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Peter Anvin" , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Vitaly Kuznetsov , "K. Y. Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , Long Li , linux-hyperv@vger.kernel.org Subject: Re: [PATCH] KVM: x86: Clear CR3[63:32] on SMM entry from long mode Date: Mon, 28 Sep 2026 15:25:34 +0800 Message-ID: <20260928072534.1987-1-odys.yuan@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260928-kvm-smm-cr3-upper-bits-v1-1-138f52dd531e@gmail.com> References: <20260928-kvm-smm-cr3-upper-bits-v1-1-138f52dd531e@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit +Cc Hyper-V folks and linux-hyperv, since the failure is triggered by Hyper-V's handling of VMRUN for a nested (L1) hypervisor, i.e. KVM running on WSL2. For the Hyper-V side: the VMRUN is rejected when the guest state has CR0.PG=0, EFER.LMA=0 and CR3[63:32] != 0, a combination that bare-metal SVM does not reject. Is that check intentional? If it is not, a Hyper-V fix would help older KVM versions as well; either way the patch avoids creating that state in the first place. The full patch is here: https://lore.kernel.org/r/20260928-kvm-smm-cr3-upper-bits-v1-1-138f52dd531e@gmail.com Thanks, Qiliang