From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: "Wanpeng Li" <wanpengli@tencent.com>,
"Jim Mattson" <jmattson@google.com>,
"Joerg Roedel" <joro@8bytes.org>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
"Reto Buerki" <reet@codelabs.ch>,
"Liran Alon" <liran.alon@oracle.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Radim Krčmář" <rkrcmar@redhat.com>
Subject: Re: [PATCH v2 8/8] KVM: x86: Fold decache_cr3() into cache_reg()
Date: Mon, 30 Sep 2019 17:27:58 +0200 [thread overview]
Message-ID: <87y2y53itd.fsf@vitty.brq.redhat.com> (raw)
In-Reply-To: <20190930150430.GA14693@linux.intel.com>
Sean Christopherson <sean.j.christopherson@intel.com> writes:
> On Mon, Sep 30, 2019 at 12:58:53PM +0200, Vitaly Kuznetsov wrote:
>> Sean Christopherson <sean.j.christopherson@intel.com> writes:
>>
>> > Handle caching CR3 (from VMX's VMCS) into struct kvm_vcpu via the common
>> > cache_reg() callback and drop the dedicated decache_cr3(). The name
>> > decache_cr3() is somewhat confusing as the caching behavior of CR3
>> > follows that of GPRs, RFLAGS and PDPTRs, (handled via cache_reg()), and
>> > has nothing in common with the caching behavior of CR0/CR4 (whose
>> > decache_cr{0,4}_guest_bits() likely provided the 'decache' verbiage).
>> >
>> > Note, this effectively adds a BUG() if KVM attempts to cache CR3 on SVM.
>> > Opportunistically add a WARN_ON_ONCE() in VMX to provide an equivalent
>> > check.
>>
>> Just to justify my idea of replacing such occasions with
>> KVM_INTERNAL_ERROR by setting a special 'kill ASAP' bit somewhere:
>>
>> This WARN_ON_ONCE() falls in the same category (IMO).
>
> Maybe something like KVM_BUG_ON? E.g.:
>
> #define KVM_BUG_ON(kvm, cond) \
> ({ \
> int r; \
> \
> if (r = WARN_ON_ONCE(cond)) \
> kvm->vm_bugged = true; \
> r; \
> )}
>
Yes, that's more or less what I meant! (to me 'vm_bugged' sounds like
there was a bug in the VM but the bug is actually in KVM so maybe
something like 'kvm_internal_bug' to make it explicit?)
--
Vitaly
next prev parent reply other threads:[~2019-09-30 15:28 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-27 21:45 [PATCH v2 0/8] KVM: x86: nVMX GUEST_CR3 bug fix, and then some Sean Christopherson
2019-09-27 21:45 ` [PATCH v2 1/8] KVM: nVMX: Always write vmcs02.GUEST_CR3 during nested VM-Enter Sean Christopherson
2019-09-27 23:37 ` Jim Mattson
2019-09-27 21:45 ` [PATCH v2 2/8] KVM: VMX: Skip GUEST_CR3 VMREAD+VMWRITE if the VMCS is up-to-date Sean Christopherson
2019-09-27 21:45 ` [PATCH v2 3/8] KVM: VMX: Consolidate to_vmx() usage in RFLAGS accessors Sean Christopherson
2019-09-30 8:48 ` Vitaly Kuznetsov
2019-09-27 21:45 ` [PATCH v2 4/8] KVM: VMX: Optimize vmx_set_rflags() for unrestricted guest Sean Christopherson
2019-09-30 8:57 ` Vitaly Kuznetsov
2019-09-30 15:19 ` Sean Christopherson
2019-09-30 15:55 ` Vitaly Kuznetsov
2019-10-09 10:40 ` Paolo Bonzini
2019-10-09 16:38 ` Sean Christopherson
2019-10-09 20:59 ` Paolo Bonzini
2019-10-09 21:30 ` Sean Christopherson
2019-09-27 21:45 ` [PATCH v2 5/8] KVM: x86: Add WARNs to detect out-of-bounds register indices Sean Christopherson
2019-09-30 9:19 ` Vitaly Kuznetsov
2019-10-09 10:50 ` Paolo Bonzini
2019-10-09 16:36 ` Sean Christopherson
2019-09-27 21:45 ` [PATCH v2 6/8] KVM: x86: Fold 'enum kvm_ex_reg' definitions into 'enum kvm_reg' Sean Christopherson
2019-09-30 9:25 ` Vitaly Kuznetsov
2019-10-09 10:52 ` Paolo Bonzini
2019-10-09 11:27 ` Vitaly Kuznetsov
2019-09-27 21:45 ` [PATCH v2 7/8] KVM: x86: Add helpers to test/mark reg availability and dirtiness Sean Christopherson
2019-09-30 9:32 ` Vitaly Kuznetsov
2019-10-09 11:00 ` Paolo Bonzini
2019-09-27 21:45 ` [PATCH v2 8/8] KVM: x86: Fold decache_cr3() into cache_reg() Sean Christopherson
2019-09-30 10:58 ` Vitaly Kuznetsov
2019-09-30 15:04 ` Sean Christopherson
2019-09-30 15:27 ` Vitaly Kuznetsov [this message]
2019-09-30 15:33 ` Sean Christopherson
2019-10-09 11:03 ` Paolo Bonzini
2019-09-30 10:42 ` [PATCH v2 0/8] KVM: x86: nVMX GUEST_CR3 bug fix, and then some Reto Buerki
2019-10-29 15:03 ` Martin Lucina
2019-10-30 9:09 ` Sean Christopherson
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