On Tue, Jun 21, 2022, Kechen Lu wrote:
> From: Sean Christopherson <seanjc@xxxxxxxxxx>
>
> Reject KVM_CAP_X86_DISABLE_EXITS if userspace attempts to disable MWAIT
> exits and KVM previously reported (via KVM_CHECK_EXTENSION) that MWAIT is
> not allowed in guest, e.g. because it's not supported or the CPU doesn't
> have an aways-running APIC timer.
>
> Fixes: 4d5422cea3b6 ("KVM: X86: Provide a capability to disable MWAIT intercepts")
> Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
> Co-developed-by: Kechen Lu <kechenl@xxxxxxxxxx>
Needs your SOB.
> Suggested-by: Chao Gao <chao.gao@xxxxxxxxx>
For code review feedback of this nature, adding Suggested-by isn't appropriate.
Suggested-by is for when the idea of the patch itself was suggested by someone,
where as Chao's feedback was a purely mechanical change.
> ---
> arch/x86/kvm/x86.c | 20 +++++++++++++-------
> 1 file changed, 13 insertions(+), 7 deletions(-)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index b419b258ed90..6ec01362a7d8 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -4199,6 +4199,16 @@ static inline bool kvm_can_mwait_in_guest(void)
> boot_cpu_has(X86_FEATURE_ARAT);
> }
>
> +static u64 kvm_get_allowed_disable_exits(void)
> +{
> + u64 r = KVM_X86_DISABLE_VALID_EXITS;
In v3 I "voted" to keep the switch to KVM_X86_DISABLE_VALID_EXITS in the next
patch[*], but seeing the result I 100% agree it's better to handle it here since
the "enable" patch previously used KVM_X86_DISABLE_VALID_EXITS.
[*] https://lore.kernel.org/all/Ytg428sleo7uMRQt@xxxxxxxxxx
> +
> + if(!kvm_can_mwait_in_guest())
Space after the "if".
