From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.20]) (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 B07D1215F5C; Tue, 16 Sep 2025 07:44:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.20 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758008692; cv=none; b=Onx+7m8z3djMxwwO3XgE/XIh83q0Twm2LSWAG/5j2JAx8qTz9HLdJCGehzg8svM5pHh/WNK5augManwcrBGfqljAX92Zugr1yKAd7xFtOW2/TgnDLyvzsdKBoxLgvGWapek55LznT/d4f0RxvkukXTTAdB7ExUY444Wk7ZOMNaQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758008692; c=relaxed/simple; bh=6m0AhTKq2P/We5qSWs7LufXVWjDoaLwb/w8yhyhl/7U=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=n60pvyNnrH6X36MsOZroARVAFtgFn3EuELbpuVrsaM/+l0nDVekepMzgt28M6PpZvzHkId7EPQOhwKgBHmmmGkVur7i438jdcKFp9U8v9latNr2Ffy5CzZoP9mbpnEwEZcOPDi/kq64g07Ved+KWKfpYmHyMXbw+sl5uIIs7720= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=ipBPs3fy; arc=none smtp.client-ip=198.175.65.20 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="ipBPs3fy" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1758008691; x=1789544691; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=6m0AhTKq2P/We5qSWs7LufXVWjDoaLwb/w8yhyhl/7U=; b=ipBPs3fygKenP1PgXzMVbGT1D5hxEhJj7HF7MIvrYB7E/AlcEooX7I3m scU5MN60nCcinBJ35FBy7QyqxMuNz8v0xo4WThG09XdbXUQpih4bmQ02F yRcX7qs1s0OajLce7rZ4YVwnrEt8owGquf+4YLEM/MuwVDTBcARiaKiKU vuargDjtvtReLbKhmEBNs/WyK/LOn55/0msFzVsZ7AobHyVyVB7yrtAmQ 3iBnzMofpFATWF4NNB9i6qKLURxGRqaw/N+vcv5mjwcxoO0cH2t2zb2lK 4/euW6vOwMDGhsjtiily31Jdeg8voTJKkXIyuOkoJbohJeHiFUgCnP0ek g==; X-CSE-ConnectionGUID: Jj6VLMIYSRuUV3BeOCmo9Q== X-CSE-MsgGUID: JHJtJr4GRjCBeX8atstQ4Q== X-IronPort-AV: E=McAfee;i="6800,10657,11554"; a="59975031" X-IronPort-AV: E=Sophos;i="6.18,268,1751266800"; d="scan'208";a="59975031" Received: from orviesa008.jf.intel.com ([10.64.159.148]) by orvoesa112.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Sep 2025 00:44:51 -0700 X-CSE-ConnectionGUID: UfI9IL35SeWbk8YHC2ewHw== X-CSE-MsgGUID: 7SXagxhRSCCeov09Y8Veug== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.18,268,1751266800"; d="scan'208";a="174948081" Received: from junlongf-mobl.ccr.corp.intel.com (HELO [10.238.1.52]) ([10.238.1.52]) by orviesa008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Sep 2025 00:44:47 -0700 Message-ID: <6235548b-d542-4f93-8fc0-6267b6215130@intel.com> Date: Tue, 16 Sep 2025 15:44:43 +0800 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 v15 17/41] KVM: VMX: Set host constant supervisor states to VMCS fields To: Sean Christopherson , Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Tom Lendacky , Mathias Krause , John Allen , Rick Edgecombe , Chao Gao , Maxim Levitsky , Zhang Yi Z References: <20250912232319.429659-1-seanjc@google.com> <20250912232319.429659-18-seanjc@google.com> Content-Language: en-US From: Xiaoyao Li In-Reply-To: <20250912232319.429659-18-seanjc@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 9/13/2025 7:22 AM, Sean Christopherson wrote: > From: Yang Weijiang > > Save constant values to HOST_{S_CET,SSP,INTR_SSP_TABLE} field explicitly. > Kernel IBT is supported and the setting in MSR_IA32_S_CET is static after > post-boot(The exception is BIOS call case but vCPU thread never across it) > and KVM doesn't need to refresh HOST_S_CET field before every VM-Enter/ > VM-Exit sequence. > > Host supervisor shadow stack is not enabled now and SSP is not accessible > to kernel mode, thus it's safe to set host IA32_INT_SSP_TAB/SSP VMCS field > to 0s. When shadow stack is enabled for CPL3, SSP is reloaded from PL3_SSP > before it exits to userspace. Check SDM Vol 2A/B Chapter 3/4 for SYSCALL/ > SYSRET/SYSENTER SYSEXIT/RDSSP/CALL etc. > > Prevent KVM module loading if host supervisor shadow stack SHSTK_EN is set > in MSR_IA32_S_CET as KVM cannot co-exit with it correctly. > > Suggested-by: Sean Christopherson > Suggested-by: Chao Gao > Signed-off-by: Yang Weijiang > Reviewed-by: Maxim Levitsky > Reviewed-by: Chao Gao > Tested-by: Mathias Krause > Tested-by: John Allen > Tested-by: Rick Edgecombe > Signed-off-by: Chao Gao > [sean: snapshot host S_CET if SHSTK *or* IBT is supported] > Signed-off-by: Sean Christopherson Reviewed-by: Xiaoyao Li