From patchwork Mon May 27 08:21:27 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Michael Tokarev X-Patchwork-Id: 13674846 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 106A1C25B74 for ; Mon, 27 May 2024 08:36:19 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1sBViu-0005Ni-JL; Mon, 27 May 2024 04:28:52 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sBVf6-0005KQ-1K; Mon, 27 May 2024 04:24:58 -0400 Received: from isrv.corpit.ru ([86.62.121.231]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sBVf3-0001AR-JC; Mon, 27 May 2024 04:24:55 -0400 Received: from tsrv.corpit.ru (tsrv.tls.msk.ru [192.168.177.2]) by isrv.corpit.ru (Postfix) with ESMTP id 2765A6A581; Mon, 27 May 2024 11:22:15 +0300 (MSK) Received: from tls.msk.ru (mjt.wg.tls.msk.ru [192.168.177.130]) by tsrv.corpit.ru (Postfix) with SMTP id 523B2D851E; Mon, 27 May 2024 11:21:41 +0300 (MSK) Received: (nullmailer pid 66462 invoked by uid 1000); Mon, 27 May 2024 08:21:38 -0000 From: Michael Tokarev To: qemu-devel@nongnu.org Cc: qemu-stable@nongnu.org, donsheng , Chao Gao , Paolo Bonzini , Michael Tokarev Subject: [Stable-9.0.1 36/44] target-i386: hyper-v: Correct kvm_hv_handle_exit return value Date: Mon, 27 May 2024 11:21:27 +0300 Message-Id: <20240527082138.66217-36-mjt@tls.msk.ru> X-Mailer: git-send-email 2.39.2 In-Reply-To: References: MIME-Version: 1.0 Received-SPF: pass client-ip=86.62.121.231; envelope-from=mjt@tls.msk.ru; helo=isrv.corpit.ru 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, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org From: donsheng This bug fix addresses the incorrect return value of kvm_hv_handle_exit for KVM_EXIT_HYPERV_SYNIC, which should be EXCP_INTERRUPT. Handling of KVM_EXIT_HYPERV_SYNIC in QEMU needs to be synchronous. This means that async_synic_update should run in the current QEMU vCPU thread before returning to KVM, returning EXCP_INTERRUPT to guarantee this. Returning 0 can cause async_synic_update to run asynchronously. One problem (kvm-unit-tests's hyperv_synic test fails with timeout error) caused by this bug: When a guest VM writes to the HV_X64_MSR_SCONTROL MSR to enable Hyper-V SynIC, a VM exit is triggered and processed by the kvm_hv_handle_exit function of the QEMU vCPU. This function then calls the async_synic_update function to set synic->sctl_enabled to true. A true value of synic->sctl_enabled is required before creating SINT routes using the hyperv_sint_route_new() function. If kvm_hv_handle_exit returns 0 for KVM_EXIT_HYPERV_SYNIC, the current QEMU vCPU thread may return to KVM and enter the guest VM before running async_synic_update. In such case, the hyperv_synic test’s subsequent call to synic_ctl(HV_TEST_DEV_SINT_ROUTE_CREATE, ...) immediately after writing to HV_X64_MSR_SCONTROL can cause QEMU’s hyperv_sint_route_new() function to return prematurely (because synic->sctl_enabled is false). If the SINT route is not created successfully, the SINT interrupt will not be fired, resulting in a timeout error in the hyperv_synic test. Fixes: 267e071bd6d6 (“hyperv: make overlay pages for SynIC”) Suggested-by: Chao Gao Signed-off-by: Dongsheng Zhang Message-ID: <20240521200114.11588-1-dongsheng.x.zhang@intel.com> Cc: qemu-stable@nongnu.org Signed-off-by: Paolo Bonzini (cherry picked from commit 84d4b72854869821eb89813c195927fdd3078c12) Signed-off-by: Michael Tokarev diff --git a/target/i386/kvm/hyperv.c b/target/i386/kvm/hyperv.c index f2a3fe650a..b94f12acc2 100644 --- a/target/i386/kvm/hyperv.c +++ b/target/i386/kvm/hyperv.c @@ -81,7 +81,7 @@ int kvm_hv_handle_exit(X86CPU *cpu, struct kvm_hyperv_exit *exit) */ async_safe_run_on_cpu(CPU(cpu), async_synic_update, RUN_ON_CPU_NULL); - return 0; + return EXCP_INTERRUPT; case KVM_EXIT_HYPERV_HCALL: { uint16_t code = exit->u.hcall.input & 0xffff; bool fast = exit->u.hcall.input & HV_HYPERCALL_FAST;