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Subject[PATCH 5.4 086/109] KVM: arm64: Fix kvm_reset_vcpu() return code being incorrect with SVE
Date
From: Steven Price <steven.price@arm.com>

If SVE is enabled then 'ret' can be assigned the return value of
kvm_vcpu_enable_sve() which may be 0 causing future "goto out" sites to
erroneously return 0 on failure rather than -EINVAL as expected.

Remove the initialisation of 'ret' and make setting the return value
explicit to avoid this situation in the future.

Fixes: 9a3cdf26e336 ("KVM: arm64/sve: Allow userspace to enable SVE for vcpus")
Cc: stable@vger.kernel.org
Reported-by: James Morse <james.morse@arm.com>
Signed-off-by: Steven Price <steven.price@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200617105456.28245-1-steven.price@arm.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/arm64/kvm/reset.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)

--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -258,7 +258,7 @@ static int kvm_vcpu_enable_ptrauth(struc
int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
{
const struct kvm_regs *cpu_reset;
- int ret = -EINVAL;
+ int ret;
bool loaded;

/* Reset PMU outside of the non-preemptible section */
@@ -281,15 +281,19 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu

if (test_bit(KVM_ARM_VCPU_PTRAUTH_ADDRESS, vcpu->arch.features) ||
test_bit(KVM_ARM_VCPU_PTRAUTH_GENERIC, vcpu->arch.features)) {
- if (kvm_vcpu_enable_ptrauth(vcpu))
+ if (kvm_vcpu_enable_ptrauth(vcpu)) {
+ ret = -EINVAL;
goto out;
+ }
}

switch (vcpu->arch.target) {
default:
if (test_bit(KVM_ARM_VCPU_EL1_32BIT, vcpu->arch.features)) {
- if (!cpu_has_32bit_el1())
+ if (!cpu_has_32bit_el1()) {
+ ret = -EINVAL;
goto out;
+ }
cpu_reset = &default_regs_reset32;
} else {
cpu_reset = &default_regs_reset;

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