From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mga12.intel.com (mga12.intel.com [192.55.52.136]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AA22D1C34 for ; Wed, 22 Jun 2022 18:43:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1655923387; x=1687459387; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=vLhzMi2QzzK4JidKA8EX0YX95XP0Zt+Cm+d/NMCKTa8=; b=cRrpQJbDCIAiOurfHHNVOVFnui/lDCkecrxJ+MMK+RxRfPeuybe4FM8u Sqhlgeh2tM6P5ZCGyv+Gg12+lRQkSqM0i5E1DYh256gqvk5rqJ9EsOr63 r11qlccXPkay4cwD9amf/40NDUhIj1LpcOvS9nQIUZGVL23pY3EGbmyae zKO/a407RL+vVIx49IPi276CtjPXNGJWQ/hfaEpi8run84JF3B/OrL4g5 uDTy4DwUWQBNzGxvP+tIyrsGcqveoGF9zNF6eiP1fF+N+wFXlaUOAU2EQ Tgqn+WTcxizqsCe1G/feei7EL6FRyXDTec+Cq8H3dMm/dB6xtjk+RD+vC g==; X-IronPort-AV: E=McAfee;i="6400,9594,10386"; a="260332086" X-IronPort-AV: E=Sophos;i="5.92,212,1650956400"; d="scan'208";a="260332086" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Jun 2022 11:43:06 -0700 X-IronPort-AV: E=Sophos;i="5.92,212,1650956400"; d="scan'208";a="677695719" Received: from bshakya-mobl.amr.corp.intel.com (HELO [10.212.188.76]) ([10.212.188.76]) by fmsmga003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Jun 2022 11:43:05 -0700 Message-ID: <99d72d58-a9bb-d75c-93af-79d497dfe176@intel.com> Date: Wed, 22 Jun 2022 11:42:46 -0700 Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Subject: Re: [PATCH Part2 v6 05/49] x86/sev: Add RMP entry lookup helpers Content-Language: en-US To: "Kalra, Ashish" , "x86@kernel.org" , "linux-kernel@vger.kernel.org" , "kvm@vger.kernel.org" , "linux-coco@lists.linux.dev" , "linux-mm@kvack.org" , "linux-crypto@vger.kernel.org" Cc: "tglx@linutronix.de" , "mingo@redhat.com" , "jroedel@suse.de" , "Lendacky, Thomas" , "hpa@zytor.com" , "ardb@kernel.org" , "pbonzini@redhat.com" , "seanjc@google.com" , "vkuznets@redhat.com" , "jmattson@google.com" , "luto@kernel.org" , "dave.hansen@linux.intel.com" , "slp@redhat.com" , "pgonda@google.com" , "peterz@infradead.org" , "srinivas.pandruvada@linux.intel.com" , "rientjes@google.com" , "dovmurik@linux.ibm.com" , "tobin@ibm.com" , "bp@alien8.de" , "Roth, Michael" , "vbabka@suse.cz" , "kirill@shutemov.name" , "ak@linux.intel.com" , "tony.luck@intel.com" , "marcorr@google.com" , "sathyanarayanan.kuppuswamy@linux.intel.com" , "alpergun@google.com" , "dgilbert@redhat.com" , "jarkko@kernel.org" References: <8f63961f00fd170ba0e561f499292175f3155d26.1655761627.git.ashish.kalra@amd.com> <25be3068-be13-a451-86d4-ff4cc12ddb23@intel.com> <681e4e45-eff1-600c-9b81-1fa9bdf24232@intel.com> From: Dave Hansen In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 6/22/22 11:34, Kalra, Ashish wrote: >> So, if the RMP entry format changes in future processors, how do we >> make sure that the kernel does not try to use *this* code on those >> processors? > Functions snp_lookup_rmpentry() and dump_rmpentry() which rely on > this structure definition will need to handle it accordingly. In other words, old kernels will break on new hardware? I think that needs to be fixed. It should be as simple as a model/family check, though. If someone (for example) attempts to use SNP (and thus snp_lookup_rmpentry() and dump_rmpentry()) code on a newer CPU, the kernel should refuse.