From: Peter Dinda <pdinda@northwestern.edu>
Date: Wed, 13 Mar 2013 15:51:29 +0000 (-0500)
Subject: User space library and example tool for accessing guest physical memory from host... 
X-Git-Url: http://v3vee.org/palacios/gitweb/gitweb.cgi?p=palacios.git;a=commitdiff_plain;h=ab570b923abf061acf9f495e5f4178e8c2af0fcc

User space library and example tool for accessing guest physical memory from host user space
---

diff --git a/linux_usr/Makefile b/linux_usr/Makefile
index e314209..609a4a4 100644
--- a/linux_usr/Makefile
+++ b/linux_usr/Makefile
@@ -39,7 +39,8 @@ BASE_EXECS = 	v3_mem \
 EXAMPLE_EXECS = v3_user_host_dev_example \
 		v3_os_debug \
 		v3_user_keyed_stream_example \
-		v3_user_keyed_stream_file 
+		v3_user_keyed_stream_file \
+		v3_guest_mem_example
 
 #
 # Currently experimental things
@@ -63,7 +64,7 @@ COPIED_EXECS = v3_x0vncserver v3_x0gui
 #
 # Libraries that we need to build
 #
-LIBS = libv3_user_host_dev.a libv3_user_keyed_stream.a libv3_ctrl.a
+LIBS = libv3_user_host_dev.a libv3_user_keyed_stream.a libv3_ctrl.a libv3_guest_mem.a
 
 BUILD_EXECS = $(BASE_EXECS) $(EXAMPLE_EXECS) $(EXPERIMENTAL_EXECS) 
 BUILD_LIBS = $(LIBS)
@@ -149,6 +150,17 @@ v3_user_keyed_stream_file : v3_user_keyed_stream_file.c libv3_user_keyed_stream.
 	$(CC) $(CFLAGS) $< -I../linux_module -L. -lv3_user_keyed_stream -o $@
 
 
+# guest memory access by mmap and example
+#
+libv3_guest_mem.a : v3_guest_mem.c v3_guest_mem.h v3_ctrl.h
+	$(CC) $(CFLAGS) -c v3_guest_mem.c 
+	$(AR) ruv libv3_guest_mem.a v3_guest_mem.o
+	rm -f v3_guest_mem.o
+
+v3_guest_mem_example : v3_guest_mem_example.c libv3_guest_mem.a
+	$(CC) $(CFLAGS) $< -L. -lv3_guest_mem -o $@
+
+
 
