From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50983) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ey7mO-0006jz-93 for qemu-devel@nongnu.org; Mon, 19 Mar 2018 23:17:41 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ey7mN-0008EZ-5w for qemu-devel@nongnu.org; Mon, 19 Mar 2018 23:17:40 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:57004 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ey7mN-0008EP-0H for qemu-devel@nongnu.org; Mon, 19 Mar 2018 23:17:39 -0400 Date: Tue, 20 Mar 2018 05:17:38 +0200 From: "Michael S. Tsirkin" Message-ID: <1521515720-612046-25-git-send-email-mst@redhat.com> References: <1521515720-612046-1-git-send-email-mst@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1521515720-612046-1-git-send-email-mst@redhat.com> Subject: [Qemu-devel] [PULL v2 24/50] postcopy: use UFFDIO_ZEROPAGE only when available List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Peter Maydell , "Dr. David Alan Gilbert" , Peter Xu , Paolo Bonzini , Peter Crosthwaite , Richard Henderson , Juan Quintela 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 Reviewed-by: Peter Xu Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- include/exec/cpu-common.h | 3 +++ exec.c | 16 ++++++++++++++++ migration/postcopy-ram.c | 13 ++++++++++--- 3 files changed, 29 insertions(+), 3 deletions(-) diff --git a/include/exec/cpu-common.h b/include/exec/cpu-common.h index 0d861a6..24d335f 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/exec.c b/exec.c index 2199b09..0eb890d 100644 --- a/exec.c +++ b/exec.c @@ -99,6 +99,11 @@ 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 @@ -1767,6 +1772,17 @@ bool qemu_ram_is_shared(RAMBlock *rb) return rb->flags & RAM_SHARED; } +/* Note: Only set at the start of postcopy */ +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/migration/postcopy-ram.c b/migration/postcopy-ram.c index 032abfb..a75b5d3 100644 --- a/migration/postcopy-ram.c +++ b/migration/postcopy-ram.c @@ -481,6 +481,10 @@ 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; } @@ -700,11 +704,14 @@ 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); -- MST