From patchwork Fri Nov 7 00:40:43 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mario Smarduch X-Patchwork-Id: 5248971 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 C4C35C11AD for ; Fri, 7 Nov 2014 00:45:29 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 1B77F2010C for ; Fri, 7 Nov 2014 00:45:28 +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 681442012B for ; Fri, 7 Nov 2014 00:45:26 +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 1XmXdD-0003Rv-4K; Fri, 07 Nov 2014 00:42:27 +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 1XmXd8-0003JO-Re for linux-arm-kernel@lists.infradead.org; Fri, 07 Nov 2014 00:42:23 +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 <0NEN00H648M2B2B0@usmailout3.samsung.com> for linux-arm-kernel@lists.infradead.org; Thu, 06 Nov 2014 19:42:02 -0500 (EST) X-AuditID: cbfec37d-b7f3b6d000005695-da-545c15597bfe Received: from usmmp1.samsung.com ( [203.254.195.77]) by uscpsbgex4.samsung.com (USCPEXMTA) with SMTP id 19.15.22165.9551C545; Thu, 06 Nov 2014 19:42:02 -0500 (EST) Received: from sisasmtp.sisa.samsung.com ([105.144.21.116]) by usmmp1.samsung.com (Oracle Communications Messaging Server 7u4-27.01(7.0.4.27.0) 64bit (built Aug 30 2012)) with ESMTP id <0NEN00KO48M1ND80@usmmp1.samsung.com>; Thu, 06 Nov 2014 19:42:01 -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, 06 Nov 2014 16:42:01 -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 v13 2/7] KVM: Add generic support for dirty page logging Date: Thu, 06 Nov 2014 16:40:43 -0800 Message-id: <1415320848-13813-3-git-send-email-m.smarduch@samsung.com> X-Mailer: git-send-email 1.7.9.5 In-reply-to: <1415320848-13813-1-git-send-email-m.smarduch@samsung.com> References: <1415320848-13813-1-git-send-email-m.smarduch@samsung.com> MIME-version: 1.0 X-Originating-IP: [105.144.129.79] X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFmpkkeLIzCtJLcpLzFFi42I5/e+wr26UaEyIwcL9LBYnrvxjtJi+YjuL xftlPYwWL14DufObGxkt3s17wWzR/ayZ0eLNJ22LOVMLLT6eOs5usenxNVaLv3f+sVns3/aP 1WLOmQcsFpPebGNy4PdYM28No8fBR4fYPHp2nmH0uHNtD5vH+U1rmD02L6n3eL/vKpvH5tPV Hp83yQVwRnHZpKTmZJalFunbJXBlNP/vZSy4pFix/vNexgbGdukuRg4OCQETiU/v3boYOYFM MYkL99azdTFycQgJLGOU+P3kFCOE08sk8fF2B1TmIqPEn47pTCAtbAK6EvvvbWQHSYgIHGCU OLHxFxOIwyzwllFix8k/YFXCAh4Sbx40s4HYLAKqEvf+7WAD2c0r4CbR9qQE4gwFiTmTbEAq OAXcJTbv2MEMYgsBVdx9+IMVxOYVEJT4MfkeC0g5s4CExPPPShAlqhLbbj5nhPhASWLa4avs ExiFZiHpmIXQsYCRaRWjWGlxckFxUnpqhYlecWJucWleul5yfu4mRki01e5gvP/V5hCjAAej Eg/vDd6YECHWxLLiytxDjBIczEoivDbsQCHelMTKqtSi/Pii0pzU4kOMTBycUg2MMfqbXuue ufvbZN3p8/lc0vdt5zbLPPnRNC3HoL/VzdWj8vdacY6OyJLPKpk3HpZetpN44PfH+g+P8eWv 8ZubvjZM7pizm2PFV2eltPeyx2tu9Gwribu42qLostKUre5dv886/TJ5vm5Cn9ifiVvjVwpd YtjCWug251zhIfu9F+8t2Pg6wezgZyWW4oxEQy3mouJEAM7coyqUAgAA X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20141106_164223_052571_1490EE5E X-CRM114-Status: GOOD ( 14.80 ) X-Spam-Score: -5.6 (-----) 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=-2.5 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_NONE, 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 --- include/linux/kvm_host.h | 9 +++++ virt/kvm/kvm_main.c | 95 ++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 104 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/kvm_main.c b/virt/kvm/kvm_main.c index 887df87..f017760 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -981,6 +981,101 @@ out: } EXPORT_SYMBOL_GPL(kvm_get_dirty_log); +#if defined(CONFIG_S390) || defined(CONFIG_PPC) || defined(CONFIG_MIPS) || \ + defined(CONFIG_IA64) || defined(CONFIG_X86) || defined(CONFIG_ARM) || \ + defined(CONFIG_ARM64) +/* + * For architectures that don't use kvm_get_dirty_log_protect() for dirty page + * logging, calling this function is illegal. Otherwise the function is defined + * in arch subtree and this restriction is removed. + */ +void kvm_arch_mmu_write_protect_pt_masked(struct kvm *kvm, + struct kvm_memory_slot *slot, + gfn_t gfn_offset, + unsigned long mask) +{ + BUG(); +} +#endif + +/** + * 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); + bool kvm_largepages_enabled(void) { return largepages_enabled;