[PATCH 0/4] KVM: s390: reset selftest and fixes

[PATCH 0/4] KVM: s390: reset selftest and fixes

[Christian Borntraeger]

By adding more testcases to the reset test, I even found a bug.

Christian Borntraeger (4):
  selftests: KVM: s390: fix early guest crash
  selftests: KVM: s390: test more register variants for the reset ioctl
  KVM: s390: Also reset registers in sync regs for initial cpu reset
  selftests: KVM: s390: check for registers to NOT change on reset

 arch/s390/kvm/kvm-s390.c                   |  18 ++-
 tools/testing/selftests/kvm/s390x/resets.c | 130 +++++++++++++++++----
 2 files changed, 123 insertions(+), 25 deletions(-)

-- 
2.25.0

[PATCH 1/4] selftests: KVM: s390: fix early guest crash

[Christian Borntraeger]

The guest crashes very early due to changes in the control registers
used by dynamic address translation. Let us use different registers
that will not crash the guest.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
 tools/testing/selftests/kvm/s390x/resets.c | 27 +++++++++++-----------
 1 file changed, 13 insertions(+), 14 deletions(-)

diff --git a/tools/testing/selftests/kvm/s390x/resets.c b/tools/testing/selftests/kvm/s390x/resets.c
index 1485bc6c8999..cbb343ad5d42 100644
--- a/tools/testing/selftests/kvm/s390x/resets.c
+++ b/tools/testing/selftests/kvm/s390x/resets.c
@@ -23,25 +23,24 @@ struct kvm_run *run;
 struct kvm_sync_regs *regs;
 static uint64_t regs_null[16];
 
-static uint64_t crs[16] = { 0x40000ULL,
-			    0x42000ULL,
-			    0, 0, 0, 0, 0,
-			    0x43000ULL,
-			    0, 0, 0, 0, 0,
-			    0x44000ULL,
-			    0, 0
-};
-
 static void guest_code_initial(void)
 {
-	/* Round toward 0 */
-	uint32_t fpc = 0x11;
+	/* set several CRs to "safe" value */
+	unsigned long cr2_59 = 0x10;	/* enable guarded storage */
+	unsigned long cr8_63 = 0x1;	/* monitor mask = 1 */
+	unsigned long cr10 = 1;		/* PER START */
+	unsigned long cr11 = -1;	/* PER END */
+
 
 	/* Dirty registers */
 	asm volatile (
-		"	lctlg	0,15,%0\n"
-		"	sfpc	%1\n"
-		: : "Q" (crs), "d" (fpc));
+		"	lghi	2,0x11\n"	/* Round toward 0 */
+		"	sfpc	2\n"		/* set fpc to !=0 */
+		"	lctlg	2,2,%0\n"
+		"	lctlg	8,8,%1\n"
+		"	lctlg	10,10,%2\n"
+		"	lctlg	11,11,%3\n"
+		: : "m" (cr2_59), "m" (cr8_63), "m" (cr10), "m" (cr11) : "2");
 	GUEST_SYNC(0);
 }
 
-- 
2.25.0

[PATCH 2/4] selftests: KVM: s390: test more register variants for the reset ioctl

[Christian Borntraeger]

We should not only test the oneregs or the get_(x)regs interfaces but
also the sync_regs. Those are usually the canonical place for register
content.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
 tools/testing/selftests/kvm/s390x/resets.c | 50 ++++++++++++++++++----
 1 file changed, 41 insertions(+), 9 deletions(-)

diff --git a/tools/testing/selftests/kvm/s390x/resets.c b/tools/testing/selftests/kvm/s390x/resets.c
index cbb343ad5d42..c385842792b7 100644
--- a/tools/testing/selftests/kvm/s390x/resets.c
+++ b/tools/testing/selftests/kvm/s390x/resets.c
@@ -20,8 +20,8 @@ struct kvm_s390_irq buf[VCPU_ID + LOCAL_IRQS];
 
