Messages in this thread | | | From | Kechen Lu <> | Subject | RE: [RFC PATCH v4 3/7] KVM: x86: Reject disabling of MWAIT interception when not allowed | Date | Wed, 20 Jul 2022 18:37:46 +0000 |
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> -----Original Message----- > From: Sean Christopherson <seanjc@google.com> > Sent: Wednesday, July 20, 2022 10:54 AM > To: Kechen Lu <kechenl@nvidia.com> > Cc: kvm@vger.kernel.org; pbonzini@redhat.com; chao.gao@intel.com; > vkuznets@redhat.com; Somdutta Roy <somduttar@nvidia.com>; linux- > kernel@vger.kernel.org > Subject: Re: [RFC PATCH v4 3/7] KVM: x86: Reject disabling of MWAIT > interception when not allowed > > External email: Use caution opening links or attachments > > > On Tue, Jun 21, 2022, Kechen Lu wrote: > > From: Sean Christopherson <seanjc@google.com> > > > > 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@google.com> > > Co-developed-by: Kechen Lu <kechenl@nvidia.com> > > Needs your SOB. >
Ack!
> > Suggested-by: Chao Gao <chao.gao@intel.com> > > 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. >
Sure I see.
> > --- > > 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. >
Yes, I agree, handling here makes sense.
> [*] https://lore.kernel.org/all/Ytg428sleo7uMRQt@google.com > > > + > > + if(!kvm_can_mwait_in_guest()) > > Space after the "if".
Ack!
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