[PATCH v2 4/8] KVM: selftests: Add memory size parameter to the demand paging test

Ben Gardon
2019-12-16T21:36:35Z

Add an argument to allow the demand paging test to work on larger and
smaller guest sizes.

Signed-off-by: Ben Gardon <bgardon@google.com>
---
.../selftests/kvm/demand_paging_test.c | 56 ++++++++++++-------
1 file changed, 35 insertions(+), 21 deletions(-)

diff --git a/tools/testing/selftests/kvm/demand_paging_test.c b/tools/testing/selftests/kvm/demand_paging_test.c
index 11de5b58995fb..4aa90a3fce99c 100644
--- a/tools/testing/selftests/kvm/demand_paging_test.c
+++ b/tools/testing/selftests/kvm/demand_paging_test.c
@@ -32,6 +32,8 @@
/* Default guest test virtual memory offset */
#define DEFAULT_GUEST_TEST_MEM 0xc0000000

+#define DEFAULT_GUEST_TEST_MEM_SIZE (1 << 30) /* 1G */
+
/*
* Guest/Host shared variables. Ensure addr_gva2hva() and/or
* sync_global_to/from_guest() are used when accessing from
@@ -264,11 +266,10 @@ static int setup_demand_paging(struct kvm_vm *vm,
return 0;
}

-#define GUEST_MEM_SHIFT 30 /* 1G */
#define PAGE_SHIFT_4K 12

static void run_test(enum vm_guest_mode mode, bool use_uffd,
- useconds_t uffd_delay)
+ useconds_t uffd_delay, uint64_t guest_memory_bytes)
{
pthread_t vcpu_thread;
pthread_t uffd_handler_thread;
@@ -276,33 +277,40 @@ static void run_test(enum vm_guest_mode mode, bool use_uffd,
int r;

/*
- * We reserve page table for 2 times of extra dirty mem which
- * will definitely cover the original (1G+) test range. Here
- * we do the calculation with 4K page size which is the
- * smallest so the page number will be enough for all archs
- * (e.g., 64K page size guest will need even less memory for
- * page tables).
+ * We reserve page table for twice the ammount of memory we intend
+ * to use in the test region for demand paging. Here we do the
+ * calculation with 4K page size which is the smallest so the page
+ * number will be enough for all archs. (e.g., 64K page size guest
+ * will need even less memory for page tables).
*/
vm = create_vm(mode, VCPU_ID,
- 2ul << (GUEST_MEM_SHIFT - PAGE_SHIFT_4K),
+ (2 * guest_memory_bytes) >> PAGE_SHIFT_4K,
guest_code);

guest_page_size = vm_get_page_size(vm);
- /*
- * A little more than 1G of guest page sized pages. Cover the
- * case where the size is not aligned to 64 pages.
- */
- guest_num_pages = (1ul << (GUEST_MEM_SHIFT -
- vm_get_page_shift(vm))) + 16;
+
+ TEST_ASSERT(guest_memory_bytes % guest_page_size == 0,
+ "Guest memory size is not guest page size aligned.");
+
+ guest_num_pages = guest_memory_bytes / guest_page_size;
+
#ifdef __s390x__
/* Round up to multiple of 1M (segment size) */
guest_num_pages = (guest_num_pages + 0xff) & ~0xffUL;
#endif
+ /*
+ * If there should be more memory in the guest test region than there
+ * can be pages in the guest, it will definitely cause problems.
+ */
+ TEST_ASSERT(guest_num_pages < vm_get_max_gfn(vm),
+ "Requested more guest memory than address space allows.\n"
+ " guest pages: %lx max gfn: %lx\n",
+ guest_num_pages, vm_get_max_gfn(vm));

host_page_size = getpagesize();
- host_num_pages = (guest_num_pages * guest_page_size) / host_page_size +
- !!((guest_num_pages * guest_page_size) %
- host_page_size);
+ TEST_ASSERT(guest_memory_bytes % host_page_size == 0,
+ "Guest memory size is not host page size aligned.");
+ host_num_pages = guest_memory_bytes / host_page_size;

guest_test_phys_mem = (vm_get_max_gfn(vm) - guest_num_pages) *
guest_page_size;
@@ -381,7 +389,8 @@ static void help(char *name)
int i;

puts("");
- printf("usage: %s [-h] [-m mode] [-u] [-d uffd_delay_usec]\n", name);
+ printf("usage: %s [-h] [-m mode] [-u] [-d uffd_delay_usec]\n"
+ " [-b bytes test memory]\n", name);
printf(" -m: specify the guest mode ID to test\n"
" (default: test all supported modes)\n"
" This option may be used multiple times.\n"
@@ -395,6 +404,8 @@ static void help(char *name)
printf(" -d: add a delay in usec to the User Fault\n"
" FD handler to simulate demand paging\n"
" overheads. Ignored without -u.\n");
+ printf(" -b: specify the number of bytes of memory which should be\n"
+ " allocated to the guest.\n");
puts("");
exit(0);
}
@@ -402,6 +413,7 @@ static void help(char *name)
int main(int argc, char *argv[])
{
bool mode_selected = false;
+ uint64_t guest_memory_bytes = DEFAULT_GUEST_TEST_MEM_SIZE;
unsigned int mode;
int opt, i;
bool use_uffd = false;
@@ -414,7 +426,7 @@ int main(int argc, char *argv[])
vm_guest_mode_params_init(VM_MODE_P40V48_4K, true, true);
#endif

- while ((opt = getopt(argc, argv, "hm:ud:")) != -1) {
+ while ((opt = getopt(argc, argv, "hm:ud:b:")) != -1) {
switch (opt) {
case 'm':
if (!mode_selected) {
@@ -435,6 +447,8 @@ int main(int argc, char *argv[])
TEST_ASSERT(uffd_delay >= 0,
"A negative UFFD delay is not supported.");
break;
+ case 'b':
+ guest_memory_bytes = strtoull(optarg, NULL, 0);
case 'h':
default:
help(argv[0]);
@@ -448,7 +462,7 @@ int main(int argc, char *argv[])
TEST_ASSERT(vm_guest_mode_params[i].supported,
"Guest mode ID %d (%s) not supported.",
i, vm_guest_mode_string(i));
- run_test(i, use_uffd, uffd_delay);
+ run_test(i, use_uffd, uffd_delay, guest_memory_bytes);
}

return 0;
--
2.24.1.735.g03f4e72817-goog