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[Qemu-devel] [PATCH v6 37/47] postcopy_ram.c: place_page and helpers
From: |
Dr. David Alan Gilbert (git) |
Subject: |
[Qemu-devel] [PATCH v6 37/47] postcopy_ram.c: place_page and helpers |
Date: |
Tue, 14 Apr 2015 18:04:03 +0100 |
From: "Dr. David Alan Gilbert" <address@hidden>
postcopy_place_page (etc) provide a way for postcopy to place a page
into guests memory atomically (using the copy ioctl on the ufd).
Signed-off-by: Dr. David Alan Gilbert <address@hidden>
---
include/migration/migration.h | 1 +
include/migration/postcopy-ram.h | 16 ++++++++
migration/postcopy-ram.c | 87 ++++++++++++++++++++++++++++++++++++++++
trace-events | 1 +
4 files changed, 105 insertions(+)
diff --git a/include/migration/migration.h b/include/migration/migration.h
index 75c3299..db06fd2 100644
--- a/include/migration/migration.h
+++ b/include/migration/migration.h
@@ -82,6 +82,7 @@ struct MigrationIncomingState {
int userfault_fd;
QEMUFile *return_path;
QemuMutex rp_mutex; /* We send replies from multiple threads */
+ void *postcopy_tmp_page;
};
MigrationIncomingState *migration_incoming_get_current(void);
diff --git a/include/migration/postcopy-ram.h b/include/migration/postcopy-ram.h
index 88793b3..5d8ec61 100644
--- a/include/migration/postcopy-ram.h
+++ b/include/migration/postcopy-ram.h
@@ -69,4 +69,20 @@ void postcopy_discard_send_range(MigrationState *ms,
PostcopyDiscardState *pds,
void postcopy_discard_send_finish(MigrationState *ms,
PostcopyDiscardState *pds);
+/*
+ * Place a page (from) at (host) efficiently
+ * There are restrictions on how 'from' must be mapped, in general best
+ * to use other postcopy_ routines to allocate.
+ * returns 0 on success
+ */
+int postcopy_place_page(MigrationIncomingState *mis, void *host, void *from,
+ bool all_zero);
+
+/*
+ * Allocate a page of memory that can be mapped at a later point in time
+ * using postcopy_place_page
+ * Returns: Pointer to allocated page
+ */
+void *postcopy_get_tmp_page(MigrationIncomingState *mis);
+
#endif
diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
index 1be3bc9..33aadbc 100644
--- a/migration/postcopy-ram.c
+++ b/migration/postcopy-ram.c
@@ -278,6 +278,10 @@ int postcopy_ram_incoming_cleanup(MigrationIncomingState
*mis)
return -1;
}
+ if (mis->postcopy_tmp_page) {
+ munmap(mis->postcopy_tmp_page, getpagesize());
+ mis->postcopy_tmp_page = NULL;
+ }
return 0;
}
@@ -344,6 +348,77 @@ int postcopy_ram_enable_notify(MigrationIncomingState *mis)
return 0;
}
+/*
+ * Place a host page (from) at (host) atomically
+ * all_zero: Hint that the page being placed is 0 throughout
+ * returns 0 on success
+ */
+int postcopy_place_page(MigrationIncomingState *mis, void *host, void *from,
+ bool all_zero)
+{
+ if (!all_zero) {
+ 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.mode = 0;
+
+ /* copy also acks to the kernel waking the stalled thread up
+ * TODO: We can inhibit that ack and only do it if it was requested
+ * which would be slightly cheaper, but we'd have to be careful
+ * of the order of updating our page state.
+ */
+ 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);
+
+ return -e;
+ }
+ } else {
+ 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 from: %p",
+ __func__, strerror(e), host, from);
+
+ return -e;
+ }
+ }
+
+ trace_postcopy_place_page(host, all_zero);
+ return 0;
+}
+
+/*
+ * Returns a target page of memory that can be mapped at a later point in time
+ * using postcopy_place_page
+ * The same address is used repeatedly, postcopy_place_page just takes the
+ * backing page away.
