* source to the destination before all the data has been copied.
*/
-#include <glib.h>
-#include <stdio.h>
-#include <unistd.h>
+#include "qemu/osdep.h"
#include "qemu-common.h"
#include "migration/migration.h"
#include "migration/postcopy-ram.h"
#include "sysemu/sysemu.h"
+#include "sysemu/balloon.h"
#include "qemu/error-report.h"
#include "trace.h"
#if defined(__linux__)
#include <poll.h>
-#include <sys/eventfd.h>
-#include <sys/mman.h>
#include <sys/ioctl.h>
#include <sys/syscall.h>
-#include <sys/types.h>
#include <asm/types.h> /* for __u64 */
#endif
-#if defined(__linux__) && defined(__NR_userfaultfd)
+#if defined(__linux__) && defined(__NR_userfaultfd) && defined(CONFIG_EVENTFD)
+#include <sys/eventfd.h>
#include <linux/userfaultfd.h>
static bool ufd_version_check(int ufd)
return false;
}
+ if (getpagesize() != ram_pagesize_summary()) {
+ bool have_hp = false;
+ /* We've got a huge page */
+#ifdef UFFD_FEATURE_MISSING_HUGETLBFS
+ have_hp = api_struct.features & UFFD_FEATURE_MISSING_HUGETLBFS;
+#endif
+ if (!have_hp) {
+ error_report("Userfault on this host does not support huge pages");
+ return false;
+ }
+ }
return true;
}
+/* Callback from postcopy_ram_supported_by_host block iterator.
+ */
+static int test_range_shared(const char *block_name, void *host_addr,
+ ram_addr_t offset, ram_addr_t length, void *opaque)
+{
+ if (qemu_ram_is_shared(qemu_ram_block_by_name(block_name))) {
+ error_report("Postcopy on shared RAM (%s) is not yet supported",
+ block_name);
+ return 1;
+ }
+ return 0;
+}
+
+/*
+ * Note: This has the side effect of munlock'ing all of RAM, that's
+ * normally fine since if the postcopy succeeds it gets turned back on at the
+ * end.
+ */
bool postcopy_ram_supported_by_host(void)
{
long pagesize = getpagesize();
goto out;
}
+ /* We don't support postcopy with shared RAM yet */
+ if (qemu_ram_foreach_block(test_range_shared, NULL)) {
+ goto out;
+ }
+
+ /*
+ * userfault and mlock don't go together; we'll put it back later if
+ * it was enabled.
+ */
+ if (munlockall()) {
+ error_report("%s: munlockall: %s", __func__, strerror(errno));
+ return -1;
+ }
+
/*
* We need to check that the ops we need are supported on anon memory
* To do that we need to register a chunk and see the flags that
return ret;
}
-/**
- * postcopy_ram_discard_range: Discard a range of memory.
- * We can assume that if we've been called postcopy_ram_hosttest returned true.
- *
- * @mis: Current incoming migration state.
- * @start, @length: range of memory to discard.
- *
- * returns: 0 on success.
- */
-int postcopy_ram_discard_range(MigrationIncomingState *mis, uint8_t *start,
- size_t length)
-{
- trace_postcopy_ram_discard_range(start, length);
- if (madvise(start, length, MADV_DONTNEED)) {
- error_report("%s MADV_DONTNEED: %s", __func__, strerror(errno));
- return -1;
- }
-
- return 0;
-}
-
/*
* Setup an area of RAM so that it *can* be used for postcopy later; this
* must be done right at the start prior to pre-copy.
* - we're going to get the copy from the source anyway.
* (Precopy will just overwrite this data, so doesn't need the discard)
*/
- if (postcopy_ram_discard_range(mis, host_addr, length)) {
+ if (ram_discard_range(mis, block_name, 0, length)) {
return -1;
}
* We turned off hugepage for the precopy stage with postcopy enabled
* we can turn it back on now.
*/
-#ifdef MADV_HUGEPAGE
- if (madvise(host_addr, length, MADV_HUGEPAGE)) {
- error_report("%s HUGEPAGE: %s", __func__, strerror(errno));
- return -1;
- }
-#endif
+ qemu_madvise(host_addr, length, QEMU_MADV_HUGEPAGE);
/*
* We can also turn off userfault now since we should have all the
mis->have_fault_thread = false;
}
+ qemu_balloon_inhibit(false);
+
+ if (enable_mlock) {
+ if (os_mlock() < 0) {
+ error_report("mlock: %s", strerror(errno));
+ /*
+ * It doesn't feel right to fail at this point, we have a valid
+ * VM state.
