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([2001:b07:6468:f312:5e2c:eb9a:a8b6:fd3e]) by smtp.gmail.com with ESMTPSA id e15sm7581619ejr.58.2021.10.06.06.36.30 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 06 Oct 2021 06:36:31 -0700 (PDT) Message-ID: Date: Wed, 6 Oct 2021 15:36:29 +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 4/9] KVM: x86: reset pdptrs_from_userspace when exiting smm Content-Language: en-US To: Sasha Levin , linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Maxim Levitsky , tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, kvm@vger.kernel.org References: <20211006133021.271905-1-sashal@kernel.org> <20211006133021.271905-4-sashal@kernel.org> From: Paolo Bonzini In-Reply-To: <20211006133021.271905-4-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 06/10/21 15:30, Sasha Levin wrote: > From: Maxim Levitsky > > [ Upstream commit 37687c403a641f251cb2ef2e7830b88aa0647ba9 ] > > When exiting SMM, pdpts are loaded again from the guest memory. > > This fixes a theoretical bug, when exit from SMM triggers entry to the > nested guest which re-uses some of the migration > code which uses this flag as a workaround for a legacy userspace. > > Signed-off-by: Maxim Levitsky > Message-Id: <20210913140954.165665-4-mlevitsk@redhat.com> > Signed-off-by: Paolo Bonzini > Signed-off-by: Sasha Levin > --- > arch/x86/kvm/x86.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index b3f855d48f72..1e7d629bbf36 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -7659,6 +7659,13 @@ static void kvm_smm_changed(struct kvm_vcpu *vcpu, bool entering_smm) > > /* Process a latched INIT or SMI, if any. */ > kvm_make_request(KVM_REQ_EVENT, vcpu); > + > + /* > + * Even if KVM_SET_SREGS2 loaded PDPTRs out of band, > + * on SMM exit we still need to reload them from > + * guest memory > + */ > + vcpu->arch.pdptrs_from_userspace = false; > } > > kvm_mmu_reset_context(vcpu); > Acked-by: Paolo Bonzini