KVM expects full pages, and this is documented precisely nowhere. Sigh.

diff --git a/main.c b/main.c
index f4e8b586a28c8c41cc85abe016f9a7b5fb330e56..0b9263f8b3107e84d8d0f9848f2368adc01a94ef 100644 (file)
--- a/main.c
+++ b/main.c
@@ -31,6 +31,7 @@
 #include <sys/types.h>
 #include <unistd.h>
 
+#define PAGE_SIZE (64 * 1024) // assumption
 #define MAXDUMPS 10
 #define RAMSIZE (64 * 1024 * 1024)
 #define PROGSTART 0x20000000
@@ -333,7 +334,9 @@ int main(int argc, char **argv) {
 
        printf("Loading binary %u bytes\n", binlen);
 
-       if (posix_memalign((void **) &progmem, 64 * 1024, binlen))
+       const unsigned progmemlen = (binlen + (PAGE_SIZE - 1)) & ~(PAGE_SIZE - 1);
+
+       if (posix_memalign((void **) &progmem, 64 * 1024, progmemlen))
                abort();
 
        if (fread(progmem, binlen, 1, binary) != 1)
@@ -370,7 +373,7 @@ int main(int argc, char **argv) {
 
        region.slot = 1;
        region.guest_phys_addr = PROGSTART;
-       region.memory_size = binlen;
+       region.memory_size = progmemlen;
        region.userspace_addr = (uint64_t) progmem;
        region.flags = KVM_MEM_READONLY;
        if (ioctl(vmfd, KVM_SET_USER_MEMORY_REGION, &region) == -1)