 #
 # VNC support is compiled separately
diff --git a/linux_usr/v3_guest_mem.c b/linux_usr/v3_guest_mem.c
new file mode 100644
index 0000000..24877eb
--- /dev/null
+++ b/linux_usr/v3_guest_mem.c
@@ -0,0 +1,124 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <fcntl.h>
+#include <sys/mman.h>
+
+#include "v3_guest_mem.h"
+
+
+#define GUEST_FILE "/proc/v3vee/v3-guests"
+//#define GUEST_FILE "/441/pdinda/test.proc"
+#define MAXLINE 65536
+
+struct v3_guest_mem_map * v3_guest_mem_get_map(char *vmdev)
+{
+  FILE *f;
+  char buf[MAXLINE];
+  char name[MAXLINE];
+  char dev[MAXLINE];
+  char state[MAXLINE];
+  uint64_t start, end;
+  
+
+  if (!(f=fopen(GUEST_FILE,"r"))) { 
+    fprintf(stderr,"Cannot open %s - is Palacios active?\n",GUEST_FILE);
+    return 0;
+  }
+  
+  // This is using the current "single memory region" model
+  // and will change when /proc convention changes to conform to
+  // multiple region model
+  while (fgets(buf,MAXLINE,f)) {
+    if (sscanf(buf,
+	       "%s %s %s [0x%llx-0x%llx]",
+	       name,
+	       dev,
+	       state,
+	       &start,
+	       &end)!=5) { 
+      fprintf(stderr, "Cannot parse following line\n%s\n",buf);
+      fclose(f);
+      return 0;
+    }
+    if (!strcmp(dev,vmdev)) { 
+      struct v3_guest_mem_map *m = 
+	(struct v3_guest_mem_map *) malloc(sizeof(struct v3_guest_mem_map)+1*sizeof(struct v3_guest_mem_block));
+      if (!m) { 
+	fprintf(stderr, "Cannot allocate space\n");
+	fclose(f);
+	return 0;
+      }
+
+      memset(m,0,sizeof(struct v3_guest_mem_map)+1*sizeof(struct v3_guest_mem_block));
+      
+      m->numblocks=1;
+      m->block[0].gpa=0;
+      m->block[0].hpa=(void*)start;
+      m->block[0].numpages = (end-start+1) / 4096;
+      fclose(f);
+      return m;
+    }
+  }
+  
+  fprintf(stderr,"%s not found\n",vmdev);
+  fclose(f);
+  return 0;
+
+}
+
+int v3_map_guest_mem(struct v3_guest_mem_map *map)
+{
+  uint64_t i;
+  
+  if (map->fd) {
+    fprintf(stderr, "Memory appears to already be mapped\n");
+    return -1;
+  }
+
+  map->fd = open("/dev/mem", O_RDWR | O_SYNC);
+
+  if (map->fd<0) { 
+    fprintf(stderr, "Cannot open /dev/mem - are you root?\n");
+    map->fd=0;
+    return -1;
+  }
+
+  for (i=0; i<map->numblocks; i++) { 
+    fprintf(stderr,"Mapping %llu bytes of /dev/mem offset 0x%llx\n",
+	    map->block[i].numpages*4096, (off_t)(map->block[i].hpa));
+    map->block[i].uva = mmap(NULL, 
+			     map->block[i].numpages*4096,
+			     PROT_READ | PROT_WRITE, 
+			     MAP_SHARED, 
+			     map->fd, 
+			     (off_t) (map->block[i].hpa));
+
+    if (map->block[i].uva == MAP_FAILED) { 
+      fprintf(stderr, "Failed to map block %llu\n",i);
+      map->block[i].uva=0;
+      v3_unmap_guest_mem(map);
+      return -1;
+    }
+  }
+   
+  return 0;
+    
+}
+
+int v3_unmap_guest_mem(struct v3_guest_mem_map *map)
+{
+  uint64_t i;
+
+  for (i=0; i<map->numblocks; i++) { 
+    if (map->block[i].uva) { 
+      munmap(map->block[i].uva, map->block[i].numpages*4096);
+      map->block[i].uva=0;
+    }
+  }
+  if (map->fd) { 
+    close(map->fd);
+    map->fd=0;
+  }
+  return 0;
+}
diff --git a/linux_usr/v3_guest_mem.h b/linux_usr/v3_guest_mem.h
new file mode 100644
index 0000000..907502c
--- /dev/null
+++ b/linux_usr/v3_guest_mem.h
@@ -0,0 +1,33 @@
+#ifndef _V3_GUEST_MEM_
+#define _V3_GUEST_MEM_
+
+#include <stdint.h>
+#include "v3_ctrl.h"
+
+struct v3_guest_mem_block {