 struct kvm_vm *vm;
 struct kvm_run *run;
-struct kvm_sync_regs *regs;
-static uint64_t regs_null[16];
+struct kvm_sync_regs *sync_regs;
+static uint8_t regs_null[512];
 
 static void guest_code_initial(void)
 {
@@ -86,6 +86,16 @@ static void assert_clear(void)
 
 	vcpu_fpu_get(vm, VCPU_ID, &fpu);
 	TEST_ASSERT(!memcmp(&fpu.fprs, regs_null, sizeof(fpu.fprs)), "fprs == 0");
+
+	/* sync regs */
+	TEST_ASSERT(!memcmp(sync_regs->gprs, regs_null, sizeof(sync_regs->gprs)),
+		    "gprs0-15 == 0 (sync_regs)");
+
+	TEST_ASSERT(!memcmp(sync_regs->acrs, regs_null, sizeof(sync_regs->acrs)),
+		    "acrs0-15 == 0 (sync_regs)");
+
+	TEST_ASSERT(!memcmp(sync_regs->vrs, regs_null, sizeof(sync_regs->vrs)),
+		    "vrs0-15 == 0 (sync_regs)");
 }
 
 static void assert_initial(void)
@@ -93,12 +103,32 @@ static void assert_initial(void)
 	struct kvm_sregs sregs;
 	struct kvm_fpu fpu;
 
+	/* KVM_GET_SREGS */
 	vcpu_sregs_get(vm, VCPU_ID, &sregs);
-	TEST_ASSERT(sregs.crs[0] == 0xE0UL, "cr0 == 0xE0");
-	TEST_ASSERT(sregs.crs[14] == 0xC2000000UL, "cr14 == 0xC2000000");
+	TEST_ASSERT(sregs.crs[0] == 0xE0UL, "cr0 == 0xE0 (KVM_GET_SREGS)");
+	TEST_ASSERT(sregs.crs[14] == 0xC2000000UL,
+		    "cr14 == 0xC2000000 (KVM_GET_SREGS)");
 	TEST_ASSERT(!memcmp(&sregs.crs[1], regs_null, sizeof(sregs.crs[1]) * 12),
-		    "cr1-13 == 0");
-	TEST_ASSERT(sregs.crs[15] == 0, "cr15 == 0");
+		    "cr1-13 == 0 (KVM_GET_SREGS)");
+	TEST_ASSERT(sregs.crs[15] == 0, "cr15 == 0 (KVM_GET_SREGS)");
+
+	/* sync regs */
+	TEST_ASSERT(sync_regs->crs[0] == 0xE0UL, "cr0 == 0xE0 (sync_regs)");
+	TEST_ASSERT(sync_regs->crs[14] == 0xC2000000UL,
+		    "cr14 == 0xC2000000 (sync_regs)");
+	TEST_ASSERT(!memcmp(&sync_regs->crs[1], regs_null, 8 * 12),
+		    "cr1-13 == 0 (sync_regs)");
+	TEST_ASSERT(sync_regs->crs[15] == 0, "cr15 == 0 (sync_regs)");
+	TEST_ASSERT(sync_regs->fpc == 0, "fpc == 0 (sync_regs)");
+	TEST_ASSERT(sync_regs->todpr == 0, "todpr == 0 (sync_regs)");
+	TEST_ASSERT(sync_regs->cputm == 0, "cputm == 0 (sync_regs)");
+	TEST_ASSERT(sync_regs->ckc == 0, "ckc == 0 (sync_regs)");
+	TEST_ASSERT(sync_regs->pp == 0, "pp == 0 (sync_regs)");
+	TEST_ASSERT(sync_regs->gbea == 1, "gbea == 1 (sync_regs)");
+
+	/* kvm_run */
+	TEST_ASSERT(run->psw_addr == 0, "psw_addr == 0 (kvm_run)");
+	TEST_ASSERT(run->psw_mask == 0, "psw_mask == 0 (kvm_run)");
 
 	vcpu_fpu_get(vm, VCPU_ID, &fpu);
 	TEST_ASSERT(!fpu.fpc, "fpc == 0");
@@ -113,6 +143,8 @@ static void assert_initial(void)
 static void assert_normal(void)
 {
 	test_one_reg(KVM_REG_S390_PFTOKEN, KVM_S390_PFAULT_TOKEN_INVALID);
+	TEST_ASSERT(sync_regs->pft == KVM_S390_PFAULT_TOKEN_INVALID,
+			"pft == 0xff.....  (sync_regs)");
 	assert_noirq();
 }
 
