From patchwork Tue Jun 3 23:19:26 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mario Smarduch X-Patchwork-Id: 4291701 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 BCE059F326 for ; Tue, 3 Jun 2014 23:22:28 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 8F4B020260 for ; Tue, 3 Jun 2014 23:22:27 +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 605AF2012F for ; Tue, 3 Jun 2014 23:22:26 +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 1Wry09-000807-GZ; Tue, 03 Jun 2014 23:20:17 +0000 Received: from mailout1.w2.samsung.com ([211.189.100.11] helo=usmailout1.samsung.com) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1Wrxzp-0006ne-20 for linux-arm-kernel@lists.infradead.org; Tue, 03 Jun 2014 23:19:58 +0000 Received: from uscpsbgex2.samsung.com (u123.gpu85.samsung.co.kr [203.254.195.123]) by mailout1.w2.samsung.com (Oracle Communications Messaging Server 7u4-24.01(7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTP id <0N6M00GJB8SL0R00@mailout1.w2.samsung.com> for linux-arm-kernel@lists.infradead.org; Tue, 03 Jun 2014 19:19:34 -0400 (EDT) X-AuditID: cbfec37b-b7fbe6d000006742-a6-538e5805c91e Received: from usmmp1.samsung.com ( [203.254.195.77]) by uscpsbgex2.samsung.com (USCPEXMTA) with SMTP id FD.42.26434.5085E835; Tue, 03 Jun 2014 19:19:33 -0400 (EDT) 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 <0N6M00AGG8SLCEC0@usmmp1.samsung.com>; Tue, 03 Jun 2014 19:19:33 -0400 (EDT) Received: from mjsmard-530U3C-530U4C-532U3C.sisa.samsung.com (105.144.129.76) by SISAEX02SJ.sisa.samsung.com (105.144.21.116) with Microsoft SMTP Server (TLS) id 14.1.421.2; Tue, 03 Jun 2014 16:19:32 -0700 From: Mario Smarduch To: kvmarm@lists.cs.columbia.edu, christoffer.dall@linaro.org, marc.zyngier@arm.com Subject: [PATCH v7 3/4] arm: dirty log write protect management support Date: Tue, 03 Jun 2014 16:19:26 -0700 Message-id: <1401837567-5527-4-git-send-email-m.smarduch@samsung.com> X-Mailer: git-send-email 1.7.9.5 In-reply-to: <1401837567-5527-1-git-send-email-m.smarduch@samsung.com> References: <1401837567-5527-1-git-send-email-m.smarduch@samsung.com> MIME-version: 1.0 X-Originating-IP: [105.144.129.76] X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFrrHLMWRmVeSWpSXmKPExsVy+t9hX13WiL5gg7WrjS1evP7HaNH7/yKr xf2r3xkt5kwttPh46ji7xabH11gt/t75x2Yx58wDFotJb7YxWXyYsZLRgctjzbw1jB6zGnrZ PO5c28PmcX7TGmaPzUvqPfq2rGL0+LxJLoA9issmJTUnsyy1SN8ugSvjZO8s5oJLvhV9l9+w NzAete1i5OSQEDCRePb6NzOELSZx4d56ti5GLg4hgWWMErPfrGaHcHqZJJbOf8MK4VxklLi8 bA0LSAubgK7E/nsb2UFsEYFQiSnLXzOBFDELPGeU+PX2DRNIQljAXeLuiv+MIDaLgKrEz9/3 gPZxcPAKuErse1ILYkoIKEjMmWQDUsEp4Cax5dwcsAohoIq2ReIgYV4BQYkfk++xgISZBSQk nn9WAgkLAc3bdvM5I8QQJYnVR8wnMArNQtIwC6FhASPTKkax0uLkguKk9NQKI73ixNzi0rx0 veT83E2MkDip3sF496vNIUYBDkYlHt4JN3uDhVgTy4orcw8xSnAwK4nwflbtCxbiTUmsrEot yo8vKs1JLT7EyMTBKdXAOEuv+HDLQ96tx6U2PQ8x6G6fo3rwqvi5vLWZs4Wkgt39irXq3pmG vSlaEnb2YP7eUxtPTluddTg1e4v/C+ZVjPu5jS+8nuh2ImXBlw67vaKbdnReWH17lvbrdbO+ XDvCf7BEPORFEPel4lxjgZRA+/tCm2eszagSPWsuH+paeCVv+anfJp5T9JRYijMSDbWYi4oT ATg5d/lxAgAA X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20140603_161957_183831_48656A93 X-CRM114-Status: GOOD ( 22.59 ) X-Spam-Score: -5.7 (-----) Cc: peter.maydell@linaro.org, kvm@vger.kernel.org, steve.capper@arm.com, linux-arm-kernel@lists.infradead.org, jays.lee@samsung.com, sungjinn.chung@samsung.com, gavin.guo@canonical.com, Mario Smarduch X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.15 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,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 This patch adds support for keeping track of VM dirty pages. As dirty page log is retrieved, the pages that have been written are write protected again for next write and log read. Signed-off-by: Mario Smarduch --- arch/arm/include/asm/kvm_host.h | 3 ++ arch/arm/kvm/arm.c | 5 --- arch/arm/kvm/mmu.c | 79 +++++++++++++++++++++++++++++++++++ arch/x86/kvm/x86.c | 86 --------------------------------------- virt/kvm/kvm_main.c | 81 ++++++++++++++++++++++++++++++++++++ 5 files changed, 163 insertions(+), 91 deletions(-) diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h index 59565f5..b760f9c 100644 --- a/arch/arm/include/asm/kvm_host.h +++ b/arch/arm/include/asm/kvm_host.h @@ -232,5 +232,8 @@ u64 kvm_arm_timer_get_reg(struct kvm_vcpu *, u64 regid); int kvm_arm_timer_set_reg(struct kvm_vcpu *, u64 regid, u64 value); void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot); +void kvm_mmu_write_protect_pt_masked(struct kvm *kvm, + struct kvm_memory_slot *slot, + gfn_t gfn_offset, unsigned long mask); #endif /* __ARM_KVM_HOST_H__ */ diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c index dfd63ac..f06fb21 100644 --- a/arch/arm/kvm/arm.c +++ b/arch/arm/kvm/arm.c @@ -780,11 +780,6 @@ long kvm_arch_vcpu_ioctl(struct file *filp, } } -int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log) -{ - return -EINVAL; -} - static int kvm_vm_ioctl_set_device_addr(struct kvm *kvm, struct kvm_arm_device_addr *dev_addr) { diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c index e5dff85..1c546c9 100644 --- a/arch/arm/kvm/mmu.c +++ b/arch/arm/kvm/mmu.c @@ -874,6 +874,85 @@ void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot) spin_unlock(&kvm->mmu_lock); } +/** + * stage2_wp_mask_range() - write protect memslot pages set in mask + * @pmd - pointer to page table + * @start_ipa - the start range of mask + * @addr - start_ipa or start range of adjusted mask if crossing PMD range + * @mask - mask of dirty pages + * + * Walk mask and write protect the associated dirty pages in the memory region. + * If mask crosses a PMD range adjust it to next page table and return. + */ +static void stage2_wp_mask_range(pmd_t *pmd, phys_addr_t start_ipa, + phys_addr_t *addr, unsigned long *mask) +{ + pte_t *pte; + bool crosses_pmd; + int i; + + for (i = __ffs(*mask), *addr = start_ipa + i * PAGE_SIZE; + *mask; + i = __ffs(*mask), *addr = start_ipa + i * PAGE_SIZE) { + crosses_pmd = !!((start_ipa & PMD_MASK) ^ (*addr & PMD_MASK)); + if (unlikely(crosses_pmd)) { + /* Adjust mask dirty bits relative to next page table */ + *mask >>= (PTRS_PER_PTE - pte_index(start_ipa)); + return; + } + + pte = pte_offset_kernel(pmd, *addr); + if (!pte_none(*pte)) + kvm_set_s2pte_readonly(pte); + *mask &= ~(1 << i); + } +} + +/** + * kvm_mmu_write_protected_pt_masked() - write protect dirty pages set in mask + * @kvm: The KVM pointer + * @slot: The memory slot associated with mask + * @gfn_offset: The gfn offset in memory slot + * @mask: The mask of dirty pages at offset 'gnf_offset' in this memory + * slot to be write protected + * + * Called from dirty page logging read function to write protect bits set in + * mask to record future writes to these pages in dirty page log. This function + * uses simplified page table walk knowing that mask spawns range of two PMDs. + * + * 'kvm->mmu_lock' must be held to protect against concurrent modification + * of page tables (2nd stage fault, mmu modifiers, ...) + * + */ +void kvm_mmu_write_protect_pt_masked(struct kvm *kvm, + struct kvm_memory_slot *slot, + gfn_t gfn_offset, unsigned long mask) +{ + pud_t *pud; + pmd_t *pmd; + phys_addr_t start_ipa = (slot->base_gfn + gfn_offset) << PAGE_SHIFT; + phys_addr_t end_ipa = start_ipa + BITS_PER_LONG * PAGE_SIZE; + phys_addr_t addr = start_ipa; + pgd_t *pgdp = kvm->arch.pgd, *pgd; + + do { + pgd = pgdp + pgd_index(addr); + if (pgd_present(*pgd)) { + pud = pud_offset(pgd, addr); + if (!pud_none(*pud) && !pud_huge(*pud)) { + pmd = pmd_offset(pud, addr); + if (!pmd_none(*pmd) && !kvm_pmd_huge(*pmd)) + stage2_wp_mask_range(pmd, start_ipa, + &addr, &mask); + else + addr += PMD_SIZE; + } else + addr += PUD_SIZE; + } else + addr += PGDIR_SIZE; + } while (mask && addr < end_ipa); +} + static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, struct kvm_memory_slot *memslot, unsigned