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[23.128.96.18]) by mx.google.com with ESMTP id d2si8510076pfr.87.2021.05.07.14.47.15; Fri, 07 May 2021 14:47:27 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=intel.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229652AbhEGVrp (ORCPT + 99 others); Fri, 7 May 2021 17:47:45 -0400 Received: from mga12.intel.com ([192.55.52.136]:12356 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229470AbhEGVrp (ORCPT ); Fri, 7 May 2021 17:47:45 -0400 IronPort-SDR: TirPp7fMImxyVBNQPLySX7/S1p4Gs4weWVEpxdk+rdJiVwxakLuR2ktZVAljTvJwQP7FiqV5AU KUBZLPHM0MOQ== X-IronPort-AV: E=McAfee;i="6200,9189,9977"; a="178382805" X-IronPort-AV: E=Sophos;i="5.82,282,1613462400"; d="scan'208";a="178382805" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 May 2021 14:46:44 -0700 IronPort-SDR: TsPHdmpeaje8A1mMeStcCLoEz/3fxdWh4p7Ouw62oeA3rCUFn7fhEWLH6qBCaFvaGcyx4h60FF wLTQ8pUkLGeQ== X-IronPort-AV: E=Sophos;i="5.82,282,1613462400"; d="scan'208";a="431677987" Received: from msandrid-mobl.amr.corp.intel.com (HELO [10.212.134.124]) ([10.212.134.124]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 May 2021 14:46:43 -0700 Subject: Re: [RFC v2 10/32] x86/tdx: Wire up KVM hypercalls To: Kuppuswamy Sathyanarayanan , Peter Zijlstra , Andy Lutomirski , Dan Williams , Tony Luck Cc: Andi Kleen , Kirill Shutemov , Kuppuswamy Sathyanarayanan , Raj Ashok , Sean Christopherson , linux-kernel@vger.kernel.org, Isaku Yamahata References: <04de6cd6549eee0b77fe3b0937c4b4b7f0e3ff2e.1619458733.git.sathyanarayanan.kuppuswamy@linux.intel.com> From: Dave Hansen Autocrypt: addr=dave.hansen@intel.com; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <04de6cd6549eee0b77fe3b0937c4b4b7f0e3ff2e.1619458733.git.sathyanarayanan.kuppuswamy@linux.intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/26/21 11:01 AM, Kuppuswamy Sathyanarayanan wrote: > From: "Kirill A. Shutemov" > > KVM hypercalls have to be wrapped into vendor-specific TDVMCALLs. How about: KVM hypercalls use the "vmcall" or "vmmcall" instructions. Although the ABI is similar, those instructions no longer function for TDX guests. Make TDVMCALLs instead of VMCALL/VMCALL. > diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h > index 338119852512..2fa85481520b 100644 > --- a/arch/x86/include/asm/kvm_para.h > +++ b/arch/x86/include/asm/kvm_para.h > @@ -6,6 +6,7 @@ > #include > #include > #include > +#include > > extern void kvmclock_init(void); > > @@ -34,6 +35,10 @@ static inline bool kvm_check_and_clear_guest_paused(void) > static inline long kvm_hypercall0(unsigned int nr) > { > long ret; > + > + if (is_tdx_guest()) > + return tdx_kvm_hypercall0(nr); ... all of these look OK. > #endif /* _ASM_X86_TDX_H */ > diff --git a/arch/x86/kernel/tdcall.S b/arch/x86/kernel/tdcall.S > index 81af70c2acbd..964bfd7fc682 100644 > --- a/arch/x86/kernel/tdcall.S > +++ b/arch/x86/kernel/tdcall.S > @@ -11,6 +11,7 @@ > * refer to TDX GHCI specification). > */ > #define TDVMCALL_EXPOSE_REGS_MASK 0xfc00 > +#define TDVMCALL_VENDOR_KVM 0x4d564b2e584454 /* "TDX.KVM" */ > > /* > * TDX guests use the TDCALL instruction to make > @@ -198,3 +199,9 @@ SYM_FUNC_START(__tdvmcall) > call do_tdvmcall > retq > SYM_FUNC_END(__tdvmcall) > + > +SYM_FUNC_START(__tdvmcall_vendor_kvm) > + movq $TDVMCALL_VENDOR_KVM, %r10 > + call do_tdvmcall > + retq > +SYM_FUNC_END(__tdvmcall_vendor_kvm) Granted, this is not a ton of assembly. But, it does look a bit weird. It needs a comment and/or a mention in the changelog. R10 is not part of the function call ABI, but it is a part of the TDVMCALL ABI. This little assembly wrapper lets us reuse do_tdvmcall() for both KVM-specific hypercalls TDVMCALL_VENDOR_KVM and the more generic __tdvmcalls. > --- a/arch/x86/kernel/tdx.c > +++ b/arch/x86/kernel/tdx.c > @@ -8,6 +8,10 @@ > > #include > > +#ifdef CONFIG_KVM_GUEST > +#include "tdx-kvm.c" > +#endif > + > static struct { > unsigned int gpa_width; > unsigned long attributes; I know KVM does weird stuff. But, this is *really* weird. Why are we #including a .c file into another .c file?