From: Nico Boehr <nrb@xxxxxxxxxxxxx> The CPU timer interrupt stays pending as long as the CPU timer value is negative. This can lead to interruption loops when the ext_new_psw mask has external interrupts enabled and the CPU timer subclass in CR0 is enabled. QEMU is able to detect this situation and panic the guest, so add a test for it. Signed-off-by: Nico Boehr <nrb@xxxxxxxxxxxxx> Reviewed-by: Thomas Huth <thuth@xxxxxxxxxx> Reviewed-by: Janosch Frank <frankja@xxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20220823103833.156942-4-nrb@xxxxxxxxxxxxx Message-Id: <20220823103833.156942-4-nrb@xxxxxxxxxxxxx> Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx> --- s390x/Makefile | 1 + s390x/panic-loop-extint.c | 59 +++++++++++++++++++++++++++++++++++++++ s390x/unittests.cfg | 6 ++++ 3 files changed, 66 insertions(+) create mode 100644 s390x/panic-loop-extint.c diff --git a/s390x/Makefile b/s390x/Makefile index efd5e0c1..e4649da5 100644 --- a/s390x/Makefile +++ b/s390x/Makefile @@ -34,6 +34,7 @@ tests += $(TEST_DIR)/migration.elf tests += $(TEST_DIR)/pv-attest.elf tests += $(TEST_DIR)/migration-cmm.elf tests += $(TEST_DIR)/migration-skey.elf +tests += $(TEST_DIR)/panic-loop-extint.elf pv-tests += $(TEST_DIR)/pv-diags.elf diff --git a/s390x/panic-loop-extint.c b/s390x/panic-loop-extint.c new file mode 100644 index 00000000..07325147 --- /dev/null +++ b/s390x/panic-loop-extint.c @@ -0,0 +1,59 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * External interrupt loop test + * + * Copyright IBM Corp. 2022 + * + * Authors: + * Nico Boehr <nrb@xxxxxxxxxxxxx> + */ +#include <libcflat.h> +#include <asm/interrupt.h> +#include <asm/barrier.h> +#include <asm/time.h> +#include <hardware.h> +#include <bitops.h> + +static void ext_int_cleanup(struct stack_frame_int *stack) +{ + /* + * Since we form a loop of ext interrupts, this code should never be + * executed. In case it is executed, something went wrong and we want to + * print a failure. + * + * Because the CPU timer subclass mask is still enabled, the CPU timer + * interrupt will fire every time we enable external interrupts, + * preventing us from printing the failure on the console. To avoid + * this, clear the CPU timer subclass mask here. + */ + stack->crs[0] &= ~BIT(CTL0_CPU_TIMER); +} + +int main(void) +{ + report_prefix_push("panic-loop-extint"); + + if (!host_is_qemu() || host_is_tcg()) { + report_skip("QEMU-KVM-only test"); + goto out; + } + + expect_ext_int(); + lowcore.ext_new_psw.mask |= PSW_MASK_EXT; + + psw_mask_set_bits(PSW_MASK_EXT); + + register_ext_cleanup_func(ext_int_cleanup); + + cpu_timer_set_ms(10); + ctl_set_bit(0, CTL0_CPU_TIMER); + mdelay(2000); + + register_ext_cleanup_func(NULL); + + report_fail("survived extint loop"); + +out: + report_prefix_pop(); + return report_summary(); +} diff --git a/s390x/unittests.cfg b/s390x/unittests.cfg index f7b1fc3d..b1b25f11 100644 --- a/s390x/unittests.cfg +++ b/s390x/unittests.cfg @@ -185,3 +185,9 @@ groups = migration [migration-skey] file = migration-skey.elf groups = migration + +[panic-loop-extint] +file = panic-loop-extint.elf +groups = panic +accel = kvm +timeout = 5 -- 2.34.1
