On Wed, Jun 28, 2017 at 08:00:23PM +0100, Dr. David Alan Gilbert (git) wrote:
> From: "Dr. David Alan Gilbert" <dgilb...@redhat.com>
>
> Use the recently added migration flag to hold whether
> each RAMBlock has the UFFDIO_ZEROPAGE capability, use it
> when it's available.
>
> This allows the use of postcopy on tmpfs as well as hugepage
> backed files.
>
> Signed-off-by: Dr. David Alan Gilbert <dgilb...@redhat.com>
> ---
> migration/migration.h | 4 ++++
> migration/postcopy-ram.c | 12 +++++++++---
> 2 files changed, 13 insertions(+), 3 deletions(-)
>
> diff --git a/migration/migration.h b/migration/migration.h
> index d9a268a3af..d109635d08 100644
> --- a/migration/migration.h
> +++ b/migration/migration.h
> @@ -20,6 +20,10 @@
> #include "exec/cpu-common.h"
> #include "qemu/coroutine_int.h"
>
> +/* Migration flags to be set using qemu_ram_set_migration_flags */
> +/* Postcopy can atomically zero pages in this RAMBlock */
> +#define QEMU_MIGFLAG_POSTCOPY_ZERO 0x00000001
> +
> /* State for the incoming migration */
> struct MigrationIncomingState {
> QEMUFile *from_src_file;
> diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
> index be2a8f8e02..96338a8070 100644
> --- a/migration/postcopy-ram.c
> +++ b/migration/postcopy-ram.c
> @@ -408,6 +408,12 @@ static int ram_block_enable_notify(const char
> *block_name, void *host_addr,
> error_report("%s userfault: Region doesn't support COPY", __func__);
> return -1;
> }
> + if (reg_struct.ioctls & ((__u64)1 << _UFFDIO_ZEROPAGE)) {
> + RAMBlock *rb = qemu_ram_block_by_name(block_name);
> + qemu_ram_set_migration_flags(rb, qemu_ram_get_migration_flags(rb) |
> + QEMU_MIGFLAG_POSTCOPY_ZERO);
Shall we use atomic_or() inside qemu_ram_set_migration_flags()? Then
no need to fetch, and we'll be thread safe as well?
> + }
> +
>
> return 0;
> }
> @@ -620,11 +626,11 @@ int postcopy_place_page(MigrationIncomingState *mis,
> void *host, void *from,
> int postcopy_place_page_zero(MigrationIncomingState *mis, void *host,
> RAMBlock *rb)
> {
> + size_t pagesize = qemu_ram_pagesize(rb);
> trace_postcopy_place_page_zero(host);
>
> - if (qemu_ram_pagesize(rb) == getpagesize()) {
> - if (qemu_ufd_copy_ioctl(mis->userfault_fd, host, NULL, getpagesize(),
> - rb)) {
> + if (qemu_ram_get_migration_flags(rb) & QEMU_MIGFLAG_POSTCOPY_ZERO) {
IIUC, _UFFDIO_ZEROPAGE is not supported on huge pages. If so, would
here worth a comment?
> + if (qemu_ufd_copy_ioctl(mis->userfault_fd, host, NULL, pagesize,
> rb)) {
> int e = errno;
> error_report("%s: %s zero host: %p",
> __func__, strerror(e), host);
> --
> 2.13.0
>
Thanks,
--
Peter Xu
