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Fri, 3 Jun 2022 06:56:48 +0000 (GMT) Received: from p-imbrenda.boeblingen.de.ibm.com (unknown [9.152.224.40]) by d06av24.portsmouth.uk.ibm.com (Postfix) with ESMTP; Fri, 3 Jun 2022 06:56:48 +0000 (GMT) From: Claudio Imbrenda To: kvm@vger.kernel.org Cc: borntraeger@de.ibm.com, frankja@linux.ibm.com, thuth@redhat.com, pasic@linux.ibm.com, david@redhat.com, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, scgl@linux.ibm.com, mimu@linux.ibm.com, nrb@linux.ibm.com Subject: [PATCH v11 06/19] KVM: s390: pv: add export before import Date: Fri, 3 Jun 2022 08:56:32 +0200 Message-Id: <20220603065645.10019-7-imbrenda@linux.ibm.com> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220603065645.10019-1-imbrenda@linux.ibm.com> References: <20220603065645.10019-1-imbrenda@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: CICVuQ9Wdk18P0CLtsfkCXDPB8uH0yFd X-Proofpoint-GUID: FNinhakI6-7pX8py-Pb2q_QZJbW94dwU X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.874,Hydra:6.0.517,FMLib:17.11.64.514 definitions=2022-06-03_02,2022-06-02_01,2022-02-23_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 lowpriorityscore=0 suspectscore=0 mlxlogscore=999 priorityscore=1501 malwarescore=0 phishscore=0 adultscore=0 spamscore=0 clxscore=1015 bulkscore=0 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2204290000 definitions=main-2206030027 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Due to upcoming changes, it will be possible to temporarily have multiple protected VMs in the same address space, although only one will be actually active. In that scenario, it is necessary to perform an export of every page that is to be imported, since the hardware does not allow a page belonging to a protected guest to be imported into a different protected guest. This also applies to pages that are shared, and thus accessible by the host. Signed-off-by: Claudio Imbrenda Reviewed-by: Janosch Frank --- arch/s390/kernel/uv.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c index 2754471cc789..02aca3c5dce1 100644 --- a/arch/s390/kernel/uv.c +++ b/arch/s390/kernel/uv.c @@ -234,6 +234,26 @@ static int make_secure_pte(pte_t *ptep, unsigned long addr, return uvcb->rc == 0x10a ? -ENXIO : -EINVAL; } +/** + * should_export_before_import - Determine whether an export is needed + * before an import-like operation + * @uvcb the Ultravisor control block of the UVC to be performed + * @mm the mm of the process + * + * Although considered as one, the Unpin Page UVC is not an actual import, + * so it is not affected. + * + * No export is needed also when there is only one protected VM, because the + * page cannot belong to the wrong VM in that case (there is no "other VM" + * it can belong to). + */ +static bool should_export_before_import(struct uv_cb_header *uvcb, struct mm_struct *mm) +{ + if (uvcb->cmd == UVC_CMD_UNPIN_PAGE_SHARED) + return false; + return atomic_read(&mm->context.protected_count) > 1; +} + /* * Requests the Ultravisor to make a page accessible to a guest. * If it's brought in the first time, it will be cleared. If @@ -277,6 +297,8 @@ int gmap_make_secure(struct gmap *gmap, unsigned long gaddr, void *uvcb) lock_page(page); ptep = get_locked_pte(gmap->mm, uaddr, &ptelock); + if (should_export_before_import(uvcb, gmap->mm)) + uv_convert_from_secure(page_to_phys(page)); rc = make_secure_pte(ptep, uaddr, page, uvcb); pte_unmap_unlock(ptep, ptelock); unlock_page(page);