xen-hvm: try to use xenforeignmemory_map_resource() to map ioreq pages

Xen 4.11 has a new API to directly map guest resources. Among the resources
that can be mapped using this API are ioreq pages.

This patch modifies QEMU to attempt to use the new API should it exist,
falling back to the previous mechanism if it is unavailable.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
Signed-off-by: Stefano Stabellini <sstabellini@kernel.org>

2 files changed, 52 insertions, 15 deletions

diff --git a/hw/i386/xen/trace-events b/hw/i386/xen/trace-events
index 8dab7bc..38616b6 100644
--- a/hw/i386/xen/trace-events
+++ b/hw/i386/xen/trace-events
@@ -15,6 +15,7 @@ cpu_ioreq_pio(void *req, uint32_t dir, uint32_t df, uint32_t data_is_ptr, uint64
 cpu_ioreq_pio_read_reg(void *req, uint64_t data, uint64_t addr, uint32_t size) "I/O=%p pio read reg data=0x%"PRIx64" port=0x%"PRIx64" size=%d"
 cpu_ioreq_pio_write_reg(void *req, uint64_t data, uint64_t addr, uint32_t size) "I/O=%p pio write reg data=0x%"PRIx64" port=0x%"PRIx64" size=%d"
 cpu_ioreq_move(void *req, uint32_t dir, uint32_t df, uint32_t data_is_ptr, uint64_t addr, uint64_t data, uint32_t count, uint32_t size) "I/O=%p copy dir=%d df=%d ptr=%d port=0x%"PRIx64" data=0x%"PRIx64" count=%d size=%d"
+xen_map_resource_ioreq(uint32_t id, void *addr) "id: %u addr: %p"
 
 # xen-mapcache.c
 xen_map_cache(uint64_t phys_addr) "want 0x%"PRIx64
diff --git a/hw/i386/xen/xen-hvm.c b/hw/i386/xen/xen-hvm.c
index 2afab65..54f99ab 100644
--- a/hw/i386/xen/xen-hvm.c
+++ b/hw/i386/xen/xen-hvm.c
@@ -1237,13 +1237,39 @@ static void xen_wakeup_notifier(Notifier *notifier, void *data)
 
 static int xen_map_ioreq_server(XenIOState *state)
 {
+    void *addr = NULL;
+    xenforeignmemory_resource_handle *fres;
     xen_pfn_t ioreq_pfn;
     xen_pfn_t bufioreq_pfn;
     evtchn_port_t bufioreq_evtchn;
     int rc;
 
+    /*
+     * Attempt to map using the resource API and fall back to normal
+     * foreign mapping if this is not supported.
+     */
+    QEMU_BUILD_BUG_ON(XENMEM_resource_ioreq_server_frame_bufioreq != 0);
+    QEMU_BUILD_BUG_ON(XENMEM_resource_ioreq_server_frame_ioreq(0) != 1);
+    fres = xenforeignmemory_map_resource(xen_fmem, xen_domid,
+                                         XENMEM_resource_ioreq_server,
+                                         state->ioservid, 0, 2,
+                                         &addr,
+                                         PROT_READ | PROT_WRITE, 0);
+    if (fres != NULL) {
+        trace_xen_map_resource_ioreq(state->ioservid, addr);
+        state->buffered_io_page = addr;
+        state->shared_page = addr + TARGET_PAGE_SIZE;
+    } else if (errno != EOPNOTSUPP) {
+        error_report("failed to map ioreq server resources: error %d handle=%p",
+                     errno, xen_xc);
+        return -1;
+    }
+
     rc = xen_get_ioreq_server_info(xen_domid, state->ioservid,
-                                   &ioreq_pfn, &bufioreq_pfn,
+                                   (state->shared_page == NULL) ?
+                                   &ioreq_pfn : NULL,
+                                   (state->buffered_io_page == NULL) ?
+                                   &bufioreq_pfn : NULL,
                                    &bufioreq_evtchn);
     if (rc < 0) {
         error_report("failed to get ioreq server info: error %d handle=%p",
@@ -1251,27 +1277,37 @@ static int xen_map_ioreq_server(XenIOState *state)
         return rc;
     }
 
-    DPRINTF("shared page at pfn %lx\n", ioreq_pfn);
-    DPRINTF("buffered io page at pfn %lx\n", bufioreq_pfn);
-    DPRINTF("buffered io evtchn is %x\n", bufioreq_evtchn);
-
-    state->shared_page = xenforeignmemory_map(xen_fmem, xen_domid,
-                                              PROT_READ | PROT_WRITE,
-                                              1, &ioreq_pfn, NULL);
     if (state->shared_page == NULL) {
-        error_report("map shared IO page returned error %d handle=%p",
-                     errno, xen_xc);
-        return -1;
+        DPRINTF("shared page at pfn %lx\n", ioreq_pfn);
+
+        state->shared_page = xenforeignmemory_map(xen_fmem, xen_domid,
+                                                  PROT_READ | PROT_WRITE,
+                                                  1, &ioreq_pfn, NULL);
+        if (state->shared_page == NULL) {
+            error_report("map shared IO page returned error %d handle=%p",
+                         errno, xen_xc);
+        }
     }
 
-    state->buffered_io_page = xenforeignmemory_map(xen_fmem, xen_domid,
-                                                   PROT_READ | PROT_WRITE,
-                                                   1, &bufioreq_pfn, NULL);
     if (state->buffered_io_page == NULL) {
-        error_report("map buffered IO page returned error %d", errno);
+        DPRINTF("buffered io page at pfn %lx\n", bufioreq_pfn);
+
+        state->buffered_io_page = xenforeignmemory_map(xen_fmem, xen_domid,
+                                                       PROT_READ | PROT_WRITE,
+                                                       1, &bufioreq_pfn,
+                                                       NULL);
+        if (state->buffered_io_page == NULL) {
+            error_report("map buffered IO page returned error %d", errno);
+            return -1;
+        }
+    }
+
+    if (state->shared_page == NULL || state->buffered_io_page == NULL) {
         return -1;
     }
 
+    DPRINTF("buffered io evtchn is %x\n", bufioreq_evtchn);
+
     state->bufioreq_remote_port = bufioreq_evtchn;
 
     return 0;