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dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:40376 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1khzmS-0000IB-Q6 for qemu-devel@archiver.kernel.org; Wed, 25 Nov 2020 13:44:40 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:38664) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1khzlB-0007tC-6a for qemu-devel@nongnu.org; Wed, 25 Nov 2020 13:43:21 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:22234) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1khzl8-0003b6-Io for qemu-devel@nongnu.org; Wed, 25 Nov 2020 13:43:20 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1606329797; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=XVGwBy4ycTONVbiL6NY2SatRbHhkmecjVK6Khec68QA=; b=HgN1wpWuO5WXoEWG1glARnrlP1c3SLNGFTSy54Qyvfd1HIR74Crsb6LE5A4hZ5AW3GOqua yu9V7nAnkkTthr0v4+wHT5FcR2/ZGdKoejsrQPE7yTNV4G3oqtF+rZCeB8KUlX4AUD9rTY eQA9VZSwbrW7FIm6iV5mh1C5BffO2GQ= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-23-3D2Wlp3HNaSMrw-hkV8enQ-1; Wed, 25 Nov 2020 13:43:15 -0500 X-MC-Unique: 3D2Wlp3HNaSMrw-hkV8enQ-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id BFAD8180E473; Wed, 25 Nov 2020 18:43:14 +0000 (UTC) Received: from work-vm (ovpn-115-12.ams2.redhat.com [10.36.115.12]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A5A5719C46; Wed, 25 Nov 2020 18:43:09 +0000 (UTC) Date: Wed, 25 Nov 2020 18:43:07 +0000 From: "Dr. David Alan Gilbert" To: Andrey Gruzdev Subject: Re: [PATCH v3 2/7] introduce UFFD-WP low-level interface helpers Message-ID: <20201125184307.GJ3222@work-vm> References: <20201119125940.20017-1-andrey.gruzdev@virtuozzo.com> <20201119125940.20017-3-andrey.gruzdev@virtuozzo.com> <20201124175712.GM3366@work-vm> <24483c0d-107f-427e-87b1-f4e039bfe486@virtuozzo.com> MIME-Version: 1.0 In-Reply-To: <24483c0d-107f-427e-87b1-f4e039bfe486@virtuozzo.com> User-Agent: Mutt/1.14.6 (2020-07-11) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dgilbert@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=216.205.24.124; envelope-from=dgilbert@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Juan Quintela , qemu-devel@nongnu.org, Peter Xu , Markus Armbruster , Paolo Bonzini , Den Lunev Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Andrey Gruzdev (andrey.gruzdev@virtuozzo.com) wrote: > On 24.11.2020 20:57, Dr. David Alan Gilbert wrote: > > * Andrey Gruzdev (andrey.gruzdev@virtuozzo.com) wrote: > > > Implemented support for the whole RAM block memory > > > protection/un-protection. Introduced higher level > > > ram_write_tracking_start() and ram_write_tracking_stop() > > > to start/stop tracking guest memory writes. > > > > > > Signed-off-by: Andrey Gruzdev > > > --- > > > include/exec/memory.h | 7 ++ > > > migration/ram.c | 267 ++++++++++++++++++++++++++++++++++++++++++ > > > migration/ram.h | 4 + > > > 3 files changed, 278 insertions(+) > > > > > > diff --git a/include/exec/memory.h b/include/exec/memory.h > > > index 0f3e6bcd5e..3d798fce16 100644 > > > --- a/include/exec/memory.h > > > +++ b/include/exec/memory.h > > > @@ -139,6 +139,13 @@ typedef struct IOMMUNotifier IOMMUNotifier; > > > /* RAM is a persistent kind memory */ > > > #define RAM_PMEM (1 << 5) > > > +/* > > > + * UFFDIO_WRITEPROTECT is used on this RAMBlock to > > > + * support 'write-tracking' migration type. > > > + * Implies ram_state->ram_wt_enabled. > > > + */ > > > +#define RAM_UF_WRITEPROTECT (1 << 6) > > > + > > > static inline void iommu_notifier_init(IOMMUNotifier *n, IOMMUNotify fn, > > > IOMMUNotifierFlag flags, > > > hwaddr start, hwaddr