[PATCH v3 03/19] KVM: arm64: Reject invalid addresses for CPU_ON PSCI call

[Oliver Upton]

DEN0022D.b 5.6.2 "Caller responsibilities" states that a PSCI
implementation may return INVALID_ADDRESS for the CPU_ON call if the
provided entry address is known to be invalid. There is an additional
caveat to this rule. Prior to PSCI v1.0, the INVALID_PARAMETERS error
is returned instead. Check the guest's PSCI version and return the
appropriate error if the IPA is invalid.

Reported-by: Reiji Watanabe <reijiw at google.com>
Signed-off-by: Oliver Upton <oupton at google.com>
---
 arch/arm64/kvm/psci.c | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kvm/psci.c b/arch/arm64/kvm/psci.c
index a0c10c11f40e..de1cf554929d 100644
--- a/arch/arm64/kvm/psci.c
+++ b/arch/arm64/kvm/psci.c
@@ -12,6 +12,7 @@
 
 #include <asm/cputype.h>
 #include <asm/kvm_emulate.h>
+#include <asm/kvm_mmu.h>
 
 #include <kvm/arm_psci.h>
 #include <kvm/arm_hypercalls.h>
@@ -70,12 +71,31 @@ static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu)
 	struct vcpu_reset_state *reset_state;
 	struct kvm *kvm = source_vcpu->kvm;
 	struct kvm_vcpu *vcpu = NULL;
-	unsigned long cpu_id;
+	unsigned long cpu_id, entry_addr;
 
 	cpu_id = smccc_get_arg1(source_vcpu);
 	if (!kvm_psci_valid_affinity(source_vcpu, cpu_id))
 		return PSCI_RET_INVALID_PARAMS;
 
+	/*
+	 * Basic sanity check: ensure the requested entry address actually
+	 * exists within the guest's address space.
+	 */
+	entry_addr = smccc_get_arg2(source_vcpu);
+	if (!kvm_ipa_valid(kvm, entry_addr)) {
+
+		/*
+		 * Before PSCI v1.0, the INVALID_PARAMETERS error is returned
+		 * instead of INVALID_ADDRESS.
+		 *
+		 * For more details, see ARM DEN0022D.b 5.6 "CPU_ON".
+		 */
+		if (kvm_psci_version(source_vcpu) < KVM_ARM_PSCI_1_0)
+			return PSCI_RET_INVALID_PARAMS;
+		else
+			return PSCI_RET_INVALID_ADDRESS;
+	}
+
 	vcpu = kvm_mpidr_to_vcpu(kvm, cpu_id);
 
 	/*
@@ -93,7 +113,7 @@ static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu)
 
 	reset_state = &vcpu->arch.reset_state;
 
-	reset_state->pc = smccc_get_arg2(source_vcpu);
+	reset_state->pc = entry_addr;
 
 	/* Propagate caller endianness */
 	reset_state->be = kvm_vcpu_is_be(source_vcpu);
-- 
2.35.1.473.g83b2b277ed-goog