arm64: KVM: Fix SMCCC handling of unimplemented SMC/HVC calls

Web:        https://git.kernel.org/torvalds/c/c0938c72f8070aabb766b06edba85941ea7911da
Commit:     c0938c72f8070aabb766b06edba85941ea7911da
Parent:     30d88c0e3ace625a92eead9ca0ad94093a8f59fe
Refname:    refs/heads/master
Author:     Marc Zyngier <[email protected]>
AuthorDate: Tue Feb 6 17:56:05 2018 +0000
Committer:  Catalin Marinas <[email protected]>
CommitDate: Tue Feb 6 22:53:48 2018 +0000

    arm64: KVM: Fix SMCCC handling of unimplemented SMC/HVC calls
    
    KVM doesn't follow the SMCCC when it comes to unimplemented calls,
    and inject an UNDEF instead of returning an error. Since firmware
    calls are now used for security mitigation, they are becoming more
    common, and the undef is counter productive.
    
    Instead, let's follow the SMCCC which states that -1 must be returned
    to the caller when getting an unknown function number.
    
    Signed-off-by: Marc Zyngier <[email protected]>
    Signed-off-by: Christoffer Dall <[email protected]>
    Signed-off-by: Catalin Marinas <[email protected]>
---
 arch/arm64/kvm/handle_exit.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
index c09fc5a576c7..520b0dad3c62 100644
--- a/arch/arm64/kvm/handle_exit.c
+++ b/arch/arm64/kvm/handle_exit.c
@@ -53,7 +53,7 @@ static int handle_hvc(struct kvm_vcpu *vcpu, struct kvm_run *run)
 
 	ret = kvm_psci_call(vcpu);
 	if (ret < 0) {
-		kvm_inject_undefined(vcpu);
+		vcpu_set_reg(vcpu, 0, ~0UL);
 		return 1;
 	}
 
@@ -62,7 +62,7 @@ static int handle_hvc(struct kvm_vcpu *vcpu, struct kvm_run *run)
 
 static int handle_smc(struct kvm_vcpu *vcpu, struct kvm_run *run)
 {
-	kvm_inject_undefined(vcpu);
+	vcpu_set_reg(vcpu, 0, ~0UL);
 	return 1;
 }
 
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