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Subject[PATCH 1/2] KVM: selftests: Implement ucall() for s390x
Date
On s390x, we can neither exit via PIO nor MMIO, but have to use
an instruction like DIAGNOSE. While we're at it, rename UCALL_PIO
to UCALL_DEFAULT, since PIO only works on x86 anyway, and this
way we can re-use the "default" type for the DIAGNOSE exit on s390x.

Now that ucall() is implemented, we can use it in the sync_reg_test
on s390x, too.

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
.../testing/selftests/kvm/include/kvm_util.h | 2 +-
tools/testing/selftests/kvm/lib/ucall.c | 34 +++++++++++++++----
.../selftests/kvm/s390x/sync_regs_test.c | 6 ++--
3 files changed, 32 insertions(+), 10 deletions(-)

diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
index e0e66b115ef2..c37aea2e33e5 100644
--- a/tools/testing/selftests/kvm/include/kvm_util.h
+++ b/tools/testing/selftests/kvm/include/kvm_util.h
@@ -167,7 +167,7 @@ int vm_create_device(struct kvm_vm *vm, struct kvm_create_device *cd);

/* ucall implementation types */
typedef enum {
- UCALL_PIO,
+ UCALL_DEFAULT,
UCALL_MMIO,
} ucall_type_t;

diff --git a/tools/testing/selftests/kvm/lib/ucall.c b/tools/testing/selftests/kvm/lib/ucall.c
index dd9a66700f96..55534dd014dc 100644
--- a/tools/testing/selftests/kvm/lib/ucall.c
+++ b/tools/testing/selftests/kvm/lib/ucall.c
@@ -30,7 +30,7 @@ void ucall_init(struct kvm_vm *vm, ucall_type_t type, void *arg)
ucall_type = type;
sync_global_to_guest(vm, ucall_type);

- if (type == UCALL_PIO)
+ if (type == UCALL_DEFAULT)
return;

if (type == UCALL_MMIO) {
@@ -84,11 +84,18 @@ void ucall_uninit(struct kvm_vm *vm)
sync_global_to_guest(vm, ucall_exit_mmio_addr);
}

-static void ucall_pio_exit(struct ucall *uc)
+static void ucall_default_exit(struct ucall *uc)
{
-#ifdef __x86_64__
+#if defined(__x86_64__)
+ /* Exit via PIO */
asm volatile("in %[port], %%al"
: : [port] "d" (UCALL_PIO_PORT), "D" (uc) : "rax");
+#elif defined(__s390x__)
+ /* Exit via DIAGNOSE 0x501 (normally used for breakpoints) */
+ asm volatile ("diag 0,%0,0x501" : : "a"(uc) : "memory");
+#else
+ fprintf(stderr, "No default ucall available on this architecture.\n");
+ exit(1);
#endif
}

@@ -113,8 +120,8 @@ void ucall(uint64_t cmd, int nargs, ...)
va_end(va);

switch (ucall_type) {
- case UCALL_PIO:
- ucall_pio_exit(&uc);
+ case UCALL_DEFAULT:
+ ucall_default_exit(&uc);
break;
case UCALL_MMIO:
ucall_mmio_exit(&uc);
@@ -128,15 +135,28 @@ uint64_t get_ucall(struct kvm_vm *vm, uint32_t vcpu_id, struct ucall *uc)
struct ucall ucall = {};
bool got_ucall = false;

-#ifdef __x86_64__
- if (ucall_type == UCALL_PIO && run->exit_reason == KVM_EXIT_IO &&
+#if defined(__x86_64__)
+ if (ucall_type == UCALL_DEFAULT && run->exit_reason == KVM_EXIT_IO &&
run->io.port == UCALL_PIO_PORT) {
struct kvm_regs regs;
vcpu_regs_get(vm, vcpu_id, &regs);
memcpy(&ucall, addr_gva2hva(vm, (vm_vaddr_t)regs.rdi), sizeof(ucall));
got_ucall = true;
}
+#elif defined(__s390x__)
+ if (ucall_type == UCALL_DEFAULT &&
+ run->exit_reason == KVM_EXIT_S390_SIEIC &&
+ run->s390_sieic.icptcode == 4 &&
+ (run->s390_sieic.ipa >> 8) == 0x83 && /* 0x83 means DIAGNOSE */
+ (run->s390_sieic.ipb >> 16) == 0x501) {
+ int reg = run->s390_sieic.ipa & 0xf;
+
+ memcpy(&ucall, addr_gva2hva(vm, run->s.regs.gprs[reg]),
+ sizeof(ucall));
+ got_ucall = true;
+ }
#endif
+
if (ucall_type == UCALL_MMIO && run->exit_reason == KVM_EXIT_MMIO &&
run->mmio.phys_addr == (uint64_t)ucall_exit_mmio_addr) {
vm_vaddr_t gva;
diff --git a/tools/testing/selftests/kvm/s390x/sync_regs_test.c b/tools/testing/selftests/kvm/s390x/sync_regs_test.c
index e85ff0d69548..bbc93094519b 100644
--- a/tools/testing/selftests/kvm/s390x/sync_regs_test.c
+++ b/tools/testing/selftests/kvm/s390x/sync_regs_test.c
@@ -25,9 +25,11 @@

static void guest_code(void)
{
+ register u64 stage asm("11") = 0;
+
for (;;) {
- asm volatile ("diag 0,0,0x501");
- asm volatile ("ahi 11,1");
+ GUEST_SYNC(0);
+ asm volatile ("ahi %0,1" : : "r"(stage));
}
}

--
2.21.0
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