[PATCH v6 1/5] selftests: kvm: s390: Add uc_map_unmap VM test case

Christoph Schlameuss
2024-10-15T08:37:57Z

Add a test case verifying basic running and interaction of ucontrol VMs.
Fill the segment and page tables for allocated memory and map memory on
first access.

* uc_map_unmap
Store and load data to mapped and unmapped memory and use pic segment
translation handling to map memory on access.

Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
---
.../selftests/kvm/s390x/ucontrol_test.c | 145 +++++++++++++++++-
1 file changed, 144 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/kvm/s390x/ucontrol_test.c b/tools/testing/selftests/kvm/s390x/ucontrol_test.c
index f257beec1430..3e649b12a0b9 100644
--- a/tools/testing/selftests/kvm/s390x/ucontrol_test.c
+++ b/tools/testing/selftests/kvm/s390x/ucontrol_test.c
@@ -16,7 +16,11 @@
#include <linux/capability.h>
#include <linux/sizes.h>

+#define PGM_SEGMENT_TRANSLATION 0x10
+
#define VM_MEM_SIZE (4 * SZ_1M)
+#define VM_MEM_EXT_SIZE (2 * SZ_1M)
+#define VM_MEM_MAX_M ((VM_MEM_SIZE + VM_MEM_EXT_SIZE) / SZ_1M)

/* so directly declare capget to check caps without libcap */
int capget(cap_user_header_t header, cap_user_data_t data);
@@ -58,6 +62,23 @@ asm("test_gprs_asm:\n"
" j 0b\n"
);

+/* Test program manipulating memory */
+extern char test_mem_asm[];
+asm("test_mem_asm:\n"
+ "xgr %r0, %r0\n"
+
+ "0:\n"
+ " ahi %r0,1\n"
+ " st %r1,0(%r5,%r6)\n"
+
+ " xgr %r1,%r1\n"
+ " l %r1,0(%r5,%r6)\n"
+ " ahi %r0,1\n"
+ " diag 0,0,0x44\n"
+
+ " j 0b\n"
+);
+
FIXTURE(uc_kvm)
{
struct kvm_s390_sie_block *sie_block;
@@ -67,6 +88,7 @@ FIXTURE(uc_kvm)
uintptr_t base_hva;
uintptr_t code_hva;
int kvm_run_size;
+ vm_paddr_t pgd;
void *vm_mem;
int vcpu_fd;
int kvm_fd;
@@ -116,7 +138,7 @@ FIXTURE_SETUP(uc_kvm)
self->base_gpa = 0;
self->code_gpa = self->base_gpa + (3 * SZ_1M);

- self->vm_mem = aligned_alloc(SZ_1M, VM_MEM_SIZE);
+ self->vm_mem = aligned_alloc(SZ_1M, VM_MEM_MAX_M * SZ_1M);
ASSERT_NE(NULL, self->vm_mem) TH_LOG("malloc failed %u", errno);
self->base_hva = (uintptr_t)self->vm_mem;
self->code_hva = self->base_hva - self->base_gpa + self->code_gpa;
@@ -222,6 +244,60 @@ TEST(uc_cap_hpage)
close(kvm_fd);
}

+/* calculate host virtual addr from guest physical addr */
+static void *gpa2hva(FIXTURE_DATA(uc_kvm) *self, u64 gpa)
+{
+ return (void *)(self->base_hva - self->base_gpa + gpa);
+}
+
+/* map / make additional memory available */
+static int uc_map_ext(FIXTURE_DATA(uc_kvm) *self, u64 vcpu_addr, u64 length)
+{
+ struct kvm_s390_ucas_mapping map = {
+ .user_addr = (u64)gpa2hva(self, vcpu_addr),
+ .vcpu_addr = vcpu_addr,
+ .length = length,
+ };
+ pr_info("ucas map %p %p 0x%llx",
+ (void *)map.user_addr, (void *)map.vcpu_addr, map.length);
+ return ioctl(self->vcpu_fd, KVM_S390_UCAS_MAP, &map);
+}
+
+/* unmap previously mapped memory */
+static int uc_unmap_ext(FIXTURE_DATA(uc_kvm) *self, u64 vcpu_addr, u64 length)
+{
+ struct kvm_s390_ucas_mapping map = {
+ .user_addr = (u64)gpa2hva(self, vcpu_addr),
+ .vcpu_addr = vcpu_addr,
+ .length = length,
+ };
+ pr_info("ucas unmap %p %p 0x%llx",
+ (void *)map.user_addr, (void *)map.vcpu_addr, map.length);
+ return ioctl(self->vcpu_fd, KVM_S390_UCAS_UNMAP, &map);
+}
+
+/* handle ucontrol exit by mapping the accessed segment */
+static void uc_handle_exit_ucontrol(FIXTURE_DATA(uc_kvm) *self)
+{
+ struct kvm_run *run = self->run;
+ u64 seg_addr;
+ int rc;
+
+ TEST_ASSERT_EQ(KVM_EXIT_S390_UCONTROL, run->exit_reason);
+ switch (run->s390_ucontrol.pgm_code) {
+ case PGM_SEGMENT_TRANSLATION:
+ seg_addr = run->s390_ucontrol.trans_exc_code & ~(SZ_1M - 1);
+ pr_info("ucontrol pic segment translation 0x%llx, mapping segment 0x%lx\n",
+ run->s390_ucontrol.trans_exc_code, seg_addr);
+ /* map / make additional memory available */
+ rc = uc_map_ext(self, seg_addr, SZ_1M);
+ TEST_ASSERT_EQ(0, rc);
+ break;
+ default:
+ TEST_FAIL("UNEXPECTED PGM CODE %d", run->s390_ucontrol.pgm_code);
+ }
+}
+
/* verify SIEIC exit
* * fail on codes not expected in the test cases
*/
@@ -255,6 +331,12 @@ static bool uc_handle_exit(FIXTURE_DATA(uc_kvm) * self)
struct kvm_run *run = self->run;

