Unmappable memory cannot be shared with the host. Ensure that the
private attribute cannot be removed from unmappable memory.
Signed-off-by: Fuad Tabba <tabba@xxxxxxxxxx>
---
virt/kvm/kvm_main.c | 43 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 43 insertions(+)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 9f6ff314bda3..adfee6592f6c 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -52,6 +52,7 @@
#include <linux/lockdep.h>
#include <linux/kthread.h>
#include <linux/suspend.h>
+#include <linux/rcupdate_wait.h>
#include <asm/processor.h>
#include <asm/ioctl.h>
@@ -2464,6 +2465,40 @@ bool kvm_range_has_memory_attributes(struct kvm *kvm, gfn_t start, gfn_t end,
return has_attrs;
}
+/*
+ * Returns true if _any_ gfn in the range [@start, @end) has _any_ attribute
+ * matching @attr.
+ */
+static bool kvm_any_range_has_memory_attribute(struct kvm *kvm, gfn_t start,
+ gfn_t end, unsigned long attr)
+{
+ XA_STATE(xas, &kvm->mem_attr_array, start);
+ bool has_attr = false;
+ void *entry;
+
+ rcu_read_lock();
+ xas_for_each(&xas, entry, end - 1) {
+ if (xas_retry(&xas, entry))
+ continue;
+
+ if (!xa_is_value(entry))
+ continue;
+
+ if ((xa_to_value(entry) & attr) == attr) {
+ has_attr = true;
+ break;
+ }
+
+ if (need_resched()) {
+ xas_pause(&xas);
+ cond_resched_rcu();
+ }
+ }
+ rcu_read_unlock();
+
+ return has_attr;
+}
+
static u64 kvm_supported_mem_attributes(struct kvm *kvm)
{
if (!kvm || kvm_arch_has_private_mem(kvm))
@@ -2614,6 +2649,14 @@ static int __kvm_vm_set_mem_attributes(struct kvm *kvm, gfn_t start, gfn_t end,
r = -EPERM;
goto out_unlock;
}
+
+ /* Unmappable memory cannot be shared. */
+ if (!(attributes & KVM_MEMORY_ATTRIBUTE_PRIVATE) &&
+ kvm_any_range_has_memory_attribute(kvm, start, end,
+ KVM_MEMORY_ATTRIBUTE_NOT_MAPPABLE)) {
+ r = -EPERM;
+ goto out_unlock;
+ }
}
/*
--
2.44.0.rc1.240.g4c46232300-goog
