From patchwork Fri Aug 9 15:59:59 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Adalbert_Laz=C4=83r?= X-Patchwork-Id: 11087045 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D1A2B112C for ; Fri, 9 Aug 2019 16:15:28 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C0888202A5 for ; Fri, 9 Aug 2019 16:15:28 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id B4BCA2022B; Fri, 9 Aug 2019 16:15:28 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4864C1FF28 for ; Fri, 9 Aug 2019 16:15:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2437207AbfHIQPM (ORCPT ); Fri, 9 Aug 2019 12:15:12 -0400 Received: from mx01.bbu.dsd.mx.bitdefender.com ([91.199.104.161]:52908 "EHLO mx01.bbu.dsd.mx.bitdefender.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2437119AbfHIQPI (ORCPT ); Fri, 9 Aug 2019 12:15:08 -0400 Received: from smtp.bitdefender.com (smtp02.buh.bitdefender.net [10.17.80.76]) by mx01.bbu.dsd.mx.bitdefender.com (Postfix) with ESMTPS id DC82D305D345; Fri, 9 Aug 2019 19:01:15 +0300 (EEST) Received: from localhost.localdomain (unknown [89.136.169.210]) by smtp.bitdefender.com (Postfix) with ESMTPSA id 7EF77305B7A1; Fri, 9 Aug 2019 19:01:14 +0300 (EEST) From: =?utf-8?q?Adalbert_Laz=C4=83r?= To: kvm@vger.kernel.org Cc: linux-mm@kvack.org, virtualization@lists.linux-foundation.org, Paolo Bonzini , =?utf-8?b?UmFkaW0gS3LEjW3DocWZ?= , Konrad Rzeszutek Wilk , Tamas K Lengyel , Mathieu Tarral , =?utf-8?q?Samuel_Laur=C3=A9?= =?utf-8?q?n?= , Patrick Colp , Jan Kiszka , Stefan Hajnoczi , Weijiang Yang , Zhang@vger.kernel.org, Yu C , =?utf-8?q?Mihai_Don=C8=9Bu?= , =?utf-8?q?Adalbert_L?= =?utf-8?q?az=C4=83r?= Subject: [RFC PATCH v6 44/92] kvm: introspection: extend the internal database of tracked pages with write_bitmap info Date: Fri, 9 Aug 2019 18:59:59 +0300 Message-Id: <20190809160047.8319-45-alazar@bitdefender.com> In-Reply-To: <20190809160047.8319-1-alazar@bitdefender.com> References: <20190809160047.8319-1-alazar@bitdefender.com> MIME-Version: 1.0 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP This will allow us to use the subpage protection feature. Signed-off-by: Adalbert Lazăr --- virt/kvm/kvmi.c | 46 +++++++++++++++++++++++++++++++++++++-------- virt/kvm/kvmi_int.h | 1 + 2 files changed, 39 insertions(+), 8 deletions(-) diff --git a/virt/kvm/kvmi.c b/virt/kvm/kvmi.c index 4a9a4430a460..e18dfffa25ac 100644 --- a/virt/kvm/kvmi.c +++ b/virt/kvm/kvmi.c @@ -32,6 +32,7 @@ static void kvmi_track_flush_slot(struct kvm *kvm, struct kvm_memory_slot *slot, static const u8 full_access = KVMI_PAGE_ACCESS_R | KVMI_PAGE_ACCESS_W | KVMI_PAGE_ACCESS_X; +static const u32 default_write_access_bitmap; void *kvmi_msg_alloc(void) { @@ -57,23 +58,32 @@ static struct kvmi_mem_access *__kvmi_get_gfn_access(struct kvmi *ikvm, return radix_tree_lookup(&ikvm->access_tree, gfn); } +/* + * TODO: intercept any SPP change made on pages present in our radix tree. + * + * bitmap must have the same value as the corresponding SPPT entry. + */ static int kvmi_get_gfn_access(struct kvmi *ikvm, const gfn_t gfn, - u8 *access) + u8 *access, u32 *write_bitmap) { struct kvmi_mem_access *m; + *write_bitmap = default_write_access_bitmap; *access = full_access; read_lock(&ikvm->access_tree_lock); m = __kvmi_get_gfn_access(ikvm, gfn); - if (m) + if (m) { *access = m->access; + *write_bitmap = m->write_bitmap; + } read_unlock(&ikvm->access_tree_lock); return m ? 