+ */
+ }
+ }
+
postcopy_state_set(POSTCOPY_INCOMING_END);
migrate_send_rp_shut(mis, qemu_file_get_error(mis->from_src_file) != 0);
if (mis->postcopy_tmp_page) {
- munmap(mis->postcopy_tmp_page, getpagesize());
+ munmap(mis->postcopy_tmp_page, mis->largest_page_size);
mis->postcopy_tmp_page = NULL;
}
+ if (mis->postcopy_tmp_zero_page) {
+ munmap(mis->postcopy_tmp_zero_page, mis->largest_page_size);
+ mis->postcopy_tmp_zero_page = NULL;
+ }
trace_postcopy_ram_incoming_cleanup_exit();
return 0;
}
+/*
+ * Disable huge pages on an area
+ */
+static int nhp_range(const char *block_name, void *host_addr,
+ ram_addr_t offset, ram_addr_t length, void *opaque)
+{
+ trace_postcopy_nhp_range(block_name, host_addr, offset, length);
+
+ /*
+ * Before we do discards we need to ensure those discards really
+ * do delete areas of the page, even if THP thinks a hugepage would
+ * be a good idea, so force hugepages off.
+ */
+ qemu_madvise(host_addr, length, QEMU_MADV_NOHUGEPAGE);
+
+ return 0;
+}
+
+/*
+ * Userfault requires us to mark RAM as NOHUGEPAGE prior to discard
+ * however leaving it until after precopy means that most of the precopy
+ * data is still THPd
+ */
+int postcopy_ram_prepare_discard(MigrationIncomingState *mis)
+{
+ if (qemu_ram_foreach_block(nhp_range, mis)) {
+ return -1;
+ }
+
+ postcopy_state_set(POSTCOPY_INCOMING_DISCARD);
+
+ return 0;
+}
+
/*
* Mark the given area of RAM as requiring notification to unwritten areas
* Used as a callback on qemu_ram_foreach_block.
error_report("%s userfault register: %s", __func__, strerror(errno));
return -1;
}
+ if (!(reg_struct.ioctls & ((__u64)1 << _UFFDIO_COPY))) {
+ error_report("%s userfault: Region doesn't support COPY", __func__);
+ return -1;
+ }
return 0;
}
MigrationIncomingState *mis = opaque;
struct uffd_msg msg;
int ret;
- size_t hostpagesize = getpagesize();
RAMBlock *rb = NULL;
RAMBlock *last_rb = NULL; /* last RAMBlock we sent part of */
while (true) {
ram_addr_t rb_offset;
- ram_addr_t in_raspace;
struct pollfd pfd[2];
/*
rb = qemu_ram_block_from_host(
(void *)(uintptr_t)msg.arg.pagefault.address,
- true, &in_raspace, &rb_offset);
+ true, &rb_offset);
if (!rb) {
error_report("postcopy_ram_fault_thread: Fault outside guest: %"
PRIx64, (uint64_t)msg.arg.pagefault.address);
break;
}
- rb_offset &= ~(hostpagesize - 1);
+ rb_offset &= ~(qemu_ram_pagesize(rb) - 1);
trace_postcopy_ram_fault_thread_request(msg.arg.pagefault.address,
qemu_ram_get_idstr(rb),
rb_offset);
if (rb != last_rb) {
last_rb = rb;
migrate_send_rp_req_pages(mis, qemu_ram_get_idstr(rb),
- rb_offset, hostpagesize);
+ rb_offset, qemu_ram_pagesize(rb));
} else {
/* Save some space */
migrate_send_rp_req_pages(mis, NULL,
- rb_offset, hostpagesize);
+ rb_offset, qemu_ram_pagesize(rb));
}
}
trace_postcopy_ram_fault_thread_exit();
return -1;
}
+ /*
+ * Ballooning can mark pages as absent while we're postcopying
+ * that would cause false userfaults.
