From: Sean Christopherson <seanjc@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Michal Luczaj <mhal@rbox.co>
Subject: Re: [PATCH v2 3/3] KVM: selftests: Add test for race in kvm_recalculate_apic_map()
Date: Thu, 1 Jun 2023 16:40:28 -0700 [thread overview]
Message-ID: <ZHksbJGKbNJpNcJI@google.com> (raw)
In-Reply-To: <ZHklss/E5uQdRktD@google.com>
On Thu, Jun 01, 2023, Sean Christopherson wrote:
> On Fri, May 26, 2023, Sean Christopherson wrote:
> > From: Michal Luczaj <mhal@rbox.co>
> >
> > Keep switching between LAPIC_MODE_X2APIC and LAPIC_MODE_DISABLED during
> > APIC map construction to hunt for TOCTOU bugs in KVM. KVM's optimized map
> > recalc makes multiple passes over the list of vCPUs, and the calculations
> > ignore vCPU's whose APIC is hardware-disabled, i.e. there's a window where
> > toggling LAPIC_MODE_DISABLED is quite interesting.
> >
> > Signed-off-by: Michal Luczaj <mhal@rbox.co>
> > Co-developed-by: Sean Christopherson <seanjc@google.com>
> > Signed-off-by: Sean Christopherson <seanjc@google.com>
> > ---
> > tools/testing/selftests/kvm/Makefile | 1 +
> > .../kvm/x86_64/recalc_apic_map_race.c | 76 +++++++++++++++++++
> > 2 files changed, 77 insertions(+)
> > create mode 100644 tools/testing/selftests/kvm/x86_64/recalc_apic_map_race.c
>
> Since there's another bug+test related to kvm_recalculate_apic_map()[*], I think
> it makes sense to name this recalc_apic_map_test, and then fold the LDR test into
> this one. The LDR test is tiny enough that I don't think it's worth a separate
> binary, even though I generally prefer to keep the selftests small.
Actually, the x2APIC test is a better fit in xapic_state_test. I'll probably
still rename this to match (almost) every other selftest name.
prev parent reply other threads:[~2023-06-01 23:40 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-26 23:50 [PATCH v2 0/3] KVM: x86: Out-of-bounds access in kvm_recalculate_phys_map() Sean Christopherson
2023-05-26 23:50 ` [PATCH v2 1/3] KVM: x86: Bail from kvm_recalculate_phys_map() if x2APIC ID is out-of-bounds Sean Christopherson
2023-05-26 23:50 ` [PATCH v2 2/3] KVM: x86: Retry APIC optimized map recalc if vCPU is added/enabled Sean Christopherson
2023-05-26 23:50 ` [PATCH v2 3/3] KVM: selftests: Add test for race in kvm_recalculate_apic_map() Sean Christopherson
2023-06-01 23:11 ` Sean Christopherson
2023-06-01 23:40 ` Sean Christopherson [this message]
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