From patchwork Mon Dec 15 07:27:59 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mario Smarduch X-Patchwork-Id: 5491131 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id DF4B19F326 for ; Mon, 15 Dec 2014 07:31:13 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id F0214209EB for ; Mon, 15 Dec 2014 07:31:12 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 07717209EA for ; Mon, 15 Dec 2014 07:31:12 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1Y0Q5j-0004qY-3H; Mon, 15 Dec 2014 07:29:15 +0000 Received: from mailout3.w2.samsung.com ([211.189.100.13] helo=usmailout3.samsung.com) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1Y0Q5V-0004hx-18 for linux-arm-kernel@lists.infradead.org; Mon, 15 Dec 2014 07:29:01 +0000 Received: from uscpsbgex4.samsung.com (u125.gpu85.samsung.co.kr [203.254.195.125]) by usmailout3.samsung.com (Oracle Communications Messaging Server 7u4-24.01(7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTP id <0NGM001OM4SCUQ00@usmailout3.samsung.com> for linux-arm-kernel@lists.infradead.org; Mon, 15 Dec 2014 02:29:00 -0500 (EST) X-AuditID: cbfec37d-b7f346d000007c38-17-548e8dbced13 Received: from usmmp2.samsung.com ( [203.254.195.78]) by uscpsbgex4.samsung.com (USCPEXMTA) with SMTP id A0.49.31800.CBD8E845; Mon, 15 Dec 2014 02:29:00 -0500 (EST) Received: from sisasmtp.sisa.samsung.com ([105.144.21.116]) by usmmp2.samsung.com (Oracle Communications Messaging Server 7u4-27.01(7.0.4.27.0) 64bit (built Aug 30 2012)) with ESMTP id <0NGM00JJK4SC9950@usmmp2.samsung.com>; Mon, 15 Dec 2014 02:29:00 -0500 (EST) Received: from mjsmard-530U3C-530U4C-532U3C.sisa.samsung.com (105.160.8.49) by SISAEX02SJ.sisa.samsung.com (105.144.21.116) with Microsoft SMTP Server (TLS) id 14.3.123.3; Sun, 14 Dec 2014 23:28:59 -0800 From: Mario Smarduch To: pbonzini@redhat.com, james.hogan@imgtec.com, christoffer.dall@linaro.org, agraf@suse.de, marc.zyngier@arm.com, cornelia.huck@de.ibm.com, borntraeger@de.ibm.com, catalin.marinas@arm.com Subject: [PATCH v15 02/11] KVM: Add generic support for dirty page logging Date: Sun, 14 Dec 2014 23:27:59 -0800 Message-id: <1418628488-3696-3-git-send-email-m.smarduch@samsung.com> X-Mailer: git-send-email 1.7.9.5 In-reply-to: <1418628488-3696-1-git-send-email-m.smarduch@samsung.com> References: <1418628488-3696-1-git-send-email-m.smarduch@samsung.com> MIME-version: 1.0 X-Originating-IP: [105.160.8.49] X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFmpkkeLIzCtJLcpLzFFi42I5/e+wn+6e3r4Qg/7J6hYnrvxjtJi+YjuL xftlPYwWL14DufObGxkt3s17wWzR/ayZ0eLNJ22LOVMLLT6eOs5usenxNVaLv3f+sVns3/aP 1WLOmQcsFpPebGNy4PdYM28No8fBR4fYPHp2nmH0uHNtD5vH+U1rmD02L6n3eL/vKpvH5tPV Hp83yQVwRnHZpKTmZJalFunbJXBl/D9wh6nglUJF88429gbG7VJdjJwcEgImEm/urGOFsMUk Ltxbz9bFyMUhJLCMUeL0851QTi+TxPV5CxkhnPOMEm+XHWUCaWET0JXYf28jO0hCROAAo8SJ jb+YQBxmgbeMEjtO/gGrEhbwkpjxah4ziM0ioCpx6V8PC4jNK+AqsWLxNaAaDqDlChJzJtmA mJwCbhJ7dyuDVAgBVfzdcJ8JolpQ4sfkeywgJcwCEhLPPytBlKhKbLv5nBFmyMYFPhMYhWYh aZiF0LCAkWkVo1hpcXJBcVJ6aoWJXnFibnFpXrpecn7uJkZItNXuYLz/1eYQowAHoxIPbwRj X4gQa2JZcWXuIUYJDmYlEd7ueKAQb0piZVVqUX58UWlOavEhRiYOTqkGxl0tpZ/+Xsm15Du2 6+K6qkNyNsJPL7htNflxSyxEe4ZXitLRRwIHOp7o6heXzJvweaXCDrMIHr6DyelVXx4ymMfH aFzYY5Nww1SLl9Oyjc/+t8ikqMVaMcdMRExb06cEak48dDTvM3+ZF4fNQ+nZuXMOndbSa8nr W6PRmp5/5fyJdy8v72+TVWIpzkg01GIuKk4EACHmuPSUAgAA X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20141214_232901_173163_7578E174 X-CRM114-Status: GOOD ( 14.18 ) X-Spam-Score: -5.0 (-----) Cc: peter.maydell@linaro.org, kvm@vger.kernel.org, steve.capper@arm.com, kvm-ia64@vger.kernel.org, kvm-ppc@vger.kernel.org, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, Mario Smarduch X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP kvm_get_dirty_log() provides generic handling of dirty bitmap, currently