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[Qemu-devel] [PATCH v5 35/45] postcopy_ram.c: place_page and helpers
From: |
Dr. David Alan Gilbert (git) |
Subject: |
[Qemu-devel] [PATCH v5 35/45] postcopy_ram.c: place_page and helpers |
Date: |
Wed, 25 Feb 2015 16:51:58 +0000 |
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 | 2 +
include/migration/postcopy-ram.h | 16 ++++++
migration/postcopy-ram.c | 113 ++++++++++++++++++++++++++++++++++++++-
trace-events | 1 +
4 files changed, 130 insertions(+), 2 deletions(-)
diff --git a/include/migration/migration.h b/include/migration/migration.h
index b1c7cad..139bb1b 100644
--- a/include/migration/migration.h
+++ b/include/migration/migration.h
@@ -94,6 +94,8 @@ struct MigrationIncomingState {
QEMUFile *return_path;
QemuMutex rp_mutex; /* We send replies from multiple threads */
PostcopyPMI postcopy_pmi;
+ void *postcopy_tmp_page;
+ long postcopy_place_skipped; /* Check for incorrect place ops */
};
MigrationIncomingState *migration_incoming_get_current(void);
diff --git a/include/migration/postcopy-ram.h b/include/migration/postcopy-ram.h
index fbb2a93..3d30280 100644
--- a/include/migration/postcopy-ram.h
+++ b/include/migration/postcopy-ram.h
@@ -80,4 +80,20 @@ void postcopy_discard_send_chunk(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,
+ long bitmap_offset, 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 33dd332..86fa5a0 100644
--- a/migration/postcopy-ram.c
+++ b/migration/postcopy-ram.c
@@ -197,7 +197,6 @@ static PostcopyPMIState postcopy_pmi_get_state_nolock(
}
/* Retrieve the state of the given page */
-__attribute__ (( unused )) /* Until later in patch series */
static PostcopyPMIState postcopy_pmi_get_state(MigrationIncomingState *mis,
size_t bitmap_index)
{
@@ -213,7 +212,6 @@ static PostcopyPMIState
postcopy_pmi_get_state(MigrationIncomingState *mis,
* Set the page state to the given state if the previous state was as expected
* Return the actual previous state.
*/
-__attribute__ (( unused )) /* Until later in patch series */
static PostcopyPMIState postcopy_pmi_change_state(MigrationIncomingState *mis,
size_t bitmap_index,
PostcopyPMIState expected_state,
@@ -477,6 +475,7 @@ static int cleanup_area(const char *block_name, void
*host_addr,
int postcopy_ram_incoming_init(MigrationIncomingState *mis, size_t ram_pages)
{
postcopy_pmi_init(mis, ram_pages);
+ mis->postcopy_place_skipped = -1;
if (qemu_ram_foreach_block(init_area, mis)) {
return -1;
@@ -495,6 +494,10 @@ 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;
}
@@ -561,6 +564,100 @@ int postcopy_ram_enable_notify(MigrationIncomingState
*mis)
return 0;
}
+/*
+ * Place a host page (from) at (host) tomically
+ * There are restrictions on how 'from' must be mapped, in general best
+ * to use other postcopy_ routines to allocate.
+ * all_zero: Hint that the page being placed is 0 throughout
+ * returns 0 on success
+ * bitmap_offset: Index into the migration bitmaps
+ *
+ * State changes:
+ * none -> received
+ * requested -> received (ack)
+ *
+ * Note the UF thread is also updating the state, and maybe none->requested
+ * at the same time.
