[PATCH v3 kvm/queue 13/16] KVM: Add KVM_EXIT_MEMORY_ERROR exit

[Chao Peng]

This new exit allows user space to handle memory-related errors.
Currently it supports two types (KVM_EXIT_MEM_MAP_SHARED/PRIVATE) of
errors which are used for shared memory <-> private memory conversion
in memory encryption usage.

After private memory is enabled, there are two places in KVM that can
exit to userspace to trigger private <-> shared conversion:
  - explicit conversion: happens when guest explicitly calls into KVM to
    map a range (as private or shared), KVM then exits to userspace to
    do the map/unmap operations.
  - implicit conversion: happens in KVM page fault handler.
    * if the fault is due to a private memory access then causes a
      userspace exit for a shared->private conversion request when the
      page has not been allocated in the private memory backend.
    * If the fault is due to a shared memory access then causes a
      userspace exit for a private->shared conversion request when the
      page has already been allocated in the private memory backend.

Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
---
 include/uapi/linux/kvm.h | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 41434322fa23..d68db3b2eeec 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -243,6 +243,18 @@ struct kvm_xen_exit {
        } u;
 };
 
+struct kvm_memory_exit {
+#define KVM_EXIT_MEM_MAP_SHARED         1
+#define KVM_EXIT_MEM_MAP_PRIVATE        2
+       __u32 type;
+       union {
+               struct {
+                       __u64 gpa;
+                       __u64 size;
+               } map;
+       } u;
+};
+
 #define KVM_S390_GET_SKEYS_NONE   1
 #define KVM_S390_SKEYS_MAX        1048576
 
@@ -282,6 +294,7 @@ struct kvm_xen_exit {
 #define KVM_EXIT_X86_BUS_LOCK     33
 #define KVM_EXIT_XEN              34
 #define KVM_EXIT_RISCV_SBI        35
+#define KVM_EXIT_MEMORY_ERROR     36
 
 /* For KVM_EXIT_INTERNAL_ERROR */
 /* Emulate instruction failed. */
@@ -499,6 +512,8 @@ struct kvm_run {
                        unsigned long args[6];
                        unsigned long ret[2];
                } riscv_sbi;
+               /* KVM_EXIT_MEMORY_ERROR */
+               struct kvm_memory_exit mem;
                /* Fix the size of the union. */
                char padding[256];
        };
-- 
2.17.1