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Thu, 23 Jul 2020 16:39:21 +0200 Subject: Re: [PATCH] KVM: fix CPU reset wrt HF2_GIF_MASK To: Vitaly Kuznetsov , qemu-devel@nongnu.org References: <20200723142701.2521161-1-vkuznets@redhat.com> From: Jan Kiszka Message-ID: <4b5a9074-decd-bec1-b60f-db103660d8bd@siemens.com> Date: Thu, 23 Jul 2020 16:39:21 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20200723142701.2521161-1-vkuznets@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=192.35.17.2; envelope-from=jan.kiszka@siemens.com; helo=thoth.sbs.de X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/23 10:39:23 X-ACL-Warn: Detected OS = Linux 3.1-3.10 X-Spam_score_int: -68 X-Spam_score: -6.9 X-Spam_bar: ------ X-Spam_report: (-6.9 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_HI=-5, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Eduardo Habkost , Marcelo Tosatti , "Dr. David Alan Gilbert" , Paolo Bonzini , =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= , Richard Henderson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 23.07.20 16:27, Vitaly Kuznetsov wrote: > HF2_GIF_MASK is set in env->hflags2 unconditionally on CPU reset > (see x86_cpu_reset()) but when calling KVM_SET_NESTED_STATE, > KVM_STATE_NESTED_GIF_SET is only valid for nSVM as e.g. nVMX code > looks like > > if (kvm_state->hdr.vmx.vmxon_pa == -1ull) { > if (kvm_state->flags & ~KVM_STATE_NESTED_EVMCS) > return -EINVAL; > } > > Also, when adjusting the environment after KVM_GET_NESTED_STATE we > need not reset HF2_GIF_MASK on VMX as e.g. x86_cpu_pending_interrupt() > expects it to be set. > > Alternatively, we could've made env->hflags2 SVM-only. > > Reported-by: Jan Kiszka > Fixes: b16c0e20c742 ("KVM: add support for AMD nested live migration") > Signed-off-by: Vitaly Kuznetsov > --- > target/i386/kvm.c | 16 +++++++++++----- > 1 file changed, 11 insertions(+), 5 deletions(-) > > diff --git a/target/i386/kvm.c b/target/i386/kvm.c > index 2b6b7443d273..3c4647fbfbf6 100644 > --- a/target/i386/kvm.c > +++ b/target/i386/kvm.c > @@ -3883,7 +3883,9 @@ static int kvm_put_nested_state(X86CPU *cpu) > } else { > env->nested_state->flags &= ~KVM_STATE_NESTED_GUEST_MODE; > } > - if (env->hflags2 & HF2_GIF_MASK) { > + > + /* Don't set KVM_STATE_NESTED_GIF_SET on VMX as it is illegal */ > + if (cpu_has_svm(env) && (env->hflags2 & HF2_GIF_MASK)) { > env->nested_state->flags |= KVM_STATE_NESTED_GIF_SET; > } else { > env->nested_state->flags &= ~KVM_STATE_NESTED_GIF_SET; > @@ -3925,10 +3927,14 @@ static int kvm_get_nested_state(X86CPU *cpu) > } else { > env->hflags &= ~HF_GUEST_MASK; > } > - if (env->nested_state->flags & KVM_STATE_NESTED_GIF_SET) { > - env->hflags2 |= HF2_GIF_MASK; > - } else { > - env->hflags2 &= ~HF2_GIF_MASK; > + > + /* Keep HF2_GIF_MASK set on !SVM as x86_cpu_pending_interrupt() needs it */ > + if (cpu_has_svm(env)) { > + if (env->nested_state->flags & KVM_STATE_NESTED_GIF_SET) { > + env->hflags2 |= HF2_GIF_MASK; > + } else { > + env->hflags2 &= ~HF2_GIF_MASK; > + } > } > > return ret; > Tested-by: Jan Kiszka Thanks! Jan -- Siemens AG, Corporate Technology, CT RDA IOT SES-DE Corporate Competence Center Embedded Linux