From nobody Tue Nov 11 00:34:12 2025 Delivered-To: importer@patchew.org Received-SPF: none (zohomail.com: 192.237.175.120 is neither permitted nor denied by domain of lists.xenproject.org) client-ip=192.237.175.120; envelope-from=xen-devel-bounces@lists.xenproject.org; helo=lists.xenproject.org; Authentication-Results: mx.zohomail.com; spf=none (zohomail.com: 192.237.175.120 is neither permitted nor denied by domain of lists.xenproject.org) smtp.mailfrom=xen-devel-bounces@lists.xenproject.org; dmarc=fail(p=none dis=none) header.from=intel.com ARC-Seal: i=1; a=rsa-sha256; t=1582915306; cv=none; d=zohomail.com; s=zohoarc; b=npFG87PkZw5hPlfPr90PGT2EaSqLUsvgA7Oeks+TLftnlaSLuVlq0dl2QVSHv/aZVZEsOpNvsanEYaSGoc2WTjVDh+l4thhSKDp/y4WH6utfhOWTled/ZnOPF0sAVRQ0WvE/FaRjqd09GQPt+lcK1UiIcgyY3UvMj3OFf+vU9y4= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1582915306; h=Content-Type:Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:To; bh=5u8BeWpI2OJ1TTT+UipIRlwYYtz15/1XOaVS490Mrvc=; b=QH7FjDh/h3l8vaySDAgILRqS084JnNiWem91Eb9MnY/A8U3bVV5LGc70nw7uuBAWR6bg5rFPfwsU39tafccm8DTs0e3EWIli2Bal3Le9g0qAGpPuuDNuTW+TIGJZizhoidPTnSESwBqdwm8WguWrmOL8idC8comm5iLM3Ou4t1o= ARC-Authentication-Results: i=1; mx.zohomail.com; spf=none (zohomail.com: 192.237.175.120 is neither permitted nor denied by domain of lists.xenproject.org) smtp.mailfrom=xen-devel-bounces@lists.xenproject.org; dmarc=fail header.from= (p=none dis=none) header.from= Return-Path: Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) by mx.zohomail.com with SMTPS id 1582915306816165.1446784162614; Fri, 28 Feb 2020 10:41:46 -0800 (PST) Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1j7kZZ-0002rZ-6Z; Fri, 28 Feb 2020 18:41:17 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1j7kZY-0002rB-Bq for xen-devel@lists.xenproject.org; Fri, 28 Feb 2020 18:41:16 +0000 Received: from mga06.intel.com (unknown [134.134.136.31]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id e112f080-5a59-11ea-8e51-bc764e2007e4; Fri, 28 Feb 2020 18:41:06 +0000 (UTC) Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by orsmga104.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 28 Feb 2020 10:41:03 -0800 Received: from tlengyel-mobl2.amr.corp.intel.com (HELO localhost.localdomain) ([10.251.159.227]) by fmsmga005.fm.intel.com with ESMTP; 28 Feb 2020 10:41:02 -0800 X-Inumbo-ID: e112f080-5a59-11ea-8e51-bc764e2007e4 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,497,1574150400"; d="scan'208";a="437512259" From: Tamas K Lengyel To: xen-devel@lists.xenproject.org Date: Fri, 28 Feb 2020 10:40:52 -0800 Message-Id: X-Mailer: git-send-email 2.20.1 In-Reply-To: References: MIME-Version: 1.0 Subject: [Xen-devel] [PATCH v11 2/3] 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 , Andrew Cooper , Ian Jackson , George Dunlap , Stefano Stabellini , Jan Beulich , Julien Grall , =?UTF-8?q?Roger=20Pau=20Monn=C3=A9?= Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable 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 mo= re performant. Signed-off-by: Tamas K Lengyel --- v11: use copy_settings function to reset special pages --- xen/arch/x86/mm/mem_sharing.c | 115 ++++++++++++++++++++++++++++++++++ xen/include/public/memory.h | 4 ++ 2 files changed, 119 insertions(+) diff --git a/xen/arch/x86/mm/mem_sharing.c b/xen/arch/x86/mm/mem_sharing.c index 4a840d09dd..a458096b01 100644 --- a/xen/arch/x86/mm/mem_sharing.c +++ b/xen/arch/x86/mm/mem_sharing.c @@ -1775,6 +1775,91 @@ static int fork(struct domain *cd, struct domain *d) return rc; } =20 +/* + * The fork reset operation is intended to be used on short-lived forks on= ly. + */ +static int fork_reset(struct domain *d, struct domain *cd, + struct mem_sharing_op_fork_reset *fr) +{ + int rc =3D 0; + struct p2m_domain* p2m =3D p2m_get_hostp2m(cd); + struct page_info *page, *tmp; + unsigned long list_position =3D 0, preempt_count =3D 0, restart =3D fr= ->opaque; + + domain_pause(cd); + + page_list_for_each_safe(page, tmp, &cd->page_list) + { + p2m_type_t p2mt; + p2m_access_t p2ma; + gfn_t gfn; + mfn_t mfn; + bool shared =3D false; + + list_position++; + + /* Resume were we left of before preemption */ + if ( restart && list_position < restart ) + continue; + + mfn =3D page_to_mfn(page); + if ( mfn_valid(mfn) ) + { + + gfn =3D mfn_to_gfn(cd, mfn); + mfn =3D __get_gfn_type_access(p2m, gfn_x(gfn), &p2mt, &p2ma, + 0, NULL, false); + + if ( p2m_is_ram(p2mt) && !p2m_is_shared(p2mt) ) + { + /* take an extra reference, must work for a shared page */ + if( !get_page(page, cd) ) + { + ASSERT_UNREACHABLE(); + return -EINVAL; + } + + shared =3D true; + preempt_count +=3D 0x10; + + /* + * Must succeed, it's a shared page that exists and + * thus its size is guaranteed to be 4k so we are not spli= tting + * large pages. + */ + rc =3D p2m->set_entry(p2m, gfn, INVALID_MFN, PAGE_ORDER_4K, + p2m_invalid, p2m_access_rwx, -1); + ASSERT(!rc); + + put_page_alloc_ref(page); + put_page(page); + } + } + + if ( !shared ) + preempt_count++; + + /* Preempt every 2MiB (shared) or 32MiB (unshared) - arbitrary. */ + if ( preempt_count >=3D 0x2000 ) + { + if ( hypercall_preempt_check() ) + { + rc =3D -ERESTART; + break; + } + preempt_count =3D 0; + } + } + + if ( rc ) + fr->opaque =3D list_position; + else + rc =3D copy_settings(cd, d); + + domain_unpause(cd); + return rc; +} + int mem_sharing_memop(XEN_GUEST_HANDLE_PARAM(xen_mem_sharing_op_t) arg) { int rc; @@ -2066,6 +2151,36 @@ int mem_sharing_memop(XEN_GUEST_HANDLE_PARAM(xen_mem= _sharing_op_t) arg) break; } =20 + case XENMEM_sharing_op_fork_reset: + { + struct domain *pd; + + rc =3D -ENOSYS; + if ( !mem_sharing_is_fork(d) ) + goto out; + + rc =3D rcu_lock_live_remote_domain_by_id(d->parent->domain_id, &pd= ); + if ( rc ) + goto out; + + rc =3D fork_reset(pd, d, &mso.u.fork_reset); + + rcu_unlock_domain(pd); + + if ( rc > 0 ) + { + if ( __copy_to_guest(arg, &mso, 1) ) + rc =3D -EFAULT; + else + rc =3D hypercall_create_continuation(__HYPERVISOR_memory_o= p, + "lh", XENMEM_sharing_op, + arg); + } + else + mso.u.fork_reset.opaque =3D 0; + break; + } + default: rc =3D -ENOSYS; break; diff --git a/xen/include/public/memory.h b/xen/include/public/memory.h index c1dbad060e..7ca07c01dd 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 =20 #define XENMEM_SHARING_OP_S_HANDLE_INVALID (-10) #define XENMEM_SHARING_OP_C_HANDLE_INVALID (-9) @@ -537,6 +538,9 @@ struct xen_mem_sharing_op { domid_t parent_domain; /* IN: parent's domain id */ uint16_t _pad[3]; /* Must be set to 0 */ } fork; + struct mem_sharing_op_fork_reset { /* OP_FORK_RESET */ + uint64_aligned_t opaque; /* Must be set to 0 */ + } fork_reset; } u; }; typedef struct xen_mem_sharing_op xen_mem_sharing_op_t; --=20 2.20.1 _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel