From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52108) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dkxnT-0001yF-9C for qemu-devel@nongnu.org; Thu, 24 Aug 2017 15:28:08 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dkxnS-0004Mq-50 for qemu-devel@nongnu.org; Thu, 24 Aug 2017 15:28:07 -0400 Received: from mx1.redhat.com ([209.132.183.28]:52426) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dkxnR-0004Lu-Rh for qemu-devel@nongnu.org; Thu, 24 Aug 2017 15:28:06 -0400 From: "Dr. David Alan Gilbert (git)" Date: Thu, 24 Aug 2017 20:27:04 +0100 Message-Id: <20170824192730.8440-7-dgilbert@redhat.com> In-Reply-To: <20170824192730.8440-1-dgilbert@redhat.com> References: <20170824192730.8440-1-dgilbert@redhat.com> Subject: [Qemu-devel] [RFC v2 06/32] postcopy: use UFFDIO_ZEROPAGE only when available List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org, maxime.coquelin@redhat.com, a.perevalov@samsung.com, mst@redhat.com, marcandre.lureau@redhat.com Cc: quintela@redhat.com, peterx@redhat.com, lvivier@redhat.com, aarcange@redhat.com, felipe@nutanix.com From: "Dr. David Alan Gilbert" Use a flag on the RAMBlock to state whether it 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 --- exec.c | 15 +++++++++++++++ include/exec/cpu-common.h | 3 +++ migration/postcopy-ram.c | 14 +++++++++++--- 3 files changed, 29 insertions(+), 3 deletions(-) diff --git a/exec.c b/exec.c index 35b4cea2ed..80c3d1d121 100644 --- a/exec.c +++ b/exec.c @@ -103,6 +103,11 @@ static MemoryRegion io_mem_unassigned; */ #define RAM_RESIZEABLE (1 << 2) +/* UFFDIO_ZEROPAGE is available on this RAMBlock to atomically + * zero the page and wake waiting processes. + * (Set during postcopy) + */ +#define RAM_UF_ZEROPAGE (1 << 3) #endif #ifdef TARGET_PAGE_BITS_VARY @@ -1705,6 +1710,16 @@ bool qemu_ram_is_shared(RAMBlock *rb) return rb->flags & RAM_SHARED; } +bool qemu_ram_is_uf_zeroable(RAMBlock *rb) +{ + return rb->flags & RAM_UF_ZEROPAGE; +} + +void qemu_ram_set_uf_zeroable(RAMBlock *rb) +{ + rb->flags |= RAM_UF_ZEROPAGE; +} + /* Called with iothread lock held. */ void qemu_ram_set_idstr(RAMBlock *new_block, const char *name, DeviceState *dev) { diff --git a/include/exec/cpu-common.h b/include/exec/cpu-common.h index 0d861a6289..24d335f95d 100644 --- a/include/exec/cpu-common.h +++ b/include/exec/cpu-common.h @@ -73,6 +73,9 @@ void qemu_ram_set_idstr(RAMBlock *block, const char *name, DeviceState *dev); void qemu_ram_unset_idstr(RAMBlock *block); const char *qemu_ram_get_idstr(RAMBlock *rb); bool qemu_ram_is_shared(RAMBlock *rb); +bool qemu_ram_is_uf_zeroable(RAMBlock *rb); +void qemu_ram_set_uf_zeroable(RAMBlock *rb); + size_t qemu_ram_pagesize(RAMBlock *block); size_t qemu_ram_pagesize_largest(void); diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c index 7a414ebad8..640b72d86d 100644 --- a/migration/postcopy-ram.c +++ b/migration/postcopy-ram.c @@ -408,6 +408,11 @@ 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_uf_zeroable(rb); + } + return 0; } @@ -617,11 +622,14 @@ 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)) { + /* Normal RAMBlocks can zero a page using UFFDIO_ZEROPAGE + * but it's not available for everything (e.g. hugetlbpages) + */ + if (qemu_ram_is_uf_zeroable(rb)) { + 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); -- 2.13.5