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| H A D | psci.c | e14e6ba56f6e9597e774ab0e28f9ba9e5f5a06c9 Fri Jan 31 16:37:20 UTC 2020 Alexandru Elisei <alexandru.elisei@arm.com> 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>
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