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h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=Nz0QNNv0fLGDzhFNnbuJNJKMV0s3O1imIgUVEdWKz+mS698UAvHUiZDp6Y5e9zIPT LlD70Xxvyda1K+zmL/sVvdEiZ+MnuSAcU67TctEOtT0yIqMVKNroMEXzUFYZ3y4WGH uPHQM+NRYNuSw3YXXvZ3P2s4aDxvlZUn/H6k7b8hIXXbRFgvwiFY3Zg08othsTJcR3 tSh5f0kJFjepSK2fEtIJS3sAe3bAmlKOkAxGKxRqJj5rJ9a065UzN4s2p3XVPAC0hf XMJxF2C+uF++5ECgCPEDZ6gkEKMCN6JI35PlQQ+QrpQCChdgUjqIq4T0i30JTc+iNe 4/csEDhLWV2ww== Message-ID: <26947f1a-2162-4083-b39f-c360d6046877@zytor.com> Date: Wed, 17 Sep 2025 21:48:10 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v15 21/41] KVM: nVMX: Prepare for enabling CET support for nested guest To: Sean Christopherson , Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Tom Lendacky , Mathias Krause , John Allen , Rick Edgecombe , Chao Gao , Maxim Levitsky , Xiaoyao Li , Zhang Yi Z References: <20250912232319.429659-1-seanjc@google.com> <20250912232319.429659-22-seanjc@google.com> Content-Language: en-US From: Xin Li Autocrypt: addr=xin@zytor.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 9/12/2025 4:22 PM, Sean Christopherson wrote: > diff --git a/arch/x86/kvm/vmx/vmcs12.h b/arch/x86/kvm/vmx/vmcs12.h > index 56fd150a6f24..4ad6b16525b9 100644 > --- a/arch/x86/kvm/vmx/vmcs12.h > +++ b/arch/x86/kvm/vmx/vmcs12.h > @@ -117,7 +117,13 @@ struct __packed vmcs12 { > natural_width host_ia32_sysenter_eip; > natural_width host_rsp; > natural_width host_rip; > - natural_width paddingl[8]; /* room for future expansion */ > + natural_width host_s_cet; > + natural_width host_ssp; > + natural_width host_ssp_tbl; > + natural_width guest_s_cet; > + natural_width guest_ssp; > + natural_width guest_ssp_tbl; > + natural_width paddingl[2]; /* room for future expansion */ > u32 pin_based_vm_exec_control; > u32 cpu_based_vm_exec_control; > u32 exception_bitmap; > @@ -294,6 +300,12 @@ static inline void vmx_check_vmcs12_offsets(void) > CHECK_OFFSET(host_ia32_sysenter_eip, 656); > CHECK_OFFSET(host_rsp, 664); > CHECK_OFFSET(host_rip, 672); > + CHECK_OFFSET(host_s_cet, 680); > + CHECK_OFFSET(host_ssp, 688); > + CHECK_OFFSET(host_ssp_tbl, 696); > + CHECK_OFFSET(guest_s_cet, 704); > + CHECK_OFFSET(guest_ssp, 712); > + CHECK_OFFSET(guest_ssp_tbl, 720); > CHECK_OFFSET(pin_based_vm_exec_control, 744); > CHECK_OFFSET(cpu_based_vm_exec_control, 748); > CHECK_OFFSET(exception_bitmap, 752); This patch modifies struct vms12 without updating the corresponding vmcs12 definition in Documentation/virt/kvm/x86/nested-vmx.rst. However, duplicating the definition within the same source tree seems unnecessary and prone to inconsistencies. E.g., the following fields are missing in Documentation/virt/kvm/x86/nested-vmx.rst: ... u64 posted_intr_desc_addr; ... u64 eoi_exit_bitmap0; u64 eoi_exit_bitmap1; u64 eoi_exit_bitmap2; u64 eoi_exit_bitmap3; u64 xss_exit_bitmap; ... What's more, the 64-bit padding fields are completely messed up; we have used 9 u64 after host_ia32_efer: u64 host_ia32_perf_global_ctrl; u64 vmread_bitmap; u64 vmwrite_bitmap; u64 vm_function_control; u64 eptp_list_address; u64 pml_address; u64 encls_exiting_bitmap; u64 tsc_multiplier; u64 padding64[1]; /* room for future expansion */ But it's 8 u64 after host_ia32_efer in the documentation: u64 padding64[8]; /* room for future expansion */ We probably should remove it from Documentation/virt/kvm/x86/nested-vmx.rst and instead add a reference to arch/x86/kvm/vmx/vmcs12.h.