reused by several architectures. Building on that we intrdoduce kvm_get_dirty_log_protect() adding write protection to mark these pages dirty for future write access, before next KVM_GET_DIRTY_LOG ioctl call from user space. Reviewed-by: Christoffer Dall Signed-off-by: Mario Smarduch --- include/linux/kvm_host.h | 9 ++++++ virt/kvm/Kconfig | 6 ++++ virt/kvm/kvm_main.c | 80 ++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 95 insertions(+) diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index e4d8f70..ed29e79 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -602,6 +602,15 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext); int kvm_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log, int *is_dirty); + +int kvm_get_dirty_log_protect(struct kvm *kvm, + struct kvm_dirty_log *log, bool *is_dirty); + +void kvm_arch_mmu_write_protect_pt_masked(struct kvm *kvm, + struct kvm_memory_slot *slot, + gfn_t gfn_offset, + unsigned long mask); + int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log); diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig index 3796a21..314950c 100644 --- a/virt/kvm/Kconfig +++ b/virt/kvm/Kconfig @@ -40,3 +40,9 @@ config KVM_VFIO config HAVE_KVM_ARCH_TLB_FLUSH_ALL bool + +config HAVE_KVM_ARCH_DIRTY_LOG_PROTECT + bool + +config KVM_GENERIC_DIRTYLOG_READ_PROTECT + bool diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 51e9dfa..55a16b2 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1001,6 +1001,86 @@ out: } EXPORT_SYMBOL_GPL(kvm_get_dirty_log); +#ifdef CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT +/** + * kvm_get_dirty_log_protect - get a snapshot of dirty pages, and if any pages + * are dirty write protect them for next write. + * @kvm: pointer to kvm instance + * @log: slot id and address to which we copy the log + * @is_dirty: flag set if any page is dirty + * + * We need to keep it in mind that VCPU threads can write to the bitmap + * concurrently. So, to avoid losing track of dirty pages we keep the + * following order: + * + * 1. Take a snapshot of the bit and clear it if needed. + * 2. Write protect the corresponding page. + * 3. Copy the snapshot to the userspace. + * 4. Upon return caller flushes TLB's if needed. + * + * Between 2 and 4, the guest may write to the page using the remaining TLB + * entry. This is not a problem because the page is reported dirty using + * the snapshot taken before and step 4 ensures that writes done after + * exiting to userspace will be logged for the next call. + * + */ +int kvm_get_dirty_log_protect(struct kvm *kvm, + struct kvm_dirty_log *log, bool *is_dirty) +{ + struct kvm_memory_slot *memslot; + int r, i; + unsigned long n; + unsigned long *dirty_bitmap; + unsigned long *dirty_bitmap_buffer; + + r = -EINVAL; + if (log->slot >= KVM_USER_MEM_SLOTS) + goto out; + + memslot = id_to_memslot(kvm->memslots, log->slot); + + dirty_bitmap = memslot->dirty_bitmap; + r = -ENOENT; + if (!dirty_bitmap) + goto out; + + n = kvm_dirty_bitmap_bytes(memslot); + + dirty_bitmap_buffer = dirty_bitmap + n / sizeof(long); + memset(dirty_bitmap_buffer, 0, n); + + spin_lock(&kvm->mmu_lock); + *is_dirty = false; + for (i = 0; i < n / sizeof(long); i++) { + unsigned long mask; + gfn_t offset; + + if (!dirty_bitmap[i]) + continue; + + *is_dirty = true; + + mask = xchg(&dirty_bitmap[i], 0); + dirty_bitmap_buffer[i] = mask; + + offset = i * BITS_PER_LONG; + kvm_arch_mmu_write_protect_pt_masked(kvm, memslot, offset, + mask); + } + + spin_unlock(&kvm->mmu_lock); + + r = -EFAULT; + if (copy_to_user(log->dirty_bitmap, dirty_bitmap_buffer, n)) + goto out; + + r = 0; +out: + return r; +} +EXPORT_SYMBOL_GPL(kvm_get_dirty_log_protect); +#endif + bool kvm_largepages_enabled(void) { return largepages_enabled;