[Qemu-devel] [QEMU][RFC V2 04/10] xen-hvm: register qemu as ioreq server and retrieve shared pages

[Julien Grall]

With QEMU disaggregation in Xen environment, each QEMU needs to ask Xen
for an ioreq server id. This id will be use to retrieve its private share
pages.

Signed-off-by: Julien Grall <address@hidden>
---
 xen-all.c |   80 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 files changed, 76 insertions(+), 4 deletions(-)

diff --git a/xen-all.c b/xen-all.c
index df6927d..5f05838 100644
--- a/xen-all.c
+++ b/xen-all.c
@@ -36,6 +36,7 @@
 
 static MemoryRegion ram_memory, ram_640k, ram_lo, ram_hi;
 static MemoryRegion *framebuffer;
+static unsigned int serverid;
 static uint32_t xen_dmid = ~0;
 
 /* Compatibility with older version */
@@ -64,6 +65,67 @@ static inline ioreq_t *xen_vcpu_ioreq(shared_iopage_t 
*shared_page, int vcpu)
 #define HVM_PARAM_BUFIOREQ_EVTCHN 26
 #endif
 
+#if __XEN_LATEST_INTERFACE_VERSION__ < 0x00040300
+static inline unsigned long xen_buffered_iopage(void)
+{
+    unsigned long pfn;
+
+    xc_get_hvm_param(xen_xc, xen_domid, HVM_PARAM_BUFIOREQ_PFN, &pfn);
+
+    return pfn;
+}
+
+static inline unsigned long xen_iopage(void)
+{
+    unsigned long pfn;
+
+    xc_get_hvm_param(xen_xc, xen_domid, HVM_PARAM_IOREQ_PFN, &pfn);
+
+    return pfn;
+}
+
+static inline evtchn_port_or_error_t xen_buffered_channel(void)
+{
+    unsigned long evtchn;
+    int rc;
+
+    rc = xc_get_hvm_param(xen_xc, xen_domid, HVM_PARAM_BUFIOREQ_EVTCHN,
+                          &evtchn);
+
+    if (rc < 0) {
+        return rc;
+    } else {
+        return evtchn;
+    }
+}
+#else
+static inline unsigned long xen_buffered_iopage(void)
+{
+    unsigned long pfn;
+
+    xc_get_hvm_param(xen_xc, xen_domid, HVM_PARAM_IO_PFN_FIRST, &pfn);
+    pfn += (serverid - 1) * 2 + 2;
+
+    return pfn;
+}
+
+static inline unsigned long xen_iopage(void)
+{
+    unsigned long pfn;
+
+    xc_get_hvm_param(xen_xc, xen_domid, HVM_PARAM_IO_PFN_FIRST, &pfn);
+    pfn += (serverid - 1) * 2 + 1;
+
+    return pfn;
+}
+
+static inline evtchn_port_or_error_t xen_buffered_channel(void)
+{
+    return xc_hvm_get_ioreq_server_buf_channel(xen_xc, xen_domid, serverid);
+}
+
+#endif
+
 #define BUFFER_IO_MAX_DELAY  100
 
 typedef struct XenPhysmap {
@@ -1112,7 +1174,15 @@ int xen_hvm_init(void)
     state->suspend.notify = xen_suspend_notifier;
     qemu_register_suspend_notifier(&state->suspend);
 
-    xc_get_hvm_param(xen_xc, xen_domid, HVM_PARAM_IOREQ_PFN, &ioreq_pfn);
+    rc = xen_xc_hvm_register_ioreq_server(xen_xc, xen_domid);
+
+    if (rc < 0) {
+        hw_error("registered server returned error %d", rc);
+    }
+
+    serverid = rc;
+
+    ioreq_pfn = xen_iopage();
     DPRINTF("shared page at pfn %lx\n", ioreq_pfn);
     state->shared_page = xc_map_foreign_range(xen_xc, xen_domid, XC_PAGE_SIZE,
                                               PROT_READ|PROT_WRITE, ioreq_pfn);
@@ -1121,7 +1191,7 @@ int xen_hvm_init(void)
                  errno, xen_xc);
     }
 
-    xc_get_hvm_param(xen_xc, xen_domid, HVM_PARAM_BUFIOREQ_PFN, &ioreq_pfn);
+    ioreq_pfn = xen_buffered_iopage();
     DPRINTF("buffered io page at pfn %lx\n", ioreq_pfn);
     state->buffered_io_page = xc_map_foreign_range(xen_xc, xen_domid, 
XC_PAGE_SIZE,
                                                    PROT_READ|PROT_WRITE, 
ioreq_pfn);
@@ -1142,12 +1212,14 @@ int xen_hvm_init(void)
         state->ioreq_local_port[i] = rc;
     }
 
-    rc = xc_get_hvm_param(xen_xc, xen_domid, HVM_PARAM_BUFIOREQ_EVTCHN,
-            &bufioreq_evtchn);
+    rc = xen_buffered_channel();
     if (rc < 0) {
         fprintf(stderr, "failed to get HVM_PARAM_BUFIOREQ_EVTCHN\n");
         return -1;
     }
+
+    bufioreq_evtchn = rc;
+
     rc = xc_evtchn_bind_interdomain(state->xce_handle, xen_domid,
             (uint32_t)bufioreq_evtchn);
     if (rc == -1) {
-- 
Julien Grall