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[84.229.155.229]) by smtp.gmail.com with ESMTPSA id l13sm1945665wrm.57.2020.03.18.23.38.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 18 Mar 2020 23:38:53 -0700 (PDT) From: Jon Doron To: kvm@vger.kernel.org, linux-hyperv@vger.kernel.org Cc: vkuznets@redhat.com, Jon Doron Subject: [PATCH v8 4/5] x86/kvm/hyper-v: enable hypercalls without hypercall page with syndbg Date: Thu, 19 Mar 2020 08:38:35 +0200 Message-Id: <20200319063836.678562-5-arilou@gmail.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200319063836.678562-1-arilou@gmail.com> References: <20200319063836.678562-1-arilou@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-hyperv-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-hyperv@vger.kernel.org Microsoft's kdvm.dll dbgtransport module does not respect the hypercall page and simply identifies the CPU being used (AMD/Intel) and according to it simply makes hypercalls with the relevant instruction (vmmcall/vmcall respectively). The relevant function in kdvm is KdHvConnectHypervisor which first checks if the hypercall page has been enabled via HV_X64_MSR_HYPERCALL_ENABLE, and in case it was not it simply sets the HV_X64_MSR_GUEST_OS_ID to 0x1000101010001 which means: build_number = 0x0001 service_version = 0x01 minor_version = 0x01 major_version = 0x01 os_id = 0x00 (Undefined) vendor_id = 1 (Microsoft) os_type = 0 (A value of 0 indicates a proprietary, closed source OS) and starts issuing the hypercall without setting the hypercall page. To resolve this issue simply enable hypercalls also if the guest_os_id is not 0 and the syndbg feature is enabled. Signed-off-by: Jon Doron --- arch/x86/kvm/hyperv.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c index b2b50c67badd..64f267f10049 100644 --- a/arch/x86/kvm/hyperv.c +++ b/arch/x86/kvm/hyperv.c @@ -1647,7 +1647,10 @@ static u64 kvm_hv_send_ipi(struct kvm_vcpu *current_vcpu, u64 ingpa, u64 outgpa, bool kvm_hv_hypercall_enabled(struct kvm *kvm) { - return READ_ONCE(kvm->arch.hyperv.hv_hypercall) & HV_X64_MSR_HYPERCALL_ENABLE; + struct kvm_hv *hv = &kvm->arch.hyperv; + + return READ_ONCE(hv->hv_hypercall) & HV_X64_MSR_HYPERCALL_ENABLE || + (hv->hv_syndbg.active && READ_ONCE(hv->hv_guest_os_id) != 0); } static void kvm_hv_hypercall_set_result(struct kvm_vcpu *vcpu, u64 result) -- 2.24.1