[Xen-devel] [PATCH v3 03/12] tools/libxenforeignmemory: add support for resource mapping

[Paul Durrant <paul.durrant@xxxxxxxxxx>]

A previous patch introduced a new HYPERVISOR_memory_op to acquire guest
resources for direct priv-mapping.

This patch adds new functionality into libxenforeignmemory to make use
of a new privcmd ioctl [1] that uses the new memory op to make such
resources available via mmap(2).

[1] 
http://xenbits.xen.org/gitweb/?p=people/pauldu/linux.git;a=commit;h=ce59a05e6712

Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
---
Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Cc: Wei Liu <wei.liu2@xxxxxxxxxx>

v2:
 - Bump minor version up to 3.
---
 tools/include/xen-sys/Linux/privcmd.h              | 11 +++++
 tools/libs/foreignmemory/Makefile                  |  2 +-
 tools/libs/foreignmemory/core.c                    | 51 ++++++++++++++++++++++
 .../libs/foreignmemory/include/xenforeignmemory.h  | 39 +++++++++++++++++
 tools/libs/foreignmemory/libxenforeignmemory.map   |  5 +++
 tools/libs/foreignmemory/linux.c                   | 45 +++++++++++++++++++
 tools/libs/foreignmemory/private.h                 | 30 +++++++++++++
 7 files changed, 182 insertions(+), 1 deletion(-)

diff --git a/tools/include/xen-sys/Linux/privcmd.h 
b/tools/include/xen-sys/Linux/privcmd.h
index 732ff7c15a..9531b728f9 100644
--- a/tools/include/xen-sys/Linux/privcmd.h
+++ b/tools/include/xen-sys/Linux/privcmd.h
@@ -86,6 +86,15 @@ typedef struct privcmd_dm_op {
        const privcmd_dm_op_buf_t __user *ubufs;
 } privcmd_dm_op_t;
 
+typedef struct privcmd_mmap_resource {
+       domid_t dom;
+       __u32 type;
+       __u32 id;
+       __u32 idx;
+       __u64 num;
+       __u64 addr;
+} privcmd_mmap_resource_t;
+
 /*
  * @cmd: IOCTL_PRIVCMD_HYPERCALL
  * @arg: &privcmd_hypercall_t
@@ -103,5 +112,7 @@ typedef struct privcmd_dm_op {
        _IOC(_IOC_NONE, 'P', 5, sizeof(privcmd_dm_op_t))
 #define IOCTL_PRIVCMD_RESTRICT                                 \
        _IOC(_IOC_NONE, 'P', 6, sizeof(domid_t))
+#define IOCTL_PRIVCMD_MMAP_RESOURCE                            \
+       _IOC(_IOC_NONE, 'P', 7, sizeof(privcmd_mmap_resource_t))
 
 #endif /* __LINUX_PUBLIC_PRIVCMD_H__ */
diff --git a/tools/libs/foreignmemory/Makefile 
b/tools/libs/foreignmemory/Makefile
index b110076621..7eb59c78cb 100644
--- a/tools/libs/foreignmemory/Makefile
+++ b/tools/libs/foreignmemory/Makefile
@@ -2,7 +2,7 @@ XEN_ROOT = $(CURDIR)/../../..
 include $(XEN_ROOT)/tools/Rules.mk
 
 MAJOR    = 1
-MINOR    = 2
+MINOR    = 3
 SHLIB_LDFLAGS += -Wl,--version-script=libxenforeignmemory.map
 
 CFLAGS   += -Werror -Wmissing-prototypes
diff --git a/tools/libs/foreignmemory/core.c b/tools/libs/foreignmemory/core.c
index a6897dc561..838640aa84 100644
--- a/tools/libs/foreignmemory/core.c
+++ b/tools/libs/foreignmemory/core.c
@@ -17,6 +17,8 @@
 #include <assert.h>
 #include <errno.h>
 
