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X-CSE-ConnectionGUID: fd97MakGSO+E+U6FBS2GMw== X-CSE-MsgGUID: uawIRaErR/KjRZuPVs4Olg== X-IronPort-AV: E=McAfee;i="6800,10657,11468"; a="63088126" X-IronPort-AV: E=Sophos;i="6.16,246,1744095600"; d="scan'208";a="63088126" Received: from orviesa006.jf.intel.com ([10.64.159.146]) by fmvoesa105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Jun 2025 07:58:21 -0700 X-CSE-ConnectionGUID: KzBtx/eNQRGPrA1Leg5Qew== X-CSE-MsgGUID: DhmJ8iDURIaOz2OiEXDsZw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.16,246,1744095600"; d="scan'208";a="149438645" Received: from agladkov-desk.ger.corp.intel.com (HELO [10.125.108.97]) ([10.125.108.97]) by orviesa006-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Jun 2025 07:58:18 -0700 Message-ID: <68938275-3f6a-46fc-9b38-2c916fdec3d6@intel.com> Date: Wed, 18 Jun 2025 07:58:17 -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 2/2] KVM: TDX: Do not clear poisoned pages To: Adrian Hunter , Tony Luck , pbonzini@redhat.com, seanjc@google.com Cc: vannapurve@google.com, Borislav Petkov , Thomas Gleixner , Ingo Molnar , Dave Hansen , x86@kernel.org, H Peter Anvin , linux-edac@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, rick.p.edgecombe@intel.com, kirill.shutemov@linux.intel.com, kai.huang@intel.com, reinette.chatre@intel.com, xiaoyao.li@intel.com, tony.lindgren@linux.intel.com, binbin.wu@linux.intel.com, isaku.yamahata@intel.com, yan.y.zhao@intel.com, chao.gao@intel.com References: <20250618120806.113884-1-adrian.hunter@intel.com> <20250618120806.113884-3-adrian.hunter@intel.com> From: Dave Hansen Content-Language: en-US Autocrypt: addr=dave.hansen@intel.com; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 6/18/25 05:08, Adrian Hunter wrote: > --- a/arch/x86/kvm/vmx/tdx.c > +++ b/arch/x86/kvm/vmx/tdx.c > @@ -282,10 +282,10 @@ static void tdx_clear_page(struct page *page) > void *dest = page_to_virt(page); > unsigned long i; > > - /* > - * The page could have been poisoned. MOVDIR64B also clears > - * the poison bit so the kernel can safely use the page again. > - */ > + /* Machine check handler may have poisoned the page */ > + if (PageHWPoison(page)) > + return; I think the old comment needs to stay in some form. There are two kinds of poisons here: One from an integrity mismatch and the other because the hardware decided the memory is bad. MOVDIR64B clears the integrity one, but not the hardware one obviously. Could we make that clear in the comment, please?