From patchwork Wed May 19 20:03:38 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Axel Rasmussen X-Patchwork-Id: 12268437 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT,USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E297BC433ED for ; Wed, 19 May 2021 20:04:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C6C5C611BD for ; Wed, 19 May 2021 20:04:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232805AbhESUGD (ORCPT ); Wed, 19 May 2021 16:06:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33230 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232803AbhESUFa (ORCPT ); Wed, 19 May 2021 16:05:30 -0400 Received: from mail-qk1-x749.google.com (mail-qk1-x749.google.com [IPv6:2607:f8b0:4864:20::749]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BC8BBC061345 for ; Wed, 19 May 2021 13:04:09 -0700 (PDT) Received: by mail-qk1-x749.google.com with SMTP id d201-20020ae9efd20000b02902e9e9d8d9dcso10660062qkg.10 for ; Wed, 19 May 2021 13:04:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=xXgCU6klz4Kb+YHqzC+5neYZZ9NaeqBCOsxs5FJ97FE=; b=vNqIyxQ+FUKJ7FHgc8qfhecfMaZ7eQQApBy7O2IY+PqnuavcPnWHadRtHk+dAV7JfZ CwoQwViWE+q2peiegAVLSVoWdqiLmIRElRxXB57LPtx00HYnsfggHb9TdtcQHIxx4krV u9ZgD4eWrJ8JOwWyTxpHWcfPxulK/phsbPSZ0qm6Ob8RA24wxe7oXGiU6KiiVSEgNOeb NT8P0HJqM3BBHva7j1I5y/jmsycOZLnvI8hK+JnTo26HXhtd8P3UsJE/Dxylx6IeNiW0 9rJOW3Vi8kLup5smn7lkxC/TRAACXFnun5C4JnhwCMjxjQiZC4WHYXvEh1loDwzfFEkw qKfA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=xXgCU6klz4Kb+YHqzC+5neYZZ9NaeqBCOsxs5FJ97FE=; b=fYnObcWHdKGFitCkTylGe7m1gWC8I1XH5mgpg6OsM9es3SZx8caxK8VRlcs1hFEEwi wLErgd0+9/xUmocQE9LI49dhxKMAUFtN6dwEjeXmlLpgi47Q5I5cy+10GG90mXI7mhfA NiRtk4gYvRwXThmbcBlnVElRgg1albq54MDs0cwK5Y4p364sJf4EiELEBePXNhhvCUsu gLd9Rpyob91+kN1QQEFjYxUMBCt8QzL91oz0R6qdD9qYOF1/gvqucgZAAjAf9ViCE4Ln d/TlDWVJTsVKRNhm9Qo+fi2y8jYsEFp5JpJDF8wSWhpLS3Dqxqxa2jsh3QK2vEg/7EXu dIQw== X-Gm-Message-State: AOAM5310xLnFLzLWZWHSr0PGjKmfkQjEL0Ewlx3DQ+S7OVIyYXIRqpUd 7f6ZFVbHFZp2LvPAP6DEwi1Uazo8hD1LE5iU0u61 X-Google-Smtp-Source: ABdhPJzKHNQQn4LgvSahjCmXI6WhdQgg4jsjKQSHm5wuUrz8cVOL1mmBYsQDpM9l3K/De0ndbUgjeya2eUhs8js/4F0y X-Received: from ajr0.svl.corp.google.com ([2620:15c:2cd:203:7eb5:10bb:834a:d5ec]) (user=axelrasmussen job=sendgmr) by 2002:ad4:5ecc:: with SMTP id jm12mr1301475qvb.5.1621454645877; Wed, 19 May 2021 13:04:05 -0700 (PDT) Date: Wed, 19 May 2021 13:03:38 -0700 In-Reply-To: <20210519200339.829146-1-axelrasmussen@google.com> Message-Id: <20210519200339.829146-10-axelrasmussen@google.com> Mime-Version: 1.0 References: <20210519200339.829146-1-axelrasmussen@google.com> X-Mailer: git-send-email 2.31.1.751.gd2f1c929bd-goog Subject: [PATCH v2 09/10] KVM: selftests: allow using UFFD minor faults for demand paging From: Axel Rasmussen To: Aaron Lewis , Alexander Graf , Andrew Jones , Andrew Morton , Ben Gardon , Emanuele Giuseppe Esposito , Eric Auger , Jacob Xu , Makarand Sonare , Oliver Upton , Paolo Bonzini , Peter Xu , Shuah Khan , Yanan