[PATCH v5 12/13] KVM: Expose KVM_MEM_PRIVATE

[Chao Peng]

KVM_MEM_PRIVATE is not exposed by default but architecture code can turn
on it by implementing kvm_arch_private_memory_supported().

Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
---
 include/linux/kvm_host.h |  1 +
 virt/kvm/kvm_main.c      | 24 +++++++++++++++++++-----
 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 186b9b981a65..0150e952a131 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1432,6 +1432,7 @@ bool kvm_arch_dy_has_pending_interrupt(struct kvm_vcpu 
*vcpu);
 int kvm_arch_post_init_vm(struct kvm *kvm);
 void kvm_arch_pre_destroy_vm(struct kvm *kvm);
 int kvm_arch_create_vm_debugfs(struct kvm *kvm);
+bool kvm_arch_private_memory_supported(struct kvm *kvm);
 
 #ifndef __KVM_HAVE_ARCH_VM_ALLOC
 /*
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 52319f49d58a..df5311755a40 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1485,10 +1485,19 @@ static void kvm_replace_memslot(struct kvm *kvm,
        }
 }
 
-static int check_memory_region_flags(const struct kvm_userspace_memory_region 
*mem)
+bool __weak kvm_arch_private_memory_supported(struct kvm *kvm)
+{
+       return false;
+}
+
+static int check_memory_region_flags(struct kvm *kvm,
+                               const struct kvm_userspace_memory_region *mem)
 {
        u32 valid_flags = KVM_MEM_LOG_DIRTY_PAGES;
 
+       if (kvm_arch_private_memory_supported(kvm))
+               valid_flags |= KVM_MEM_PRIVATE;
+
 #ifdef __KVM_HAVE_READONLY_MEM
        valid_flags |= KVM_MEM_READONLY;
 #endif
@@ -1900,7 +1909,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
        int as_id, id;
        int r;
 
-       r = check_memory_region_flags(mem);
+       r = check_memory_region_flags(kvm, mem);
        if (r)
                return r;
 
@@ -1913,10 +1922,12 @@ int __kvm_set_memory_region(struct kvm *kvm,
                return -EINVAL;
        if (mem->guest_phys_addr & (PAGE_SIZE - 1))
                return -EINVAL;
-       /* We can read the guest memory with __xxx_user() later on. */
        if ((mem->userspace_addr & (PAGE_SIZE - 1)) ||
-           (mem->userspace_addr != untagged_addr(mem->userspace_addr)) ||
-            !access_ok((void __user *)(unsigned long)mem->userspace_addr,
+           (mem->userspace_addr != untagged_addr(mem->userspace_addr)))
+               return -EINVAL;
+       /* We can read the guest memory with __xxx_user() later on. */
+       if (!(mem->flags & KVM_MEM_PRIVATE) &&
+           !access_ok((void __user *)(unsigned long)mem->userspace_addr,
                        mem->memory_size))
                return -EINVAL;
        if (as_id >= KVM_ADDRESS_SPACE_NUM || id >= KVM_MEM_SLOTS_NUM)
@@ -1957,6 +1968,9 @@ int __kvm_set_memory_region(struct kvm *kvm,
                if ((kvm->nr_memslot_pages + npages) < kvm->nr_memslot_pages)
                        return -EINVAL;
        } else { /* Modify an existing slot. */
+               /* Private memslots are immutable, they can only be deleted. */
+               if (mem->flags & KVM_MEM_PRIVATE)
+                       return -EINVAL;
                if ((mem->userspace_addr != old->userspace_addr) ||
                    (npages != old->npages) ||
                    ((mem->flags ^ old->flags) & KVM_MEM_READONLY))
-- 
2.17.1