[PATCH] QEMU/KVM: large page support

Marcelo Tosatti
2008-02-23T14:48:12Z

Add an option so the user can specify the hugetlbfs mounted path, with
fallback to 4k pages on error.

Align the 4GB+ memslot on large page boundary.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

Index: kvm-userspace.gitpara/qemu/hw/pc.c
===================================================================
--- kvm-userspace.gitpara.orig/qemu/hw/pc.c
+++ kvm-userspace.gitpara/qemu/hw/pc.c
@@ -854,6 +854,15 @@ static void pc_init1(ram_addr_t ram_size
/* above 4giga memory allocation */
if (above_4g_mem_size > 0) {
ram_addr = qemu_ram_alloc(above_4g_mem_size);
+ if (hpagesize) {
+ if (ram_addr & (hpagesize-1)) {
+ unsigned long aligned_addr;
+ aligned_addr = (ram_addr + hpagesize - 1) &
+ ~(hpagesize-1);
+ qemu_ram_alloc(aligned_addr - ram_addr);
+ ram_addr = aligned_addr;
+ }
+ }
cpu_register_physical_memory(0x100000000, above_4g_mem_size, ram_addr);

if (kvm_enabled())
Index: kvm-userspace.gitpara/qemu/sysemu.h
===================================================================
--- kvm-userspace.gitpara.orig/qemu/sysemu.h
+++ kvm-userspace.gitpara/qemu/sysemu.h
@@ -99,6 +99,7 @@ extern int no_quit;
extern int semihosting_enabled;
extern int autostart;
extern int old_param;
+extern int hpagesize;
extern const char *bootp_filename;

Index: kvm-userspace.gitpara/qemu/vl.c
===================================================================
--- kvm-userspace.gitpara.orig/qemu/vl.c
+++ kvm-userspace.gitpara/qemu/vl.c
@@ -237,6 +237,9 @@ int semihosting_enabled = 0;
int autostart = 1;
int time_drift_fix = 0;
unsigned int kvm_shadow_memory = 0;
+const char *hugetlbpath = NULL;
+const char *hugetlbfile = NULL;
+int hpagesize = 0;
const char *cpu_vendor_string;
#ifdef TARGET_ARM
int old_param = 0;
@@ -8071,6 +8074,7 @@ static void help(int exitcode)
#endif
"-tdf inject timer interrupts that got lost\n"
"-kvm-shadow-memory megs set the amount of shadow pages to be allocated\n"
+ "-hugetlb-path set the path to hugetlbfs mounted directory, also enables allocation of guest memory with huge pages\n"
"-option-rom rom load a file, rom, into the option ROM space\n"
#ifdef TARGET_SPARC
"-prom-env variable=value set OpenBIOS nvram variables\n"
@@ -8189,6 +8193,7 @@ enum {
QEMU_OPTION_incoming,
QEMU_OPTION_tdf,
QEMU_OPTION_kvm_shadow_memory,
+ QEMU_OPTION_hugetlbpath,
};

typedef struct QEMUOption {
@@ -8310,6 +8315,7 @@ const QEMUOption qemu_options[] = {
#endif
{ "clock", HAS_ARG, QEMU_OPTION_clock },
{ "startdate", HAS_ARG, QEMU_OPTION_startdate },
+ { "hugetlb-path", HAS_ARG, QEMU_OPTION_hugetlbpath },
{ NULL },
};

@@ -8561,6 +8567,94 @@ void qemu_get_launch_info(int *argc, cha
*opt_incoming = incoming;
}

+
+static int gethugepagesize(void)
+{
+ int ret, fd;
+ char buf[4096];
+ char *needle = "Hugepagesize:";
+ char *size;
+ unsigned long hugepagesize;
+
+ fd = open("/proc/meminfo", O_RDONLY);
+ if (fd < 0) {
+ perror("open");
+ exit(0);
+ }
+
+ ret = read(fd, buf, sizeof(buf));
+ if (ret < 0) {
+ perror("read");
+ exit(0);
+ }
+
+ size = strstr(buf, needle);
+ if (!size)
+ return 0;
+ size += strlen(needle);
+ hugepagesize = strtol(size, NULL, 0);
+ return hugepagesize;
+}
+
+void cleanup_hugetlb(void)
+{
+ if (hugetlbfile)
+ unlink(hugetlbfile);
+}
+
+void *alloc_huge_area(unsigned long memory, const char *path)
+{
+ void *area;
+ int fd;
+ char *filename;
+ char *tmpfile = "/kvm.XXXXXX";
+
+ filename = qemu_malloc(4096);
+ if (!filename)
+ return NULL;
+
+ memset(filename, 0, 4096);
+ strncpy(filename, path, 4096 - strlen(tmpfile) - 1);
+ strcat(filename, tmpfile);
+
+ hpagesize = gethugepagesize() * 1024;
+ if (!hpagesize)
+ return NULL;
+
+ mkstemp(filename);
+ fd = open(filename, O_RDWR);
+ if (fd < 0) {
+ perror("open");
+ hpagesize = 0;
+ exit(0);
+ }
+ memory = (memory+hpagesize-1) & ~(hpagesize-1);
+
+ area = mmap(0, memory, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
+ if (area == MAP_FAILED) {
+ perror("mmap");
+ hpagesize = 0;
+ exit(0);
+ }
+
+ hugetlbfile = filename;
+ atexit(cleanup_hugetlb);
+
+ return area;
+}
+
+void *qemu_alloc_physram(unsigned long memory)
+{
+ void *area = NULL;
+
+ if (hugetlbpath)
+ area = alloc_huge_area(memory, hugetlbpath);
+ if (!area)
+ area = qemu_vmalloc(memory);
+
+ return area;
+}
+
int main(int argc, char **argv)
{
#ifdef CONFIG_GDBSTUB
@@ -9159,6 +9253,9 @@ int main(int argc, char **argv)
case QEMU_OPTION_kvm_shadow_memory:
kvm_shadow_memory = (int64_t)atoi(optarg) * 1024 * 1024 / 4096;
break;
+ case QEMU_OPTION_hugetlbpath:
+ hugetlbpath = optarg;
+ break;
case QEMU_OPTION_name:
qemu_name = optarg;
break;
@@ -9394,7 +9491,7 @@ int main(int argc, char **argv)

ret = kvm_qemu_check_extension(KVM_CAP_USER_MEMORY);
if (ret) {
- phys_ram_base = qemu_vmalloc(phys_ram_size);
+ phys_ram_base = qemu_alloc_physram(phys_ram_size);
if (!phys_ram_base) {
fprintf(stderr, "Could not allocate physical memory\n");
exit(1);