From: Alexandru Elisei <alexandru.elisei@arm.com>
To: kvm@vger.kernel.org
Cc: pbonzini@redhat.com, drjones@redhat.com, maz@kernel.org,
andre.przywara@arm.com, vladimir.murzin@arm.com,
mark.rutland@arm.com
Subject: [kvm-unit-tests PATCH v4 02/10] arm/arm64: psci: Don't run C code without stack or vectors
Date: Fri, 31 Jan 2020 16:37:20 +0000 [thread overview]
Message-ID: <20200131163728.5228-3-alexandru.elisei@arm.com> (raw)
In-Reply-To: <20200131163728.5228-1-alexandru.elisei@arm.com>
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>
---
arm/psci.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)
diff --git a/arm/psci.c b/arm/psci.c
index 5c1accb6cea4..ffc09a2e9858 100644
--- a/arm/psci.c
+++ b/arm/psci.c
@@ -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;
}
--
2.20.1
next prev parent reply other threads:[~2020-01-31 16:38 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-31 16:37 [kvm-unit-tests PATCH v4 00/10] arm/arm64: Various fixes Alexandru Elisei
2020-01-31 16:37 ` [kvm-unit-tests PATCH v4 01/10] Makefile: Use no-stack-protector compiler options Alexandru Elisei
2020-01-31 16:44 ` Thomas Huth
2020-01-31 17:27 ` Laurent Vivier
2020-01-31 16:37 ` Alexandru Elisei [this message]
2020-01-31 16:37 ` [kvm-unit-tests PATCH v4 03/10] arm64: timer: Add ISB after register writes Alexandru Elisei
2020-01-31 16:37 ` [kvm-unit-tests PATCH v4 04/10] arm64: timer: Add ISB before reading the counter value Alexandru Elisei
2020-01-31 16:37 ` [kvm-unit-tests PATCH v4 05/10] arm64: timer: Make irq_received volatile Alexandru Elisei
2020-01-31 16:37 ` [kvm-unit-tests PATCH v4 06/10] arm64: timer: EOIR the interrupt after masking the timer Alexandru Elisei
2020-01-31 16:37 ` [kvm-unit-tests PATCH v4 07/10] arm64: timer: Wait for the GIC to sample timer interrupt state Alexandru Elisei
2020-01-31 16:37 ` [kvm-unit-tests PATCH v4 08/10] arm64: timer: Check the " Alexandru Elisei
2020-01-31 16:37 ` [kvm-unit-tests PATCH v4 09/10] arm64: timer: Test behavior when timer disabled or masked Alexandru Elisei
2020-01-31 16:37 ` [kvm-unit-tests PATCH v4 10/10] arm/arm64: Perform dcache clean + invalidate after turning MMU off Alexandru Elisei
2020-02-03 18:59 ` [kvm-unit-tests PATCH v4 00/10] arm/arm64: Various fixes Andrew Jones
2020-02-04 17:36 ` Alexandru Elisei
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