long fault_status) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index c5582c3..a603ca3 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3569,92 +3569,6 @@ static int kvm_vm_ioctl_reinject(struct kvm *kvm, return 0; } -/** - * kvm_vm_ioctl_get_dirty_log - get and clear the log of dirty pages in a slot - * @kvm: kvm instance - * @log: slot id and address to which we copy the log - * - * We need to keep it in mind that VCPU threads can write to the bitmap - * concurrently. So, to avoid losing data, we keep the following order for - * each bit: - * - * 1. Take a snapshot of the bit and clear it if needed. - * 2. Write protect the corresponding page. - * 3. Flush TLB's if needed. - * 4. Copy the snapshot to the userspace. - * - * Between 2 and 3, the guest may write to the page using the remaining TLB - * entry. This is not a problem because the page will be reported dirty at - * step 4 using the snapshot taken before and step 3 ensures that successive - * writes will be logged for the next call. - */ -int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log) -{ - int r; - struct kvm_memory_slot *memslot; - unsigned long n, i; - unsigned long *dirty_bitmap; - unsigned long *dirty_bitmap_buffer; - bool is_dirty = false; - - mutex_lock(&kvm->slots_lock); - - 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); - - 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_mmu_write_protect_pt_masked(kvm, memslot, offset, mask); - } - - spin_unlock(&kvm->mmu_lock); - - /* See the comments in kvm_mmu_slot_remove_write_access(). */ - lockdep_assert_held(&kvm->slots_lock); - - /* - * All the TLBs can be flushed out of mmu lock, see the comments in - * kvm_mmu_slot_remove_write_access(). - */ - if (is_dirty) - kvm_flush_remote_tlbs(kvm); - - r = -EFAULT; - if (copy_to_user(log->dirty_bitmap, dirty_bitmap_buffer, n)) - goto out; - - r = 0; -out: - mutex_unlock(&kvm->slots_lock); - return r; -} - int kvm_vm_ioctl_irq_line(struct kvm *kvm, struct kvm_irq_level *irq_event, bool line_status) { diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index ba25765..d8d5091 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -429,6 +429,87 @@ static int kvm_init_mmu_notifier(struct kvm *kvm) return mmu_notifier_register(&kvm->mmu_notifier, current->mm); } + +/** + * kvm_vm_ioctl_get_dirty_log - get and clear the log of dirty pages in a slot + * @kvm: kvm instance + * @log: slot id and address to which we copy the log + * + * We need to keep it in mind that VCPU threads can write to the bitmap + * concurrently. So, to avoid losing data, we keep the following order for + * each bit: + * + * 1. Take a snapshot of the bit and clear it if needed. + * 2. Write protect the corresponding page. + * 3. Flush TLB's if needed. + * 4. Copy the snapshot to the userspace. + * + * Between 2 and 3, the guest may write to the page using the remaining TLB + * entry. This is not a problem because the page will be reported dirty at + * step 4 using the snapshot taken before and step 3 ensures that successive + * writes will be logged for the next call. + */ + +int __weak kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, + struct kvm_dirty_log *log) +{ + int r; + struct kvm_memory_slot *memslot; + unsigned long n, i; + unsigned long *dirty_bitmap; + unsigned long *dirty_bitmap_buffer; + bool is_dirty = false; + + mutex_lock(&kvm->slots_lock); + + 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); + + 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_mmu_write_protect_pt_masked(kvm, memslot, offset, mask); + } + if (is_dirty) + kvm_flush_remote_tlbs(kvm); + + spin_unlock(&kvm->mmu_lock); + + r = -EFAULT; + if (copy_to_user(log->dirty_bitmap, dirty_bitmap_buffer, n)) + goto out; + + r = 0; +out: + mutex_unlock(&kvm->slots_lock); + return r; +} + #else /* !(CONFIG_MMU_NOTIFIER && KVM_ARCH_WANT_MMU_NOTIFIER) */ static int kvm_init_mmu_notifier(struct kvm *kvm)