From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.15]) (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 8279A2BE027; Wed, 27 Aug 2025 06:22:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.15 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756275736; cv=none; b=BmjQv/aPE83aKq34XrJRIZFl5Z1vgENmIyU+1519z/Huob8QuOPaIdCkz849Ya3U3G85D0eaqE5ENaAne+s9OYOUv8w/sKS9JjpSuDrMBFFUaWZJl6hAwRwliyI526I6JXr+YrG1RUEEZjkYfukD3FyWbi2APObsdNd8Q5dsrJA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756275736; c=relaxed/simple; bh=ghqyHuxRn2YZ182BMZRUnoAXRhnwuthZ2gQmVN6HRL8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=jHbPKEgrytBIkMjQxTfVvq9vn+lgnswjC3oVb4awIHb2gMgyPC2RICoZV49HG4smBNNchKMlRfS4qrBR+WuUqhtqFzX8r03GrLjrIfdbOmKbIiedHmqrFfhLs+b9SHI7Fp7KN820/y8P4vB6Zl9BWvqw3FYWkVdJm5ce4dw3BMU= 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=gXDA9Nil; arc=none smtp.client-ip=198.175.65.15 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="gXDA9Nil" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1756275735; x=1787811735; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=ghqyHuxRn2YZ182BMZRUnoAXRhnwuthZ2gQmVN6HRL8=; b=gXDA9NilouEZJlf/QPHqsP00Ty4TVn5YuhCnBF6PsPIqyJW8AT6Jn5pg s3ERZJjMzUttPGkndsz8qGA+Ah2UZptOOxrO+LaLCUGjwAL6M1Uw1Yzon CBnbUOs2mwwq3XevUhCDMgv9j4zGWeja5/YlI9PIcgxSJNnYLuxldhjxY e2F0mc9zqmoE9uKJ/PWN/APtON62BKkIC82xVHUYK5IyuS0Slly5cXUMo Dnapr7tFQSlFObF43S4rS6COzgHskoisHVEWfdsc3/hV9gjMGurj79HJO I+kRjjOaxuUcHJU0Fq5uQcEKoQrBFNfkddfdPXkJsmjyfzO1HYbGbCHiU w==; X-CSE-ConnectionGUID: wLsczntMRZeiRMyDnmWmxQ== X-CSE-MsgGUID: e3+WSjyeQ36nx4HIwjQ15Q== X-IronPort-AV: E=McAfee;i="6800,10657,11534"; a="62167177" X-IronPort-AV: E=Sophos;i="6.18,214,1751266800"; d="scan'208";a="62167177" Received: from orviesa008.jf.intel.com ([10.64.159.148]) by orvoesa107.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Aug 2025 23:22:13 -0700 X-CSE-ConnectionGUID: gRB1mM8XS+GLSYvJNO1mxw== X-CSE-MsgGUID: b5KA2KaPRzStWr4+UE8efw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.18,214,1751266800"; d="scan'208";a="169942757" Received: from xiaoyaol-hp-g830.ccr.corp.intel.com (HELO [10.124.238.14]) ([10.124.238.14]) by orviesa008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Aug 2025 23:22:07 -0700 Message-ID: <6fe55bc3-dd79-4f7d-9927-7d4f40f7b246@intel.com> Date: Wed, 27 Aug 2025 14:22:03 +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 v2] KVM: TDX: Force split irqchip for TDX at irqchip creation time To: Sagi Shahar , Sean Christopherson , Paolo Bonzini , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , Binbin Wu , Ira Weiny , "H. Peter Anvin" Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, x86@kernel.org References: <20250827011726.2451115-1-sagis@google.com> Content-Language: en-US From: Xiaoyao Li In-Reply-To: <20250827011726.2451115-1-sagis@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 8/27/2025 9:17 AM, Sagi Shahar wrote: > TDX module protects the EOI-bitmap which prevents the use of in-kernel > I/O APIC. See more details in the original patch [1] > > The current implementation already enforces the use of split irqchip for > TDX but it does so at the vCPU creation time which is generally to late > to fallback to split irqchip. > > This patch follows Sean's recomendation from [2] and move the check if > I/O APIC is supported for the VM at irqchip creation time. > > [1] https://lore.kernel.org/lkml/20250222014757.897978-11-binbin.wu@linux.intel.com/ > [2] https://lore.kernel.org/lkml/aK3vZ5HuKKeFuuM4@google.com/ > > Suggested-by: Sean Christopherson > Signed-off-by: Sagi Shahar > --- > arch/x86/include/asm/kvm_host.h | 1 + > arch/x86/kvm/vmx/tdx.c | 6 ++++++ > arch/x86/kvm/x86.c | 9 +++++++++ > 3 files changed, 16 insertions(+) > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index f19a76d3ca0e..6a4019d3a184 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -1357,6 +1357,7 @@ struct kvm_arch { > u8 vm_type; > bool has_private_mem; > bool has_protected_state; > + bool has_protected_eoi; > bool pre_fault_allowed; > struct hlist_head *mmu_page_hash; > struct list_head active_mmu_pages; > diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c > index 66744f5768c8..9637d9da1af1 100644 > --- a/arch/x86/kvm/vmx/tdx.c > +++ b/arch/x86/kvm/vmx/tdx.c > @@ -658,6 +658,12 @@ int tdx_vm_init(struct kvm *kvm) > */ > kvm->max_vcpus = min_t(int, kvm->max_vcpus, num_present_cpus()); > > + /* > + * TDX Module doesn't allow the hypervisor to modify the EOI-bitmap, > + * i.e. all EOIs are accelerated and never trigger exits. > + */ > + kvm->arch.has_protected_eoi = true; I prefer putting it along with the lines kvm->arch.has_protected_state = true; kvm->arch.has_private_mem = true; Otherwise, Reviewed-by: Xiaoyao Li > kvm_tdx->state = TD_STATE_UNINITIALIZED; > > return 0; > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index a1c49bc681c4..57b4d5ba2568 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -6966,6 +6966,15 @@ int kvm_arch_vm_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg) > if (irqchip_in_kernel(kvm)) > goto create_irqchip_unlock; > > + /* > + * Disallow an in-kernel I/O APIC if the VM has protected EOIs, > + * i.e. if KVM can't intercept EOIs and thus can't properly > + * emulate level-triggered interrupts. > + */ > + r = -ENOTTY; > + if (kvm->arch.has_protected_eoi) > + goto create_irqchip_unlock; > + > r = -EINVAL; > if (kvm->created_vcpus) > goto create_irqchip_unlock;