+  void     *gpa;      // guest physical address is
+  void     *hpa;      // mapped to this host physical address
+  void     *uva;      // which is mapped here in this process
+  uint64_t numpages;  // this many 4K pages
+};
+
+// Whole memory map of guest's physical memory
+// that is backed by host physical memory (ie, everything we 
+// can read or write from the host user space)
+struct v3_guest_mem_map {
+  int      fd;              // used by mmap
+  uint64_t numblocks;
+  struct v3_guest_mem_block block[0];
+};
+
+// This function gets the basic memory map, but does not map it
+struct v3_guest_mem_map * v3_guest_mem_get_map(char *vmdev);
+// This function mmaps it into the guest address space
+// and fills out the "myaddr" fields
+int v3_map_guest_mem(struct v3_guest_mem_map *map);
+// This function unmaps it - it assumes myaddrs are valid
+int v3_unmap_guest_mem(struct v3_guest_mem_map *map);
+
+
+#endif
+
diff --git a/linux_usr/v3_guest_mem_example.c b/linux_usr/v3_guest_mem_example.c
new file mode 100644
index 0000000..4dd6235
--- /dev/null
+++ b/linux_usr/v3_guest_mem_example.c
@@ -0,0 +1,96 @@
+#include <stdint.h>
+#include <stdio.h>
+
+#include "v3_guest_mem.h"
+
+void usage() 
+{
+  fprintf(stderr,"usage: v3_guest_mem_example /dev/v3-vmN read|write gpa_hex numbytes [<data]\n");
+}
+
+int main(int argc, char *argv[])
+{
+  char *vmdev;
+  enum {READ, WRITE} mode;
+  uint64_t gpa;
+  uint64_t numbytes;
+  struct v3_guest_mem_map *map;
+  uint64_t i;
+    
+  if (argc!=5) { 
+    usage();
+    return -1;
+  }
+
+  vmdev=argv[1];
+  
+  if (toupper(argv[2][0])=='R') { 
+    mode=READ;
+  } else if (toupper(argv[2][0]=='W')) {
+    mode=WRITE;
+  } else {
+    fprintf(stderr,"Unknown mode %s\n", argv[2]);
+    return -1;
+  }
+  
+  if (sscanf(argv[3],"%llx",&gpa)!=1) { 
+    fprintf(stderr,"Don't understand address %s\n",argv[3]);
+    return -1;
+  }
+
+  numbytes=atol(argv[4]);
+
+  if (!(map=v3_guest_mem_get_map(vmdev))) { 
+    fprintf(stderr,"Cannot get guest memory map for %s\n",vmdev);
+    return -1;
+  }
+  
+  for (i=0; i< map->numblocks; i++) { 
+    fprintf(stderr,"Region %llu: gpa=%p, hpa=%p, numpages=%llu\n", 
+	    i, map->block[i].gpa, map->block[i].hpa, map->block[i].numpages);
+  }  
+
+  if (map->numblocks!=1) { 
+    fprintf(stderr,"Don't handle multiregion map yet\n");
+    return -1;
+  }
+  
+  if (!( ((void*)(gpa) >= map->block[0].gpa) &&
+	 (numbytes <= map->block[0].numpages*4096))) { 
+    fprintf(stderr,"request (%p to %p) is out of range\n",
+	    gpa, gpa+numbytes-1);
+    return -1;
+  }
+
+  if (v3_map_guest_mem(map)) { 
+    fprintf(stderr, "Cannot map guest memory\n");
+    free(map);
+    return -1;
+  }
+
+  for (i=0; i<numbytes; i++) {
+    uint8_t cur;
+    if (mode==WRITE) {
+      if (read(0,&cur,1)!=1) { 
+	fprintf(stderr,"can't get data from stdin for byte %llu\n", i);
+	break;
+      }
+      *((uint8_t*)(map->block[0].uva+gpa+i))=cur;
+    } else {
+      cur = *((uint8_t *)(map->block[0].uva+gpa+i));
+      //      fprintf(stderr, "read %llu from uva=%p, ptr=%p\n",i,map->block[0].uva, map->block[0].uva+gpa+i);
+      if (write(1,&cur,1)!=1) { 
+	fprintf(stderr,"can't write data to stdout for byte %llu\n", i);
+	break;
+      }
+    }
+  }
+      
+
+  if (v3_unmap_guest_mem(map)) { 
+    fprintf(stderr, "Cannot unmap guest memory\n");
+    free(map);
+    return -1;
+  }
+}
+