From: David Brazdil <dbrazdil@google.com>
To: kvmarm@lists.cs.columbia.edu
Cc: Mark Rutland <mark.rutland@arm.com>,
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Marc Zyngier <maz@kernel.org>,
Sudeep Holla <sudeep.holla@arm.com>,
linux-kernel@vger.kernel.org, James Morse <james.morse@arm.com>,
linux-arm-kernel@lists.infradead.org,
Catalin Marinas <catalin.marinas@arm.com>,
kernel-team@android.com, David Brazdil <dbrazdil@google.com>,
Will Deacon <will@kernel.org>,
Julien Thierry <julien.thierry.kdev@gmail.com>
Subject: [PATCH] KVM: arm64: Allow PSCI SYSTEM_OFF/RESET to return
Date: Tue, 29 Dec 2020 16:00:59 +0000 [thread overview]
Message-ID: <20201229160059.64135-1-dbrazdil@google.com> (raw)
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: David Brazdil <dbrazdil@google.com>
---
arch/arm64/kvm/hyp/nvhe/psci-relay.c | 13 +++++--------
1 file changed, 5 insertions(+), 8 deletions(-)
diff --git a/arch/arm64/kvm/hyp/nvhe/psci-relay.c b/arch/arm64/kvm/hyp/nvhe/psci-relay.c
index e3947846ffcb..8e7128cb7667 100644
--- a/arch/arm64/kvm/hyp/nvhe/psci-relay.c
+++ b/arch/arm64/kvm/hyp/nvhe/psci-relay.c
@@ -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:
--
2.29.2.729.g45daf8777d-goog
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next reply other threads:[~2020-12-29 16:02 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-29 16:00 David Brazdil [this message]
2020-12-29 17:04 ` [PATCH] KVM: arm64: Allow PSCI SYSTEM_OFF/RESET to return Russell King - ARM Linux admin
2020-12-30 10:06 ` Marc Zyngier
2020-12-29 17:16 ` Marc Zyngier
2020-12-30 11:03 ` David Brazdil
2021-01-15 11:33 ` Marc Zyngier
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