[PATCH v8 14/14] KVM: s390: selftest: memop: Add cmpxchg tests

Janis Schoetterl-Glausch
2023-02-07T16:42:51Z

Test successful exchange, unsuccessful exchange, storage key protection
and invalid arguments.

Signed-off-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com>
Acked-by: Janosch Frank <frankja@linux.ibm.com>
---
tools/testing/selftests/kvm/s390x/memop.c | 407 +++++++++++++++++++++-
1 file changed, 392 insertions(+), 15 deletions(-)

diff --git a/tools/testing/selftests/kvm/s390x/memop.c b/tools/testing/selftests/kvm/s390x/memop.c
index c5fec84ef3c2..8e4b94d7b8dd 100644
--- a/tools/testing/selftests/kvm/s390x/memop.c
+++ b/tools/testing/selftests/kvm/s390x/memop.c
@@ -9,6 +9,7 @@
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
+#include <pthread.h>

#include <linux/bits.h>

@@ -26,6 +27,7 @@ enum mop_target {
enum mop_access_mode {
READ,
WRITE,
+ CMPXCHG,
};

struct mop_desc {
@@ -44,13 +46,16 @@ struct mop_desc {
enum mop_access_mode mode;
void *buf;
uint32_t sida_offset;
+ void *old;
+ uint8_t old_value[16];
+ bool *cmpxchg_success;
uint8_t ar;
uint8_t key;
};

const uint8_t NO_KEY = 0xff;

-static struct kvm_s390_mem_op ksmo_from_desc(const struct mop_desc *desc)
+static struct kvm_s390_mem_op ksmo_from_desc(struct mop_desc *desc)
{
struct kvm_s390_mem_op ksmo = {
.gaddr = (uintptr_t)desc->gaddr,
@@ -77,6 +82,11 @@ static struct kvm_s390_mem_op ksmo_from_desc(const struct mop_desc *desc)
ksmo.op = KVM_S390_MEMOP_ABSOLUTE_READ;
if (desc->mode == WRITE)
ksmo.op = KVM_S390_MEMOP_ABSOLUTE_WRITE;
+ if (desc->mode == CMPXCHG) {
+ ksmo.op = KVM_S390_MEMOP_ABSOLUTE_CMPXCHG;
+ ksmo.old_addr = (uint64_t)desc->old;
+ memcpy(desc->old_value, desc->old, desc->size);
+ }
break;
case INVALID:
ksmo.op = -1;
@@ -135,9 +145,13 @@ static void print_memop(struct kvm_vcpu *vcpu, const struct kvm_s390_mem_op *ksm
case KVM_S390_MEMOP_ABSOLUTE_WRITE:
printf("ABSOLUTE, WRITE, ");
break;
+ case KVM_S390_MEMOP_ABSOLUTE_CMPXCHG:
+ printf("ABSOLUTE, CMPXCHG, ");
+ break;
}
- printf("gaddr=%llu, size=%u, buf=%llu, ar=%u, key=%u",
- ksmo->gaddr, ksmo->size, ksmo->buf, ksmo->ar, ksmo->key);
+ printf("gaddr=%llu, size=%u, buf=%llu, ar=%u, key=%u, old_addr=%llx",
+ ksmo->gaddr, ksmo->size, ksmo->buf, ksmo->ar, ksmo->key,
+ ksmo->old_addr);
if (ksmo->flags & KVM_S390_MEMOP_F_CHECK_ONLY)
printf(", CHECK_ONLY");
if (ksmo->flags & KVM_S390_MEMOP_F_INJECT_EXCEPTION)
@@ -147,24 +161,30 @@ static void print_memop(struct kvm_vcpu *vcpu, const struct kvm_s390_mem_op *ksm
puts(")");
}

-static void memop_ioctl(struct test_info info, struct kvm_s390_mem_op *ksmo)
+static int err_memop_ioctl(struct test_info info, struct kvm_s390_mem_op *ksmo,
+ struct mop_desc *desc)
{
struct kvm_vcpu *vcpu = info.vcpu;

if (!vcpu)
- vm_ioctl(info.vm, KVM_S390_MEM_OP, ksmo);
+ return __vm_ioctl(info.vm, KVM_S390_MEM_OP, ksmo);
else
- vcpu_ioctl(vcpu, KVM_S390_MEM_OP, ksmo);
+ return __vcpu_ioctl(vcpu, KVM_S390_MEM_OP, ksmo);
}

