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authorSean Christopherson <sean.j.christopherson@intel.com>2020-02-18 13:07:29 -0800
committerPaolo Bonzini <pbonzini@redhat.com>2020-03-16 17:57:24 +0100
commit0dff084607bd555d6f74db2af8406a9da9f0fc3a (patch)
tree4538ceb5b97d97af484089302f460a978cc362e6 /virt
parent163da372dec52183a4f6142c302716b939ec5df5 (diff)
downloadlinux-0dff084607bd555d6f74db2af8406a9da9f0fc3a.tar.gz
KVM: Provide common implementation for generic dirty log functions
Move the implementations of KVM_GET_DIRTY_LOG and KVM_CLEAR_DIRTY_LOG for CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT into common KVM code. The arch specific implemenations are extremely similar, differing only in whether the dirty log needs to be sync'd from hardware (x86) and how the TLBs are flushed. Add new arch hooks to handle sync and TLB flush; the sync will also be used for non-generic dirty log support in a future patch (s390). The ulterior motive for providing a common implementation is to eliminate the dependency between arch and common code with respect to the memslot referenced by the dirty log, i.e. to make it obvious in the code that the validity of the memslot is guaranteed, as a future patch will rework memslot handling such that id_to_memslot() can return NULL. Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/arm/arm.c48
-rw-r--r--virt/kvm/kvm_main.c91
2 files changed, 75 insertions, 64 deletions
diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
index d65a0faa46d8..bfdba1caf59d 100644
--- a/virt/kvm/arm/arm.c
+++ b/virt/kvm/arm/arm.c
@@ -1183,55 +1183,15 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
return r;
}
-/**
- * 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)
+void kvm_arch_sync_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot)
{
- bool flush = false;
- int r;
-
- mutex_lock(&kvm->slots_lock);
-
- r = kvm_get_dirty_log_protect(kvm, log, &flush);
- if (flush)
- kvm_flush_remote_tlbs(kvm);
-
- mutex_unlock(&kvm->slots_lock);
- return r;
}
-int kvm_vm_ioctl_clear_dirty_log(struct kvm *kvm, struct kvm_clear_dirty_log *log)
+void kvm_arch_flush_remote_tlbs_memslot(struct kvm *kvm,
+ struct kvm_memory_slot *memslot)
{
- bool flush = false;
- int r;
-
- mutex_lock(&kvm->slots_lock);
-
- r = kvm_clear_dirty_log_protect(kvm, log, &flush);
-
- if (flush)
- kvm_flush_remote_tlbs(kvm);
-
- mutex_unlock(&kvm->slots_lock);
- return r;
+ kvm_flush_remote_tlbs(kvm);
}
static int kvm_vm_ioctl_set_device_addr(struct kvm *kvm,
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 1632e466ad6f..7420aa468b75 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -856,7 +856,7 @@ static int kvm_vm_release(struct inode *inode, struct file *filp)
/*
* Allocation size is twice as large as the actual dirty bitmap size.
- * See x86's kvm_vm_ioctl_get_dirty_log() why this is needed.
+ * See kvm_vm_ioctl_get_dirty_log() why this is needed.
*/
static int kvm_create_dirty_bitmap(struct kvm_memory_slot *memslot)
{
@@ -1104,12 +1104,9 @@ int __kvm_set_memory_region(struct kvm *kvm,
* Make a full copy of the old memslot, the pointer will become stale
* when the memslots are re-sorted by update_memslots(), and the old
* memslot needs to be referenced after calling update_memslots(), e.g.
- * to free its resources and for arch specific behavior. Kill @tmp
- * after making a copy to deter potentially dangerous usage.
+ * to free its resources and for arch specific behavior.
*/
- tmp = id_to_memslot(__kvm_memslots(kvm, as_id), id);
- old = *tmp;
- tmp = NULL;
+ old = *id_to_memslot(__kvm_memslots(kvm, as_id), id);
if (!mem->memory_size)
return kvm_delete_memslot(kvm, mem, &old, as_id);
@@ -1201,6 +1198,7 @@ static int kvm_vm_ioctl_set_memory_region(struct kvm *kvm,
return kvm_set_memory_region(kvm, mem);
}
+#ifndef CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT
int kvm_get_dirty_log(struct kvm *kvm,
struct kvm_dirty_log *log, int *is_dirty)
{
@@ -1234,13 +1232,12 @@ int kvm_get_dirty_log(struct kvm *kvm,
}
EXPORT_SYMBOL_GPL(kvm_get_dirty_log);
-#ifdef CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT
+#else /* CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT */
/**
* kvm_get_dirty_log_protect - get a snapshot of dirty pages
* and reenable dirty page tracking for the corresponding pages.
* @kvm: pointer to kvm instance
* @log: slot id and address to which we copy the log
- * @flush: true if TLB flush is needed by caller
*
* 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
@@ -1257,8 +1254,7 @@ EXPORT_SYMBOL_GPL(kvm_get_dirty_log);
* 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 *flush)
+static int kvm_get_dirty_log_protect(struct kvm *kvm, struct kvm_dirty_log *log)
{
struct kvm_memslots *slots;
struct kvm_memory_slot *memslot;
@@ -1266,6 +1262,7 @@ int kvm_get_dirty_log_protect(struct kvm *kvm,
unsigned long n;
unsigned long *dirty_bitmap;
unsigned long *dirty_bitmap_buffer;
+ bool flush;
as_id = log->slot >> 16;
id = (u16)log->slot;
@@ -1279,8 +1276,10 @@ int kvm_get_dirty_log_protect(struct kvm *kvm,
if (!dirty_bitmap)
return -ENOENT;
+ kvm_arch_sync_dirty_log(kvm, memslot);
+
n = kvm_dirty_bitmap_bytes(memslot);
- *flush = false;
+ flush = false;
if (kvm->manual_dirty_log_protect) {
/*
* Unlike kvm_get_dirty_log, we always return false in *flush,
@@ -1303,7 +1302,7 @@ int kvm_get_dirty_log_protect(struct kvm *kvm,
if (!dirty_bitmap[i])
continue;
- *flush = true;
+ flush = true;
mask = xchg(&dirty_bitmap[i], 0);
dirty_bitmap_buffer[i] = mask;
@@ -1314,21 +1313,55 @@ int kvm_get_dirty_log_protect(struct kvm *kvm,
spin_unlock(&kvm->mmu_lock);
}
+ if (flush)
+ kvm_arch_flush_remote_tlbs_memslot(kvm, memslot);
+
if (copy_to_user(log->dirty_bitmap, dirty_bitmap_buffer, n))
return -EFAULT;
return 0;
}
-EXPORT_SYMBOL_GPL(kvm_get_dirty_log_protect);
+
+
+/**
+ * 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.
+ */
+static int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
+ struct kvm_dirty_log *log)
+{
+ int r;
+
+ mutex_lock(&kvm->slots_lock);
+
+ r = kvm_get_dirty_log_protect(kvm, log);
+
+ mutex_unlock(&kvm->slots_lock);
+ return r;
+}
/**
* kvm_clear_dirty_log_protect - clear dirty bits in the bitmap
* and reenable dirty page tracking for the corresponding pages.
* @kvm: pointer to kvm instance
* @log: slot id and address from which to fetch the bitmap of dirty pages
- * @flush: true if TLB flush is needed by caller
*/
-int kvm_clear_dirty_log_protect(struct kvm *kvm,
- struct kvm_clear_dirty_log *log, bool *flush)
+static int kvm_clear_dirty_log_protect(struct kvm *kvm,
+ struct kvm_clear_dirty_log *log)
{
struct kvm_memslots *slots;
struct kvm_memory_slot *memslot;
@@ -1337,6 +1370,7 @@ int kvm_clear_dirty_log_protect(struct kvm *kvm,
unsigned long i, n;
unsigned long *dirty_bitmap;
unsigned long *dirty_bitmap_buffer;
+ bool flush;
as_id = log->slot >> 16;
id = (u16)log->slot;
@@ -1360,7 +1394,9 @@ int kvm_clear_dirty_log_protect(struct kvm *kvm,
(log->num_pages < memslot->npages - log->first_page && (log->num_pages & 63)))
return -EINVAL;
- *flush = false;
+ kvm_arch_sync_dirty_log(kvm, memslot);
+
+ flush = false;
dirty_bitmap_buffer = kvm_second_dirty_bitmap(memslot);
if (copy_from_user(dirty_bitmap_buffer, log->dirty_bitmap, n))
return -EFAULT;
@@ -1383,17 +1419,32 @@ int kvm_clear_dirty_log_protect(struct kvm *kvm,
* a problem if userspace sets them in log->dirty_bitmap.
*/
if (mask) {
- *flush = true;
+ flush = true;
kvm_arch_mmu_enable_log_dirty_pt_masked(kvm, memslot,
offset, mask);
}
}
spin_unlock(&kvm->mmu_lock);
+ if (flush)
+ kvm_arch_flush_remote_tlbs_memslot(kvm, memslot);
+
return 0;
}
-EXPORT_SYMBOL_GPL(kvm_clear_dirty_log_protect);
-#endif
+
+static int kvm_vm_ioctl_clear_dirty_log(struct kvm *kvm,
+ struct kvm_clear_dirty_log *log)
+{
+ int r;
+
+ mutex_lock(&kvm->slots_lock);
+
+ r = kvm_clear_dirty_log_protect(kvm, log);
+
+ mutex_unlock(&kvm->slots_lock);
+ return r;
+}
+#endif /* CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT */
bool kvm_largepages_enabled(void)
{