[RFC,v2,5/6] KVM: moving dirty bitmaps to user space

Message ID	20100420200225.efca602f.yoshikawa.takuya@oss.ntt.co.jp (mailing list archive)
State	New, archived
Headers	show Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by demeter.kernel.org (8.14.3/8.14.3) with ESMTP id o3KAwmka008322 for <patchwork-kvm@patchwork.kernel.org>; Tue, 20 Apr 2010 10:58:48 GMT Date: Tue, 20 Apr 2010 20:02:25 +0900 From: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp> To: avi@redhat.com, mtosatti@redhat.com Cc: kvm@vger.kernel.org, kvm-ia64@vger.kernel.org, kvm-ppc@vger.kernel.org, fernando@oss.ntt.co.jp Subject: [PATCH RFC v2 5/6] KVM: moving dirty bitmaps to user space Message-Id: <20100420200225.efca602f.yoshikawa.takuya@oss.ntt.co.jp> In-Reply-To: <20100420195349.dab60b1d.yoshikawa.takuya@oss.ntt.co.jp> References: <20100420195349.dab60b1d.yoshikawa.takuya@oss.ntt.co.jp> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: kvm-owner@vger.kernel.org Precedence: bulk

diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c index d60dafe..c3f0b70 100644 --- a/arch/ia64/kvm/kvm-ia64.c +++ b/arch/ia64/kvm/kvm-ia64.c @@ -1823,11 +1823,19 @@ static int kvm_ia64_sync_dirty_log(struct kvm *kvm, n = kvm_dirty_bitmap_bytes(memslot); base = memslot->base_gfn / BITS_PER_LONG; + r = -EFAULT; + if (!access_ok(VERIFY_WRITE, memslot->dirty_bitmap, n)) + goto out; + for (i = 0; i < n/sizeof(long); ++i) { if (dirty_bitmap[base + i]) memslot->is_dirty = true; - memslot->dirty_bitmap[i] = dirty_bitmap[base + i]; + if (__put_user(dirty_bitmap[base + i], + &memslot->dirty_bitmap[i])) { + r = -EFAULT; + goto out; + } dirty_bitmap[base + i] = 0; } r = 0; @@ -1858,7 +1866,7 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, if (memslot->is_dirty) { kvm_flush_remote_tlbs(kvm); n = kvm_dirty_bitmap_bytes(memslot); - memset(memslot->dirty_bitmap, 0, n); + clear_user(memslot->dirty_bitmap, n); memslot->is_dirty = false; } r = 0; diff --git a/arch/powerpc/kvm/book3s.c b/arch/powerpc/kvm/book3s.c index 53b45cf..b074e19 100644 --- a/arch/powerpc/kvm/book3s.c +++ b/arch/powerpc/kvm/book3s.c @@ -1137,7 +1137,7 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, kvmppc_mmu_pte_pflush(vcpu, ga, ga_end); n = kvm_dirty_bitmap_bytes(memslot); - memset(memslot->dirty_bitmap, 0, n); + clear_user(memslot->dirty_bitmap, n); memslot->is_dirty = false; } diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 6f0b706..ad55353 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2727,7 +2727,8 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, int r; struct kvm_memory_slot *memslot; unsigned long n; - unsigned long *dirty_bitmap = NULL; + unsigned long __user *dirty_bitmap; + unsigned long __user *dirty_bitmap_old; mutex_lock(&kvm->slots_lock); @@ -2742,11 +2743,9 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, n = kvm_dirty_bitmap_bytes(memslot); - r = -ENOMEM; - dirty_bitmap = vmalloc(n); - if (!dirty_bitmap) - goto out; - memset(dirty_bitmap, 0, n); + dirty_bitmap = memslot->dirty_bitmap; + dirty_bitmap_old = memslot->dirty_bitmap_old; + clear_user(dirty_bitmap_old, n); /* If nothing is dirty, don't bother messing with page tables. */ if (memslot->is_dirty) { @@ -2756,24 +2755,25 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, kvm_mmu_slot_remove_write_access(kvm, log->slot); spin_unlock(&kvm->mmu_lock); + r = -ENOMEM; slots = kzalloc(sizeof(struct kvm_memslots), GFP_KERNEL); if (!slots) - goto out_free; + goto out; memcpy(slots, kvm->memslots, sizeof(struct kvm_memslots)); - slots->memslots[log->slot].dirty_bitmap = dirty_bitmap; + slots->memslots[log->slot].dirty_bitmap = dirty_bitmap_old; + slots->memslots[log->slot].dirty_bitmap_old = dirty_bitmap; slots->memslots[log->slot].is_dirty = false; old_slots = kvm->memslots; rcu_assign_pointer(kvm->memslots, slots); synchronize_srcu_expedited(&kvm->srcu); - dirty_bitmap = old_slots->memslots[log->slot].dirty_bitmap; kfree(old_slots); + + dirty_bitmap_old = dirty_bitmap; } - r = kvm_copy_dirty_bitmap(log->dirty_bitmap, dirty_bitmap, n); -out_free: - vfree(dirty_bitmap); + r = kvm_copy_dirty_bitmap(log->dirty_bitmap, dirty_bitmap_old, n); out: mutex_unlock(&kvm->slots_lock); return r; diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 42b7161..d4d217a 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -116,7 +116,8 @@ struct kvm_memory_slot { unsigned long npages; unsigned long flags; unsigned long *rmap; - unsigned long *dirty_bitmap; + unsigned long __user *dirty_bitmap; + unsigned long __user *dirty_bitmap_old; bool is_dirty; struct { unsigned long rmap_pde; @@ -331,7 +332,7 @@ long kvm_arch_vcpu_ioctl(struct file *filp, int kvm_dev_ioctl_check_extension(long ext); int kvm_copy_dirty_bitmap(unsigned long __user *to, - const unsigned long *from, + const unsigned long __user *from, unsigned long bytes); int kvm_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log); int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 66c4daf..9323639 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -433,8 +433,20 @@ out_err_nodisable: static void kvm_destroy_dirty_bitmap(struct kvm_memory_slot *memslot) { - vfree(memslot->dirty_bitmap); + unsigned long user_addr; + unsigned long n = kvm_dirty_bitmap_bytes(memslot); + + if (!memslot->dirty_bitmap) + return; + + user_addr = min((unsigned long)memslot->dirty_bitmap, + (unsigned long)memslot->dirty_bitmap_old); + down_write(&current->mm->mmap_sem); + do_munmap(current->mm, user_addr, 2 * n); + up_write(&current->mm->mmap_sem); + memslot->dirty_bitmap = NULL; + memslot->dirty_bitmap_old = NULL; } /* @@ -468,8 +480,12 @@ void kvm_free_physmem(struct kvm *kvm) int i; struct kvm_memslots *slots = kvm->memslots; - for (i = 0; i < slots->nmemslots; ++i) + for (i = 0; i < slots->nmemslots; ++i) { + /* We don't munmap dirty bitmaps by ourselves. */ + slots->memslots[i].dirty_bitmap = NULL; + slots->memslots[i].dirty_bitmap_old = NULL; kvm_free_physmem_slot(&slots->memslots[i], NULL); + } kfree(kvm->memslots); } @@ -523,13 +539,22 @@ static int kvm_vm_release(struct inode *inode, struct file *filp) static int kvm_create_dirty_bitmap(struct kvm_memory_slot *memslot) { - unsigned long dirty_bytes = kvm_dirty_bitmap_bytes(memslot); + unsigned long user_addr; + unsigned long n = kvm_dirty_bitmap_bytes(memslot); - memslot->dirty_bitmap = vmalloc(dirty_bytes); - if (!memslot->dirty_bitmap) - return -ENOMEM; + down_write(&current->mm->mmap_sem); + user_addr = do_mmap(NULL, 0, 2 * n, + PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_ANONYMOUS, 0); + up_write(&current->mm->mmap_sem); + + if (IS_ERR((void *)user_addr)) + return PTR_ERR((void *)user_addr); + + memslot->dirty_bitmap = (unsigned long __user *)user_addr; + memslot->dirty_bitmap_old = (unsigned long __user *)(user_addr + n); + clear_user(memslot->dirty_bitmap, 2 * n); - memset(memslot->dirty_bitmap, 0, dirty_bytes); return 0; } @@ -778,13 +803,45 @@ int kvm_vm_ioctl_set_memory_region(struct kvm *kvm, } int kvm_copy_dirty_bitmap(unsigned long __user *to, - const unsigned long *from, + const unsigned long __user *from, unsigned long bytes) { - if (copy_to_user(to, from, bytes)) +#if defined(CONFIG_X86_64) || defined(CONFIG_PPC64) || defined(CONFIG_IA64) + if (copy_in_user(to, from, bytes)) { + printk(KERN_WARNING "%s: copy_in_user failed.\n", __func__); return -EFAULT; + } + return 0; +#else + int num, bufbytes; + unsigned long buf[32]; + if (!access_ok(VERIFY_READ, from, bytes) || + !access_ok(VERIFY_WRITE, to, bytes)) { + goto out_fault; + } + + bufbytes = sizeof(buf); + num = bufbytes / sizeof(buf[0]); + + for (; bytes > bufbytes; bytes -= bufbytes, to += num, from += num) { + if (__copy_from_user(buf, from, bufbytes)) + goto out_fault; + if (__copy_to_user(to, buf, bufbytes)) + goto out_fault; + } + if (bytes > 0) { + if (__copy_from_user(buf, from, bytes)) + goto out_fault; + if (__copy_to_user(to, buf, bytes)) + goto out_fault; + } return 0; + +out_fault: + printk(KERN_WARNING "%s: copy to(from) user failed.\n", __func__); + return -EFAULT; +#endif } int kvm_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log) @@ -1194,13 +1251,35 @@ int kvm_clear_guest(struct kvm *kvm, gpa_t gpa, unsigned long len) } EXPORT_SYMBOL_GPL(kvm_clear_guest); +/* + * Please use generic *_user bitops once they become available. + * Be careful setting the bit won't be done atomically. + */ static int __mark_page_dirty(unsigned long nr, - unsigned long *dirty_bitmap) + unsigned long __user *dirty_bitmap) { + unsigned long user_addr; + u8 val; + #ifdef __BIG_ENDIAN nr = nr ^ BITOP_LE_SWIZZLE; #endif - __set_bit(nr, dirty_bitmap); + user_addr = (unsigned long)dirty_bitmap + nr / 8; + if (!access_ok(VERIFY_WRITE, user_addr, 1)) + goto out_fault; + + if (__get_user(val, (u8 __user *)user_addr)) + goto out_fault; + + val |= 1U << (nr % 8); + if (__put_user(val, (u8 __user *)user_addr)) + goto out_fault; + + return 0; + +out_fault: + printk(KERN_WARNING "%s: setting user bit failed.\n", __func__); + return -EFAULT; } void mark_page_dirty(struct kvm *kvm, gfn_t gfn)

[RFC,v2,5/6] KVM: moving dirty bitmaps to user space

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Patch