-static int err_memop_ioctl(struct test_info info, struct kvm_s390_mem_op *ksmo)
+static void memop_ioctl(struct test_info info, struct kvm_s390_mem_op *ksmo,
+ struct mop_desc *desc)
{
- struct kvm_vcpu *vcpu = info.vcpu;
+ int r;

- if (!vcpu)
- return __vm_ioctl(info.vm, KVM_S390_MEM_OP, ksmo);
- else
- return __vcpu_ioctl(vcpu, KVM_S390_MEM_OP, ksmo);
+ r = err_memop_ioctl(info, ksmo, desc);
+ if (ksmo->op == KVM_S390_MEMOP_ABSOLUTE_CMPXCHG) {
+ if (desc->cmpxchg_success) {
+ int diff = memcmp(desc->old_value, desc->old, desc->size);
+ *desc->cmpxchg_success = !diff;
+ }
+ }
+ TEST_ASSERT(!r, __KVM_IOCTL_ERROR("KVM_S390_MEM_OP", r));
}

#define MEMOP(err, info_p, mop_target_p, access_mode_p, buf_p, size_p, ...) \
@@ -187,7 +207,7 @@ static int err_memop_ioctl(struct test_info info, struct kvm_s390_mem_op *ksmo)
} \
__ksmo = ksmo_from_desc(&__desc); \
print_memop(__info.vcpu, &__ksmo); \
- err##memop_ioctl(__info, &__ksmo); \
+ err##memop_ioctl(__info, &__ksmo, &__desc); \
})

#define MOP(...) MEMOP(, __VA_ARGS__)
@@ -201,6 +221,8 @@ static int err_memop_ioctl(struct test_info info, struct kvm_s390_mem_op *ksmo)
#define AR(a) ._ar = 1, .ar = (a)
#define KEY(a) .f_key = 1, .key = (a)
#define INJECT .f_inject = 1
+#define CMPXCHG_OLD(o) .old = (o)
+#define CMPXCHG_SUCCESS(s) .cmpxchg_success = (s)

#define CHECK_N_DO(f, ...) ({ f(__VA_ARGS__, CHECK_ONLY); f(__VA_ARGS__); })

@@ -210,8 +232,8 @@ static int err_memop_ioctl(struct test_info info, struct kvm_s390_mem_op *ksmo)
#define CR0_FETCH_PROTECTION_OVERRIDE (1UL << (63 - 38))
#define CR0_STORAGE_PROTECTION_OVERRIDE (1UL << (63 - 39))

-static uint8_t mem1[65536];
-static uint8_t mem2[65536];
+static uint8_t __aligned(PAGE_SIZE) mem1[65536];
+static uint8_t __aligned(PAGE_SIZE) mem2[65536];

struct test_default {
struct kvm_vm *kvm_vm;
@@ -243,6 +265,8 @@ enum stage {
STAGE_SKEYS_SET,
/* Guest copied memory (locations up to test case) */
STAGE_COPIED,
+ /* End of guest code reached */
+ STAGE_DONE,
};

#define HOST_SYNC(info_p, stage) \
@@ -254,6 +278,9 @@ enum stage {
\
vcpu_run(__vcpu); \
get_ucall(__vcpu, &uc); \
+ if (uc.cmd == UCALL_ABORT) { \
+ REPORT_GUEST_ASSERT_2(uc, "hints: %lu, %lu"); \
+ } \
ASSERT_EQ(uc.cmd, UCALL_SYNC); \
ASSERT_EQ(uc.args[1], __stage); \
}) \
@@ -293,6 +320,44 @@ static void default_read(struct test_info copy_cpu, struct test_info mop_cpu,
ASSERT_MEM_EQ(mem1, mem2, size);
}

