From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.13]) (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 9006E944D; Tue, 12 Mar 2024 02:59:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.13 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710212373; cv=none; b=CsYSrGkPCpVkM+9FtK6gKqE8KM4/PsmVILHAUxPYbY17PGpTDXP/KImbFXzRiemnhGX+xUJXkCPCjMq0pH+b0USKPZAVGqJ8qKn1v2DKYxizrfJ42zT9Dj48Av0XOclG1YNgNFG6484ZckOdDtlcBg4kmoTBL12NInsDOs1ZSR4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710212373; c=relaxed/simple; bh=Sxl6t66ITIwHPGNrR+W7/MelDwyA12T4A8C+abUZIWo=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=BLEYZbLE3mH0shNGKIS+zIkCDPoFmifDqmGFFXN0Ux9FkTF6mZm7E/UOqGHYrgQCmlWdwxyGz4mv7YR7jx7jtfgAOQnzWqrCvzeVVJQgOQPqFdc6DCc96VXOZwAS6OdWwGujfkcwPm+uGKgeHlyn+SUXtDvg1X4Ur0AOiswjb9M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=none smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=DF2KIUKO; arc=none smtp.client-ip=198.175.65.13 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="DF2KIUKO" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1710212372; x=1741748372; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=Sxl6t66ITIwHPGNrR+W7/MelDwyA12T4A8C+abUZIWo=; b=DF2KIUKOB8Uvqa/aC5mBi1HfheMz6twE4gJhm4nVPiilk/9C+68ripJ9 r6e7SIYQhXFCPKSR280EnDNlvxGqAY7LBmm92LpLQfYgbPGl5iXNhAwxC Ny9bMNrQB4LD74R5SHSqvRgT2PzQL5ld8k82Z7ouCct8UpGCSYtSDYPfG +2xoxDvoTeaP3GrDCzS9Q8sg3mNs5dKzs89lDg8G0cDiWqE+SN3f3aFh2 2fdLo7xnqWCEOSm86VtRXbIqpxk8DigQb/Hbb0K2XogzUZr/9tLIA+05U SoOycbwSOmItwsPG8EgOjhQYIWy7lPz1ZSWNN4mkRvne2Gp8Ebklfthn/ Q==; X-IronPort-AV: E=McAfee;i="6600,9927,11010"; a="16047944" X-IronPort-AV: E=Sophos;i="6.07,118,1708416000"; d="scan'208";a="16047944" Received: from fmviesa001.fm.intel.com ([10.60.135.141]) by orvoesa105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Mar 2024 19:59:31 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.07,118,1708416000"; d="scan'208";a="42369466" Received: from binbinwu-mobl.ccr.corp.intel.com (HELO [10.125.242.247]) ([10.125.242.247]) by smtpauth.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Mar 2024 19:59:27 -0700 Message-ID: <6d24f7b1-a271-43de-ba94-847a3c9e0d8c@linux.intel.com> Date: Tue, 12 Mar 2024 10:59:25 +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 01/16] KVM: x86/mmu: Exit to userspace with -EFAULT if private fault hits emulation To: "Gupta, Pankaj" , Sean Christopherson , Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Yan Zhao , Isaku Yamahata , Michael Roth , Yu Zhang , Chao Peng , Fuad Tabba , David Matlack References: <20240228024147.41573-1-seanjc@google.com> <20240228024147.41573-2-seanjc@google.com> <2441bd2a-a0b1-5184-bac8-28c94b151c93@amd.com> From: Binbin Wu In-Reply-To: <2441bd2a-a0b1-5184-bac8-28c94b151c93@amd.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 3/7/2024 8:52 PM, Gupta, Pankaj wrote: >> Exit to userspace with -EFAULT / KVM_EXIT_MEMORY_FAULT if a private >> fault >> triggers emulation of any kind, as KVM doesn't currently support >> emulating >> access to guest private memory.  Practically speaking, private faults >> and >> emulation are already mutually exclusive, but there are edge cases upon >> edge cases where KVM can return RET_PF_EMULATE, and adding one last >> check > > edge cases upon edge cases? > > Just curious about the details of the edge cases scenarios? Same question out of curiosity. > >> to harden against weird, unexpected combinations is inexpensive. >> >> Suggested-by: Yan Zhao >> Signed-off-by: Sean Christopherson >> --- >>   arch/x86/kvm/mmu/mmu.c          |  8 -------- >>   arch/x86/kvm/mmu/mmu_internal.h | 13 +++++++++++++ >>   2 files changed, 13 insertions(+), 8 deletions(-) >> >> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c >> index e4cc7f764980..e2fd74e06ff8 100644 >> --- a/arch/x86/kvm/mmu/mmu.c >> +++ b/arch/x86/kvm/mmu/mmu.c >> @@ -4309,14 +4309,6 @@ static inline u8 kvm_max_level_for_order(int >> order) >>       return PG_LEVEL_4K; >>   } >>   -static void kvm_mmu_prepare_memory_fault_exit(struct kvm_vcpu *vcpu, >> -                          struct kvm_page_fault *fault) >> -{ >> -    kvm_prepare_memory_fault_exit(vcpu, fault->gfn << PAGE_SHIFT, >> -                      PAGE_SIZE, fault->write, fault->exec, >> -                      fault->is_private); >> -} >> - >>   static int kvm_faultin_pfn_private(struct kvm_vcpu *vcpu, >>                      struct kvm_page_fault *fault) >>   { >> diff --git a/arch/x86/kvm/mmu/mmu_internal.h >> b/arch/x86/kvm/mmu/mmu_internal.h >> index 0669a8a668ca..0eea6c5a824d 100644 >> --- a/arch/x86/kvm/mmu/mmu_internal.h >> +++ b/arch/x86/kvm/mmu/mmu_internal.h >> @@ -279,6 +279,14 @@ enum { >>       RET_PF_SPURIOUS, >>   }; >>   +static inline void kvm_mmu_prepare_memory_fault_exit(struct >> kvm_vcpu *vcpu, >> +                             struct kvm_page_fault *fault) >> +{ >> +    kvm_prepare_memory_fault_exit(vcpu, fault->gfn << PAGE_SHIFT, >> +                      PAGE_SIZE, fault->write, fault->exec, >> +                      fault->is_private); >> +} >> + >>   static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, >> gpa_t cr2_or_gpa, >>                       u32 err, bool prefetch, int *emulation_type) >>   { >> @@ -320,6 +328,11 @@ static inline int kvm_mmu_do_page_fault(struct >> kvm_vcpu *vcpu, gpa_t cr2_or_gpa, >>       else >>           r = vcpu->arch.mmu->page_fault(vcpu, &fault); >>   +    if (r == RET_PF_EMULATE && fault.is_private) { >> +        kvm_mmu_prepare_memory_fault_exit(vcpu, &fault); >> +        return -EFAULT; >> +    } >> + >>       if (fault.write_fault_to_shadow_pgtable && emulation_type) >>           *emulation_type |= EMULTYPE_WRITE_PF_TO_SP; > >