Wang Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Axel Rasmussen Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org UFFD handling of MINOR faults is a new feature whose use case is to speed up demand paging (compared to MISSING faults). So, it's interesting to let this selftest exercise this new mode. Modify the demand paging test to have the option of using UFFD minor faults, as opposed to missing faults. Now, when turning on userfaultfd with '-u', the desired mode has to be specified ("MISSING" or "MINOR"). If we're in minor mode, before registering, prefault via the *alias*. This way, the guest will trigger minor faults, instead of missing faults, and we can UFFDIO_CONTINUE to resolve them. Modify the page fault handler function to use the right ioctl depending on the mode we're running in. In MINOR mode, use UFFDIO_CONTINUE. Signed-off-by: Axel Rasmussen --- .../selftests/kvm/demand_paging_test.c | 112 ++++++++++++------ 1 file changed, 79 insertions(+), 33 deletions(-) diff --git a/tools/testing/selftests/kvm/demand_paging_test.c b/tools/testing/selftests/kvm/demand_paging_test.c index 01890a7b0155..df7190261923 100644 --- a/tools/testing/selftests/kvm/demand_paging_test.c +++ b/tools/testing/selftests/kvm/demand_paging_test.c @@ -74,33 +74,48 @@ static void *vcpu_worker(void *data) return NULL; } -static int handle_uffd_page_request(int uffd, uint64_t addr) +static int handle_uffd_page_request(int uffd_mode, int uffd, uint64_t addr) { - pid_t tid; + pid_t tid = syscall(__NR_gettid); struct timespec start; struct timespec ts_diff; - struct uffdio_copy copy; int r; - tid = syscall(__NR_gettid); + clock_gettime(CLOCK_MONOTONIC, &start); - copy.src = (uint64_t)guest_data_prototype; - copy.dst = addr; - copy.len = demand_paging_size; - copy.mode = 0; + if (uffd_mode == UFFDIO_REGISTER_MODE_MISSING) { + struct uffdio_copy copy; - clock_gettime(CLOCK_MONOTONIC, &start); + copy.src = (uint64_t)guest_data_prototype; + copy.dst = addr; + copy.len = demand_paging_size; + copy.mode = 0; + + r = ioctl(uffd, UFFDIO_COPY, ©); + if (r == -1) { + pr_info("Failed UFFDIO_COPY in 0x%lx from thread %d with errno: %d\n", + addr, tid, errno); + return r; + } + } else if (uffd_mode == UFFDIO_REGISTER_MODE_MINOR) { + struct uffdio_continue cont = {0}; + + cont.range.start = addr; + cont.range.len = demand_paging_size; - r = ioctl(uffd, UFFDIO_COPY, ©); - if (r == -1) { - pr_info("Failed Paged in 0x%lx from thread %d with errno: %d\n", - addr, tid, errno); - return r; + r = ioctl(uffd, UFFDIO_CONTINUE, &cont); + if (r == -1) { + pr_info("Failed UFFDIO_CONTINUE in 0x%lx from thread %d with errno: %d\n", + addr, tid, errno); + return r; + } + } else { + TEST_FAIL("Invalid uffd mode %d", uffd_mode); } ts_diff = timespec_elapsed(start); - PER_PAGE_DEBUG("UFFDIO_COPY %d \t%ld ns\n", tid, + PER_PAGE_DEBUG("UFFD page-in %d \t%ld ns\n", tid, timespec_to_ns(ts_diff)); PER_PAGE_DEBUG("Paged in %ld bytes at 0x%lx from