From 53c810c364d7a2d5cebd5a0e4c882643af3b0a0e Mon Sep 17 00:00:00 2001 From: Mario Smarduch Date: Thu, 15 Jan 2015 15:58:57 -0800 Subject: [PATCH] KVM: arm: dirty logging write protect support Add support to track dirty pages between user space KVM_GET_DIRTY_LOG ioctl calls. We call kvm_get_dirty_log_protect() function to do most of the work. Reviewed-by: Christoffer Dall Reviewed-by: Marc Zyngier Signed-off-by: Mario Smarduch --- arch/arm/kvm/Kconfig | 1 + arch/arm/kvm/arm.c | 34 ++++++++++++++++++++++++++++++++++ arch/arm/kvm/mmu.c | 22 ++++++++++++++++++++++ 3 files changed, 57 insertions(+) diff --git a/arch/arm/kvm/Kconfig b/arch/arm/kvm/Kconfig index f27f3360e52b..a8d1ace3ea51 100644 --- a/arch/arm/kvm/Kconfig +++ b/arch/arm/kvm/Kconfig @@ -24,6 +24,7 @@ config KVM select HAVE_KVM_ARCH_TLB_FLUSH_ALL select KVM_MMIO select KVM_ARM_HOST + select KVM_GENERIC_DIRTYLOG_READ_PROTECT depends on ARM_VIRT_EXT && ARM_LPAE ---help--- Support hosting virtualized guest machines. You will also diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c index 2d6d91001062..1434410e7f46 100644 --- a/arch/arm/kvm/arm.c +++ b/arch/arm/kvm/arm.c @@ -787,9 +787,43 @@ long kvm_arch_vcpu_ioctl(struct file *filp, } } +/** + * 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 + * + * Steps 1-4 below provide general overview of dirty page logging. See + * kvm_get_dirty_log_protect() function description for additional details. + * + * We call kvm_get_dirty_log_protect() to handle steps 1-3, upon return we + * always flush the TLB (step 4) even if previous step failed and the dirty + * bitmap may be corrupt. Regardless of previous outcome the KVM logging API + * does not preclude user space subsequent dirty log read. Flushing TLB ensures + * writes will be marked dirty for next log read. + * + * 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. Flush TLB's if needed. + */ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log) { +#ifdef CONFIG_ARM + bool is_dirty = false; + int r; + + mutex_lock(&kvm->slots_lock); + + r = kvm_get_dirty_log_protect(kvm, log, &is_dirty); + + if (is_dirty) + kvm_flush_remote_tlbs(kvm); + + mutex_unlock(&kvm->slots_lock); + return r; +#else /* arm64 */ return -EINVAL; +#endif } static int kvm_vm_ioctl_set_device_addr(struct kvm *kvm, diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c index c9e5f384832e..565e903f6f78 100644 --- a/arch/arm/kvm/mmu.c +++ b/arch/arm/kvm/mmu.c @@ -1029,6 +1029,28 @@ void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot) spin_unlock(&kvm->mmu_lock); kvm_flush_remote_tlbs(kvm); } + +/** + * kvm_arch_mmu_write_protect_pt_masked() - write protect dirty pages + * @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 'gfn_offset' in this memory + * slot to be write protected + * + * Walks bits set in mask write protects the associated pte's. Caller must + * acquire kvm_mmu_lock. + */ +void kvm_arch_mmu_write_protect_pt_masked(struct kvm *kvm, + struct kvm_memory_slot *slot, + gfn_t gfn_offset, unsigned long mask) +{ + phys_addr_t base_gfn = slot->base_gfn + gfn_offset; + phys_addr_t start = (base_gfn + __ffs(mask)) << PAGE_SHIFT; + phys_addr_t end = (base_gfn + __fls(mask) + 1) << PAGE_SHIFT; + + stage2_wp_range(kvm, start, end); +} #endif static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, -- GitLab