+static void default_cmpxchg(struct test_default *test, uint8_t key)
+{
+ for (int size = 1; size <= 16; size *= 2) {
+ for (int offset = 0; offset < 16; offset += size) {
+ uint8_t __aligned(16) new[16] = {};
+ uint8_t __aligned(16) old[16];
+ bool succ;
+
+ prepare_mem12();
+ default_write_read(test->vcpu, test->vcpu, LOGICAL, 16, NO_KEY);
+
+ memcpy(&old, mem1, 16);
+ MOP(test->vm, ABSOLUTE, CMPXCHG, new + offset,
+ size, GADDR_V(mem1 + offset),
+ CMPXCHG_OLD(old + offset),
+ CMPXCHG_SUCCESS(&succ), KEY(key));
+ HOST_SYNC(test->vcpu, STAGE_COPIED);
+ MOP(test->vm, ABSOLUTE, READ, mem2, 16, GADDR_V(mem2));
+ TEST_ASSERT(succ, "exchange of values should succeed");
+ memcpy(mem1 + offset, new + offset, size);
+ ASSERT_MEM_EQ(mem1, mem2, 16);
+
+ memcpy(&old, mem1, 16);
+ new[offset]++;
+ old[offset]++;
+ MOP(test->vm, ABSOLUTE, CMPXCHG, new + offset,
+ size, GADDR_V(mem1 + offset),
+ CMPXCHG_OLD(old + offset),
+ CMPXCHG_SUCCESS(&succ), KEY(key));
+ HOST_SYNC(test->vcpu, STAGE_COPIED);
+ MOP(test->vm, ABSOLUTE, READ, mem2, 16, GADDR_V(mem2));
+ TEST_ASSERT(!succ, "exchange of values should not succeed");
+ ASSERT_MEM_EQ(mem1, mem2, 16);
+ ASSERT_MEM_EQ(&old, mem1, 16);
+ }
+ }
+}
+
static void guest_copy(void)
{
GUEST_SYNC(STAGE_INITED);
@@ -377,6 +442,248 @@ static void test_copy_key(void)
kvm_vm_free(t.kvm_vm);
}