+ */
+int postcopy_place_page(MigrationIncomingState *mis, void *host, void *from,
+ long bitmap_offset, bool all_zero)
+{
+ PostcopyPMIState old_state, tmp_state, new_state;
+
+ 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 pmi=%d",
+ __func__, strerror(e), host, from,
+ postcopy_pmi_get_state(mis, bitmap_offset));
+
+ 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 pmi=%d",
+ __func__, strerror(e), host, from,
+ postcopy_pmi_get_state(mis, bitmap_offset));
+
+ return -e;
+ }
+ }
+
+ bitmap_offset &= ~(mis->postcopy_pmi.host_bits-1);
+ new_state = POSTCOPY_PMI_RECEIVED;
+ tmp_state = postcopy_pmi_get_state(mis, bitmap_offset);
+ do {
+ old_state = tmp_state;
+ tmp_state = postcopy_pmi_change_state(mis, bitmap_offset, old_state,
+ new_state);
+ } while (old_state != tmp_state);
+ trace_postcopy_place_page(bitmap_offset, host, all_zero, old_state);
+
+ 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) {
+ perror("mapping postcopy tmp page");
+ return NULL;
+ }
+ }
+
+ return mis->postcopy_tmp_page;
+}
+
#else
/* No target OS support, stubs just fail */
bool postcopy_ram_supported_by_host(void)
@@ -608,6 +705,18 @@ int postcopy_ram_enable_notify(MigrationIncomingState *mis)
{
assert(0);
}
+
+int postcopy_place_page(MigrationIncomingState *mis, void *host, void *from,
+ long bitmap_offset, bool all_zero)
+{
+ assert(0);
+}
+
+void *postcopy_get_tmp_page(MigrationIncomingState *mis)
+{
+ assert(0);
+}
+
#endif
/* ------------------------------------------------------------------------- */
diff --git a/trace-events b/trace-events
index 781cf5c..16a91d9 100644
--- a/trace-events
+++ b/trace-events
@@ -1497,6 +1497,7 @@
rdma_start_outgoing_migration_after_rdma_source_init(void) ""
postcopy_discard_send_finish(const char *ramblock, int nwords, int ncmds) "%s
mask words sent=%d in %d commands"
postcopy_cleanup_area(const char *ramblock, void *host_addr, size_t offset,
size_t length) "%s: %p offset=%zx length=%zx"
postcopy_init_area(const char *ramblock, void *host_addr, size_t offset,
size_t length) "%s: %p offset=%zx length=%zx"
+postcopy_place_page(unsigned long offset, void *host_addr, bool all_zero, int
old_state) "offset=%lx host=%p all_zero=%d old_state=%d"
# kvm-all.c
kvm_ioctl(int type, void *arg) "type 0x%x, arg %p"
--
2.1.0
- [Qemu-devel] [PATCH v5 25/45] qemu_savevm_state_complete: Postcopy changes, (continued)
- [Qemu-devel] [PATCH v5 25/45] qemu_savevm_state_complete: Postcopy changes, Dr. David Alan Gilbert (git), 2015/02/25
- [Qemu-devel] [PATCH v5 26/45] Postcopy page-map-incoming (PMI) structure, Dr. David Alan Gilbert (git), 2015/02/25
- [Qemu-devel] [PATCH v5 29/45] postcopy: ram_enable_notify to switch on userfault, Dr. David Alan Gilbert (git), 2015/02/25
- [Qemu-devel] [PATCH v5 28/45] postcopy: Incoming initialisation, Dr. David Alan Gilbert (git), 2015/02/25
- [Qemu-devel] [PATCH v5 27/45] Postcopy: Maintain sentmap and calculate discard, Dr. David Alan Gilbert (git), 2015/02/25
- [Qemu-devel] [PATCH v5 30/45] Postcopy: Postcopy startup in migration thread, Dr. David Alan Gilbert (git), 2015/02/25
- [Qemu-devel] [PATCH v5 31/45] Postcopy end in migration_thread, Dr. David Alan Gilbert (git), 2015/02/25
- [Qemu-devel] [PATCH v5 32/45] Page request: Add MIG_RP_CMD_REQ_PAGES reverse command, Dr. David Alan Gilbert (git), 2015/02/25
- [Qemu-devel] [PATCH v5 33/45] Page request: Process incoming page request, Dr. David Alan Gilbert (git), 2015/02/25
- [Qemu-devel] [PATCH v5 34/45] Page request: Consume pages off the post-copy queue, Dr. David Alan Gilbert (git), 2015/02/25
- [Qemu-devel] [PATCH v5 35/45] postcopy_ram.c: place_page and helpers,
Dr. David Alan Gilbert (git) <=
- [Qemu-devel] [PATCH v5 36/45] Postcopy: Use helpers to map pages during migration, Dr. David Alan Gilbert (git), 2015/02/25
- [Qemu-devel] [PATCH v5 38/45] Don't sync dirty bitmaps in postcopy, Dr. David Alan Gilbert (git), 2015/02/25
- [Qemu-devel] [PATCH v5 39/45] Host page!=target page: Cleanup bitmaps, Dr. David Alan Gilbert (git), 2015/02/25
- [Qemu-devel] [PATCH v5 37/45] qemu_ram_block_from_host, Dr. David Alan Gilbert (git), 2015/02/25
- [Qemu-devel] [PATCH v5 40/45] Postcopy; Handle userfault requests, Dr. David Alan Gilbert (git), 2015/02/25
- [Qemu-devel] [PATCH v5 42/45] postcopy: Wire up loadvm_postcopy_handle_{run, end} commands, Dr. David Alan Gilbert (git), 2015/02/25
- [Qemu-devel] [PATCH v5 41/45] Start up a postcopy/listener thread ready for incoming page data, Dr. David Alan Gilbert (git), 2015/02/25
- [Qemu-devel] [PATCH v5 43/45] End of migration for postcopy, Dr. David Alan Gilbert (git), 2015/02/25
- [Qemu-devel] [PATCH v5 45/45] Inhibit ballooning during postcopy, Dr. David Alan Gilbert (git), 2015/02/25
- [Qemu-devel] [PATCH v5 44/45] Disable mlock around incoming postcopy, Dr. David Alan Gilbert (git), 2015/02/25