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KVM: arm64: nVHE: Handle hyp panics

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Restore the host context when panicking from hyp to give the best chance
of the panic being clean.

The host requires that registers be preserved such as x18 for the shadow
callstack. If the panic is caused by an exception from EL1, the host
context is still valid so the panic can return straight back to the
host. If the panic comes from EL2 then it's most likely that the hyp
context is active and the host context needs to be restored.

There are windows before and after the host context is saved and
restored that restoration is attempted incorrectly and the panic won't
be clean.

Signed-off-by: Andrew Scull <ascull@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200915104643.2543892-14-ascull@google.com
This commit is contained in:
Andrew Scull
2020-09-15 11:46:37 +01:00
committed by Marc Zyngier
parent 4e3393a969
commit a2e102e20f
3 changed files with 63 additions and 33 deletions
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2
arch/arm64/include/asm/kvm_hyp.h
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@@ -94,7 +94,7 @@ u64 __guest_enter(struct kvm_vcpu *vcpu);
void __noreturn hyp_panic(void);
#ifdef __KVM_NVHE_HYPERVISOR__
void __noreturn __hyp_do_panic(unsigned long, ...);
void __noreturn __hyp_do_panic(bool restore_host, u64 spsr, u64 elr, u64 par);
#endif
#endif /* __ARM64_KVM_HYP_H__ */