On 21/01/18 12:32, gregkh@linuxfoundation.org wrote:

This is a note to let you know that I've just added the patch titled

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

to the 3.18-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: arm64-kvm-fix-smccc-handling-of-unimplemented-smc-hvc-calls.patch and it can be found in the queue-3.18 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From acfb3b883f6d6a4b5d27ad7fdded11f6a09ae6dd Mon Sep 17 00:00:00 2001 From: Marc Zyngier marc.zyngier@arm.com Date: Tue, 16 Jan 2018 10:23:47 +0000 Subject: arm64: KVM: Fix SMCCC handling of unimplemented SMC/HVC calls

From: Marc Zyngier marc.zyngier@arm.com

commit acfb3b883f6d6a4b5d27ad7fdded11f6a09ae6dd upstream.

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 marc.zyngier@arm.com Signed-off-by: Christoffer Dall christoffer.dall@linaro.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

---

arch/arm64/kvm/handle_exit.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/arch/arm64/kvm/handle_exit.c +++ b/arch/arm64/kvm/handle_exit.c @@ -34,7 +34,7 @@ static int handle_hvc(struct kvm_vcpu *v ret = kvm_psci_call(vcpu); if (ret < 0) {

• kvm_inject_undefined(vcpu);
  

• vcpu_set_reg(vcpu, 0, ~0UL);
  

  return 1; }

@@ -43,7 +43,7 @@ static int handle_hvc(struct kvm_vcpu *v static int handle_smc(struct kvm_vcpu *vcpu, struct kvm_run *run) {

• kvm_inject_undefined(vcpu);

• vcpu_set_reg(vcpu, 0, ~0UL); return 1;

}

Patches currently in stable-queue which might be from marc.zyngier@arm.com are

queue-3.18/arm64-kvm-fix-smccc-handling-of-unimplemented-smc-hvc-calls.patch

This doesn't compile on 3.18. Here's the 3.18 fix:

From 1dd2c482cc168ebe2d099db0ea7b2a5ca239c182 Mon Sep 17 00:00:00 2001

From: Marc Zyngier marc.zyngier@arm.com Date: Fri, 12 Jan 2018 07:34:43 +0000 Subject: [PATCH] arm64: KVM: Fix SMCCC handling of unimplemented SMC/HVC calls

commit acfb3b883f6d6a4b5d27ad7fdded11f6a09ae6dd upstream.

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 marc.zyngier@arm.com Signed-off-by: Christoffer Dall christoffer.dall@linaro.org --- 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 34b8bd0711e9..e738bff5eec1 100644 --- a/arch/arm64/kvm/handle_exit.c +++ b/arch/arm64/kvm/handle_exit.c @@ -34,7 +34,7 @@ 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_reg(vcpu, 0) = ~0UL; return 1; }

@@ -43,7 +43,7 @@ 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_reg(vcpu, 0) = ~0UL; return 1; }