[PATCH v6 2/5] selftests: kvm: s390: Add uc_skey VM test case

Christoph Schlameuss
2024-10-15T14:15:51Z

Add a test case manipulating s390 storage keys from within the ucontrol
VM.

Storage key instruction (ISKE, SSKE and RRBE) intercepts and
Keyless-subset facility are disabled on first use, where the skeys are
setup by KVM in non ucontrol VMs.

Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
---
.../selftests/kvm/include/s390x/processor.h | 6 +
.../selftests/kvm/s390x/ucontrol_test.c | 130 +++++++++++++++++-
2 files changed, 134 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/kvm/include/s390x/processor.h b/tools/testing/selftests/kvm/include/s390x/processor.h
index 481bd2fd6a32..33fef6fd9617 100644
--- a/tools/testing/selftests/kvm/include/s390x/processor.h
+++ b/tools/testing/selftests/kvm/include/s390x/processor.h
@@ -32,4 +32,10 @@ static inline void cpu_relax(void)
barrier();
}

+/* Get the instruction length */
+static inline int insn_length(unsigned char code)
+{
+ return ((((int)code + 64) >> 7) + 1) << 1;
+}
+
#endif
diff --git a/tools/testing/selftests/kvm/s390x/ucontrol_test.c b/tools/testing/selftests/kvm/s390x/ucontrol_test.c
index 3e649b12a0b9..c1bc199d6e85 100644
--- a/tools/testing/selftests/kvm/s390x/ucontrol_test.c
+++ b/tools/testing/selftests/kvm/s390x/ucontrol_test.c
@@ -79,6 +79,33 @@ asm("test_mem_asm:\n"
" j 0b\n"
);

+/* Test program manipulating storage keys */
+extern char test_skey_asm[];
+asm("test_skey_asm:\n"
+ "xgr %r0, %r0\n"
+
+ "0:\n"
+ " ahi %r0,1\n"
+ " st %r1,0(%r5,%r6)\n"
+
+ " iske %r1,%r6\n"
+ " ahi %r0,1\n"
+ " diag 0,0,0x44\n"
+
+ " sske %r1,%r6\n"
+ " xgr %r1,%r1\n"
+ " iske %r1,%r6\n"
+ " ahi %r0,1\n"
+ " diag 0,0,0x44\n"
+
+ " rrbe %r1,%r6\n"
+ " iske %r1,%r6\n"
+ " ahi %r0,1\n"
+ " diag 0,0,0x44\n"
+
+ " j 0b\n"
+);
+
FIXTURE(uc_kvm)
{
struct kvm_s390_sie_block *sie_block;
@@ -298,8 +325,49 @@ static void uc_handle_exit_ucontrol(FIXTURE_DATA(uc_kvm) *self)
}
}

-/* verify SIEIC exit
+/*
+ * Disable skey intercepts
+ * (KVM would init the skeys here)
+ */
+static void uc_skey_enable(FIXTURE_DATA(uc_kvm) *self)
+{
+ struct kvm_s390_sie_block *sie_block = self->sie_block;
+
+ /* disable KSS */
+ sie_block->cpuflags &= ~CPUSTAT_KSS;
+ /* disable skey inst interception */
+ sie_block->ictl &= ~(ICTL_ISKE | ICTL_SSKE | ICTL_RRBE);
+}
+
+/*
+ * Handle the instruction intercept
+ * Returns if interception is handled / execution can be continued
+ */
+static bool uc_handle_insn_ic(FIXTURE_DATA(uc_kvm) *self)
+{
+ struct kvm_s390_sie_block *sie_block = self->sie_block;
+ int ilen = insn_length(sie_block->ipa >> 8);
+ struct kvm_run *run = self->run;
+
+ switch (run->s390_sieic.ipa) {
+ case 0xB229: /* ISKE */
+ case 0xB22b: /* SSKE */
+ case 0xB22a: /* RRBE */
+ uc_skey_enable(self);
+
+ /* rewind to reexecute intercepted instruction */
+ run->psw_addr = run->psw_addr - ilen;
+ pr_info("rewind guest addr to 0x%.16llx\n", run->psw_addr);
+ return true;
+ default:
+ return false;
+ }
+}
+
+/*
+ * Handle the SIEIC exit
* * fail on codes not expected in the test cases
+ * Returns if interception is handled / execution can be continued
*/
static bool uc_handle_sieic(FIXTURE_DATA(uc_kvm) * self)
{
@@ -315,7 +383,10 @@ static bool uc_handle_sieic(FIXTURE_DATA(uc_kvm) * self)
case ICPT_INST:
/* end execution in caller on intercepted instruction */
pr_info("sie instruction interception\n");
- return false;
+ return uc_handle_insn_ic(self);
+ case ICPT_KSS:
+ uc_skey_enable(self);
+ return true;
case ICPT_OPEREXC:
/* operation exception */
TEST_FAIL("sie exception on %.4x%.8x", sie_block->ipa, sie_block->ipb);
@@ -472,4 +543,59 @@ TEST_F(uc_kvm, uc_gprs)
ASSERT_EQ(1, sync_regs->gprs[0]);
}

