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

From: Amit Daniel Kachhap
Date: Tue Mar 26 2019 - 23:21:36 EST

On 3/26/19 11:31 PM, Kristina Martsenko wrote:
On 26/03/2019 04:03, Amit Daniel Kachhap wrote:

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

The documentation makes sense so in this case a pr_err like message will suffice. Btw there is one WARN in the function kvm_set_ipa_limit in the same file.

Amit D