kvm: support adding read only memory to VMs

Read only memory is useful for triggering VM exits when the VM writes to
memory while allowing reads transparently and quickly. For example, a
virtual device implementation might not care if the VM reads a memory
mapped device register, but a exit would be required if the VM wrote to
the same register.

TEST=cargo test -p kvm; ./build_test
BUG=chromium:800626

Change-Id: Ic605b2cfc2a1e44941d91945f9390b9abb820040
Reviewed-on: https://chromium-review.googlesource.com/903075
Commit-Ready: Zach Reizner <zachr@chromium.org>
Tested-by: Zach Reizner <zachr@chromium.org>
Reviewed-by: Zach Reizner <zachr@chromium.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/vm_control/src/lib.rs b/vm_control/src/lib.rs
index 6688077..dbcbece 100644
--- a/vm_control/src/lib.rs
+++ b/vm_control/src/lib.rs
@@ -205,7 +205,7 @@ impl VmRequest {
                 };
                 let pfn = *next_mem_pfn;
                 let slot =
-                    match vm.add_device_memory(GuestAddress(pfn << 12), mmap, false) {
+                    match vm.add_device_memory(GuestAddress(pfn << 12), mmap, false, false) {
                         Ok(slot) => slot,
                         Err(e) => return VmResponse::Err(e),
                     };