[Xen-devel] [QEMU][RFC PATCH 6/6] xen: handle qemu disaggregation

[Julien Grall <julien.grall@xxxxxxxxxx>]

* Register QEMU in Xen as server
* Retrieve it's own shared pages
* Check if the page is already mapping before to populate

Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
---
 xen-all.c |   62 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 files changed, 59 insertions(+), 3 deletions(-)

diff --git a/xen-all.c b/xen-all.c
index 2d001b8..6b7acd7 100644
--- a/xen-all.c
+++ b/xen-all.c
@@ -61,6 +61,45 @@ static inline ioreq_t *xen_vcpu_ioreq(shared_iopage_t 
*shared_page, int vcpu)
 }
 #  define FMT_ioreq_size "u"
 #endif
+#if __XEN_LATEST_INTERFACE_VERSION__ < 0x00040200
+static inline unsigned long xen_buffered_iopage()
+{
+    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_BUFIOREQ_PFN, &pfn);
+
+    return pfn;
+}
+#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;
+}
+#endif
 
 #define BUFFER_IO_MAX_DELAY  100
 
@@ -349,6 +388,10 @@ void xen_ram_alloc(ram_addr_t ram_addr, ram_addr_t size, 
MemoryRegion *mr)
         return;
     }
 
+    if (xen_map_cache(ram_addr, size, 0)) {
+        return;
+    }
+
     trace_xen_ram_alloc(ram_addr, size);
 
     nr_pfn = size >> TARGET_PAGE_BITS;
@@ -1046,7 +1089,14 @@ static void xenstore_record_dm_state(struct xs_handle 
*xs, const char *state)
         exit(1);
     }
 
-    snprintf(path, sizeof (path), "/local/domain/0/device-model/%u/state", 
xen_domid);
+    if (!xen_dmid) {
+        snprintf(path, sizeof (path), "/local/domain/0/device-model/%u/state", 
xen_domid);
+    }
+    else {
+        snprintf(path, sizeof (path), "/local/domain/0/dms/%u/%u/state",
+                 xen_domid, xen_dmid);
+    }
+
     if (!xs_write(xs, XBT_NULL, path, state, strlen(state))) {
         fprintf(stderr, "error recording dm state\n");
         exit(1);
@@ -1077,6 +1127,7 @@ static void xen_change_state_handler(void *opaque, int 
running,
                                      RunState state)
 {
     if (running) {
+        is_running = 1;
         /* record state running */
         xenstore_record_dm_state(xenstore, "running");
     }
@@ -1137,7 +1188,12 @@ 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 = xc_hvm_register_ioreq_server(xen_xc, xen_domid, &serverid);
+
+    if (rc)
+        hw_error("registered server returned error %d", 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);
@@ -1146,7 +1202,7 @@ 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);
-- 
Julien Grall


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