+TEST_F(uc_kvm, uc_skey)
+{
+ struct kvm_sync_regs *sync_regs = &self->run->s.regs;
+ u64 test_vaddr = VM_MEM_SIZE - (SZ_1M / 2);
+ struct kvm_run *run = self->run;
+ const u8 skeyvalue = 0x34;
+
+ /* copy test_skey_asm to code_hva / code_gpa */
+ TH_LOG("copy code %p to vm mapped memory %p / %p",
+ &test_skey_asm, (void *)self->code_hva, (void *)self->code_gpa);
+ memcpy((void *)self->code_hva, &test_skey_asm, PAGE_SIZE);
+
+ /* set register content for test_skey_asm to access not mapped memory */
+ sync_regs->gprs[1] = skeyvalue;
+ sync_regs->gprs[5] = self->base_gpa;
+ sync_regs->gprs[6] = test_vaddr;
+ run->kvm_dirty_regs |= KVM_SYNC_GPRS;
+
+ /* DAT disabled + 64 bit mode */
+ run->psw_mask = 0x0000000180000000ULL;
+ run->psw_addr = self->code_gpa;
+
+ ASSERT_EQ(0, uc_run_once(self));
+ ASSERT_EQ(true, uc_handle_exit(self));
+ ASSERT_EQ(1, sync_regs->gprs[0]);
+
+ /* ISKE */
+ ASSERT_EQ(0, uc_run_once(self));
+ ASSERT_EQ(false, uc_handle_exit(self));
+ ASSERT_EQ(2, sync_regs->gprs[0]);
+ /* assert initial skey (ACC = 0, R & C = 1) */
+ ASSERT_EQ(0x06, sync_regs->gprs[1]);
+ uc_assert_diag44(self);
+
+ /* SSKE + ISKE */
+ sync_regs->gprs[1] = skeyvalue;
+ run->kvm_dirty_regs |= KVM_SYNC_GPRS;
+ ASSERT_EQ(0, uc_run_once(self));
+ ASSERT_EQ(false, uc_handle_exit(self));
+ ASSERT_EQ(3, sync_regs->gprs[0]);
+ ASSERT_EQ(skeyvalue, sync_regs->gprs[1]);
+ uc_assert_diag44(self);
+
+ /* RRBE + ISKE */
+ sync_regs->gprs[1] = skeyvalue;
+ run->kvm_dirty_regs |= KVM_SYNC_GPRS;
+ ASSERT_EQ(0, uc_run_once(self));
+ ASSERT_EQ(false, uc_handle_exit(self));
+ ASSERT_EQ(4, sync_regs->gprs[0]);
+ /* assert R reset but rest of skey unchanged */
+ ASSERT_EQ(skeyvalue & 0xfa, sync_regs->gprs[1]);
+ ASSERT_EQ(0, sync_regs->gprs[1] & 0x04);
+ uc_assert_diag44(self);
+}
+
TEST_HARNESS_MAIN
--
2.47.0