@@ -137,7 +169,7 @@ static void test_normal(void)
 	/* Create VM */
 	vm = vm_create_default(VCPU_ID, 0, guest_code_initial);
 	run = vcpu_state(vm, VCPU_ID);
-	regs = &run->s.regs;
+	sync_regs = &run->s.regs;
 
 	vcpu_run(vm, VCPU_ID);
 
@@ -153,7 +185,7 @@ static void test_initial(void)
 	printf("Testing initial reset\n");
 	vm = vm_create_default(VCPU_ID, 0, guest_code_initial);
 	run = vcpu_state(vm, VCPU_ID);
-	regs = &run->s.regs;
+	sync_regs = &run->s.regs;
 
 	vcpu_run(vm, VCPU_ID);
 
@@ -170,7 +202,7 @@ static void test_clear(void)
 	printf("Testing clear reset\n");
 	vm = vm_create_default(VCPU_ID, 0, guest_code_initial);
 	run = vcpu_state(vm, VCPU_ID);
-	regs = &run->s.regs;
+	sync_regs = &run->s.regs;
 
 	vcpu_run(vm, VCPU_ID);
 
-- 
2.25.0

[PATCH 3/4] KVM: s390: Also reset registers in sync regs for initial cpu reset

[Christian Borntraeger]

When we do the initial CPU reset we must not only clear the registers
in the internal data structures but also in kvm_run sync_regs. For
modern userspace sync_regs is the only place that it looks at.

Cc: stable@vger.kernel.org
Fixes: 7de3f1423ff943 ("KVM: s390: Add new reset vcpu API")
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
 arch/s390/kvm/kvm-s390.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 6b1842a9feed..81f54ddedb3d 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -3529,7 +3529,10 @@ static void kvm_arch_vcpu_ioctl_initial_reset(struct kvm_vcpu *vcpu)
 	/* Initial reset is a superset of the normal reset */
 	kvm_arch_vcpu_ioctl_normal_reset(vcpu);
 
-	/* this equals initial cpu reset in pop, but we don't switch to ESA */
+	/*
+	 * This equals initial cpu reset in pop, but we don't switch to ESA.
+	 * We do not even reset the internal data, but also ...
+	 */
 	vcpu->arch.sie_block->gpsw.mask = 0;
 	vcpu->arch.sie_block->gpsw.addr = 0;
 	kvm_s390_set_prefix(vcpu, 0);
@@ -3538,6 +3541,19 @@ static void kvm_arch_vcpu_ioctl_initial_reset(struct kvm_vcpu *vcpu)
 	memset(vcpu->arch.sie_block->gcr, 0, sizeof(vcpu->arch.sie_block->gcr));
 	vcpu->arch.sie_block->gcr[0] = CR0_INITIAL_MASK;
 	vcpu->arch.sie_block->gcr[14] = CR14_INITIAL_MASK;
+
+	/* ... the data in sync regs */
+	memset(vcpu->run->s.regs.crs, 0, sizeof(vcpu->run->s.regs.crs));
+	vcpu->run->s.regs.ckc = 0;
+	vcpu->run->s.regs.crs[0] = CR0_INITIAL_MASK;
+	vcpu->run->s.regs.crs[14] = CR14_INITIAL_MASK;
+	vcpu->run->psw_addr = 0;
+	vcpu->run->psw_mask = 0;
+	vcpu->run->s.regs.todpr = 0;
+	vcpu->run->s.regs.cputm = 0;
+	vcpu->run->s.regs.ckc = 0;
+	vcpu->run->s.regs.pp = 0;
+	vcpu->run->s.regs.gbea = 1;
 	vcpu->run->s.regs.fpc = 0;
 	/*
 	 * Do not reset these registers in the protected case, as some of
-- 
2.25.0

