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([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id ho17sm6910381ejc.101.2021.10.26.09.15.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 26 Oct 2021 09:15:10 -0700 (PDT) Message-ID: <35e414f8-c9b4-826c-e679-6b2ac3584536@redhat.com> Date: Tue, 26 Oct 2021 18:15:07 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.1.0 Subject: Re: [PATCH MANUALSEL 5.14 2/5] KVM: x86: WARN if APIC HW/SW disable static keys are non-zero on unload Content-Language: en-US To: Sasha Levin , linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Sean Christopherson , tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, kvm@vger.kernel.org References: <20211025203828.1404503-1-sashal@kernel.org> <20211025203828.1404503-2-sashal@kernel.org> From: Paolo Bonzini In-Reply-To: <20211025203828.1404503-2-sashal@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 25/10/21 22:38, Sasha Levin wrote: > From: Sean Christopherson > > [ Upstream commit 9139a7a64581c80d157027ae20e86f2f24d4292c ] > > WARN if the static keys used to track if any vCPU has disabled its APIC > are left elevated at module exit. Unlike the underflow case, nothing in > the static key infrastructure will complain if a key is left elevated, > and because an elevated key only affects performance, nothing in KVM will > fail if either key is improperly incremented. > > Signed-off-by: Sean Christopherson > Message-Id: <20211013003554.47705-3-seanjc@google.com> > Signed-off-by: Paolo Bonzini > Signed-off-by: Sasha Levin > --- > arch/x86/kvm/lapic.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c > index ba5a27879f1d..18cb699b0a14 100644 > --- a/arch/x86/kvm/lapic.c > +++ b/arch/x86/kvm/lapic.c > @@ -2942,5 +2942,7 @@ int kvm_apic_accept_events(struct kvm_vcpu *vcpu) > void kvm_lapic_exit(void) > { > static_key_deferred_flush(&apic_hw_disabled); > + WARN_ON(static_branch_unlikely(&apic_hw_disabled.key)); > static_key_deferred_flush(&apic_sw_disabled); > + WARN_ON(static_branch_unlikely(&apic_sw_disabled.key)); > } > NACK Paolo