ukvm_hv_init() is now responsible for guest memory allocation

mato · mato · commit b6826b9ef480 · 2017-03-28T13:04:38.000+02:00
API change:

struct hv *ukvm_hv_init(size_t mem_size).

The caller may use (hv-&gt;mem) and (hv-&gt;mem_size) after calling this
function.

Rationale:

FreeBSD's vmm requires mapping guest memory from the vmm device (as
opposed to anonymous memory). Also, we may want to tweak mem_size based
on {arch,backend}-specific requirements so this gives us a way to do it.
We do however lose the option of mmap()ing arbitrary objects into guest
memory, too bad.
diff --git a/ukvm/ukvm.h b/ukvm/ukvm.h
@@ -68,9 +68,10 @@ inline void *ukvm_checked_gpa_p(struct ukvm_hv *hv, ukvm_gpa_t gpa, size_t sz,
 }
 
 /*
- * Initialise hypervisor, with (mem_size) bytes of guest memory at (mem).
+ * Initialise hypervisor, with (mem_size) bytes of guest memory.
+ * (hv->mem) and (hv->mem_size) are valid after this function has been called.
  */
-struct ukvm_hv *ukvm_hv_init(uint8_t *mem, size_t mem_size);
+struct ukvm_hv *ukvm_hv_init(size_t mem_size);
 
 /*
  * Initialise VCPU state with (gpa_ep) as the entry point and (gpa_kend) as the
diff --git a/ukvm/ukvm_hv_kvm.c b/ukvm/ukvm_hv_kvm.c
@@ -31,7 +31,7 @@
 #include "ukvm.h"
 #include "ukvm_hv_kvm.h"
 
-struct ukvm_hv *ukvm_hv_init(uint8_t *mem, size_t mem_size)
+struct ukvm_hv *ukvm_hv_init(size_t mem_size)
 {
     int ret;
 
@@ -70,18 +70,22 @@ struct ukvm_hv *ukvm_hv_init(uint8_t *mem, size_t mem_size)
     if (hvb->vcpurun == MAP_FAILED)
         err(1, "KVM: VCPU mmap failed");
 
+    hv->mem = mmap(NULL, mem_size, PROT_READ | PROT_WRITE,
+               MAP_SHARED | MAP_ANONYMOUS, -1, 0);
+    if (hv->mem == MAP_FAILED)
+        err(1, "Error allocating guest memory");
+    hv->mem_size = mem_size;
+
     struct kvm_userspace_memory_region region = {
         .slot = 0,
         .guest_phys_addr = 0,
-        .memory_size = mem_size,
-        .userspace_addr = (uint64_t)mem,
+        .memory_size = hv->mem_size,
+        .userspace_addr = (uint64_t)hv->mem,
     };
     ret = ioctl(hvb->vmfd, KVM_SET_USER_MEMORY_REGION, &region);
     if (ret == -1)
         err(1, "KVM: ioctl (SET_USER_MEMORY_REGION) failed");
 
     hv->b = hvb;
-    hv->mem = mem;
-    hv->mem_size = mem_size;
     return hv;
 }
diff --git a/ukvm/ukvm_main.c b/ukvm/ukvm_main.c
@@ -21,6 +21,7 @@
 #define _GNU_SOURCE
 #include <assert.h>
 #include <err.h>
+#include <libgen.h>
 #include <signal.h>
 #include <stdint.h>
 #include <stdio.h>
@@ -110,7 +111,6 @@ static void usage(const char *prog)
 
 int main(int argc, char **argv)
 {
-    uint8_t *mem;
     size_t mem_size = 0x20000000;
     ukvm_gpa_t gpa_ep, gpa_kend;
     const char *prog;
@@ -163,14 +163,9 @@ int main(int argc, char **argv)
     if (sigaction(SIGTERM, &sa, NULL) == -1)
         err(1, "Could not install signal handler");
 
-    mem = mmap(NULL, mem_size, PROT_READ | PROT_WRITE,
-               MAP_SHARED | MAP_ANONYMOUS, -1, 0);
-    if (mem == MAP_FAILED)
-        err(1, "Error allocating guest memory");
+    struct ukvm_hv *hv = ukvm_hv_init(mem_size);
 
-    ukvm_elf_load(elffile, mem, mem_size, &gpa_ep, &gpa_kend);
-
-    struct ukvm_hv *hv = ukvm_hv_init(mem, mem_size);
+    ukvm_elf_load(elffile, hv->mem, hv->mem_size, &gpa_ep, &gpa_kend);
 
     char *cmdline;
     ukvm_hv_vcpu_init(hv, gpa_ep, gpa_kend, &cmdline);