switch (run->exit_reason) {
+ case KVM_EXIT_S390_UCONTROL:
+ /** check program interruption code
+ * handle page fault --> ucas map
+ */
+ uc_handle_exit_ucontrol(self);
+ break;
case KVM_EXIT_S390_SIEIC:
return uc_handle_sieic(self);
default:
@@ -286,6 +368,67 @@ static void uc_assert_diag44(FIXTURE_DATA(uc_kvm) * self)
TEST_ASSERT_EQ(0x440000, sie_block->ipb);
}

+TEST_F(uc_kvm, uc_map_unmap)
+{
+ struct kvm_sync_regs *sync_regs = &self->run->s.regs;
+ struct kvm_run *run = self->run;
+ const u64 disp = 1;
+ int rc;
+
+ /* copy test_mem_asm to code_hva / code_gpa */
+ TH_LOG("copy code %p to vm mapped memory %p / %p",
+ &test_mem_asm, (void *)self->code_hva, (void *)self->code_gpa);
+ memcpy((void *)self->code_hva, &test_mem_asm, PAGE_SIZE);
+
+ /* DAT disabled + 64 bit mode */
+ run->psw_mask = 0x0000000180000000ULL;
+ run->psw_addr = self->code_gpa;
+
+ /* set register content for test_mem_asm to access not mapped memory*/
+ sync_regs->gprs[1] = 0x55;
+ sync_regs->gprs[5] = self->base_gpa;
+ sync_regs->gprs[6] = VM_MEM_SIZE + disp;
+ run->kvm_dirty_regs |= KVM_SYNC_GPRS;
+
+ /* run and expect to fail with ucontrol pic segment translation */
+ ASSERT_EQ(0, uc_run_once(self));
+ ASSERT_EQ(1, sync_regs->gprs[0]);
+ ASSERT_EQ(KVM_EXIT_S390_UCONTROL, run->exit_reason);
+
+ ASSERT_EQ(PGM_SEGMENT_TRANSLATION, run->s390_ucontrol.pgm_code);
+ ASSERT_EQ(self->base_gpa + VM_MEM_SIZE, run->s390_ucontrol.trans_exc_code);
+
+ /* fail to map memory with not segment aligned address */
+ rc = uc_map_ext(self, self->base_gpa + VM_MEM_SIZE + disp, VM_MEM_EXT_SIZE);
+ ASSERT_GT(0, rc)
+ TH_LOG("ucas map for non segment address should fail but didn't; "
+ "result %d not expected, %s", rc, strerror(errno));
+
+ /* map / make additional memory available */
+ rc = uc_map_ext(self, self->base_gpa + VM_MEM_SIZE, VM_MEM_EXT_SIZE);
+ ASSERT_EQ(0, rc)
+ TH_LOG("ucas map result %d not expected, %s", rc, strerror(errno));
+ ASSERT_EQ(0, uc_run_once(self));
+ ASSERT_EQ(false, uc_handle_exit(self));
+ uc_assert_diag44(self);
+
+ /* assert registers and memory are in expected state */
+ ASSERT_EQ(2, sync_regs->gprs[0]);
+ ASSERT_EQ(0x55, sync_regs->gprs[1]);
+ ASSERT_EQ(0x55, *(u32 *)gpa2hva(self, self->base_gpa + VM_MEM_SIZE + disp));
+
+ /* unmap and run loop again */
+ rc = uc_unmap_ext(self, self->base_gpa + VM_MEM_SIZE, VM_MEM_EXT_SIZE);
+ ASSERT_EQ(0, rc)
+ TH_LOG("ucas unmap result %d not expected, %s", rc, strerror(errno));
+ ASSERT_EQ(0, uc_run_once(self));
+ ASSERT_EQ(3, sync_regs->gprs[0]);
+ ASSERT_EQ(KVM_EXIT_S390_UCONTROL, run->exit_reason);
+ ASSERT_EQ(PGM_SEGMENT_TRANSLATION, run->s390_ucontrol.pgm_code);
+ /* handle ucontrol exit and remap memory after previous map and unmap */
+ ASSERT_EQ(true, uc_handle_exit(self));
+}
+
TEST_F(uc_kvm, uc_gprs)
{
struct kvm_sync_regs *sync_regs = &self->run->s.regs;
--
2.47.0