[RFC,server,06/11] vfio-user: handle PCI config space accesses

Commit Message

Jag Raman July 19, 2021, 8 p.m. UTC

Define and register handlers for PCI config space accesses

Signed-off-by: Elena Ufimtseva <[e-mail]>
Signed-off-by: John G Johnson <[e-mail]>
Signed-off-by: Jagannathan Raman <[e-mail]>
---
 hw/remote/vfio-user-obj.c | 41 +++++++++++++++++++++++++++++++++++++++++
 hw/remote/trace-events    |  2 ++
 2 files changed, 43 insertions(+)

Comments

John Levon July 26, 2021, 3:10 p.m. UTC | #1

On Mon, Jul 19, 2021 at 04:00:08PM -0400, Jagannathan Raman wrote:

> Define and register handlers for PCI config space accesses
> 
> Signed-off-by: Elena Ufimtseva <[e-mail]>
> Signed-off-by: John G Johnson <[e-mail]>
> Signed-off-by: Jagannathan Raman <[e-mail]>
> ---
>  hw/remote/vfio-user-obj.c | 41 +++++++++++++++++++++++++++++++++++++++++
>  hw/remote/trace-events    |  2 ++
>  2 files changed, 43 insertions(+)
> 
> diff --git a/hw/remote/vfio-user-obj.c b/hw/remote/vfio-user-obj.c
> index 6a2d0f5..60d9fa8 100644
> --- a/hw/remote/vfio-user-obj.c
> +++ b/hw/remote/vfio-user-obj.c
> @@ -36,6 +36,7 @@
>  #include "sysemu/runstate.h"
>  #include "qemu/notify.h"
>  #include "qemu/thread.h"
> +#include "qemu/main-loop.h"
>  #include "qapi/error.h"
>  #include "sysemu/sysemu.h"
>  #include "hw/qdev-core.h"
> @@ -131,6 +132,35 @@ static void *vfu_object_ctx_run(void *opaque)
>      return NULL;
>  }
>  
> +static ssize_t vfu_object_cfg_access(vfu_ctx_t *vfu_ctx, char * const buf,
> +                                     size_t count, loff_t offset,
> +                                     const bool is_write)
> +{
> +    VfuObject *o = vfu_get_private(vfu_ctx);
> +    uint32_t val = 0;
> +    int i;
> +
> +    qemu_mutex_lock_iothread();
> +
> +    for (i = 0; i < count; i++) {
> +        if (is_write) {
> +            val = *((uint8_t *)(buf + i));
> +            trace_vfu_cfg_write((offset + i), val);
> +            pci_default_write_config(PCI_DEVICE(o->pci_dev),
> +                                     (offset + i), val, 1);
> +        } else {
> +            val = pci_default_read_config(PCI_DEVICE(o->pci_dev),
> +                                          (offset + i), 1);
> +            *((uint8_t *)(buf + i)) = (uint8_t)val;
> +            trace_vfu_cfg_read((offset + i), val);
> +        }
> +    }

Is it always OK to split up the access into single bytes like this?

regards
john

Patch

diff --git a/hw/remote/vfio-user-obj.c b/hw/remote/vfio-user-obj.c
index 6a2d0f5..60d9fa8 100644
--- a/hw/remote/vfio-user-obj.c
+++ b/hw/remote/vfio-user-obj.c
@@ -36,6 +36,7 @@ 
 #include "sysemu/runstate.h"
 #include "qemu/notify.h"
 #include "qemu/thread.h"
+#include "qemu/main-loop.h"
 #include "qapi/error.h"
 #include "sysemu/sysemu.h"
 #include "hw/qdev-core.h"
@@ -131,6 +132,35 @@  static void *vfu_object_ctx_run(void *opaque)
     return NULL;
 }
 
+static ssize_t vfu_object_cfg_access(vfu_ctx_t *vfu_ctx, char * const buf,
+                                     size_t count, loff_t offset,
+                                     const bool is_write)
+{
+    VfuObject *o = vfu_get_private(vfu_ctx);
+    uint32_t val = 0;
+    int i;
+
+    qemu_mutex_lock_iothread();
+
+    for (i = 0; i < count; i++) {
+        if (is_write) {
+            val = *((uint8_t *)(buf + i));
+            trace_vfu_cfg_write((offset + i), val);
+            pci_default_write_config(PCI_DEVICE(o->pci_dev),
+                                     (offset + i), val, 1);
+        } else {
+            val = pci_default_read_config(PCI_DEVICE(o->pci_dev),
+                                          (offset + i), 1);
+            *((uint8_t *)(buf + i)) = (uint8_t)val;
+            trace_vfu_cfg_read((offset + i), val);
+        }
+    }
+
+    qemu_mutex_unlock_iothread();
+
+    return count;
+}
+
 static void vfu_object_machine_done(Notifier *notifier, void *data)
 {
     VfuObject *o = container_of(notifier, VfuObject, machine_done);
@@ -167,6 +197,17 @@  static void vfu_object_machine_done(Notifier *notifier, void *data)
                    pci_get_word(o->pci_dev->config + PCI_SUBSYSTEM_VENDOR_ID),
                    pci_get_word(o->pci_dev->config + PCI_SUBSYSTEM_ID));
 
+    ret = vfu_setup_region(o->vfu_ctx, VFU_PCI_DEV_CFG_REGION_IDX,
+                           pci_config_size(o->pci_dev), &vfu_object_cfg_access,
+                           VFU_REGION_FLAG_RW | VFU_REGION_FLAG_ALWAYS_CB,
+                           NULL, 0, -1, 0);
+    if (ret < 0) {
+        error_setg(&error_abort,
+                   "vfu: Failed to setup config space handlers for %s- %s",
+                   o->devid, strerror(errno));
+        return;
+    }
+
     qemu_thread_create(&o->vfu_ctx_thread, "VFU ctx runner", vfu_object_ctx_run,
                        o, QEMU_THREAD_JOINABLE);
 }
diff --git a/hw/remote/trace-events b/hw/remote/trace-events
index 7da12f0..2ef7884 100644
--- a/hw/remote/trace-events
+++ b/hw/remote/trace-events
@@ -5,3 +5,5 @@  mpqemu_recv_io_error(int cmd, int size, int nfds) "failed to receive %d size %d,
 
 # vfio-user-obj.c
 vfu_prop(const char *prop, const char *val) "vfu: setting %s as %s"
+vfu_cfg_read(uint32_t offset, uint32_t val) "vfu: cfg: 0x%u -> 0x%x"
+vfu_cfg_write(uint32_t offset, uint32_t val) "vfu: cfg: 0x%u <- 0x%x"