stratovirt/vfio-adding-ram-device-region-to-vfio-bar-region.patch

From 7d40dbe810cf21added24d7cf2425a62bae4b25b Mon Sep 17 00:00:00 2001
From: "Xinle.Guo" <guoxinle1@huawei.com>
Date: Tue, 24 Aug 2021 15:29:08 +0800
Subject: [PATCH 06/10] vfio: adding ram device region to vfio bar region

The ram device region was added to memory region of parent bus.
But vfio bar region could not manage ram device region when
adding or deleting sub region. To fix this problem, it should be
added as sub region of vfio bar region. The VM exits when
guest tries to read/write device bar region. Using ram device
region which remaps mmio region can improve I/O performance. So,
the memory region should look like as follows:

				|----- IO region ----------|
|-----|---- IO region ----|-----|------|-ram device region-|(memory region)
        virtio bar region          vfio bar region

So, guest can read/write host device bar region directly.

Signed-off-by: Xinle.Guo <guoxinle1@huawei.com>
---
 vfio/src/lib.rs      |  4 ++--
 vfio/src/vfio_pci.rs | 35 ++++++++++++++++++++---------------
 2 files changed, 22 insertions(+), 17 deletions(-)

diff --git a/vfio/src/lib.rs b/vfio/src/lib.rs
index be70f45..801b7d0 100644
--- a/vfio/src/lib.rs
+++ b/vfio/src/lib.rs
@@ -23,8 +23,8 @@ pub mod errors {
             PciErr(pci::errors::Error, pci::errors::ErrorKind);
         }
         errors {
-            UnregMemBar(id: usize) {
-                display("Failed to unmap BAR {} in memory space.", id)
+            AddRegBar(id: usize) {
+                display("Failed to add sub region at the BAR {} in memory space.", id)
             }
             VfioIoctl(ioctl: String, result: i32) {
                 display("Vfio ioctl failed: {}, result is: {}", ioctl, result)
diff --git a/vfio/src/vfio_pci.rs b/vfio/src/vfio_pci.rs
index b42e321..e366e47 100644
--- a/vfio/src/vfio_pci.rs
+++ b/vfio/src/vfio_pci.rs
@@ -345,19 +345,19 @@ impl VfioPciDevice {
                 .chain_err(|| "Failed to get vfio bar info")?;
             let size = vfio_bar.size;
 
+            let region = Region::init_container_region(size);
             let bar_region = if i == table_bar {
-                let region = Region::init_container_region(size);
                 region
                     .add_subregion(
                         Region::init_io_region(table_size as u64, table_ops.clone()),
                         table_offset,
                     )
-                    .chain_err(|| ErrorKind::UnregMemBar(i as usize))?;
+                    .chain_err(|| ErrorKind::AddRegBar(i as usize))?;
 
                 if table_offset > 0 {
                     region
                         .add_subregion(Region::init_io_region(table_offset, bar_ops.clone()), 0)
-                        .chain_err(|| ErrorKind::UnregMemBar(i as usize))?;
+                        .chain_err(|| ErrorKind::AddRegBar(i as usize))?;
                 }
 
                 if table_offset + table_size < size {
@@ -369,11 +369,14 @@ impl VfioPciDevice {
                             ),
                             table_offset + table_size,
                         )
-                        .chain_err(|| ErrorKind::UnregMemBar(i as usize))?;
+                        .chain_err(|| ErrorKind::AddRegBar(i as usize))?;
                 }
                 region
             } else {
-                Region::init_io_region(size, bar_ops.clone())
+                region
+                    .add_subregion(Region::init_io_region(size, bar_ops.clone()), 0)
+                    .chain_err(|| ErrorKind::AddRegBar(i as usize))?;
+                region
             };
 
             self.pci_config
@@ -634,14 +637,16 @@ impl VfioPciDevice {
                 .chain_err(|| "Failed to create HostMemMapping")?;
 
                 let ram_device = Region::init_ram_device_region(Arc::new(host_mmap));
-                // Avoid being covered by user memory region.
-                ram_device.set_priority(1);
-                let parent_bus = self.parent_bus.upgrade().unwrap();
-                let locked_parent_bus = parent_bus.lock().unwrap();
-                locked_parent_bus
-                    .mem_region
-                    .add_subregion(ram_device, gpa + mmap.offset)
-                    .chain_err(|| "Failed add to mem region")?;
+                let bar = self
+                    .pci_config
+                    .bars
+                    .get_mut(i as usize)
+                    .chain_err(|| "Failed to get pci bar info")?;
+                bar.region
+                    .as_ref()
+                    .unwrap()
+                    .add_subregion(ram_device, mmap.offset)
+                    .chain_err(|| ErrorKind::AddRegBar(i as usize))?;
             }
         }
         Ok(())
@@ -757,7 +762,7 @@ impl PciDevOps for VfioPciDevice {
             return;
         }
 
-        if offset >= (BAR_0 as usize) && offset < (BAR_5 as usize) + REG_SIZE {
+        if ranges_overlap(offset, end, BAR_0 as usize, BAR_5 as usize + REG_SIZE) {
             self.pci_config.read(offset, data);
             return;
         }
@@ -806,7 +811,7 @@ impl PciDevOps for VfioPciDevice {
             cap_offset = msix.lock().unwrap().msix_cap_offset as usize;
         }
 
-        if ranges_overlap(offset, end, COMMAND as usize, COMMAND as usize + 4) {
+        if ranges_overlap(offset, end, COMMAND as usize, COMMAND as usize + REG_SIZE) {
             self.pci_config
                 .write(offset, data, self.dev_id.load(Ordering::Acquire));
 
-- 
2.25.1