+static void test_cmpxchg_key(void)
+{
+ struct test_default t = test_default_init(guest_copy_key);
+
+ HOST_SYNC(t.vcpu, STAGE_SKEYS_SET);
+
+ default_cmpxchg(&t, NO_KEY);
+ default_cmpxchg(&t, 0);
+ default_cmpxchg(&t, 9);
+
+ kvm_vm_free(t.kvm_vm);
+}
+
+static __uint128_t cut_to_size(int size, __uint128_t val)
+{
+ switch (size) {
+ case 1:
+ return (uint8_t)val;
+ case 2:
+ return (uint16_t)val;
+ case 4:
+ return (uint32_t)val;
+ case 8:
+ return (uint64_t)val;
+ case 16:
+ return val;
+ }
+ GUEST_ASSERT_1(false, "Invalid size");
+ return 0;
+}
+
+static bool popcount_eq(__uint128_t a, __uint128_t b)
+{
+ unsigned int count_a, count_b;
+
+ count_a = __builtin_popcountl((uint64_t)(a >> 64)) +
+ __builtin_popcountl((uint64_t)a);
+ count_b = __builtin_popcountl((uint64_t)(b >> 64)) +
+ __builtin_popcountl((uint64_t)b);
+ return count_a == count_b;
+}
+
+static __uint128_t rotate(int size, __uint128_t val, int amount)
+{
+ unsigned int bits = size * 8;
+
+ amount = (amount + bits) % bits;
+ val = cut_to_size(size, val);
+ return (val << (bits - amount)) | (val >> amount);
+}
+
+const unsigned int max_block = 16;
+
+static void choose_block(bool guest, int i, int *size, int *offset)
+{
+ unsigned int rand;
+
+ rand = i;
+ if (guest) {
+ rand = rand * 19 + 11;
+ *size = 1 << ((rand % 3) + 2);
+ rand = rand * 19 + 11;
+ *offset = (rand % max_block) & ~(*size - 1);
+ } else {
+ rand = rand * 17 + 5;
+ *size = 1 << (rand % 5);
+ rand = rand * 17 + 5;
+ *offset = (rand % max_block) & ~(*size - 1);
+ }
+}
+
+static __uint128_t permutate_bits(bool guest, int i, int size, __uint128_t old)
+{
+ unsigned int rand;
+ int amount;
+ bool swap;
+
+ rand = i;
+ rand = rand * 3 + 1;
+ if (guest)
+ rand = rand * 3 + 1;
+ swap = rand % 2 == 0;
+ if (swap) {
+ int i, j;
+ __uint128_t new;
+ uint8_t byte0, byte1;
+
+ rand = rand * 3 + 1;
+ i = rand % size;
+ rand = rand * 3 + 1;
+ j = rand % size;
+ if (i == j)
+ return old;
+ new = rotate(16, old, i * 8);
+ byte0 = new & 0xff;
+ new &= ~0xff;
+ new = rotate(16, new, -i * 8);
+ new = rotate(16, new, j * 8);
+ byte1 = new & 0xff;
+ new = (new & ~0xff) | byte0;
+ new = rotate(16, new, -j * 8);
+ new = rotate(16, new, i * 8);
+ new = new | byte1;
+ new = rotate(16, new, -i * 8);
+ return new;
+ }
+ rand = rand * 3 + 1;
+ amount = rand % (size * 8);
+ return rotate(size, old, amount);
+}
+
+static bool _cmpxchg(int size, void *target, __uint128_t *old_addr, __uint128_t new)
+{
+ bool ret;
+
+ switch (size) {
+ case 4: {
+ uint32_t old = *old_addr;
+
+ asm volatile ("cs %[old],%[new],%[address]"
+ : [old] "+d" (old),
+ [address] "+Q" (*(uint32_t *)(target))
+ : [new] "d" ((uint32_t)new)
+ : "cc"
+ );
+ ret = old == (uint32_t)*old_addr;
+ *old_addr = old;
+ return ret;
+ }
+ case 8: {
+ uint64_t old = *old_addr;
+
+ asm volatile ("csg %[old],%[new],%[address]"
+ : [old] "+d" (old),
+ [address] "+Q" (*(uint64_t *)(target))
+ : [new] "d" ((uint64_t)new)
+ : "cc"
+ );
+ ret = old == (uint64_t)*old_addr;
+ *old_addr = old;
+ return ret;
+ }
+ case 16: {
+ __uint128_t old = *old_addr;
+
+ asm volatile ("cdsg %[old],%[new],%[address]"
+ : [old] "+d" (old),
+ [address] "+Q" (*(__uint128_t *)(target))
+ : [new] "d" (new)
+ : "cc"
+ );
+ ret = old == *old_addr;
+ *old_addr = old;
+ return ret;
+ }
+ }
+ GUEST_ASSERT_1(false, "Invalid size");
+ return 0;
+}
+
+const unsigned int cmpxchg_iter_outer = 100, cmpxchg_iter_inner = 10000;
+
+static void guest_cmpxchg_key(void)
+{
+ int size, offset;
+ __uint128_t old, new;
+
+ set_storage_key_range(mem1, max_block, 0x10);
+ set_storage_key_range(mem2, max_block, 0x10);
+ GUEST_SYNC(STAGE_SKEYS_SET);
+
+ for (int i = 0; i < cmpxchg_iter_outer; i++) {
+ do {
+ old = 1;
+ } while (!_cmpxchg(16, mem1, &old, 0));
+ for (int j = 0; j < cmpxchg_iter_inner; j++) {
+ choose_block(true, i + j, &size, &offset);
+ do {
+ new = permutate_bits(true, i + j, size, old);
+ } while (!_cmpxchg(size, mem2 + offset, &old, new));
+ }
+ }
+
+ GUEST_SYNC(STAGE_DONE);
+}
+
+static void *run_guest(void *data)
+{
+ struct test_info *info = data;
+
+ HOST_SYNC(*info, STAGE_DONE);
+ return NULL;
+}
+
+static char *quad_to_char(__uint128_t *quad, int size)
+{
+ return ((char *)quad) + (sizeof(*quad) - size);
+}
+
+static void test_cmpxchg_key_concurrent(void)
+{
+ struct test_default t = test_default_init(guest_cmpxchg_key);
+ int size, offset;
+ __uint128_t old, new;
+ bool success;
+ pthread_t thread;
+
+ HOST_SYNC(t.vcpu, STAGE_SKEYS_SET);
+ prepare_mem12();
+ MOP(t.vcpu, LOGICAL, WRITE, mem1, max_block, GADDR_V(mem2));
+ pthread_create(&thread, NULL, run_guest, &t.vcpu);
+
+ for (int i = 0; i < cmpxchg_iter_outer; i++) {
+ do {
+ old = 0;
+ new = 1;
+ MOP(t.vm, ABSOLUTE, CMPXCHG, &new,
+ sizeof(new), GADDR_V(mem1),
+ CMPXCHG_OLD(&old),
+ CMPXCHG_SUCCESS(&success), KEY(1));
+ } while (!success);
+ for (int j = 0; j < cmpxchg_iter_inner; j++) {
+ choose_block(false, i + j, &size, &offset);
+ do {
+ new = permutate_bits(false, i + j, size, old);
+ MOP(t.vm, ABSOLUTE, CMPXCHG, quad_to_char(&new, size),
+ size, GADDR_V(mem2 + offset),
+ CMPXCHG_OLD(quad_to_char(&old, size)),
+ CMPXCHG_SUCCESS(&success), KEY(1));
+ } while (!success);
+ }
+ }
+
+ pthread_join(thread, NULL);
+
+ MOP(t.vcpu, LOGICAL, READ, mem2, max_block, GADDR_V(mem2));
+ TEST_ASSERT(popcount_eq(*(__uint128_t *)mem1, *(__uint128_t *)mem2),
+ "Must retain number of set bits");
+
+ kvm_vm_free(t.kvm_vm);
+}
+
static void guest_copy_key_fetch_prot(void)
{
/*
@@ -457,6 +764,24 @@ static void test_errors_key(void)
kvm_vm_free(t.kvm_vm);
}