Re: [PATCH 3/4] KVM: s390: Also reset registers in sync regs for initial cpu reset

[David Hildenbrand]

On 09.03.20 16:00, Christian Borntraeger wrote:
> When we do the initial CPU reset we must not only clear the registers
> in the internal data structures but also in kvm_run sync_regs. For
> modern userspace sync_regs is the only place that it looks at.
> 
> Cc: stable@vger.kernel.org
> Fixes: 7de3f1423ff943 ("KVM: s390: Add new reset vcpu API")
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> ---
>  arch/s390/kvm/kvm-s390.c | 18 +++++++++++++++++-
>  1 file changed, 17 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index 6b1842a9feed..81f54ddedb3d 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -3529,7 +3529,10 @@ static void kvm_arch_vcpu_ioctl_initial_reset(struct kvm_vcpu *vcpu)
>  	/* Initial reset is a superset of the normal reset */
>  	kvm_arch_vcpu_ioctl_normal_reset(vcpu);
>  
> -	/* this equals initial cpu reset in pop, but we don't switch to ESA */
> +	/*
> +	 * This equals initial cpu reset in pop, but we don't switch to ESA.
> +	 * We do not even reset the internal data, but also ...

s/even/only ?

-- 
Thanks,

David / dhildenb

Re: [PATCH 3/4] KVM: s390: Also reset registers in sync regs for initial cpu reset

[Christian Borntraeger]

On 09.03.20 16:39, David Hildenbrand wrote:
> On 09.03.20 16:00, Christian Borntraeger wrote:
>> When we do the initial CPU reset we must not only clear the registers
>> in the internal data structures but also in kvm_run sync_regs. For
>> modern userspace sync_regs is the only place that it looks at.
>>
>> Cc: stable@vger.kernel.org
>> Fixes: 7de3f1423ff943 ("KVM: s390: Add new reset vcpu API")
>> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
>> ---
>>  arch/s390/kvm/kvm-s390.c | 18 +++++++++++++++++-
>>  1 file changed, 17 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
>> index 6b1842a9feed..81f54ddedb3d 100644
>> --- a/arch/s390/kvm/kvm-s390.c
>> +++ b/arch/s390/kvm/kvm-s390.c
>> @@ -3529,7 +3529,10 @@ static void kvm_arch_vcpu_ioctl_initial_reset(struct kvm_vcpu *vcpu)
>>  	/* Initial reset is a superset of the normal reset */
>>  	kvm_arch_vcpu_ioctl_normal_reset(vcpu);
>>  
>> -	/* this equals initial cpu reset in pop, but we don't switch to ESA */
>> +	/*
>> +	 * This equals initial cpu reset in pop, but we don't switch to ESA.
>> +	 * We do not even reset the internal data, but also ...
> 
> s/even/only ?

ack and fixed. I will give this series some time but it might be worthwile still for 5.6 (even
with the tests). 

[PATCH 4/4] selftests: KVM: s390: check for registers to NOT change on reset

[Christian Borntraeger]

Normal reset and initial CPU reset do not clear all registers. Add a
test that those registers are NOT changed.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
 tools/testing/selftests/kvm/s390x/resets.c | 55 +++++++++++++++++++++-
 1 file changed, 53 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/kvm/s390x/resets.c b/tools/testing/selftests/kvm/s390x/resets.c
index c385842792b7..b567705f0d41 100644
--- a/tools/testing/selftests/kvm/s390x/resets.c
+++ b/tools/testing/selftests/kvm/s390x/resets.c
@@ -40,8 +40,22 @@ static void guest_code_initial(void)
 		"	lctlg	8,8,%1\n"
 		"	lctlg	10,10,%2\n"
 		"	lctlg	11,11,%3\n"
-		: : "m" (cr2_59), "m" (cr8_63), "m" (cr10), "m" (cr11) : "2");
-	GUEST_SYNC(0);
+		/* now clobber some general purpose regs */
+		"	llihh	0,0xffff\n"
+		"	llihl	1,0x5555\n"
+		"	llilh	2,0xaaaa\n"
+		"	llill	3,0x0000\n"
+		/* now clobber a floating point reg */
+		"	lghi	4,0x1\n"
+		"	cdgbr	0,4\n"
+		/* now clobber an access reg */
+		"	sar	9,4\n"
+		/* We embed diag 501 here to control register content */
+		"	diag 0,0,0x501\n"
+		:
+		: "m" (cr2_59), "m" (cr8_63), "m" (cr10), "m" (cr11)
+		/* no clobber list as this should not return */
+		);
 }
 
