From patchwork Mon May 13 14:38:21 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexandre Chartre X-Patchwork-Id: 10941075 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 68D946C5 for ; Mon, 13 May 2019 14:40:04 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 58E0427BA5 for ; Mon, 13 May 2019 14:40:04 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 4C9D927FA1; Mon, 13 May 2019 14:40:04 +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=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 E0F0D27BA5 for ; Mon, 13 May 2019 14:40:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730514AbfEMOkC (ORCPT ); Mon, 13 May 2019 10:40:02 -0400 Received: from aserp2130.oracle.com ([141.146.126.79]:37302 "EHLO aserp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730447AbfEMOkC (ORCPT ); Mon, 13 May 2019 10:40:02 -0400 Received: from pps.filterd (aserp2130.oracle.com [127.0.0.1]) by aserp2130.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x4DEd3jQ193102; Mon, 13 May 2019 14:39:24 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=from : to : cc : subject : date : message-id : in-reply-to : references; s=corp-2018-07-02; bh=5Qtz3s/XQzDItLwgII6a7yqyolD8+y7jKItUNNZ5jHw=; b=bc0UAXJuEUDdxvyu9LwCdXHqD4qh6pNojWMqcM9jSLBAxGM6igASeeKPL3IWePb5ch0s fbCFf/kSYwqFzCOuWD0pbNuB78gAyLFK5Ed4veTVvUvCkVI2DR43VeRRk0g9ufQAr0sw e6QhuGNeEnywPiXsoWdU2luDBNsmNNUqdcfqgUJyVy51fsmTOMsXHwAuC4cslhey/L9A UYFWoKFzlhctdRm9y9d9iC7Djqvsf9+FCNhU/NbXFxMpjmDvfMOaaoR1Y5lpKRNKz4fW VMMMFGBaxysR4n+y/P893dNcj5PpeJwOEyHs1Tnsryx4DvPOgcmS7i7F6ug4vAd8pZZL 3A== Received: from aserv0022.oracle.com (aserv0022.oracle.com [141.146.126.234]) by aserp2130.oracle.com with ESMTP id 2sdkwdfkxg-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 13 May 2019 14:39:24 +0000 Received: from achartre-desktop.fr.oracle.com (dhcp-10-166-106-34.fr.oracle.com [10.166.106.34]) by aserv0022.oracle.com (8.14.4/8.14.4) with ESMTP id x4DEcZQG022780; Mon, 13 May 2019 14:39:16 GMT From: Alexandre Chartre To: pbonzini@redhat.com, rkrcmar@redhat.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, hpa@zytor.com, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, kvm@vger.kernel.org, x86@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: konrad.wilk@oracle.com, jan.setjeeilers@oracle.com, liran.alon@oracle.com, jwadams@google.com, alexandre.chartre@oracle.com Subject: [RFC KVM 13/27] kvm/isolation: add KVM page table entry set functions Date: Mon, 13 May 2019 16:38:21 +0200 Message-Id: <1557758315-12667-14-git-send-email-alexandre.chartre@oracle.com> X-Mailer: git-send-email 1.7.1 In-Reply-To: <1557758315-12667-1-git-send-email-alexandre.chartre@oracle.com> References: <1557758315-12667-1-git-send-email-alexandre.chartre@oracle.com> X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9255 signatures=668686 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=2 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1905130103 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Add wrappers around the page table entry (pgd/p4d/pud/pmd) set function to check that an existing entry is not being overwritten. Signed-off-by: Alexandre Chartre --- arch/x86/kvm/isolation.c | 107 ++++++++++++++++++++++++++++++++++++++++++++++ 1 files changed, 107 insertions(+), 0 deletions(-) diff --git a/arch/x86/kvm/isolation.c b/arch/x86/kvm/isolation.c index 6ec86df..b681e4f 100644 --- a/arch/x86/kvm/isolation.c +++ b/arch/x86/kvm/isolation.c @@ -342,6 +342,113 @@ static inline void kvm_p4d_free(struct mm_struct *mm, p4d_t *p4d) return p4d; } +/* + * kvm_set_pXX() functions are equivalent to kernel set_pXX() functions + * but, in addition, they ensure that they are not overwriting an already + * existing reference in the page table. Otherwise an error is returned. + * + * Note that this is not used for PTE because a PTE entry points to page + * frames containing the actual user data, and not to another entry in the + * page table. However this is used for PGD. + */ + +static int kvm_set_pmd(pmd_t *pmd, pmd_t pmd_value) +{ +#ifdef DEBUG + /* + * The pmd pointer should come from kvm_pmd_alloc() or kvm_pmd_offset() + * both of which check if the pointer is in the KVM page table. So this + * is a paranoid check to ensure the pointer is really in the KVM page + * table. + */ + if (!kvm_valid_pgt_entry(pmd)) { + pr_err("PMD %px is not in KVM page table\n", pmd); + return -EINVAL; + } +#endif + if (pmd_val(*pmd) == pmd_val(pmd_value)) + return 0; + + if (!pmd_none(*pmd)) { + pr_err("PMD %px: overwriting %lx with %lx\n", + pmd, pmd_val(*pmd), pmd_val(pmd_value)); + return -EBUSY; + } + + set_pmd(pmd, pmd_value); + + return 0; +} + +static int kvm_set_pud(pud_t *pud, pud_t pud_value) +{ +#ifdef DEBUG + /* + * The pud pointer should come from kvm_pud_alloc() or kvm_pud_offset() + * both of which check if the pointer is in the KVM page table. So this + * is a paranoid check to ensure the pointer is really in the KVM page + * table. + */ + if (!kvm_valid_pgt_entry(pud)) { + pr_err("PUD %px is not in KVM page table\n", pud); + return -EINVAL; + } +#endif + if (pud_val(*pud) == pud_val(pud_value)) + return 0; + + if (!pud_none(*pud)) { + pr_err("PUD %px: overwriting %lx\n", pud, pud_val(*pud)); + return -EBUSY; + } + + set_pud(pud, pud_value); + + return 0; +} + +static int kvm_set_p4d(p4d_t *p4d, p4d_t p4d_value) +{ +#ifdef DEBUG + /* + * The p4d pointer should come from kvm_p4d_alloc() or kvm_p4d_offset() + * both of which check if the pointer is in the KVM page table. So this + * is a paranoid check to ensure the pointer is really in the KVM page + * table. + */ + if (!kvm_valid_pgt_entry(p4d)) { + pr_err("P4D %px is not in KVM page table\n", p4d); + return -EINVAL; + } +#endif + if (p4d_val(*p4d) == p4d_val(p4d_value)) + return 0; + + if (!p4d_none(*p4d)) { + pr_err("P4D %px: overwriting %lx\n", p4d, p4d_val(*p4d)); + return -EBUSY; + } + + set_p4d(p4d, p4d_value); + + return 0; +} + +static int kvm_set_pgd(pgd_t *pgd, pgd_t pgd_value) +{ + if (pgd_val(*pgd) == pgd_val(pgd_value)) + return 0; + + if (!pgd_none(*pgd)) { + pr_err("PGD %px: overwriting %lx\n", pgd, pgd_val(*pgd)); + return -EBUSY; + } + + set_pgd(pgd, pgd_value); + + return 0; +} + static int kvm_isolation_init_mm(void) {