guest_memory: Introduce set_memory_policy() method

set_memory_policy() method accepts MemoryPolicy bitmask - a
set of hints what kind of memory advices GuestMemory can
provide to the kernel. For the time being we support only
one advice - MADV_HUGEPAGE.

BUG=b:174206107
TEST=arc.Boot.vm on hatch-arc-r

Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Change-Id: Ibc3e4a2bb2ac7059de80dfba45e1cee3af4c3bcc
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/2812546
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Chirantan Ekbote <chirantan@chromium.org>

4 files changed, 35 insertions, 2 deletions

diff --git a/src/linux.rs b/src/linux.rs
index b78d4ea17..5efa2bb1f 100644
--- a/src/linux.rs
+++ b/src/linux.rs
@@ -55,7 +55,7 @@ use resources::{Alloc, MmioType, SystemAllocator};
 use rutabaga_gfx::RutabagaGralloc;
 use sync::Mutex;
 use vm_control::*;
-use vm_memory::{GuestAddress, GuestMemory};
+use vm_memory::{GuestAddress, GuestMemory, MemoryPolicy};
 
 #[cfg(all(target_arch = "x86_64", feature = "gdb"))]
 use crate::gdb::{gdb_thread, GdbStub};
@@ -2291,6 +2291,11 @@ pub fn run_config(cfg: Config) -> Result<()> {
     let guest_mem_layout =
         Arch::guest_memory_layout(&components).map_err(Error::GuestMemoryLayout)?;
     let guest_mem = GuestMemory::new(&guest_mem_layout).unwrap();
+    let mut mem_policy = MemoryPolicy::empty();
+    if components.hugepages {
+        mem_policy |= MemoryPolicy::USE_HUGEPAGES;
+    }
+    guest_mem.set_memory_policy(mem_policy);
     let kvm = Kvm::new_with_path(&cfg.kvm_device_path).map_err(Error::CreateKvm)?;
     let vm = KvmVm::new(&kvm, guest_mem).map_err(Error::CreateVm)?;
 
diff --git a/src/plugin/mod.rs b/src/plugin/mod.rs
index 7da482b3d..8236425c0 100644
--- a/src/plugin/mod.rs
+++ b/src/plugin/mod.rs
@@ -34,7 +34,7 @@ use base::{
 use kvm::{Cap, Datamatch, IoeventAddress, Kvm, Vcpu, VcpuExit, Vm};
 use minijail::{self, Minijail};
 use net_util::{Error as TapError, Tap, TapT};
-use vm_memory::GuestMemory;
+use vm_memory::{GuestMemory, MemoryPolicy};
 
 use self::process::*;
 use self::vcpu::*;
@@ -691,6 +691,11 @@ pub fn run_config(cfg: Config) -> Result<()> {
     };
     let vcpu_count = cfg.vcpu_count.unwrap_or(1) as u32;
     let mem = GuestMemory::new(&[]).unwrap();
+    let mut mem_policy = MemoryPolicy::empty();
+    if cfg.hugepages {
+        mem_policy |= MemoryPolicy::USE_HUGEPAGES;
+    }
+    mem.set_memory_policy(mem_policy);
     let kvm = Kvm::new_with_path(&cfg.kvm_device_path).map_err(Error::CreateKvm)?;
     let mut vm = Vm::new(&kvm, mem).map_err(Error::CreateVm)?;
     vm.create_irq_chip().map_err(Error::CreateIrqChip)?;
diff --git a/vm_memory/Cargo.toml b/vm_memory/Cargo.toml
index df599aacc..a1f569d1b 100644
--- a/vm_memory/Cargo.toml
+++ b/vm_memory/Cargo.toml
@@ -11,5 +11,6 @@ data_model = { path = "../data_model" } # provided by ebuild
 libc = "*"
 base = { path = "../base" } # provided by ebuild
 syscall_defines = { path = "../syscall_defines" } # provided by ebuild
+bitflags = "1"
 
 [workspace]
diff --git a/vm_memory/src/guest_memory.rs b/vm_memory/src/guest_memory.rs
index bb5d11649..62ba134e7 100644
--- a/vm_memory/src/guest_memory.rs
+++ b/vm_memory/src/guest_memory.rs
@@ -22,6 +22,8 @@ use cros_async::{mem, BackingMemory};
 use data_model::volatile_memory::*;
 use data_model::DataInit;
 
+use bitflags::bitflags;
+
 #[derive(Debug)]
 pub enum Error {
     DescriptorChainOverflow,
@@ -85,6 +87,12 @@ impl Display for Error {
     }
 }
 
+bitflags! {
+    pub struct MemoryPolicy: u32 {
+        const USE_HUGEPAGES = 1;
+    }
+}
+
 struct MemoryRegion {
     mapping: MemoryMapping,
     guest_base: GuestAddress,
@@ -259,6 +267,20 @@ impl GuestMemory {
         })
     }
 
+    /// Handles guest memory policy hints/advices.
+    pub fn set_memory_policy(&self, mem_policy: MemoryPolicy) {
+        if mem_policy.contains(MemoryPolicy::USE_HUGEPAGES) {
+            for (_, region) in self.regions.iter().enumerate() {
+                let ret = region.mapping.use_hugepages();
+
+                match ret {
+                    Err(err) => println!("Failed to enable HUGEPAGE for mapping {}", err),
+                    Ok(_) => (),
+                }
+            }
+        }
+    }
+
     /// Perform the specified action on each region's addresses.
     ///
     /// Callback is called with arguments: