Commit efaa83a3 authored by Collin Walling's avatar Collin Walling Committed by Christian Borntraeger
Browse files

KVM: selftests: sync_regs test for diag318 



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 to 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.

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.

Signed-off-by: default avatarCollin Walling <walling@linux.ibm.com>
Link: https://lore.kernel.org/r/20201207154125.10322-1-walling@linux.ibm.com


Acked-by: default avatarJanosch Frank <frankja@linux.ibm.com>
Acked-by: default avatarCornelia Huck <cohuck@redhat.com>
Reviewed-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
parent 0cd2a787

tools/testing/selftests/kvm/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -36,7 +36,7 @@ endif 
LIBKVM = lib/assert.c lib/elf.c lib/io.c lib/kvm_util.c lib/sparsebit.c lib/test_util.c

LIBKVM_x86_64 = lib/x86_64/processor.c lib/x86_64/vmx.c lib/x86_64/svm.c lib/x86_64/ucall.c

LIBKVM_aarch64 = lib/aarch64/processor.c lib/aarch64/ucall.c

LIBKVM_s390x = lib/s390x/processor.c lib/s390x/ucall.c

LIBKVM_s390x = lib/s390x/processor.c lib/s390x/ucall.c lib/s390x/diag318_test_handler.c



TEST_GEN_PROGS_x86_64 = x86_64/cr4_cpuid_sync_test

TEST_GEN_PROGS_x86_64 += x86_64/evmcs_test

tools/testing/selftests/kvm/include/s390x/diag318_test_handler.h

0 → 100644
+13 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0-or-later

 *

 * Test handler for the s390x DIAGNOSE 0x0318 instruction.

 *

 * Copyright (C) 2020, IBM

 */



#ifndef SELFTEST_KVM_DIAG318_TEST_HANDLER

#define SELFTEST_KVM_DIAG318_TEST_HANDLER



uint64_t get_diag318_info(void);



#endif

tools/testing/selftests/kvm/lib/s390x/diag318_test_handler.c

0 → 100644
+82 −0
Original line number Diff line number Diff line 
// 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	6



#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];



	TEST_ASSERT(diag318_info != 0, "DIAGNOSE 0x0318 info not set");



	kvm_vm_free(vm);



	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;

}

tools/testing/selftests/kvm/s390x/sync_regs_test.c

+15 −1
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ 


#include "test_util.h"

#include "kvm_util.h"

#include "diag318_test_handler.h"



#define VCPU_ID 5
@@ -70,7 +71,7 @@ static void compare_sregs(struct kvm_sregs *left, struct kvm_sync_regs *right) 


#undef REG_COMPARE



#define TEST_SYNC_FIELDS   (KVM_SYNC_GPRS|KVM_SYNC_ACRS|KVM_SYNC_CRS)

#define TEST_SYNC_FIELDS   (KVM_SYNC_GPRS|KVM_SYNC_ACRS|KVM_SYNC_CRS|KVM_SYNC_DIAG318)

#define INVALID_SYNC_FIELD 0x80000000



int main(int argc, char *argv[])
@@ -152,6 +153,12 @@ int main(int argc, char *argv[]) 


	run->kvm_valid_regs = TEST_SYNC_FIELDS;

	run->kvm_dirty_regs = KVM_SYNC_GPRS | KVM_SYNC_ACRS;



	if (get_diag318_info() > 0) {

		run->s.regs.diag318 = get_diag318_info();

		run->kvm_dirty_regs |= KVM_SYNC_DIAG318;

	}



	rv = _vcpu_run(vm, VCPU_ID);

	TEST_ASSERT(rv == 0, "vcpu_run failed: %d\n", rv);

	TEST_ASSERT(run->exit_reason == KVM_EXIT_S390_SIEIC,
@@ -164,6 +171,9 @@ int main(int argc, char *argv[]) 
	TEST_ASSERT(run->s.regs.acrs[0]  == 1 << 11,

		    "acr0 sync regs value incorrect 0x%x.",

		    run->s.regs.acrs[0]);

	TEST_ASSERT(run->s.regs.diag318 == get_diag318_info(),

		    "diag318 sync regs value incorrect 0x%llx.",

		    run->s.regs.diag318);



	vcpu_regs_get(vm, VCPU_ID, &regs);

	compare_regs(&regs, &run->s.regs);
@@ -177,6 +187,7 @@ int main(int argc, char *argv[]) 
	run->kvm_valid_regs = TEST_SYNC_FIELDS;

	run->kvm_dirty_regs = 0;

	run->s.regs.gprs[11] = 0xDEADBEEF;

	run->s.regs.diag318 = 0x4B1D;

	rv = _vcpu_run(vm, VCPU_ID);

	TEST_ASSERT(rv == 0, "vcpu_run failed: %d\n", rv);

	TEST_ASSERT(run->exit_reason == KVM_EXIT_S390_SIEIC,
@@ -186,6 +197,9 @@ int main(int argc, char *argv[]) 
	TEST_ASSERT(run->s.regs.gprs[11] != 0xDEADBEEF,

		    "r11 sync regs value incorrect 0x%llx.",

		    run->s.regs.gprs[11]);

	TEST_ASSERT(run->s.regs.diag318 != 0x4B1D,

		    "diag318 sync regs value incorrect 0x%llx.",

		    run->s.regs.diag318);



	kvm_vm_free(vm);

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