[PATCH v2 19/23] vfio-user: no-mmap DMA support

From: John Johnson <john.g.johnson@oracle.com>
To: qemu-devel@nongnu.org
Cc: alex.williamson@redhat.com, clg@redhat.com, philmd@linaro.org
Subject: [PATCH v2 19/23] vfio-user: no-mmap DMA support
Date: Wed,  1 Feb 2023 21:55:55 -0800	[thread overview]
Message-ID: <fd72fb2ae20724145f72ca6f2308f712603738e1.1675228037.git.john.g.johnson@oracle.com> (raw)
In-Reply-To: <cover.1675228037.git.john.g.johnson@oracle.com>
In-Reply-To: <cover.1675228037.git.john.g.johnson@oracle.com>

Force remote process to use DMA r/w messages instead
of directly mapping guest memory.

Signed-off-by: John G Johnson <john.g.johnson@oracle.com>
Signed-off-by: Elena Ufimtseva <elena.ufimtseva@oracle.com>
Signed-off-by: Jagannathan Raman <jag.raman@oracle.com>
---
 hw/vfio/user.h     | 1 +
 hw/vfio/user-pci.c | 5 +++++
 hw/vfio/user.c     | 2 +-
 3 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/hw/vfio/user.h b/hw/vfio/user.h
index b89e5ca..fe0115b 100644
--- a/hw/vfio/user.h
+++ b/hw/vfio/user.h
@@ -83,6 +83,7 @@ typedef struct VFIOUserProxy {
 
 /* VFIOProxy flags */
 #define VFIO_PROXY_CLIENT        0x1
+#define VFIO_PROXY_NO_MMAP       0x2
 #define VFIO_PROXY_FORCE_QUEUED  0x4
 #define VFIO_PROXY_NO_POST       0x8
 
diff --git a/hw/vfio/user-pci.c b/hw/vfio/user-pci.c
index a0aa320..bf84d7c 100644
--- a/hw/vfio/user-pci.c
+++ b/hw/vfio/user-pci.c
@@ -40,6 +40,7 @@ OBJECT_DECLARE_SIMPLE_TYPE(VFIOUserPCIDevice, VFIO_USER_PCI)
 struct VFIOUserPCIDevice {
     VFIOPCIDevice device;
     char *sock_name;
+    bool no_direct_dma; /* disable shared mem for DMA */
     bool send_queued;   /* all sends are queued */
     bool no_post;       /* all regions write are sync */
 };
@@ -160,6 +161,9 @@ static void vfio_user_pci_realize(PCIDevice *pdev, Error **errp)
     vbasedev->proxy = proxy;
     vfio_user_set_handler(vbasedev, vfio_user_pci_process_req, vdev);
 
+    if (udev->no_direct_dma) {
+        proxy->flags |= VFIO_PROXY_NO_MMAP;
+    }
     if (udev->send_queued) {
         proxy->flags |= VFIO_PROXY_FORCE_QUEUED;
     }
@@ -269,6 +273,7 @@ static void vfio_user_instance_finalize(Object *obj)
 
 static Property vfio_user_pci_dev_properties[] = {
     DEFINE_PROP_STRING("socket", VFIOUserPCIDevice, sock_name),
+    DEFINE_PROP_BOOL("no-direct-dma", VFIOUserPCIDevice, no_direct_dma, false),
     DEFINE_PROP_BOOL("x-send-queued", VFIOUserPCIDevice, send_queued, false),
     DEFINE_PROP_BOOL("x-no-posted-writes", VFIOUserPCIDevice, no_post, false),
     DEFINE_PROP_END_OF_LIST(),
diff --git a/hw/vfio/user.c b/hw/vfio/user.c
index fe6e476..0a7b354 100644
--- a/hw/vfio/user.c
+++ b/hw/vfio/user.c
@@ -1806,7 +1806,7 @@ static int vfio_user_io_dma_map(VFIOContainer *container, MemoryRegion *mr,
      * map->vaddr enters as a QEMU process address
      * make it either a file offset for mapped areas or 0
      */
-    if (fd != -1) {
+    if (fd != -1 && (container->proxy->flags & VFIO_PROXY_NO_MMAP) == 0) {
         void *addr = (void *)(uintptr_t)map->vaddr;
 
         map->vaddr = qemu_ram_block_host_offset(mr->ram_block, addr);
-- 
1.9.4


