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arm64: hyp/kvm: Make hyp-stub reject kvm_call_hyp()

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A later patch implements kvm_arch_hardware_disable(), to remove kvm
from el2, and re-instate the hyp-stub.

This can happen while guests are running, particularly when kvm_reboot()
calls kvm_arch_hardware_disable() on each cpu. This can interrupt a guest,
remove kvm, then allow the guest to be scheduled again. This causes
kvm_call_hyp() to be run against the hyp-stub.

Change the hyp-stub to return a new exception type when this happens,
and add code to kvm's handle_exit() to tell userspace we failed to
enter the guest.

Signed-off-by: James Morse <james.morse@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
James Morse
2016-04-27 17:47:04 +01:00
committed by Will Deacon
parent ad72e59ff2
commit c94b0cf282
3 changed files with 12 additions and 2 deletions
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5
arch/arm64/kernel/hyp-stub.S
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@@ -23,6 +23,7 @@
#include <asm/assembler.h>
#include <asm/kvm_arm.h>
#include <asm/kvm_asm.h>
#include <asm/ptrace.h>
#include <asm/virt.h>
@@ -70,8 +71,8 @@ el1_sync:
msr vbar_el2, x1
b 9f
/* Unrecognised call type */
2: mov x0, xzr
/* Someone called kvm_call_hyp() against the hyp-stub... */
2: mov x0, #ARM_EXCEPTION_HYP_GONE
9: eret
ENDPROC(el1_sync)