end, > > > diff --git a/migration/ram.c b/migration/ram.c > > > index 7811cde643..7f273c9996 100644 > > > --- a/migration/ram.c > > > +++ b/migration/ram.c > > > @@ -56,6 +56,12 @@ > > > #include "savevm.h" > > > #include "qemu/iov.h" > > > #include "multifd.h" > > > +#include > > > +#include > > > +#include > > > +#include > > > +#include > > > +#include "sysemu/runstate.h" > > > /***********************************************************/ > > > /* ram save/restore */ > > > @@ -298,6 +304,8 @@ struct RAMSrcPageRequest { > > > struct RAMState { > > > /* QEMUFile used for this migration */ > > > QEMUFile *f; > > > + /* UFFD file descriptor, used in 'write-tracking' migration */ > > > + int uffdio_fd; > > > /* Last block that we have visited searching for dirty pages */ > > > RAMBlock *last_seen_block; > > > /* Last block from where we have sent data */ > > > @@ -453,6 +461,181 @@ static QemuThread *decompress_threads; > > > static QemuMutex decomp_done_lock; > > > static QemuCond decomp_done_cond; > > > +/** > > > + * uffd_create_fd: create UFFD file descriptor > > > + * > > > + * Returns non-negative file descriptor or negative value in case of an error > > > + */ > > > +static int uffd_create_fd(void) > > > +{ > > > + int uffd; > > > + struct uffdio_api api_struct; > > > + uint64_t ioctl_mask = BIT(_UFFDIO_REGISTER) | BIT(_UFFDIO_UNREGISTER); > > > > You need to be a bit careful about doing this in migration/ram.c - it's > > generic code; at minimum it needs ifdef'ing for Linux. > > > > Yes, it's totally linux-specific, I think better to move this code out of > migration/ram.c, as Peter proposed. > > > > + uffd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK); > > > + if (uffd < 0) { > > > + error_report("uffd_create_fd() failed: UFFD not supported"); > > > + return -1; > > > + } > > > + > > > + api_struct.api = UFFD_API; > > > + api_struct.features = UFFD_FEATURE_PAGEFAULT_FLAG_WP; > > > + if (ioctl(uffd, UFFDIO_API, &api_struct)) { > > > + error_report("uffd_create_fd() failed: " > > > + "API version not supported version=%llx errno=%i", > > > + api_struct.api, errno); > > > + goto fail; > > > + } > > > + > > > + if ((api_struct.ioctls & ioctl_mask) != ioctl_mask) { > > > + error_report("uffd_create_fd() failed: " > > > + "PAGEFAULT_FLAG_WP feature missing"); > > > + goto fail; > > > + } > > > + > > > + return uffd; > > > > Should we be putting that somewher that we can share with postcopy? > > > > Sure, maybe to util/uffd-wp.c + include/qemu/uffd-wp.h. > What do you think? Or how about a userfaultfd.c somewhere? Dave > > > +fail: > > > + close(uffd); > > > + return -1; > > > +} > > > + > > > +/** > > > + * uffd_close_fd: close UFFD file descriptor > > > + * > > > + * @uffd: UFFD file descriptor > > > + */ > > > +static void uffd_close_fd(int uffd) > > > +{ > > > + assert(uffd >= 0); > > > + close(uffd); > > > +} > > > + > > > +/** > > > + * uffd_register_memory: register memory range with UFFD > > > + * > > > + * Returns 0 in case of success, negative value on error > > > + * > > > + * @uffd: UFFD file descriptor > > > + * @start: starting virtual address of memory range > > > + * @length: length of memory range > > > + * @track_missing: generate events on missing-page faults > > > + * @track_wp: generate events on write-protected-page faults > > > + */ > > > +static int uffd_register_memory(int uffd, hwaddr start, hwaddr length, > > > + bool track_missing, bool track_wp) > > > +{ > > > + struct uffdio_register uffd_register; > > > + > > > + uffd_register.range.start = start; > > > + uffd_register.range.len = length; > > > + uffd_register.mode = (track_missing ? UFFDIO_REGISTER_MODE_MISSING : 0) | > > > + (track_wp ? UFFDIO_REGISTER_MODE_WP : 0); > > > + > > > + if (ioctl(uffd, UFFDIO_REGISTER, &uffd_register)) { > > > + error_report("uffd_register_memory() failed: " > > > + "start=%0"PRIx64" len=%"PRIu64" mode=%llu errno=%i", > > > + start, length, uffd_register.mode, errno); > > > + return -1; > > > + } > > > + > > > + return 0; > > > +} > > > + > > > +/** > > > + * uffd_protect_memory: protect/unprotect memory range for writes with UFFD > > > + * > > > + * Returns 0 on success or negative value in case of error > > > + * > > > + * @uffd: UFFD file descriptor > > > + * @start: starting virtual address of memory range > > > + * @length: length of memory range > > > + * @wp: write-protect/unprotect > > > + */ > > > +static int uffd_protect_memory(int uffd, hwaddr start, hwaddr length, bool wp) > > > +{ > > > + struct uffdio_writeprotect uffd_writeprotect; > > > + int res; > > > + > > > + uffd_writeprotect.range.start = start; > > > + uffd_writeprotect.range.len = length; > > > + uffd_writeprotect.mode = (wp ? UFFDIO_WRITEPROTECT_MODE_WP : 0); > > > + > > > + do { > > > + res = ioctl(uffd, UFFDIO_WRITEPROTECT, &uffd_writeprotect); > > > + } while (res < 0 && errno == EINTR); > > > + if (res < 0) { > > > + error_report("uffd_protect_memory() failed: " > > > + "start=%0"PRIx64" len=%"PRIu64" mode=%llu errno=%i", > > > + start, length, uffd_writeprotect.mode, errno); > > > + return -1; > > > + } > > > + > > > + return 0; > > > +} > > > + > > > +__attribute__ ((unused)) > > > +static int uffd_read_events(int uffd, struct uffd_msg *msgs, int count); > > > +__attribute__ ((unused)) > > > +static bool uffd_poll_events(int uffd, int tmo); > > > + > > > +/** > > > + * uffd_read_events: read pending UFFD events > > > + * > > > + * Returns number of fetched messages, 0 if non is available or > > > + * negative value in case of an error > > > + * > > > + * @uffd: UFFD file descriptor > > > + * @msgs: pointer to message buffer > > > + * @count: number of messages that can fit in the buffer > > > + */ > > > +static int uffd_read_events(int uffd, struct uffd_msg *msgs, int count) > > > +{ > > > + ssize_t res; > > > + do { > > > + res = read(uffd, msgs, count * sizeof(struct uffd_msg)); > > > + } while (res < 0 && errno == EINTR); > > > + > > > + if ((res < 0 && errno == EAGAIN)) { > > > + return 0; > > > + } > > > + if (res < 0) { > > > + error_report("uffd_read_events() failed: errno=%i", errno); > > > + return -1; > > > + } > > > + > > > + return (int) (res / sizeof(struct uffd_msg)); > > > +} > > > + > > > +/** > > > + * uffd_poll_events: poll UFFD file descriptor for read > > > + * > > > + * Returns true if events are available for read, false otherwise > > > + * > > > + * @uffd: UFFD file descriptor > > > + * @tmo: timeout in milliseconds, 0 for non-blocking operation, > > > + * negative value for infinite wait > > > + */ > > > +static bool uffd_poll_events(int uffd, int tmo) > > > +{ > > > + int res; > > > + struct pollfd poll_fd = { .fd = uffd, .events = POLLIN, .revents = 0 }; > > > + > > > + do { > > > + res = poll(&poll_fd, 1, tmo); > > > + } while (res < 0 && errno == EINTR); > > > + > > > + if (res == 0) { > > > + return false; > > > + } > > > + if (res < 0) { > > > + error_report("uffd_poll_events() failed: errno=%i", errno); > > > + return false; > > > + } > > > + > > > + return (poll_fd.revents & POLLIN) != 0; > > > +} > > > + > > > static bool do_compress_ram_page(QEMUFile *f, z_stream *stream, RAMBlock *block, > > > ram_addr_t offset, uint8_t *source_buf); > > > @@ -3788,6 +3971,90 @@ static int ram_resume_prepare(MigrationState *s, void *opaque) > > > return 0; > > > } > > > +/** > > > + * ram_write_tracking_start: start UFFD-WP memory tracking > > > + * > > > + * Returns 0 for success or negative value in case of error > > > + * > > > + */ > > > +int ram_write_tracking_start(void) > > > +{ > > > + int uffd; > > > + RAMState *rs = ram_state; > > > + RAMBlock *bs; > > > + > > > + /* Open UFFD file descriptor */ > > > + uffd = uffd_create_fd(); > > > + if (uffd < 0) { > > > + return uffd; > > > + } > > > + rs->uffdio_fd = uffd; > > > + > > > + RAMBLOCK_FOREACH_NOT_IGNORED(bs) { > > > + /* Nothing to do with read-only and MMIO-writable regions */ > > > + if (bs->mr->readonly || bs->mr->rom_device) { > > > + continue; > > > + } > > > + > > > + /* Register block memory with UFFD to track writes */ > > > + if (uffd_register_memory(rs->uffdio_fd, (hwaddr) bs->host, > > > + bs->max_length, false, true)) { > > > + goto fail; > > > + } > > > + /* Apply UFFD write protection to the block memory range */ > > > + if (uffd_protect_memory(rs->uffdio_fd, (hwaddr) bs->host, > > > + bs->max_length, true)) { > > > + goto fail; > > > + } > > > + bs->flags |= RAM_UF_WRITEPROTECT; > > > + > > > + info_report("UFFD-WP write-tracking enabled: " > > > + "block_id=%s page_size=%zu start=%p length=%lu " > > > + "romd_mode=%i ram=%i readonly=%i nonvolatile=%i rom_device=%i", > > > + bs->idstr, bs->page_size, bs->host, bs->max_length, > > > + bs->mr->romd_mode, bs->mr->ram, bs->mr->readonly, > > > + bs->mr->nonvolatile, bs->mr->rom_device); > > > + } > > > + > > > + return 0; > > > + > > > +fail: > > > + uffd_close_fd(uffd); > > > + rs->uffdio_fd = -1; > > > + return -1; > > > +} > > > + > > > +/** > > > + * ram_write_tracking_stop: stop UFFD-WP memory tracking and remove protection > > > + */ > > > +void ram_write_tracking_stop(void) > > > +{ > > > + RAMState *rs = ram_state; > > > + RAMBlock *bs; > > > + assert(rs->uffdio_fd >= 0); > > > + > > > + RAMBLOCK_FOREACH_NOT_IGNORED(bs) { > > > + if ((bs->flags & RAM_UF_WRITEPROTECT) == 0) { > > > + continue; > > > + } > > > + info_report("UFFD-WP write-tracking disabled: " > > > + "block_id=%s page_size=%zu start=%p length=%lu " > > > + "romd_mode=%i ram=%i readonly=%i nonvolatile=%i rom_device=%i", > > > + bs->idstr, bs->page_size, bs->host, bs->max_length, > > > + bs->mr->romd_mode, bs->mr->ram, bs->mr->readonly, > > > + bs->mr->nonvolatile, bs->mr->rom_device); > > > + /* Cleanup flags */ > > > + bs->flags &= ~RAM_UF_WRITEPROTECT; > > > + } > > > + > > > + /* > > > + * Close UFFD file descriptor to remove protection, > > > + * release registered memory regions and flush wait queues > > > + */ > > > + uffd_close_fd(rs->uffdio_fd); > > > + rs->uffdio_fd = -1; > > > +} > > > + > > > static SaveVMHandlers savevm_ram_handlers = { > > > .save_setup = ram_save_setup, > > > .save_live_iterate = ram_save_iterate, > > > diff --git a/migration/ram.h b/migration/ram.h > > > index 011e85414e..3611cb51de 100644 > > > --- a/migration/ram.h > > > +++ b/migration/ram.h > > > @@ -79,4 +79,8 @@ void colo_flush_ram_cache(void); > > > void colo_release_ram_cache(void); > > > void colo_incoming_start_dirty_log(void); > > > +/* Live snapshots */ > > > +int ram_write_tracking_start(void); > > > +void ram_write_tracking_stop(void); > > > + > > > #endif > > > -- > > > 2.25.1 > > > > > > -- > Andrey Gruzdev, Principal Engineer > Virtuozzo GmbH +7-903-247-6397 > virtuzzo.com > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK