From: Sean Christopherson <seanjc@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
mlevitsk@redhat.com, vkuznets@redhat.com
Subject: Re: [PATCH v2 2/9] KVM: x86: remove return value of kvm_vcpu_block
Date: Tue, 20 Sep 2022 00:42:27 +0000 [thread overview]
Message-ID: <YykMc2NDOzvG+xoy@google.com> (raw)
In-Reply-To: <Yv0aHXcmuivyJDXw@google.com>
On Wed, Aug 17, 2022, Sean Christopherson wrote:
> Side topic, usage of kvm_apic_accept_events() appears to be broken (though nothing
> can trigger the bug). If kvm_apic_accept_events() were to return an -errno, then
> kvm_arch_vcpu_ioctl_run() would return '0' to userspace without updating
> vcpu->run->exit_reason. I think an easy fix is to drop the return value entirely
> and then WARN if kvm_check_nested_events() returns something other than -EBUSY.
>
> if (is_guest_mode(vcpu)) {
> r = kvm_check_nested_events(vcpu);
> if (r < 0) {
> WARN_ON_ONCE(r != -EBUSY);
> return;
> }
For posterity, I was wrong. Way down the stack, vmx_complete_nested_posted_interrupt()
can return -ENXIO after filling vcpu->run->exit_reason via kvm_handle_memory_failure().
That's the entire reason why negative values from kvm_check_nested_events() and
kvm_apic_accept_events() are morphed to '0', i.e. to "exit to userspace".
next prev parent reply other threads:[~2022-09-20 0:42 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-11 21:05 [PATCH v2 0/9] KVM: x86: never write to memory from kvm_vcpu_check_block Paolo Bonzini
2022-08-11 21:05 ` [PATCH v2 1/9] KVM: x86: check validity of argument to KVM_SET_MP_STATE Paolo Bonzini
2022-08-15 13:31 ` Maxim Levitsky
2022-08-16 22:50 ` Sean Christopherson
2022-08-11 21:05 ` [PATCH v2 2/9] KVM: x86: remove return value of kvm_vcpu_block Paolo Bonzini
2022-08-16 23:34 ` Sean Christopherson
2022-08-17 14:10 ` Maxim Levitsky
2022-08-17 15:31 ` Paolo Bonzini
2022-08-17 16:41 ` Sean Christopherson
2022-08-17 16:49 ` Paolo Bonzini
2022-09-20 0:42 ` Sean Christopherson [this message]
2022-08-11 21:05 ` [PATCH v2 3/9] KVM: x86: make kvm_vcpu_{block,halt} return whether vCPU is runnable Paolo Bonzini
2022-08-11 21:06 ` [PATCH v2 4/9] KVM: mips, x86: do not rely on KVM_REQ_UNHALT Paolo Bonzini
2022-08-11 21:06 ` [PATCH v2 5/9] KVM: remove KVM_REQ_UNHALT Paolo Bonzini
2022-08-11 21:06 ` [PATCH v2 6/9] KVM: x86: make vendor code check for all nested events Paolo Bonzini
2022-08-16 23:47 ` Sean Christopherson
2022-08-17 14:10 ` Maxim Levitsky
2022-08-11 21:06 ` [PATCH v2 7/9] KVM: nVMX: Make an event request when pending an MTF nested VM-Exit Paolo Bonzini
2022-08-17 14:11 ` Maxim Levitsky
2022-08-11 21:06 ` [PATCH v2 8/9] KVM: x86: lapic does not have to process INIT if it is blocked Paolo Bonzini
2022-08-17 0:07 ` Sean Christopherson
2022-08-17 14:11 ` Maxim Levitsky
2022-08-17 15:33 ` Paolo Bonzini
2022-08-11 21:06 ` [PATCH v2 9/9] KVM: x86: never write to memory from kvm_vcpu_check_block Paolo Bonzini
2022-08-16 23:45 ` Sean Christopherson
2022-08-17 14:11 ` Maxim Levitsky
2022-09-20 0:32 ` Sean Christopherson
2022-09-20 0:55 ` Sean Christopherson
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