Re: [PATCH v7 7/10] KVM: arm/arm64: context-switch ptrauth registers

From: Kristina Martsenko
Date: Tue Mar 26 2019 - 14:01:50 EST

On 26/03/2019 04:03, Amit Daniel Kachhap wrote:
> Hi,
> On 3/26/19 1:34 AM, Kristina Martsenko wrote:
>> On 19/03/2019 08:30, Amit Daniel Kachhap wrote:
>>> From: Mark Rutland <mark.rutland@xxxxxxx>
>>> When pointer authentication is supported, a guest may wish to use it.
>>> This patch adds the necessary KVM infrastructure for this to work, with
>>> a semi-lazy context switch of the pointer auth state.
>> [...]
>>> +ÂÂÂ if (test_bit(KVM_ARM_VCPU_PTRAUTH_ADDRESS, vcpu->arch.features) ||
>>> +ÂÂÂÂÂÂÂ test_bit(KVM_ARM_VCPU_PTRAUTH_GENERIC, vcpu->arch.features)) {
>>> +ÂÂÂÂÂÂÂ /* Verify that KVM startup matches the conditions for ptrauth */
>>> +ÂÂÂÂÂÂÂ if (WARN_ON(!vcpu_has_ptrauth(vcpu)))
>>> +ÂÂÂ }
>> I think this now needs to have "goto out;" instead of "return -EINVAL;",
>> since 5.1-rcX contains commit e761a927bc9a ("KVM: arm/arm64: Reset the
>> VCPU without preemption and vcpu state loaded") which changed some of
>> this code.
> ok missed the changes for this commit.

One more thing - I think the WARN_ON() here should be removed. Otherwise
if panic_on_warn is set then userspace can panic the kernel. I think
WARN_ON is only for internal kernel errors (see comment in