+#include <sys/mman.h>
+
 #include "private.h"
 
 xenforeignmemory_handle *xenforeignmemory_open(xentoollog_logger *logger,
@@ -120,6 +122,55 @@ int xenforeignmemory_restrict(xenforeignmemory_handle 
*fmem,
     return osdep_xenforeignmemory_restrict(fmem, domid);
 }
 
+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)
+{
+    xenforeignmemory_resource_handle *fres;
+    int rc;
+
+    /* Check flags only contains POSIX defined values */
+    if ( flags & ~(MAP_SHARED | MAP_PRIVATE) )
+    {
+        errno = EINVAL;
+        return NULL;
+    }
+
+    fres = calloc(1, sizeof(*fres));
+    if ( !fres )
+        return NULL;
+
+    fres->domid = domid;
+    fres->type = type;
+    fres->id = id;
+    fres->frame = frame;
+    fres->nr_frames = nr_frames;
+    fres->addr = *paddr;
+    fres->prot = prot;
+    fres->flags = flags;
+
+    rc = osdep_xenforeignmemory_map_resource(fmem, fres);
+    if ( rc )
+        goto fail;
+
+    *paddr = fres->addr;
+    return fres;
+
+fail:
+    free(fres);
+
+    return NULL;
+}
+
+void xenforeignmemory_unmap_resource(
+    xenforeignmemory_handle *fmem, xenforeignmemory_resource_handle *fres)
+{
+    osdep_xenforeignmemory_unmap_resource(fmem, fres);
+
+    free(fres);
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/tools/libs/foreignmemory/include/xenforeignmemory.h 
b/tools/libs/foreignmemory/include/xenforeignmemory.h
index f4814c390f..21ec3df6df 100644
--- a/tools/libs/foreignmemory/include/xenforeignmemory.h
+++ b/tools/libs/foreignmemory/include/xenforeignmemory.h
@@ -138,6 +138,45 @@ int xenforeignmemory_unmap(xenforeignmemory_handle *fmem,
 int xenforeignmemory_restrict(xenforeignmemory_handle *fmem,
                               domid_t domid);
 
+typedef struct xenforeignmemory_resource_handle 
xenforeignmemory_resource_handle;
+
+/**
+ * This function maps a guest resource.
+ *
+ * @parm fmem handle to the open foreignmemory interface
+ * @parm domid the domain id
+ * @parm type the resource type
+ * @parm id the type-specific resource identifier
+ * @parm frame base frame index within the resource
+ * @parm nr_frames number of frames to map
+ * @parm paddr pointer to an address passed through to mmap(2)
+ * @parm prot passed through to mmap(2)
+ * @parm POSIX-only flags passed through to mmap(2)
+ * @return pointer to foreignmemory resource handle on success, NULL on
+ *         failure
+ *
+ * *paddr is used, on entry, as a hint address for foreign map placement
+ * (see mmap(2)) so should be set to NULL if no specific placement is
+ * required. On return *paddr contains the address where the resource is
+ * mapped.
+ * As for xenforeignmemory_map2() flags is a set of additional flags
+ * for mmap(2). Not all of the flag combinations are possible due to
+ * implementation details on different platforms.
+ */
+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);
+
+/**
+ * This function releases a previously acquired resource.
+ *
+ * @parm fmem handle to the open foreignmemory interface
+ * @parm fres handle to the acquired resource
+ */
+void xenforeignmemory_unmap_resource(
+    xenforeignmemory_handle *fmem, xenforeignmemory_resource_handle *fres);
+
 #endif
 
