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Sat, 10 Oct 2026 02:38:41 +0000 Date: Sat, 10 Oct 2026 10:37:54 +0800 From: Yan Zhao To: Binbin Wu CC: Sean Christopherson , Paolo Bonzini , Kiryl Shutsemau , Rick Edgecombe , Dave Hansen , , , , , James Houghton , Xiaoyao Li , Ackerley Tng , Vishal Annapurve , Sashiko Bot Subject: Re: [PATCH v2 3/3] KVM: TDX: Ratelimit the "EPT Violation on pending acceptance page" warning Message-ID: Reply-To: Yan Zhao References: <20260930001127.3170009-1-seanjc@google.com> <20260930001127.3170009-4-seanjc@google.com> <2036b58e-d2cb-4992-97d4-cb136bb0a387@linux.intel.com> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <2036b58e-d2cb-4992-97d4-cb136bb0a387@linux.intel.com> X-ClientProxiedBy: SI1PR02CA0007.apcprd02.prod.outlook.com (2603:1096:4:1f7::6) To BL0PR11MB3236.namprd11.prod.outlook.com (2603:10b6:208:60::18) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BL0PR11MB3236:EE_|LV8PR11MB8747:EE_ X-MS-Office365-Filtering-Correlation-Id: 4662859a-b73b-4a3e-4f67-08df26779897 X-LD-Processed: 46c98d88-e344-4ed4-8496-4ed7712e255d,ExtAddr X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|7416014|366016|376014|23010399003|261009223027099003|56012099006|11063799006|4143699003|5023799004|18002099003|22082099003|6133799003|10067099003; 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But would it be better to print for each guest? > > Sashiko reported the issue due to the change introduced in the patch 2. > > Will this change allow a malicious or buggy userspace VMM to flood the host > kernel log? > > By replacing kvm_vm_dead() with KVM_REQ_TRIPLE_FAULT and returning 1, KVM > will clear the request during vcpu_enter_guest() and exit to userspace with > KVM_EXIT_SHUTDOWN. If the VMM ignores this exit and repeatedly calls KVM_RUN > without resetting the vCPU, KVM will immediately re-enter the guest. > > In this case, is the Fixes tag pointing to e6a85781f783 needed? Upon further reflection, in an extreme scenario where 100 vCPUs access the unaccepted page simultaneously, pr_warn() could theoretically be invoked for 100 times. So pr_warn_ratelimited() is still the better choice. So, Reviewed-by: Yan Zhao > >> Fixes: e6a85781f783 ("KVM: TDX: Detect unexpected SEPT violations due to pending SPTEs") > >> Cc: stable@vger.kernel.org > >> Reported-by: Sashiko Bot > >> Closes: https://lore.kernel.org/all/20260923164348.2DB2D1F000FF@smtp.kernel.org > >> Signed-off-by: Sean Christopherson > >> --- > >> arch/x86/kvm/vmx/tdx.c | 4 ++-- > >> 1 file changed, 2 insertions(+), 2 deletions(-) > >> > >> diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c > >> index e3723f1222fc..4cac43299851 100644 > >> --- a/arch/x86/kvm/vmx/tdx.c > >> +++ b/arch/x86/kvm/vmx/tdx.c > >> @@ -1937,8 +1937,8 @@ static int tdx_handle_ept_violation(struct kvm_vcpu *vcpu) > >> > >> if (vt_is_tdx_private_gpa(vcpu->kvm, gpa)) { > >> if (tdx_is_sept_violation_unexpected_pending(vcpu)) { > >> - pr_warn("Guest access before accepting 0x%llx on vCPU %d\n", > >> - gpa, vcpu->vcpu_id); > >> + pr_warn_ratelimited("Guest access before accepting 0x%llx on vCPU %d\n", > >> + gpa, vcpu->vcpu_id); > >> kvm_prepare_shutdown_exit(vcpu); > >> return 0; > >> } > >> -- > >> 2.56.0.rc1.315.gc6ed9934b7-goog > >> > > >