thread %d\n", demand_paging_size, addr, tid); @@ -111,6 +126,7 @@ static int handle_uffd_page_request(int uffd, uint64_t addr) bool quit_uffd_thread; struct uffd_handler_args { + int uffd_mode; int uffd; int pipefd; useconds_t delay; @@ -187,7 +203,7 @@ static void *uffd_handler_thread_fn(void *arg) if (delay) usleep(delay); addr = msg.arg.pagefault.address; - r = handle_uffd_page_request(uffd, addr); + r = handle_uffd_page_request(uffd_args->uffd_mode, uffd, addr); if (r < 0) return NULL; pages++; @@ -203,13 +219,32 @@ static void *uffd_handler_thread_fn(void *arg) static void setup_demand_paging(struct kvm_vm *vm, pthread_t *uffd_handler_thread, int pipefd, - useconds_t uffd_delay, + int uffd_mode, useconds_t uffd_delay, struct uffd_handler_args *uffd_args, - void *hva, uint64_t len) + void *hva, void *alias, uint64_t len) { + bool is_minor = (uffd_mode == UFFDIO_REGISTER_MODE_MINOR); int uffd; struct uffdio_api uffdio_api; struct uffdio_register uffdio_register; + uint64_t expected_ioctls = ((uint64_t) 1) << _UFFDIO_COPY; + + PER_PAGE_DEBUG("Userfaultfd %s mode, faults resolved with %s\n", + is_minor ? "MINOR" : "MISSING", + is_minor ? "UFFDIO_CONINUE" : "UFFDIO_COPY"); + + /* In order to get minor faults, prefault via the alias. */ + if (is_minor) { + size_t p; + + expected_ioctls = ((uint64_t) 1) << _UFFDIO_CONTINUE; + + TEST_ASSERT(alias != NULL, "Alias required for minor faults"); + for (p = 0; p < (len / demand_paging_size); ++p) { + memcpy(alias + (p * demand_paging_size), + guest_data_prototype, demand_paging_size); + } + } uffd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK); TEST_ASSERT(uffd >= 0, "uffd creation failed, errno: %d", errno); @@ -222,12 +257,13 @@ static void setup_demand_paging(struct kvm_vm *vm, uffdio_register.range.start = (uint64_t)hva; uffdio_register.range.len = len; - uffdio_register.mode = UFFDIO_REGISTER_MODE_MISSING; + uffdio_register.mode = uffd_mode; TEST_ASSERT(ioctl(uffd, UFFDIO_REGISTER, &uffdio_register) != -1, "ioctl UFFDIO_REGISTER failed"); - TEST_ASSERT((uffdio_register.ioctls & UFFD_API_RANGE_IOCTLS) == - UFFD_API_RANGE_IOCTLS, "unexpected userfaultfd ioctl set"); + TEST_ASSERT((uffdio_register.ioctls & expected_ioctls) == + expected_ioctls, "missing userfaultfd ioctls"); + uffd_args->uffd_mode = uffd_mode; uffd_args->uffd = uffd; uffd_args->pipefd = pipefd; uffd_args->delay = uffd_delay; @@ -239,7 +275,7 @@ static void setup_demand_paging(struct kvm_vm *vm, } struct test_params { - bool use_uffd; + int uffd_mode; useconds_t uffd_delay; enum vm_mem_backing_src_type src_type; bool partition_vcpu_memory_access; @@ -276,7 +312,7 @@ static void run_test(enum vm_guest_mode mode, void *arg) perf_test_setup_vcpus(vm, nr_vcpus, guest_percpu_mem_size, p->partition_vcpu_memory_access); - if (p->use_uffd) { + if (p->uffd_mode) { uffd_handler_threads = malloc(nr_vcpus * sizeof(*uffd_handler_threads)); TEST_ASSERT(uffd_handler_threads, "Memory allocation failed"); @@ -290,6 +326,7 @@ static void run_test(enum vm_guest_mode mode, void *arg) for (vcpu_id = 0; vcpu_id < nr_vcpus; vcpu_id++) { vm_paddr_t vcpu_gpa; void *vcpu_hva; + void *vcpu_alias; uint64_t vcpu_mem_size; @@ -304,8 +341,9 @@ static void run_test(enum vm_guest_mode mode, void *arg) PER_VCPU_DEBUG("Added VCPU %d with test mem gpa [%lx, %lx)\n", vcpu_id, vcpu_gpa, vcpu_gpa + vcpu_mem_size); - /* Cache the HVA pointer of the region */ + /* Cache the host addresses of the region */ vcpu_hva = addr_gpa2hva(vm, vcpu_gpa); + vcpu_alias = addr_gpa2alias(vm, vcpu_gpa); /* * Set up user fault fd to handle demand paging @@ -316,8 +354,9 @@ static void run_test(enum vm_guest_mode mode, void *arg) TEST_ASSERT(!r, "Failed to set up pipefd"); setup_demand_paging(vm, &uffd_handler_threads[vcpu_id], - pipefds[vcpu_id * 2], p->uffd_delay, - &uffd_args[vcpu_id], vcpu_hva, + pipefds[vcpu_id * 2], p->uffd_mode, + p->uffd_delay, &uffd_args[vcpu_id], + vcpu_hva, vcpu_alias, vcpu_mem_size); } } @@ -346,7 +385,7 @@ static void run_test(enum vm_guest_mode mode, void *arg) pr_info("All vCPU threads joined\n"); - if (p->use_uffd) { + if (p->uffd_mode) { char c; /* Tell the user fault fd handler threads to quit */ @@ -368,7 +407,7 @@ static void run_test(enum vm_guest_mode mode, void *arg) free(guest_data_prototype); free(vcpu_threads); - if (p->use_uffd) { + if (p->uffd_mode) { free(uffd_handler_threads); free(uffd_args); free(pipefds); @@ -378,11 +417,11 @@ static void run_test(enum vm_guest_mode mode, void *arg) static void help(char *name) { puts(""); - printf("usage: %s [-h] [-m mode] [-u] [-d uffd_delay_usec]\n" + printf("usage: %s [-h] [-m mode] [-u mode] [-d uffd_delay_usec]\n" " [-b memory] [-t type] [-v vcpus] [-o]\n", name); guest_modes_help(); - printf(" -u: use User Fault FD to handle vCPU page\n" - " faults.\n"); + printf(" -u: use userfaultfd to handle vCPU page faults. Mode is a\n" + " UFFD registration mode: 'MISSING' or 'MINOR'.\n"); printf(" -d: add a delay in usec to the User Fault\n" " FD handler to simulate demand paging\n" " overheads. Ignored without -u.\n"); @@ -409,13 +448,17 @@ int main(int argc, char *argv[]) guest_modes_append_default(); - while ((opt = getopt(argc, argv, "hm:ud:b:t:v:o")) != -1) { + while ((opt = getopt(argc, argv, "hm:u:d:b:t:v:o")) != -1) { switch (opt) { case 'm': guest_modes_cmdline(optarg); break; case 'u': - p.use_uffd = true; + if (!strcmp("MISSING", optarg)) + p.uffd_mode = UFFDIO_REGISTER_MODE_MISSING; + else if (!strcmp("MINOR", optarg)) + p.uffd_mode = UFFDIO_REGISTER_MODE_MINOR; + TEST_ASSERT(p.uffd_mode, "UFFD mode must be 'MISSING' or 'MINOR'."); break; case 'd': p.uffd_delay = strtoul(optarg, NULL, 0); @@ -442,6 +485,9 @@ int main(int argc, char *argv[]) } } + TEST_ASSERT(p.uffd_mode != UFFDIO_REGISTER_MODE_MINOR || p.src_type == VM_MEM_SRC_SHMEM, + "userfaultfd MINOR mode requires shared memory; pick a different -t"); + for_each_guest_mode(run_test, &p); return 0;