0 : -1; } -static int kvmi_set_gfn_access(struct kvm *kvm, gfn_t gfn, u8 access) +static int kvmi_set_gfn_access(struct kvm *kvm, gfn_t gfn, u8 access, + u32 write_bitmap) { struct kvmi_mem_access *m; struct kvmi_mem_access *__m; @@ -87,6 +97,7 @@ static int kvmi_set_gfn_access(struct kvm *kvm, gfn_t gfn, u8 access) m->gfn = gfn; m->access = access; + m->write_bitmap = write_bitmap; if (radix_tree_preload(GFP_KERNEL)) { err = -KVM_ENOMEM; @@ -100,6 +111,7 @@ static int kvmi_set_gfn_access(struct kvm *kvm, gfn_t gfn, u8 access) __m = __kvmi_get_gfn_access(ikvm, gfn); if (__m) { __m->access = access; + __m->write_bitmap = write_bitmap; kvmi_arch_update_page_tracking(kvm, NULL, __m); if (access == full_access) { radix_tree_delete(&ikvm->access_tree, gfn); @@ -124,12 +136,22 @@ static int kvmi_set_gfn_access(struct kvm *kvm, gfn_t gfn, u8 access) return err; } +static bool spp_access_allowed(gpa_t gpa, unsigned long bitmap) +{ + u32 off = (gpa & ~PAGE_MASK); + u32 spp = off / 128; + + return test_bit(spp, &bitmap); +} + static bool kvmi_restricted_access(struct kvmi *ikvm, gpa_t gpa, u8 access) { + u32 allowed_bitmap; u8 allowed_access; int err; - err = kvmi_get_gfn_access(ikvm, gpa_to_gfn(gpa), &allowed_access); + err = kvmi_get_gfn_access(ikvm, gpa_to_gfn(gpa), &allowed_access, + &allowed_bitmap); if (err) return false; @@ -138,8 +160,14 @@ static bool kvmi_restricted_access(struct kvmi *ikvm, gpa_t gpa, u8 access) * We want to be notified only for violations involving access * bits that we've specifically cleared */ - if ((~allowed_access) & access) + if ((~allowed_access) & access) { + bool write_access = (access & KVMI_PAGE_ACCESS_W); + + if (write_access && spp_access_allowed(gpa, allowed_bitmap)) + return false; + return true; + } return false; } @@ -1126,8 +1154,9 @@ void kvmi_handle_requests(struct kvm_vcpu *vcpu) int kvmi_cmd_get_page_access(struct kvmi *ikvm, u64 gpa, u8 *access) { gfn_t gfn = gpa_to_gfn(gpa); + u32 ignored_write_bitmap; - kvmi_get_gfn_access(ikvm, gfn, access); + kvmi_get_gfn_access(ikvm, gfn, access, &ignored_write_bitmap); return 0; } @@ -1136,10 +1165,11 @@ int kvmi_cmd_set_page_access(struct kvmi *ikvm, u64 gpa, u8 access) { gfn_t gfn = gpa_to_gfn(gpa); u8 ignored_access; + u32 write_bitmap; - kvmi_get_gfn_access(ikvm, gfn, &ignored_access); + kvmi_get_gfn_access(ikvm, gfn, &ignored_access, &write_bitmap); - return kvmi_set_gfn_access(ikvm->kvm, gfn, access); + return kvmi_set_gfn_access(ikvm->kvm, gfn, access, write_bitmap); } int kvmi_cmd_control_events(struct kvm_vcpu *vcpu, unsigned int event_id, diff --git a/virt/kvm/kvmi_int.h b/virt/kvm/kvmi_int.h index 3f0c7a03b4a1..d9a10a3b7082 100644 --- a/virt/kvm/kvmi_int.h +++ b/virt/kvm/kvmi_int.h @@ -141,6 +141,7 @@ struct kvmi { struct kvmi_mem_access { gfn_t gfn; u8 access; + u32 write_bitmap; struct kvmi_arch_mem_access arch; };