+ */
+ qemu_balloon_inhibit(true);
+
trace_postcopy_ram_enable_notify();
return 0;
* Place a host page (from) at (host) atomically
* returns 0 on success
*/
-int postcopy_place_page(MigrationIncomingState *mis, void *host, void *from)
+int postcopy_place_page(MigrationIncomingState *mis, void *host, void *from,
+ size_t pagesize)
{
struct uffdio_copy copy_struct;
copy_struct.dst = (uint64_t)(uintptr_t)host;
copy_struct.src = (uint64_t)(uintptr_t)from;
- copy_struct.len = getpagesize();
+ copy_struct.len = pagesize;
copy_struct.mode = 0;
/* copy also acks to the kernel waking the stalled thread up
*/
if (ioctl(mis->userfault_fd, UFFDIO_COPY, ©_struct)) {
int e = errno;
- error_report("%s: %s copy host: %p from: %p",
- __func__, strerror(e), host, from);
+ error_report("%s: %s copy host: %p from: %p (size: %zd)",
+ __func__, strerror(e), host, from, pagesize);
return -e;
}
* Place a zero page at (host) atomically
* returns 0 on success
*/
-int postcopy_place_page_zero(MigrationIncomingState *mis, void *host)
+int postcopy_place_page_zero(MigrationIncomingState *mis, void *host,
+ size_t pagesize)
{
- struct uffdio_zeropage zero_struct;
+ trace_postcopy_place_page_zero(host);
- zero_struct.range.start = (uint64_t)(uintptr_t)host;
- zero_struct.range.len = getpagesize();
- zero_struct.mode = 0;
+ if (pagesize == getpagesize()) {
+ struct uffdio_zeropage zero_struct;
+ zero_struct.range.start = (uint64_t)(uintptr_t)host;
+ zero_struct.range.len = getpagesize();
+ zero_struct.mode = 0;
- if (ioctl(mis->userfault_fd, UFFDIO_ZEROPAGE, &zero_struct)) {
- int e = errno;
- error_report("%s: %s zero host: %p",
- __func__, strerror(e), host);
+ if (ioctl(mis->userfault_fd, UFFDIO_ZEROPAGE, &zero_struct)) {
+ int e = errno;
+ error_report("%s: %s zero host: %p",
+ __func__, strerror(e), host);
- return -e;
+ return -e;
+ }
+ } else {
+ /* The kernel can't use UFFDIO_ZEROPAGE for hugepages */
+ if (!mis->postcopy_tmp_zero_page) {
+ mis->postcopy_tmp_zero_page = mmap(NULL, mis->largest_page_size,
+ PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS,
+ -1, 0);
+ if (mis->postcopy_tmp_zero_page == MAP_FAILED) {
+ int e = errno;
+ mis->postcopy_tmp_zero_page = NULL;
+ error_report("%s: %s mapping large zero page",
+ __func__, strerror(e));
+ return -e;
+ }
+ memset(mis->postcopy_tmp_zero_page, '\0', mis->largest_page_size);
+ }
+ return postcopy_place_page(mis, host, mis->postcopy_tmp_zero_page,
+ pagesize);
}
- trace_postcopy_place_page_zero(host);
return 0;
}
void *postcopy_get_tmp_page(MigrationIncomingState *mis)
{
if (!mis->postcopy_tmp_page) {
- mis->postcopy_tmp_page = mmap(NULL, getpagesize(),
+ mis->postcopy_tmp_page = mmap(NULL, mis->largest_page_size,
PROT_READ | PROT_WRITE, MAP_PRIVATE |
MAP_ANONYMOUS, -1, 0);
- if (!mis->postcopy_tmp_page) {
+ if (mis->postcopy_tmp_page == MAP_FAILED) {
+ mis->postcopy_tmp_page = NULL;
error_report("%s: %s", __func__, strerror(errno));
return NULL;
}
return -1;
}
-int postcopy_ram_discard_range(MigrationIncomingState *mis, uint8_t *start,
- size_t length)
+int postcopy_ram_prepare_discard(MigrationIncomingState *mis)
{
assert(0);
return -1;
return -1;
}
-int postcopy_place_page(MigrationIncomingState *mis, void *host, void *from)
+int postcopy_place_page(MigrationIncomingState *mis, void *host, void *from,
+ size_t pagesize)
{
assert(0);
return -1;
}
-int postcopy_place_page_zero(MigrationIncomingState *mis, void *host)
+int postcopy_place_page_zero(MigrationIncomingState *mis, void *host,
+ size_t pagesize)
{
assert(0);
return -1;
if (pds->cur_entry == MAX_DISCARDS_PER_COMMAND) {
/* Full set, ship it! */
- qemu_savevm_send_postcopy_ram_discard(ms->file, pds->ramblock_name,
+ qemu_savevm_send_postcopy_ram_discard(ms->to_dst_file,
+ pds->ramblock_name,
pds->cur_entry,
pds->start_list,
pds->length_list);
{
/* Anything unsent? */
if (pds->cur_entry) {
- qemu_savevm_send_postcopy_ram_discard(ms->file, pds->ramblock_name,
+ qemu_savevm_send_postcopy_ram_discard(ms->to_dst_file,
+ pds->ramblock_name,
pds->cur_entry,
pds->start_list,
pds->length_list);
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