On 14/10/2020 21.27, Collin Walling wrote:
> The DIAGNOSE 0x0318 instruction, unique to s390x, is a privileged call
> that must be intercepted via SIE, handled in userspace, and the
> information set by the instruction is communicated back to KVM.
>
> To test the instruction interception, an ad-hoc handler is defined which
> simply has a VM execute the instruction and then userspace will extract
> the necessary info. The handler is defined such that the instruction
> invocation occurs only once. It is up the the caller to determine how the
> info returned by this handler should be used.
>
> The diag318 info is communicated from userspace to KVM via a sync_regs
> call. This is tested during a sync_regs test, where the diag318 info is
> requested via the handler, then the info is stored in the appropriate
> register in KVM via a sync registers call.
>
> The diag318 info is checked to be 0 after a normal and clear reset.
>
> If KVM does not support diag318, then the tests will print a message
> stating that diag318 was skipped, and the asserts will simply test
> against a value of 0.
Thanks a lot for writing the test! Looks pretty good already, but I still
have some comments / questions below...
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/lib/s390x/diag318_test_handler.c
> @@ -0,0 +1,80 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Test handler for the s390x DIAGNOSE 0x0318 instruction.
> + *
> + * Copyright (C) 2020, IBM
> + */
> +
> +#include "test_util.h"
> +#include "kvm_util.h"
> +
> +#define VCPU_ID 5
> +
> +#define ICPT_INSTRUCTION 0x04
> +#define IPA0_DIAG 0x8300
> +
> +static void guest_code(void)
> +{
> + uint64_t diag318_info = 0x12345678;
> +
> + asm volatile ("diag %0,0,0x318\n" : : "d" (diag318_info));
> +}
> +
> +/*
> + * The DIAGNOSE 0x0318 instruction call must be handled via userspace. As such,
> + * we create an ad-hoc VM here to handle the instruction then extract the
> + * necessary data. It is up to the caller to decide what to do with that data.
> + */
> +static uint64_t diag318_handler(void)
> +{
> + struct kvm_vm *vm;
> + struct kvm_run *run;
> + uint64_t reg;
> + uint64_t diag318_info;
> +
> + vm = vm_create_default(VCPU_ID, 0, guest_code);
> + vcpu_run(vm, VCPU_ID);
> + run = vcpu_state(vm, VCPU_ID);
> +
> + TEST_ASSERT(run->exit_reason == KVM_EXIT_S390_SIEIC,
> + "DIAGNOSE 0x0318 instruction was not intercepted");
> + TEST_ASSERT(run->s390_sieic.icptcode == ICPT_INSTRUCTION,
> + "Unexpected intercept code: 0x%x", run->s390_sieic.icptcode);
> + TEST_ASSERT((run->s390_sieic.ipa & 0xff00) == IPA0_DIAG,
> + "Unexpected IPA0 code: 0x%x", (run->s390_sieic.ipa & 0xff00));
> +
> + reg = (run->s390_sieic.ipa & 0x00f0) >> 4;
> + diag318_info = run->s.regs.gprs[reg];
> +
> + kvm_vm_free(vm);
Could you please add a
TEST_ASSERT(diag_318_info == 0x12345678, ...)
here?
> + return diag318_info;
> +}
> +
> +uint64_t get_diag318_info(void)
> +{
> + static uint64_t diag318_info;
> + static bool printed_skip;
> +
> + /*
> + * If KVM does not support diag318, then return 0 to
> + * ensure tests do not break.
> + */
> + if (!kvm_check_cap(KVM_CAP_S390_DIAG318)) {
> + if (!printed_skip) {
> + fprintf(stdout, "KVM_CAP_S390_DIAG318 not supported. "
> + "Skipping diag318 test.\n");
> + printed_skip = true;
> + }
> + return 0;
> + }
> +
> + /*
> + * If a test has previously requested the diag318 info,
> + * then don't bother spinning up a temporary VM again.
> + */
> + if (!diag318_info)
> + diag318_info = diag318_handler();
> +
> + return diag318_info;
> +}
> diff --git a/tools/testing/selftests/kvm/s390x/resets.c b/tools/testing/selftests/kvm/s390x/resets.c
> index b143db6d8693..d0416ba94ec5 100644
> --- a/tools/testing/selftests/kvm/s390x/resets.c
> +++ b/tools/testing/selftests/kvm/s390x/resets.c
> @@ -12,6 +12,7 @@
>
> #include "test_util.h"
> #include "kvm_util.h"
> +#include "diag318_test_handler.h"
>
> #define VCPU_ID 3
> #define LOCAL_IRQS 32
> @@ -110,6 +111,8 @@ static void assert_clear(void)
>
> TEST_ASSERT(!memcmp(sync_regs->vrs, regs_null, sizeof(sync_regs->vrs)),
> "vrs0-15 == 0 (sync_regs)");
> +
> + TEST_ASSERT(sync_regs->diag318 == 0, "diag318 == 0 (sync_regs)");
> }
>
> static void assert_initial_noclear(void)
> @@ -182,6 +185,7 @@ 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)");
> + TEST_ASSERT(sync_regs->diag318 == 0, "diag318 == 0 (sync_regs)");
> assert_noirq();
> }
>
> @@ -206,6 +210,7 @@ static void test_normal(void)
> /* Create VM */
> vm = vm_create_default(VCPU_ID, 0, guest_code_initial);
> run = vcpu_state(vm, VCPU_ID);
> + run->s.regs.diag318 = get_diag318_info();
> sync_regs = &run->s.regs;
Not sure, but don't you have to mark KVM_SYNC_DIAG318 in run->kvm_valid_regs
and run->kvm_dirty_regs here...
> vcpu_run(vm, VCPU_ID);
> @@ -250,6 +255,7 @@ static void test_clear(void)
> pr_info("Testing clear reset\n");
> vm = vm_create_default(VCPU_ID, 0, guest_code_initial);
> run = vcpu_state(vm, VCPU_ID);
> + run->s.regs.diag318 = get_diag318_info();
> sync_regs = &run->s.regs;
... and here?
Thomas
