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author | Alexandru Elisei <alexandru.elisei@arm.com> | 2020-01-31 16:37:20 +0000 |
---|---|---|
committer | Andrew Jones <drjones@redhat.com> | 2020-04-03 09:40:33 +0200 |
commit | e14e6ba56f6e9597e774ab0e28f9ba9e5f5a06c9 (patch) | |
tree | 158a52f727ad6cb4c133757b2d5569bbbd85e635 | |
parent | 2087da55d7a253bfd02ea4b184a0e4af9b1ec5dd (diff) | |
download | kvm-unit-tests-e14e6ba56f6e9597e774ab0e28f9ba9e5f5a06c9.tar.gz |
arm/arm64: psci: Don't run C code without stack or vectors
The psci test performs a series of CPU_ON/CPU_OFF cycles for CPU 1. This is
done by setting the entry point for the CPU_ON call to the physical address
of the C function cpu_psci_cpu_die.
The compiler is well within its rights to use the stack when generating
code for cpu_psci_cpu_die. However, because no stack initialization has
been done, the stack pointer is zero, as set by KVM when creating the VCPU.
This causes a data abort without a change in exception level. The VBAR_EL1
register is also zero (the KVM reset value for VBAR_EL1), the MMU is off,
and we end up trying to fetch instructions from address 0x200.
At this point, a stage 2 instruction abort is generated which is taken to
KVM. KVM interprets this as an instruction fetch from an I/O region, and
injects a prefetch abort into the guest. Prefetch abort is a synchronous
exception, and on guest return the VCPU PC will be set to VBAR_EL1 + 0x200,
which is... 0x200. The VCPU ends up in an infinite loop causing a prefetch
abort while fetching the instruction to service the said abort.
To avoid all of this, lets use the assembly function halt as the CPU_ON
entry address. Also, expand the check to test that we only get
PSCI_RET_SUCCESS exactly once, as we're never offlining the CPU during the
test.
Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: Andrew Jones <drjones@redhat.com>
-rw-r--r-- | arm/psci.c | 14 |
1 files changed, 11 insertions, 3 deletions
@@ -79,13 +79,14 @@ static void cpu_on_secondary_entry(void) cpumask_set_cpu(cpu, &cpu_on_ready); while (!cpu_on_start) cpu_relax(); - cpu_on_ret[cpu] = psci_cpu_on(cpus[1], __pa(cpu_psci_cpu_die)); + cpu_on_ret[cpu] = psci_cpu_on(cpus[1], __pa(halt)); cpumask_set_cpu(cpu, &cpu_on_done); } static bool psci_cpu_on_test(void) { bool failed = false; + int ret_success = 0; int cpu; cpumask_set_cpu(1, &cpu_on_ready); @@ -104,7 +105,7 @@ static bool psci_cpu_on_test(void) cpu_on_start = 1; smp_mb(); - cpu_on_ret[0] = psci_cpu_on(cpus[1], __pa(cpu_psci_cpu_die)); + cpu_on_ret[0] = psci_cpu_on(cpus[1], __pa(halt)); cpumask_set_cpu(0, &cpu_on_done); while (!cpumask_full(&cpu_on_done)) @@ -113,12 +114,19 @@ static bool psci_cpu_on_test(void) for_each_present_cpu(cpu) { if (cpu == 1) continue; - if (cpu_on_ret[cpu] != PSCI_RET_SUCCESS && cpu_on_ret[cpu] != PSCI_RET_ALREADY_ON) { + if (cpu_on_ret[cpu] == PSCI_RET_SUCCESS) { + ret_success++; + } else if (cpu_on_ret[cpu] != PSCI_RET_ALREADY_ON) { report_info("unexpected cpu_on return value: caller=CPU%d, ret=%d", cpu, cpu_on_ret[cpu]); failed = true; } } + if (ret_success != 1) { + report_info("got %d CPU_ON success", ret_success); + failed = true; + } + return !failed; } |