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[23.128.96.18]) by mx.google.com with ESMTP id w9si682121ilv.15.2021.05.19.13.15.28; Wed, 19 May 2021 13:15:40 -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 S1355055AbhESQA2 (ORCPT + 99 others); Wed, 19 May 2021 12:00:28 -0400 Received: from mga17.intel.com ([192.55.52.151]:12728 "EHLO mga17.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1355046AbhESQA1 (ORCPT ); Wed, 19 May 2021 12:00:27 -0400 IronPort-SDR: tPMrkotKm0z4TRyFCowZd5jXu9Nlb9LZ7sAGEhWg/qLbYzOMyGDxrLyAPIbsW/I7G2J4doXZff WEPaIIBJ2u1w== X-IronPort-AV: E=McAfee;i="6200,9189,9989"; a="181287198" X-IronPort-AV: E=Sophos;i="5.82,313,1613462400"; d="scan'208";a="181287198" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 May 2021 08:59:07 -0700 IronPort-SDR: KX8HN55gRTtx1o223ApTBGDmY2sO0VGE12XpbWwCDLvJo67fCrndXXVSCfEWxzBSlIKQApyUK7 M+JT5Sqj8Q4A== X-IronPort-AV: E=Sophos;i="5.82,313,1613462400"; d="scan'208";a="474683001" Received: from mconrado-mobl1.amr.corp.intel.com (HELO [10.209.83.57]) ([10.209.83.57]) by fmsmga002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 May 2021 08:59:06 -0700 Subject: Re: [RFC v2 29/32] x86/tdx: Add helper to do MapGPA TDVMALL 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 References: <7d43f57c3b178a905ef2505cef5313844c497984.1619458733.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: <7d43f57c3b178a905ef2505cef5313844c497984.1619458733.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" > > MapGPA TDVMCALL requests the host VMM to map a GPA range as private or > shared memory mappings. Shared GPA mappings can be used for > communication beteen TD guest and host VMM, for example for > paravirtualized IO. As usual, I hate the changelog. This appears to just be regurgitating the spec. Is this just for part of converting an existing mapping between private and shared? If so, please say that. > The new helper tdx_map_gpa() provides access to the operation. You got your own name wrong. It's tdg_map_gpa() in the patch. BTW, I agree with Sean on this one: "tdg" is a horrible prefix. You just proved Sean's point by mistyping it. *EVERYONE* is going to rpeat that mistake: tdg -> tdx. > diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h > index dc80cf7f7d08..4789798d7737 100644 > --- a/arch/x86/include/asm/tdx.h > +++ b/arch/x86/include/asm/tdx.h > @@ -7,6 +7,11 @@ > > #ifndef __ASSEMBLY__ > > +enum tdx_map_type { > + TDX_MAP_PRIVATE, > + TDX_MAP_SHARED, > +}; I like the enum, but please call out that this is a software construct, not a part of any hardware or VMM ABI. > #ifdef CONFIG_INTEL_TDX_GUEST > > #include > @@ -112,6 +117,8 @@ unsigned short tdg_inw(unsigned short port); > unsigned int tdg_inl(unsigned short port); > > extern phys_addr_t tdg_shared_mask(void); > +extern int tdg_map_gpa(phys_addr_t gpa, int numpages, > + enum tdx_map_type map_type); > > #else // !CONFIG_INTEL_TDX_GUEST > > @@ -155,6 +162,12 @@ static inline phys_addr_t tdg_shared_mask(void) > { > return 0; > } > + > +static inline int tdg_map_gpa(phys_addr_t gpa, int numpages, > + enum tdx_map_type map_type) > +{ > + return -ENODEV; > +} FWIW, you could probably get away with just inlining tdg_map_gpa(): static inline int tdg_map_gpa(phys_addr_t gpa, int numpages, ... { u64 ret; if (!IS_ENABLED(CONFIG_INTEL_TDX_GUEST)) return -ENODEV; if (map_type == TDX_MAP_SHARED) gpa |= tdg_shared_mask(); ret = tdvmcall(TDVMCALL_MAP_GPA, gpa, ... return ret ? -EIO : 0; } Then you don't have three copies of the function signature that can get out of sync. > #endif /* CONFIG_INTEL_TDX_GUEST */ > #endif /* __ASSEMBLY__ */ > #endif /* _ASM_X86_TDX_H */ > diff --git a/arch/x86/kernel/tdx.c b/arch/x86/kernel/tdx.c > index 7e391cd7aa2b..074136473011 100644 > --- a/arch/x86/kernel/tdx.c > +++ b/arch/x86/kernel/tdx.c > @@ -15,6 +15,8 @@ > #include "tdx-kvm.c" > #endif > > +#define TDVMCALL_MAP_GPA 0x10001 > + > static struct { > unsigned int gpa_width; > unsigned long attributes; > @@ -98,6 +100,17 @@ static void tdg_get_info(void) > physical_mask &= ~tdg_shared_mask(); > } > > +int tdg_map_gpa(phys_addr_t gpa, int numpages, enum tdx_map_type map_type) > +{ > + u64 ret; > + > + if (map_type == TDX_MAP_SHARED) > + gpa |= tdg_shared_mask(); > + > + ret = tdvmcall(TDVMCALL_MAP_GPA, gpa, PAGE_SIZE * numpages, 0, 0); > + return ret ? -EIO : 0; > +} The naming Intel chose here is nasty. This doesn't "map" anything. It modifies an existing mapping from what I can tell. We could name it much better than the spec, perhaps: tdx_hcall_gpa_intent() BTW, all of these hypercalls need a consistent prefix. It also needs a comment: /* * Inform the VMM of the guest's intent for this physical page: * shared with the VMM or private to the guest. The VMM is * expected to change its mapping of the page in response. * * Note: shared->private conversions require further guest * action to accept the page. */ The intent here is important. It makes it clear that this function really only plays a role in the conversion process.