 /*
diff --git a/tools/libs/foreignmemory/libxenforeignmemory.map 
b/tools/libs/foreignmemory/libxenforeignmemory.map
index 716ecaf15c..d5323c87d9 100644
--- a/tools/libs/foreignmemory/libxenforeignmemory.map
+++ b/tools/libs/foreignmemory/libxenforeignmemory.map
@@ -14,3 +14,8 @@ VERS_1.2 {
        global:
                xenforeignmemory_map2;
 } VERS_1.1;
+VERS_1.3 {
+       global:
+               xenforeignmemory_map_resource;
+               xenforeignmemory_unmap_resource;
+} VERS_1.2;
diff --git a/tools/libs/foreignmemory/linux.c b/tools/libs/foreignmemory/linux.c
index 374e45aed5..4447723cb1 100644
--- a/tools/libs/foreignmemory/linux.c
+++ b/tools/libs/foreignmemory/linux.c
@@ -277,6 +277,51 @@ int 
osdep_xenforeignmemory_restrict(xenforeignmemory_handle *fmem,
     return ioctl(fmem->fd, IOCTL_PRIVCMD_RESTRICT, &domid);
 }
 
+void osdep_xenforeignmemory_unmap_resource(
+    xenforeignmemory_handle *fmem, xenforeignmemory_resource_handle *fres)
+{
+    (void) munmap(fres->addr, fres->nr_frames << PAGE_SHIFT);
+}
+
+int osdep_xenforeignmemory_map_resource(
+    xenforeignmemory_handle *fmem, xenforeignmemory_resource_handle *fres)
+{
+    privcmd_mmap_resource_t mr;
+    int rc;
+
+    fres->addr = mmap(fres->addr, fres->nr_frames << PAGE_SHIFT,
+                      fres->prot, fres->flags | MAP_SHARED, fmem->fd, 0);
+    if ( fres->addr == MAP_FAILED )
+        return -1;
+
+    memset(&mr, 0, sizeof(mr));
+    mr.dom = fres->domid;
+    mr.type = fres->type;
+    mr.id = fres->id;
+    mr.idx = fres->frame;
+    mr.num = fres->nr_frames;
+    mr.addr = (uintptr_t)fres->addr;
+
+    rc = ioctl(fmem->fd, IOCTL_PRIVCMD_MMAP_RESOURCE, &mr);
+    if ( rc )
+    {
+        int saved_errno;
+
+        if ( errno != ENOTTY )
+            PERROR("ioctl failed");
+        else
+            errno = EOPNOTSUPP;
+
+        saved_errno = errno;
+        osdep_xenforeignmemory_unmap_resource(fmem, fres);
+        errno = saved_errno;
+
+        return -1;
+    }
+
+    return 0;
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/tools/libs/foreignmemory/private.h 
b/tools/libs/foreignmemory/private.h
index c5c07cc4c4..9ff94b724d 100644
--- a/tools/libs/foreignmemory/private.h
+++ b/tools/libs/foreignmemory/private.h
@@ -42,6 +42,36 @@ void *compat_mapforeign_batch(xenforeignmem_handle *fmem, 
uint32_t dom,
                               xen_pfn_t *arr, int num);
 #endif
 
+struct xenforeignmemory_resource_handle {
+    domid_t domid;
+    unsigned int type;
+    unsigned int id;
+    unsigned long frame;
+    unsigned long nr_frames;
+    void *addr;
+    int prot;
+    int flags;
+};
+
+#ifndef __linux__
+static inline int osdep_xenforeignmemory_map_resource(
+    xenforeignmemory_handle *fmem, xenforeignmemory_resource_handle *fres)
+{
+    errno = EOPNOTSUPP;
+    return -1;
+}
+
+static inline void osdep_xenforeignmemory_unmap_resource(
+    xenforeignmemory_handle *fmem, xenforeignmemory_resource_handle *fres)
+{
+}
+#else
+int osdep_xenforeignmemory_map_resource(
+    xenforeignmemory_handle *fmem, xenforeignmemory_resource_handle *fres);
+void osdep_xenforeignmemory_unmap_resource(
+    xenforeignmemory_handle *fmem, xenforeignmemory_resource_handle *fres);
+#endif
+
 #define PERROR(_f...) \
     xtl_log(fmem->logger, XTL_ERROR, errno, "xenforeignmemory", _f)
 
-- 
2.11.0


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