From: Sean Christopherson <seanjc@google.com>
To: Maxim Levitsky <mlevitsk@redhat.com>
Cc: Bandan Das <bsd@redhat.com>, Wei Huang <wei.huang2@amd.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
pbonzini@redhat.com, vkuznets@redhat.com, joro@8bytes.org,
bp@alien8.de, tglx@linutronix.de, mingo@redhat.com,
x86@kernel.org, jmattson@google.com, wanpengli@tencent.com,
dgilbert@redhat.com
Subject: Re: [PATCH 1/2] KVM: x86: Add emulation support for #GP triggered by VM instructions
Date: Thu, 14 Jan 2021 09:19:40 -0800 [thread overview]
Message-ID: <YAB9LIIVg8iEfXsb@google.com> (raw)
In-Reply-To: <db574a30f50a2f556dc983f18f78f28c933fdac7.camel@redhat.com>
On Thu, Jan 14, 2021, Maxim Levitsky wrote:
> On Tue, 2021-01-12 at 15:00 -0500, Bandan Das wrote:
> > Sean Christopherson <seanjc@google.com> writes:
> > ...
> > > > - if ((emulation_type & EMULTYPE_VMWARE_GP) &&
> > > > - !is_vmware_backdoor_opcode(ctxt)) {
> > > > - kvm_queue_exception_e(vcpu, GP_VECTOR, 0);
> > > > - return 1;
> > > > + if (emulation_type & EMULTYPE_PARAVIRT_GP) {
> > > > + vminstr = is_vm_instr_opcode(ctxt);
> > > > + if (!vminstr && !is_vmware_backdoor_opcode(ctxt)) {
> > > > + kvm_queue_exception_e(vcpu, GP_VECTOR, 0);
> > > > + return 1;
> > > > + }
> > > > + if (vminstr)
> > > > + return vminstr;
> > >
> > > I'm pretty sure this doesn't correctly handle a VM-instr in L2 that hits a bad
> > > L0 GPA and that L1 wants to intercept. The intercept bitmap isn't checked until
> > > x86_emulate_insn(), and the vm*_interception() helpers expect nested VM-Exits to
> > > be handled further up the stack.
>
> Actually IMHO this exactly what we want. We want L0 to always intercept
> these #GPs, and hide them from the guest.
>
> What we do need to do (and I prepared and attached a patch for that, is that
> if we run a guest, we want to inject corresponding vmexit (like
> SVM_EXIT_VMRUN) instead of emulating the instruction.
Yes, lack of forwarding to L1 as a nested exit is what I meant by "doesn't
correctly handle".
next prev parent reply other threads:[~2021-01-14 17:20 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-12 6:37 [PATCH 1/2] KVM: x86: Add emulation support for #GP triggered by VM instructions Wei Huang
2021-01-12 6:37 ` [PATCH 2/2] KVM: SVM: Add support for VMCB address check change Wei Huang
2021-01-12 19:18 ` Sean Christopherson
2021-01-14 11:39 ` Maxim Levitsky
2021-01-14 12:04 ` Maxim Levitsky
2021-01-12 11:09 ` [PATCH 1/2] KVM: x86: Add emulation support for #GP triggered by VM instructions Maxim Levitsky
2021-01-12 21:05 ` Wei Huang
2021-01-12 12:15 ` Vitaly Kuznetsov
2021-01-12 15:11 ` Andy Lutomirski
2021-01-12 15:17 ` Maxim Levitsky
2021-01-12 15:22 ` Andy Lutomirski
2021-01-12 15:46 ` Bandan Das
2021-01-12 15:51 ` Andy Lutomirski
2021-01-12 17:56 ` Sean Christopherson
2021-01-13 4:55 ` Wei Huang
2021-01-12 21:50 ` Wei Huang
2021-01-12 14:01 ` Paolo Bonzini
2021-01-12 17:42 ` Sean Christopherson
2021-01-13 12:35 ` Paolo Bonzini
2021-01-15 7:00 ` Wei Huang
2021-01-17 18:20 ` Paolo Bonzini
2021-01-12 17:36 ` Sean Christopherson
2021-01-12 17:59 ` Sean Christopherson
2021-01-12 18:58 ` Andy Lutomirski
2021-01-13 5:15 ` Wei Huang
2021-01-14 11:42 ` Maxim Levitsky
2021-01-13 5:03 ` Wei Huang
2021-01-13 12:40 ` Paolo Bonzini
2021-01-12 19:40 ` Sean Christopherson
2021-01-12 20:00 ` Bandan Das
2021-01-14 11:47 ` Maxim Levitsky
2021-01-14 17:19 ` Sean Christopherson [this message]
2021-01-14 11:55 ` Maxim Levitsky
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