vfio: Implement bar mappable

if device bar is mappable, map bar's gpa to hpa in EPT, guest vcpu
could access this bar directly through EPT without trapping. This
could improve performance.

vm.add_mmio_memory could help do this, here vfio_pci send
RegisterMmapMemory request through vm_control socket to do this.

BUG=chromium:992270
TEST=none

Change-Id: I3b4274372f7dcd32e18084d55f037b6fe45ed422
Signed-off-by: Xiong Zhang <xiong.y.zhang@intel.corp-partner.google.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/1581147
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Daniel Verkamp <dverkamp@chromium.org>

1 files changed, 22 insertions, 0 deletions

diff --git a/vm_control/src/lib.rs b/vm_control/src/lib.rs
index eccee10..7e5faf5 100644
--- a/vm_control/src/lib.rs
+++ b/vm_control/src/lib.rs
@@ -201,6 +201,13 @@ pub enum VmMemoryRequest {
         height: u32,
         format: u32,
     },
+    /// Register mmaped memory into kvm's EPT.
+    RegisterMmapMemory {
+        fd: MaybeOwnedFd,
+        size: usize,
+        offset: usize,
+        gpa: u64,
+    },
 }
 
 impl VmMemoryRequest {
@@ -260,6 +267,21 @@ impl VmMemoryRequest {
                     Err(e) => VmMemoryResponse::Err(e),
                 }
             }
+            RegisterMmapMemory {
+                ref fd,
+                size,
+                offset,
+                gpa,
+            } => {
+                let mmap = match MemoryMapping::from_fd_offset(fd, size, offset) {
+                    Ok(v) => v,
+                    Err(_e) => return VmMemoryResponse::Err(SysError::new(EINVAL)),
+                };
+                match vm.add_mmio_memory(GuestAddress(gpa), mmap, false, false) {
+                    Ok(_) => VmMemoryResponse::Ok,
+                    Err(e) => VmMemoryResponse::Err(e),
+                }
+            }
         }
     }
 }