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X-CSE-ConnectionGUID: Ba2hUmIORXqnIry3gyBsuw== X-CSE-MsgGUID: IWxbdFUTT6aJOIbIUQzqoQ== X-IronPort-AV: E=McAfee;i="6700,10204,11419"; a="47563252" X-IronPort-AV: E=Sophos;i="6.15,251,1739865600"; d="scan'208";a="47563252" Received: from fmviesa001.fm.intel.com ([10.60.135.141]) by orvoesa111.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Apr 2025 06:44:56 -0700 X-CSE-ConnectionGUID: aUbIapIhRh2FojMYdjJSkw== X-CSE-MsgGUID: aYBXuvakQm+vbq/sgnuG6w== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.15,251,1739865600"; d="scan'208";a="165212060" Received: from bkammerd-mobl.amr.corp.intel.com (HELO [10.124.223.145]) ([10.124.223.145]) by smtpauth.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Apr 2025 06:44:55 -0700 Message-ID: Date: Wed, 30 Apr 2025 06:44:53 -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: [V2 PATCH] x86/tdx: add VIRT_CPUID2 virtualization if REDUCE_VE was not successful To: Zhiquan Li , Jun Miao , kirill.shutemov@linux.intel.com, dave.hansen@linux.intel.com Cc: x86@kernel.org, linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, "Du, Fan" References: <20250429143114.1724280-1-jun.miao@intel.com> <20250429143114.1724280-2-jun.miao@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 4/29/25 19:15, Zhiquan Li wrote: > On 2025/4/29 22:50, Dave Hansen wrote: >> On 4/29/25 07:31, Jun Miao wrote: >>> REDUCE_VE can only be enabled if x2APIC_ID has been properly configured >>> with unique values for each VCPU. Check if VMM has provided an activated >>> topology configuration first as it is the prerequisite of REDUCE_VE and >>> ENUM_TOPOLOGY, so move it to reduce_unnecessary_ve(). The function >>> enable_cpu_topology_enumeration() was very little and can be >>> integrated into reduce_unnecessary_ve(). >> Isn't this just working around VMM bugs? Shouldn't we just panic as >> quickly as possible so the VMM config gets fixed rather than adding kludges? > > Now failed to virtualize these two cases will cause TD VM regression vs > legacy VM. Do you mean the panic will just for the #VE caused by CPUID > leaf 0x2? Or both (+ VMM not configure topology) will panic? I'm not really parsing this response. I don't understand what you are asking. > Currently the most customer's complaints come from the CPUID leaf 0x2 > not virtualization, and most of access come from user space. Is it > appropriate for such behavior directly cause a guest kernel panic? If a VMM doesn't properly configure topology properly and allows REDUCE_VE, then panic. They obviously got something wrong because that configuration doesn't make any sense.