by: Igor Mammedov Message-Id: <20200219160953.13771-78-imammedo@redhat.com> --- backends/hostmem-file.c | 1 - backends/hostmem-memfd.c | 1 - backends/hostmem.c | 12 +----------- exec.c | 11 ----------- include/sysemu/hostmem.h | 2 +- include/sysemu/sysemu.h | 1 - vl.c | 3 ++- 7 files changed, 4 insertions(+), 27 deletions(-) diff --git a/backends/hostmem-file.c b/backends/hostmem-file.c index cb319a9157..c8c355f5aa 100644 --- a/backends/hostmem-file.c +++ b/backends/hostmem-file.c @@ -51,7 +51,6 @@ file_backend_memory_alloc(HostMemoryBackend *backend, Error **errp) return; } - backend->force_prealloc = mem_prealloc; name = host_memory_backend_get_name(backend); memory_region_init_ram_from_file(&backend->mr, OBJECT(backend), name, diff --git a/backends/hostmem-memfd.c b/backends/hostmem-memfd.c index 26070b425e..74ba9879c4 100644 --- a/backends/hostmem-memfd.c +++ b/backends/hostmem-memfd.c @@ -45,7 +45,6 @@ memfd_backend_memory_alloc(HostMemoryBackend *backend, Error **errp) return; } - backend->force_prealloc = mem_prealloc; fd = qemu_memfd_create(TYPE_MEMORY_BACKEND_MEMFD, backend->size, m->hugetlb, m->hugetlbsize, m->seal ? F_SEAL_GROW | F_SEAL_SHRINK | F_SEAL_SEAL : 0, diff --git a/backends/hostmem.c b/backends/hostmem.c index 0988986016..a70867b255 100644 --- a/backends/hostmem.c +++ b/backends/hostmem.c @@ -215,7 +215,7 @@ static bool host_memory_backend_get_prealloc(Object *obj, Error **errp) { HostMemoryBackend *backend = MEMORY_BACKEND(obj); - return backend->prealloc || backend->force_prealloc; + return backend->prealloc; } static void host_memory_backend_set_prealloc(Object *obj, bool value, @@ -224,14 +224,6 @@ static void host_memory_backend_set_prealloc(Object *obj, bool value, Error *local_err = NULL; HostMemoryBackend *backend = MEMORY_BACKEND(obj); - if (backend->force_prealloc) { - if (value) { - error_setg(errp, - "remove -mem-prealloc to use the prealloc property"); - return; - } - } - if (!host_memory_backend_mr_inited(backend)) { backend->prealloc = value; return; @@ -288,8 +280,6 @@ static void host_memory_backend_init(Object *obj) /* TODO: convert access to globals to compat properties */ backend->merge = machine_mem_merge(machine); backend->dump = machine_dump_guest_core(machine); - backend->prealloc = mem_prealloc; - backend->prealloc_threads = 1; } static void host_memory_backend_post_init(Object *obj) diff --git a/exec.c b/exec.c index 6ebff8bd3a..8c0258a7ae 100644 --- a/exec.c +++ b/exec.c @@ -1801,8 +1801,6 @@ static void *file_ram_alloc(RAMBlock *block, bool truncate, Error **errp) { - Error *err = NULL; - MachineState *ms = MACHINE(qdev_get_machine()); void *area; block->page_size = qemu_fd_getpagesize(fd); @@ -1858,15 +1856,6 @@ static void *file_ram_alloc(RAMBlock *block, return NULL; } - if (mem_prealloc) { - os_mem_prealloc(fd, area, memory, ms->smp.cpus, &err); - if (err) { - error_propagate(errp, err); - qemu_ram_munmap(fd, area, memory); - return NULL; - } - } - block->fd = fd; return area; } diff --git a/include/sysemu/hostmem.h b/include/sysemu/hostmem.h index bdf86665ab..8276e53683 100644 --- a/include/sysemu/hostmem.h +++ b/include/sysemu/hostmem.h @@ -70,7 +70,7 @@ struct HostMemoryBackend { /* protected */ uint64_t size; bool merge, dump, use_canonical_path; - bool prealloc, force_prealloc, is_mapped, share; + bool prealloc, is_mapped, share; uint32_t prealloc_threads; DECLARE_BITMAP(host_nodes, MAX_NODES + 1); HostMemPolicy policy; diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h index ae78b2a122..55bdd57a9b 100644 --- a/include/sysemu/sysemu.h +++ b/include/sysemu/sysemu.h @@ -50,7 +50,6 @@ extern uint8_t *boot_splash_filedata; extern bool enable_mlock; extern bool enable_cpu_pm; extern QEMUClockType rtc_clock; -extern int mem_prealloc; #define MAX_OPTION_ROMS 16 typedef struct QEMUOptionRom { diff --git a/vl.c b/vl.c index afc682e168..54857f7afa 100644 --- a/vl.c +++ b/vl.c @@ -140,7 +140,6 @@ enum vga_retrace_method vga_retrace_method = VGA_RETRACE_DUMB; int display_opengl; const char* keyboard_layout = NULL; ram_addr_t ram_size; -int mem_prealloc = 0; /* force preallocation of physical target memory */ bool enable_mlock = false; bool enable_cpu_pm = false; int nb_nics; @@ -2883,6 +2882,7 @@ int main(int argc, char **argv, char **envp) const char *mem_path = NULL; BlockdevOptionsQueue bdo_queue = QSIMPLEQ_HEAD_INITIALIZER(bdo_queue); QemuPluginList plugin_list = QTAILQ_HEAD_INITIALIZER(plugin_list); + int mem_prealloc = 0; /* force preallocation of physical target memory */ os_set_line_buffering(); @@ -3984,6 +3984,7 @@ int main(int argc, char **argv, char **envp) val = g_strdup_printf("%d", current_machine->smp.cpus); object_register_sugar_prop("memory-backend", "prealloc-threads", val); g_free(val); + object_register_sugar_prop("memory-backend", "prealloc", "on"); } /* -- 2.11.0