 static void test_one_reg(uint64_t id, uint64_t value)
@@ -98,6 +112,21 @@ static void assert_clear(void)
 		    "vrs0-15 == 0 (sync_regs)");
 }
 
+static void assert_initial_noclear(void)
+{
+	TEST_ASSERT(sync_regs->gprs[0] == 0xffff000000000000UL,
+		    "gpr0 == 0xffff000000000000 (sync_regs)");
+	TEST_ASSERT(sync_regs->gprs[1] == 0x0000555500000000UL,
+		    "gpr1 == 0x0000555500000000 (sync_regs)");
+	TEST_ASSERT(sync_regs->gprs[2] == 0x00000000aaaa0000UL,
+		    "gpr2 == 0x00000000aaaa0000 (sync_regs)");
+	TEST_ASSERT(sync_regs->gprs[3] == 0x0000000000000000UL,
+		    "gpr3 == 0x0000000000000000 (sync_regs)");
+	TEST_ASSERT(sync_regs->fprs[0] == 0x3ff0000000000000UL,
+		    "fpr0 == 0f1 (sync_regs)");
+	TEST_ASSERT(sync_regs->acrs[9] == 1, "ar9 == 1 (sync_regs)");
+}
+
 static void assert_initial(void)
 {
 	struct kvm_sregs sregs;
@@ -140,6 +169,14 @@ static void assert_initial(void)
 	test_one_reg(KVM_REG_S390_CLOCK_COMP, 0);
 }
 
+static void assert_normal_noclear(void)
+{
+	TEST_ASSERT(sync_regs->crs[2] == 0x10, "cr2 == 10 (sync_regs)");
+	TEST_ASSERT(sync_regs->crs[8] == 1, "cr10 == 1 (sync_regs)");
+	TEST_ASSERT(sync_regs->crs[10] == 1, "cr10 == 1 (sync_regs)");
+	TEST_ASSERT(sync_regs->crs[11] == -1, "cr11 == -1 (sync_regs)");
+}
+
 static void assert_normal(void)
 {
 	test_one_reg(KVM_REG_S390_PFTOKEN, KVM_S390_PFAULT_TOKEN_INVALID);
@@ -176,7 +213,13 @@ static void test_normal(void)
 	inject_irq(VCPU_ID);
 
 	vcpu_ioctl(vm, VCPU_ID, KVM_S390_NORMAL_RESET, 0);
+
+	/* must clears */
 	assert_normal();
+	/* must not clears */
+	assert_normal_noclear();
+	assert_initial_noclear();
+
 	kvm_vm_free(vm);
 }
 
@@ -192,8 +235,13 @@ static void test_initial(void)
 	inject_irq(VCPU_ID);
 
 	vcpu_ioctl(vm, VCPU_ID, KVM_S390_INITIAL_RESET, 0);
+
+	/* must clears */
 	assert_normal();
 	assert_initial();
+	/* must not clears */
+	assert_initial_noclear();
+
 	kvm_vm_free(vm);
 }
 
@@ -209,9 +257,12 @@ static void test_clear(void)
 	inject_irq(VCPU_ID);
 
 	vcpu_ioctl(vm, VCPU_ID, KVM_S390_CLEAR_RESET, 0);
+
+	/* must clears */
 	assert_normal();
 	assert_initial();
 	assert_clear();
+
 	kvm_vm_free(vm);
 }
 
-- 
2.25.0