+ * Returns: Pointer to allocated page
+ *
+ */
+void *postcopy_get_tmp_page(MigrationIncomingState *mis)
+{
+ if (!mis->postcopy_tmp_page) {
+ mis->postcopy_tmp_page = mmap(NULL, getpagesize(),
+ PROT_READ | PROT_WRITE, MAP_PRIVATE |
+ MAP_ANONYMOUS, -1, 0);
+ if (!mis->postcopy_tmp_page) {
+ error_report("%s: %s", __func__, strerror(errno));
+ return NULL;
+ }
+ }
+
+ return mis->postcopy_tmp_page;
+}
+
#else
/* No target OS support, stubs just fail */
bool postcopy_ram_supported_by_host(void)
@@ -373,6 +448,18 @@ int postcopy_ram_enable_notify(MigrationIncomingState *mis)
{
assert(0);
}
+
+int postcopy_place_page(MigrationIncomingState *mis, void *host, void *from,
+ bool all_zero)
+{
+ assert(0);
+}
+
+void *postcopy_get_tmp_page(MigrationIncomingState *mis)
+{
+ assert(0);
+}
+
#endif
/* ------------------------------------------------------------------------- */
diff --git a/trace-events b/trace-events
index c4b92ce..b65740c 100644
--- a/trace-events
+++ b/trace-events
@@ -1499,6 +1499,7 @@ postcopy_discard_send_finish(const char *ramblock, int
nwords, int ncmds) "%s ma
postcopy_cleanup_area(const char *ramblock, void *host_addr, size_t offset,
size_t length) "%s: %p offset=%zx length=%zx"
postcopy_ram_discard_range(void *start, void *end) "%p,%p"
postcopy_init_area(const char *ramblock, void *host_addr, size_t offset,
size_t length) "%s: %p offset=%zx length=%zx"
+postcopy_place_page(void *host_addr, bool all_zero) "host=%p all_zero=%d"
# kvm-all.c
kvm_ioctl(int type, void *arg) "type 0x%x, arg %p"
--
2.1.0
- [Qemu-devel] [PATCH v6 32/47] Postcopy: Postcopy startup in migration thread, (continued)
- [Qemu-devel] [PATCH v6 32/47] Postcopy: Postcopy startup in migration thread, Dr. David Alan Gilbert (git), 2015/04/14
- [Qemu-devel] [PATCH v6 30/47] postcopy: Incoming initialisation, Dr. David Alan Gilbert (git), 2015/04/14
- [Qemu-devel] [PATCH v6 33/47] Postcopy end in migration_thread, Dr. David Alan Gilbert (git), 2015/04/14
- [Qemu-devel] [PATCH v6 29/47] Postcopy: Maintain sentmap and calculate discard, Dr. David Alan Gilbert (git), 2015/04/14
- [Qemu-devel] [PATCH v6 35/47] Page request: Process incoming page request, Dr. David Alan Gilbert (git), 2015/04/14
- [Qemu-devel] [PATCH v6 36/47] Page request: Consume pages off the post-copy queue, Dr. David Alan Gilbert (git), 2015/04/14
- [Qemu-devel] [PATCH v6 34/47] Page request: Add MIG_RP_MSG_REQ_PAGES reverse command, Dr. David Alan Gilbert (git), 2015/04/14
- [Qemu-devel] [PATCH v6 38/47] Postcopy: Use helpers to map pages during migration, Dr. David Alan Gilbert (git), 2015/04/14
- [Qemu-devel] [PATCH v6 40/47] Don't sync dirty bitmaps in postcopy, Dr. David Alan Gilbert (git), 2015/04/14
- [Qemu-devel] [PATCH v6 39/47] qemu_ram_block_from_host, Dr. David Alan Gilbert (git), 2015/04/14
- [Qemu-devel] [PATCH v6 37/47] postcopy_ram.c: place_page and helpers,
Dr. David Alan Gilbert (git) <=
- [Qemu-devel] [PATCH v6 41/47] Host page!=target page: Cleanup bitmaps, Dr. David Alan Gilbert (git), 2015/04/14
- [Qemu-devel] [PATCH v6 43/47] Start up a postcopy/listener thread ready for incoming page data, Dr. David Alan Gilbert (git), 2015/04/14
- [Qemu-devel] [PATCH v6 31/47] postcopy: ram_enable_notify to switch on userfault, Dr. David Alan Gilbert (git), 2015/04/14
- [Qemu-devel] [PATCH v6 42/47] Postcopy; Handle userfault requests, Dr. David Alan Gilbert (git), 2015/04/14
- [Qemu-devel] [PATCH v6 46/47] Disable mlock around incoming postcopy, Dr. David Alan Gilbert (git), 2015/04/14
- [Qemu-devel] [PATCH v6 45/47] End of migration for postcopy, Dr. David Alan Gilbert (git), 2015/04/14
- [Qemu-devel] [PATCH v6 44/47] postcopy: Wire up loadvm_postcopy_handle_ commands, Dr. David Alan Gilbert (git), 2015/04/14
- [Qemu-devel] [PATCH v6 47/47] Inhibit ballooning during postcopy, Dr. David Alan Gilbert (git), 2015/04/14
- Re: [Qemu-devel] [PATCH v6 00/47] Postcopy implementation, Li, Liang Z, 2015/04/27