[Qemu-devel] [PULL 2/3] xen-hvm: try to use xenforeignmemory_map_resource() to map ioreq pages

[Stefano Stabellini <sstabellini@kernel.org>]

From: Paul Durrant <paul.durrant@citrix.com>

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>
---
 configure                   |  5 ++++
 hw/i386/xen/trace-events    |  1 +
 hw/i386/xen/xen-hvm.c       | 66 ++++++++++++++++++++++++++++++++++-----------
 include/hw/xen/xen_common.h | 16 +++++++++++
 4 files changed, 73 insertions(+), 15 deletions(-)

diff --git a/configure b/configure
index a6a4616..be6edc7 100755
--- a/configure
+++ b/configure
@@ -2231,12 +2231,17 @@ EOF
 #undef XC_WANT_COMPAT_DEVICEMODEL_API
 #define __XEN_TOOLS__
 #include <xendevicemodel.h>
+#include <xenforeignmemory.h>
 int main(void) {
   xendevicemodel_handle *xd;
+  xenforeignmemory_handle *xfmem;
 
   xd = xendevicemodel_open(0, 0);
   xendevicemodel_pin_memory_cacheattr(xd, 0, 0, 0, 0);
 
+  xfmem = xenforeignmemory_open(0, 0);
+  xenforeignmemory_map_resource(xfmem, 0, 0, 0, 0, 0, NULL, 0, 0);
+
   return 0;
 }
 EOF
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;
diff --git a/include/hw/xen/xen_common.h b/include/hw/xen/xen_common.h
index bbf207d..93f631e 100644
--- a/include/hw/xen/xen_common.h
+++ b/include/hw/xen/xen_common.h
@@ -119,6 +119,22 @@ static inline int xendevicemodel_pin_memory_cacheattr(
     return xc_domain_pin_memory_cacheattr(xen_xc, domid, start, end, type);
 }
 
+typedef void xenforeignmemory_resource_handle;
+
+#define XENMEM_resource_ioreq_server 0
+
+#define XENMEM_resource_ioreq_server_frame_bufioreq 0
+#define XENMEM_resource_ioreq_server_frame_ioreq(n) (1 + (n))
+
+static inline xenforeignmemory_resource_handle *xenforeignmemory_map_resource(
+    xenforeignmemory_handle *fmem, domid_t domid, unsigned int type,
+    unsigned int id, unsigned long frame, unsigned long nr_frames,
+    void **paddr, int prot, int flags)
+{
+    errno = EOPNOTSUPP;
+    return NULL;
+}
+
 #endif /* CONFIG_XEN_CTRL_INTERFACE_VERSION < 41100 */
 
 #if CONFIG_XEN_CTRL_INTERFACE_VERSION < 41000
-- 
1.9.1