[Xen-devel] [PATCH v3 03/10] ioreq: add fields to allow internal ioreq servers

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

Internal ioreq servers are plain function handlers implemented inside
of the hypervisor. Note that most fields used by current (external)
ioreq servers are not needed for internal ones, and hence have been
placed inside of a struct and packed in an union together with the
only internal specific field, a function pointer to a handler.

This is required in order to have PCI config accesses forwarded to
external ioreq servers or to internal ones (ie: QEMU emulated devices
vs vPCI passthrough), and is the first step in order to allow
unprivileged domains to use vPCI.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
Reviewed-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
---
Changes since v2:
 - Drop the vcpu parameter from the handler.

Changes since v1:
 - Do not add an internal field to the ioreq server struct, whether a
   server is internal or external can already be inferred from the id.
 - Add an extra parameter to the internal handler in order to pass
   user-provided opaque data to the handler.
---
 xen/include/asm-x86/hvm/domain.h | 30 +++++++++++++++++++-----------
 1 file changed, 19 insertions(+), 11 deletions(-)

diff --git a/xen/include/asm-x86/hvm/domain.h b/xen/include/asm-x86/hvm/domain.h
index bcc5621797..56a32e3e35 100644
--- a/xen/include/asm-x86/hvm/domain.h
+++ b/xen/include/asm-x86/hvm/domain.h
@@ -52,21 +52,29 @@ struct hvm_ioreq_vcpu {
 #define MAX_NR_IO_RANGES  256
 
 struct hvm_ioreq_server {
-    struct domain          *target, *emulator;
-
+    struct domain          *target;
     /* Lock to serialize toolstack modifications */
     spinlock_t             lock;
-
-    struct hvm_ioreq_page  ioreq;
-    struct list_head       ioreq_vcpu_list;
-    struct hvm_ioreq_page  bufioreq;
-
-    /* Lock to serialize access to buffered ioreq ring */
-    spinlock_t             bufioreq_lock;
-    evtchn_port_t          bufioreq_evtchn;
     struct rangeset        *range[NR_IO_RANGE_TYPES];
     bool                   enabled;
-    uint8_t                bufioreq_handling;
+
+    union {
+        struct {
+            struct domain          *emulator;
+            struct hvm_ioreq_page  ioreq;
+            struct list_head       ioreq_vcpu_list;
+            struct hvm_ioreq_page  bufioreq;
+
+            /* Lock to serialize access to buffered ioreq ring */
+            spinlock_t             bufioreq_lock;
+            evtchn_port_t          bufioreq_evtchn;
+            uint8_t                bufioreq_handling;
+        };
+        struct {
+            void                   *data;
+            int (*handler)(ioreq_t *, void *);
+        };
+    };
 };
 
 /*
-- 
2.23.0


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