From patchwork Wed Dec 18 19:40:56 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tamas K Lengyel X-Patchwork-Id: 11301805 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id F212413A4 for ; Wed, 18 Dec 2019 19:43:23 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id D7BD2206D8 for ; Wed, 18 Dec 2019 19:43:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D7BD2206D8 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1ihfDO-0000DB-TD; Wed, 18 Dec 2019 19:42:34 +0000 Received: from all-amaz-eas1.inumbo.com ([34.197.232.57] helo=us1-amaz-eas2.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1ihfDN-0000BI-8p for xen-devel@lists.xenproject.org; Wed, 18 Dec 2019 19:42:33 +0000 X-Inumbo-ID: 651b6b6a-21ce-11ea-90f3-12813bfff9fa Received: from mga04.intel.com (unknown [192.55.52.120]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id 651b6b6a-21ce-11ea-90f3-12813bfff9fa; Wed, 18 Dec 2019 19:41:33 +0000 (UTC) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga104.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 18 Dec 2019 11:41:31 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.69,330,1571727600"; d="scan'208";a="210196426" Received: from tlengyel-mobl2.amr.corp.intel.com (HELO localhost.localdomain) ([10.254.103.7]) by orsmga008.jf.intel.com with ESMTP; 18 Dec 2019 11:41:30 -0800 From: Tamas K Lengyel To: xen-devel@lists.xenproject.org Date: Wed, 18 Dec 2019 11:40:56 -0800 Message-Id: <22a6cb7bd5593ed38cf6f66c26c4734a04718e1a.1576697796.git.tamas.lengyel@intel.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: References: MIME-Version: 1.0 Subject: [Xen-devel] [PATCH v2 19/20] x86/mem_sharing: reset a fork X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Tamas K Lengyel , Tamas K Lengyel , Wei Liu , Konrad Rzeszutek Wilk , George Dunlap , Andrew Cooper , Ian Jackson , Stefano Stabellini , Jan Beulich , Julien Grall , =?utf-8?q?Roger_Pau_Monn=C3=A9?= Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" Implement hypercall that allows a fork to shed all memory that got allocated for it during its execution and re-load its vCPU context from the parent VM. This allows the forked VM to reset into the same state the parent VM is in a faster way then creating a new fork would be. Measurements show about a 2x speedup during normal fuzzing operations. Performance may vary depending how much memory got allocated for the forked VM. If it has been completely deduplicated from the parent VM then creating a new fork would likely be more performant. Signed-off-by: Tamas K Lengyel --- xen/arch/x86/mm/mem_sharing.c | 105 ++++++++++++++++++++++++++++++++++ xen/include/public/memory.h | 1 + 2 files changed, 106 insertions(+) diff --git a/xen/arch/x86/mm/mem_sharing.c b/xen/arch/x86/mm/mem_sharing.c index e93ad2ec5a..4735a334b9 100644 --- a/xen/arch/x86/mm/mem_sharing.c +++ b/xen/arch/x86/mm/mem_sharing.c @@ -1622,6 +1622,87 @@ static int mem_sharing_fork(struct domain *d, struct domain *cd) return 0; } +struct gfn_free; +struct gfn_free { + struct gfn_free *next; + struct page_info *page; + gfn_t gfn; +}; + +static int mem_sharing_fork_reset(struct domain *d, struct domain *cd) +{ + int rc; + + struct p2m_domain* p2m = p2m_get_hostp2m(cd); + struct gfn_free *list = NULL; + struct page_info *page; + + page_list_for_each(page, &cd->page_list) + { + mfn_t mfn = page_to_mfn(page); + if ( mfn_valid(mfn) ) + { + p2m_type_t p2mt; + p2m_access_t p2ma; + gfn_t gfn = mfn_to_gfn(cd, mfn); + mfn = __get_gfn_type_access(p2m, gfn_x(gfn), &p2mt, &p2ma, + 0, NULL, false); + if ( p2m_is_ram(p2mt) ) + { + struct gfn_free *gfn_free; + if ( !get_page(page, cd) ) + goto err_reset; + + /* + * We can't free the page while iterating over the page_list + * so we build a separate list to loop over. + * + * We want to iterate over the page_list instead of checking + * gfn from 0 to max_gfn because this is ~10x faster. + */ + gfn_free = xmalloc(struct gfn_free); + if ( !gfn_free ) + goto err_reset; + + gfn_free->gfn = gfn; + gfn_free->page = page; + gfn_free->next = list; + list = gfn_free; + } + } + } + + while ( list ) + { + struct gfn_free *next = list->next; + + rc = p2m->set_entry(p2m, list->gfn, INVALID_MFN, PAGE_ORDER_4K, + p2m_invalid, p2m_access_rwx, -1); + put_page_alloc_ref(list->page); + put_page(list->page); + + xfree(list); + list = next; + + ASSERT(!rc); + } + + if ( (rc = fork_hvm(d, cd)) ) + return rc; + + err_reset: + while ( list ) + { + struct gfn_free *next = list->next; + + put_page(list->page); + xfree(list); + list = next; + } + + return 0; +} + int mem_sharing_memop(XEN_GUEST_HANDLE_PARAM(xen_mem_sharing_op_t) arg) { int rc; @@ -1905,6 +1986,30 @@ int mem_sharing_memop(XEN_GUEST_HANDLE_PARAM(xen_mem_sharing_op_t) arg) rcu_unlock_domain(pd); break; } + + case XENMEM_sharing_op_fork_reset: + { + struct domain *pd; + + rc = -EINVAL; + if ( mso.u.fork._pad[0] || mso.u.fork._pad[1] || + mso.u.fork._pad[2] ) + goto out; + + rc = -ENOSYS; + if ( !d->parent ) + goto out; + + rc = rcu_lock_live_remote_domain_by_id(d->parent->domain_id, &pd); + if ( rc ) + goto out; + + rc = mem_sharing_fork_reset(pd, d); + + rcu_unlock_domain(pd); + break; + } + default: rc = -ENOSYS; break; diff --git a/xen/include/public/memory.h b/xen/include/public/memory.h index 90a3f4498e..e3d063e22e 100644 --- a/xen/include/public/memory.h +++ b/xen/include/public/memory.h @@ -483,6 +483,7 @@ DEFINE_XEN_GUEST_HANDLE(xen_mem_access_op_t); #define XENMEM_sharing_op_audit 7 #define XENMEM_sharing_op_range_share 8 #define XENMEM_sharing_op_fork 9 +#define XENMEM_sharing_op_fork_reset 10 #define XENMEM_SHARING_OP_S_HANDLE_INVALID (-10) #define XENMEM_SHARING_OP_C_HANDLE_INVALID (-9)