+static void test_errors_cmpxchg_key(void)
+{
+ struct test_default t = test_default_init(guest_copy_key_fetch_prot);
+ int i;
+
+ HOST_SYNC(t.vcpu, STAGE_INITED);
+ HOST_SYNC(t.vcpu, STAGE_SKEYS_SET);
+
+ for (i = 1; i <= 16; i *= 2) {
+ __uint128_t old = 0;
+
+ ERR_PROT_MOP(t.vm, ABSOLUTE, CMPXCHG, mem2, i, GADDR_V(mem2),
+ CMPXCHG_OLD(&old), KEY(2));
+ }
+
+ kvm_vm_free(t.kvm_vm);
+}
+
static void test_termination(void)
{
struct test_default t = test_default_init(guest_error_key);
@@ -692,6 +1017,38 @@ static void test_errors(void)
kvm_vm_free(t.kvm_vm);
}

+static void test_errors_cmpxchg(void)
+{
+ struct test_default t = test_default_init(guest_idle);
+ __uint128_t old;
+ int rv, i, power = 1;
+
+ HOST_SYNC(t.vcpu, STAGE_INITED);
+
+ for (i = 0; i < 32; i++) {
+ if (i == power) {
+ power *= 2;
+ continue;
+ }
+ rv = ERR_MOP(t.vm, ABSOLUTE, CMPXCHG, mem1, i, GADDR_V(mem1),
+ CMPXCHG_OLD(&old));
+ TEST_ASSERT(rv == -1 && errno == EINVAL,
+ "ioctl allows bad size for cmpxchg");
+ }
+ for (i = 1; i <= 16; i *= 2) {
+ rv = ERR_MOP(t.vm, ABSOLUTE, CMPXCHG, mem1, i, GADDR((void *)~0xfffUL),
+ CMPXCHG_OLD(&old));
+ TEST_ASSERT(rv > 0, "ioctl allows bad guest address for cmpxchg");
+ }
+ for (i = 2; i <= 16; i *= 2) {
+ rv = ERR_MOP(t.vm, ABSOLUTE, CMPXCHG, mem1, i, GADDR_V(mem1 + 1),
+ CMPXCHG_OLD(&old));
+ TEST_ASSERT(rv == -1 && errno == EINVAL,
+ "ioctl allows bad alignment for cmpxchg");
+ }
+
+ kvm_vm_free(t.kvm_vm);
+}

int main(int argc, char *argv[])
{
@@ -720,6 +1077,16 @@ int main(int argc, char *argv[])
.test = test_copy_key,
.requirements_met = extension_cap > 0,
},
+ {
+ .name = "cmpxchg with storage keys",
+ .test = test_cmpxchg_key,
+ .requirements_met = extension_cap & 0x2,
+ },
+ {
+ .name = "concurrently cmpxchg with storage keys",
+ .test = test_cmpxchg_key_concurrent,
+ .requirements_met = extension_cap & 0x2,
+ },
{
.name = "copy with key storage protection override",
.test = test_copy_key_storage_prot_override,
@@ -740,6 +1107,16 @@ int main(int argc, char *argv[])
.test = test_errors_key,
.requirements_met = extension_cap > 0,
},
+ {
+ .name = "error checks for cmpxchg with key",
+ .test = test_errors_cmpxchg_key,
+ .requirements_met = extension_cap & 0x2,
+ },
+ {
+ .name = "error checks for cmpxchg",
+ .test = test_errors_cmpxchg,
+ .requirements_met = extension_cap & 0x2,
+ },
{
.name = "termination",
.test = test_termination,
--
2.37.2