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AJvYcCVoApecFQi2iHpKo4Gcof1so1/F5b31fnnXgpShWQV45k64am+GA9O+uU/5uiEV8Ezs3pw=@vger.kernel.org X-Gm-Message-State: AOJu0YwCuZTAfAAyvDrP1uoQRndZLfHRxU/5QZi3b8E6xH/aMu8uJGhx 3INlyua1XMtZWZINFKGFaO6JvfiD23giPuFVvrFHdZTwEZplfhfEjfUVwopkpde3jq+/J3qFrgR OcFkbZQ== X-Google-Smtp-Source: AGHT+IG5HQksB4judqGvjW1pzujJJNo/IYUdyJnORfoyyo5Ie1UQl2Dtw+suRKCMbwyv8Q4JlydJDqEiPms= X-Received: from pjvc17.prod.google.com ([2002:a17:90a:d911:b0:34c:567d:ede4]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:2ec3:b0:34f:62e7:4cec with SMTP id 98e67ed59e1d1-34f68b4c743mr8717162a91.5.1767969872102; Fri, 09 Jan 2026 06:44:32 -0800 (PST) Date: Fri, 9 Jan 2026 06:44:29 -0800 In-Reply-To: <288eaa68-7d4d-4c1b-ae70-419554d1d8f2@intel.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260109041523.1027323-1-seanjc@google.com> <20260109041523.1027323-4-seanjc@google.com> <288eaa68-7d4d-4c1b-ae70-419554d1d8f2@intel.com> Message-ID: Subject: Re: [PATCH v3 3/4] KVM: nVMX: Disallow access to vmcs12 fields that aren't supported by "hardware" From: Sean Christopherson To: Xiaoyao Li Cc: Paolo Bonzini , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Chao Gao , Xin Li , Yosry Ahmed Content-Type: text/plain; charset="us-ascii" On Fri, Jan 09, 2026, Xiaoyao Li wrote: > On 1/9/2026 12:15 PM, Sean Christopherson wrote: > > diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c > > index 61113ead3d7b..ac7a17560c8f 100644 > > --- a/arch/x86/kvm/vmx/nested.c > > +++ b/arch/x86/kvm/vmx/nested.c > > @@ -111,6 +111,9 @@ static void init_vmcs_shadow_fields(void) > > field <= GUEST_TR_AR_BYTES, > > "Update vmcs12_write_any() to drop reserved bits from AR_BYTES"); > > + if (get_vmcs12_field_offset(field) < 0) > > + continue; > > + > > why shadow_read_only_fields[] doesn't need such guard? > > IIUC, copy_vmcs12_to_shadow() will VMWRITE shadowed readonly field even if > it doesn't exist on the hardware? Because I fixated on the existing checks and didn't look at the first for-loop. This time around I'll test by hacking in shadowed fields arbitrary shadow fields.