Commit 2c91ef39 authored by David Brazdil's avatar David Brazdil Committed by Marc Zyngier
Browse files

KVM: arm64: Allow PSCI SYSTEM_OFF/RESET to return 



The KVM/arm64 PSCI relay assumes that SYSTEM_OFF and SYSTEM_RESET should
not return, as dictated by the PSCI spec. However, there is firmware out
there which breaks this assumption, leading to a hyp panic. Make KVM
more robust to broken firmware by allowing these to return.

Signed-off-by: default avatarDavid Brazdil <dbrazdil@google.com>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20201229160059.64135-1-dbrazdil@google.com
parent 7ded92e2

arch/arm64/kvm/hyp/nvhe/psci-relay.c

+5 −8
Original line number Diff line number Diff line
@@ -77,12 +77,6 @@ static unsigned long psci_forward(struct kvm_cpu_context *host_ctxt) 
			 cpu_reg(host_ctxt, 2), cpu_reg(host_ctxt, 3));

}



static __noreturn unsigned long psci_forward_noreturn(struct kvm_cpu_context *host_ctxt)

{

	psci_forward(host_ctxt);

	hyp_panic(); /* unreachable */

}



static unsigned int find_cpu_id(u64 mpidr)

{

	unsigned int i;
@@ -251,10 +245,13 @@ static unsigned long psci_0_2_handler(u64 func_id, struct kvm_cpu_context *host_ 
	case PSCI_0_2_FN_MIGRATE_INFO_TYPE:

	case PSCI_0_2_FN64_MIGRATE_INFO_UP_CPU:

		return psci_forward(host_ctxt);

	/*

	 * SYSTEM_OFF/RESET should not return according to the spec.

	 * Allow it so as to stay robust to broken firmware.

	 */

	case PSCI_0_2_FN_SYSTEM_OFF:

	case PSCI_0_2_FN_SYSTEM_RESET:

		psci_forward_noreturn(host_ctxt);

		unreachable();

		return psci_forward(host_ctxt);

	case PSCI_0_2_FN64_CPU_SUSPEND:

		return psci_cpu_suspend(func_id, host_ctxt);

	case PSCI_0_2_FN64_CPU_ON: