From patchwork Fri Nov 14 01:57:43 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mario Smarduch X-Patchwork-Id: 5302561 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 801E3C11AC for ; Fri, 14 Nov 2014 02:01:04 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 9224D20125 for ; Fri, 14 Nov 2014 02:01:03 +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 8CC9220121 for ; Fri, 14 Nov 2014 02:01:02 +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 1Xp6AR-0001VJ-RF; Fri, 14 Nov 2014 01:59:19 +0000 Received: from mailout4.w2.samsung.com ([211.189.100.14] helo=usmailout4.samsung.com) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1Xp6AO-0001Lw-Nr for linux-arm-kernel@lists.infradead.org; Fri, 14 Nov 2014 01:59:17 +0000 Received: from uscpsbgex4.samsung.com (u125.gpu85.samsung.co.kr [203.254.195.125]) by usmailout4.samsung.com (Oracle Communications Messaging Server 7u4-24.01(7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTP id <0NF0009PVAU8PO90@usmailout4.samsung.com> for linux-arm-kernel@lists.infradead.org; Thu, 13 Nov 2014 20:58:56 -0500 (EST) X-AuditID: cbfec37d-b7f3b6d000005695-b9-546561df6503 Received: from usmmp2.samsung.com ( [203.254.195.78]) by uscpsbgex4.samsung.com (USCPEXMTA) with SMTP id C8.38.22165.FD165645; Thu, 13 Nov 2014 20:58:55 -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 <0NF0007XXAU71V40@usmmp2.samsung.com>; Thu, 13 Nov 2014 20:58:55 -0500 (EST) Received: from mjsmard-530U3C-530U4C-532U3C.sisa.samsung.com (105.144.129.79) by SISAEX02SJ.sisa.samsung.com (105.144.21.116) with Microsoft SMTP Server (TLS) id 14.3.123.3; Thu, 13 Nov 2014 17:58:55 -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 v14 2/7] KVM: Add generic support for dirty page logging Date: Thu, 13 Nov 2014 17:57:43 -0800 Message-id: <1415930268-7674-3-git-send-email-m.smarduch@samsung.com> X-Mailer: git-send-email 1.7.9.5 In-reply-to: <1415930268-7674-1-git-send-email-m.smarduch@samsung.com> References: <1415930268-7674-1-git-send-email-m.smarduch@samsung.com> MIME-version: 1.0 X-Originating-IP: [105.144.129.79] X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFmpkkeLIzCtJLcpLzFFi42I5/e+wn+79xNQQg40PbCxOXPnHaDF9xXYW i/fLehgtXrwGcuc3NzJavJv3gtmi+1kzo8WbT9oWc6YWWnw8dZzdYtPja6wWf+/8Y7PYv+0f q8WcMw9YLCa92cbkwO+xZt4aRo+Djw6xefTsPMPocefaHjaP85vWMHtsXlLv8X7fVTaPzaer PT5vkgvgjOKySUnNySxLLdK3S+DKePHuK3vBJoWKDbO2szYw/pXsYuTkkBAwkTi68DcjhC0m ceHeerYuRi4OIYFljBLnd+xmgXB6mST2/b7JBFIlJHCRUeLUFHcQm01AV2L/vY3sIEUiAgcY JU5s/MUE4jALvGWU2HHyD1iHsICHxLYNT9hAbBYBVYkD/cfBbF4BV4nlJ5uBdnMA7VaQmDPJ BsTkFHCTaH0pDrHLVWLSoemMENWCEj8m32MBKWEWkJB4/lkJokRVYtvN51APKElMO3yVfQKj 0CwkHbMQOhYwMq1iFCstTi4oTkpPrTDRK07MLS7NS9dLzs/dxAiJttodjPe/2hxiFOBgVOLh XeGcGiLEmlhWXJl7iFGCg1lJhPdQJFCINyWxsiq1KD++qDQntfgQIxMHp1QDo6rmKk7bfPc+ AUvhB/77toWlT9rpmLNZZtuVR0srr+yYK9kSaPPYZKPhe9ME1tMZrr88ZDoYWvPl9/6s8BF4 rqPYcnyZm9LaafxbCvgOn/N/dNNWdrbM8lLl9Xu+c80WunLP2+HArc7oD3bBqr4GhwSc/n4o XcSmu1rB0Wf+5WMRu387To08rMRSnJFoqMVcVJwIANwuEVSUAgAA X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20141113_175916_956882_3DD48505 X-CRM114-Status: GOOD ( 14.63 ) X-Spam-Score: -6.0 (------) 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=-3.6 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_LOW, 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. Signed-off-by: Mario Smarduch Reviewed-by: Christoffer Dall --- 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 a4c33b3..c55dd75 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -590,6 +590,15 @@ 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 887df87..f50909c 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -981,6 +981,86 @@ 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;