From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4AB0CC11D1E for ; Thu, 20 Feb 2020 20:11:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2421820722 for ; Thu, 20 Feb 2020 20:11:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729020AbgBTULq (ORCPT ); Thu, 20 Feb 2020 15:11:46 -0500 Received: from mga05.intel.com ([192.55.52.43]:53786 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728770AbgBTULq (ORCPT ); Thu, 20 Feb 2020 15:11:46 -0500 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by fmsmga105.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 20 Feb 2020 12:11:46 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,465,1574150400"; d="scan'208";a="383253442" Received: from sjchrist-coffee.jf.intel.com (HELO linux.intel.com) ([10.54.74.202]) by orsmga004.jf.intel.com with ESMTP; 20 Feb 2020 12:11:45 -0800 Date: Thu, 20 Feb 2020 12:11:45 -0800 From: Sean Christopherson To: Xiaoyao Li Cc: Paolo Bonzini , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 1/3] KVM: x86: Add EMULTYPE_PF when emulation is triggered by a page fault Message-ID: <20200220201145.GI3972@linux.intel.com> References: <20200218230310.29410-1-sean.j.christopherson@intel.com> <20200218230310.29410-2-sean.j.christopherson@intel.com> <7d564331-9a77-d59a-73d3-a7452fd7b15f@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7d564331-9a77-d59a-73d3-a7452fd7b15f@intel.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Wed, Feb 19, 2020 at 05:01:41PM +0800, Xiaoyao Li wrote: > On 2/19/2020 7:03 AM, Sean Christopherson wrote: > >Add a new emulation type flag to explicitly mark emulation related to a > >page fault. Move the propation of the GPA into the emulator from the > >page fault handler into x86_emulate_instruction, using EMULTYPE_PF as an > >indicator that cr2 is valid. Similarly, don't propagate cr2 into the > >exception.address when it's *not* valid. > > > >Signed-off-by: Sean Christopherson > >--- > > arch/x86/include/asm/kvm_host.h | 12 +++++++++--- > > arch/x86/kvm/mmu/mmu.c | 10 ++-------- > > arch/x86/kvm/x86.c | 25 +++++++++++++++++++------ > > 3 files changed, 30 insertions(+), 17 deletions(-) > > > >diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > >index 4dffbc10d3f8..10c1e8f472b6 100644 > >--- a/arch/x86/include/asm/kvm_host.h > >+++ b/arch/x86/include/asm/kvm_host.h > >@@ -1370,8 +1370,9 @@ extern u64 kvm_mce_cap_supported; > > * decode the instruction length. For use *only* by > > * kvm_x86_ops->skip_emulated_instruction() implementations. > > * > >- * EMULTYPE_ALLOW_RETRY - Set when the emulator should resume the guest to > >- * retry native execution under certain conditions. > >+ * EMULTYPE_ALLOW_RETRY_PF - Set when the emulator should resume the guest to > >+ * retry native execution under certain conditions, > >+ * Can only be set in conjunction with EMULTYPE_PF. > > * > > * EMULTYPE_TRAP_UD_FORCED - Set when emulating an intercepted #UD that was > > * triggered by KVM's magic "force emulation" prefix, > >@@ -1384,13 +1385,18 @@ extern u64 kvm_mce_cap_supported; > > * backdoor emulation, which is opt in via module param. > > * VMware backoor emulation handles select instructions > > * and reinjects the #GP for all other cases. > >+ * > >+ * EMULTYPE_PF - Set when emulating MMIO by way of an intercepted #PF, in which > >+ * case the CR2/GPA value pass on the stack is valid. > > */ > > #define EMULTYPE_NO_DECODE (1 << 0) > > #define EMULTYPE_TRAP_UD (1 << 1) > > #define EMULTYPE_SKIP (1 << 2) > >-#define EMULTYPE_ALLOW_RETRY (1 << 3) > >+#define EMULTYPE_ALLOW_RETRY_PF (1 << 3) > > How about naming it as EMULTYPE_PF_ALLOW_RETRY and exchanging the bit > position with EMULTYPE_PF ? Hmm, EMULTYPE_PF_ALLOW_RETRY does sound better. I'm on the fence regarding shuffling the bits. If I were to shuffle the bits, I'd do a more thorough reorder so that the #UD and #PF types are consecutive, e.g. #define EMULTYPE_NO_DECODE (1 << 0) #define EMULTYPE_TRAP_UD (1 << 1) #define EMULTYPE_TRAP_UD_FORCED (1 << 2) #define EMULTYPE_SKIP (1 << 3) #define EMULTYPE_VMWARE_GP (1 << 4) #define EMULTYPE_PF (1 << 5) #define EMULTYPE_PF_ALLOW_RETRY (1 << 6) Part of me really wants to do that, the other part of me thinks it's unnecessary thrash. > > #define EMULTYPE_TRAP_UD_FORCED (1 << 4) > > #define EMULTYPE_VMWARE_GP (1 << 5) > >+#define EMULTYPE_PF (1 << 6) > >+ > > int kvm_emulate_instruction(struct kvm_vcpu *vcpu, int emulation_type); > > int kvm_emulate_instruction_from_buffer(struct kvm_vcpu *vcpu, > > void *insn, int insn_len); > >diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > >index 7011a4e54866..258624d46588 100644 > >--- a/arch/x86/kvm/mmu/mmu.c > >+++ b/arch/x86/kvm/mmu/mmu.c > >@@ -5416,18 +5416,12 @@ EXPORT_SYMBOL_GPL(kvm_mmu_unprotect_page_virt); > > int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 error_code, > > void *insn, int insn_len) > > { > >- int r, emulation_type = 0; > >+ int r, emulation_type = EMULTYPE_PF; > > bool direct = vcpu->arch.mmu->direct_map; > > if (WARN_ON(!VALID_PAGE(vcpu->arch.mmu->root_hpa))) > > return RET_PF_RETRY; > >- /* With shadow page tables, fault_address contains a GVA or nGPA. */ > >- if (vcpu->arch.mmu->direct_map) { > >- vcpu->arch.gpa_available = true; > >- vcpu->arch.gpa_val = cr2_or_gpa; > >- } > >- > > r = RET_PF_INVALID; > > if (unlikely(error_code & PFERR_RSVD_MASK)) { > > r = handle_mmio_page_fault(vcpu, cr2_or_gpa, direct); > >@@ -5472,7 +5466,7 @@ int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 error_code, > > * for L1 isn't going to magically fix whatever issue cause L2 to fail. > > */ > > if (!mmio_info_in_cache(vcpu, cr2_or_gpa, direct) && !is_guest_mode(vcpu)) > >- emulation_type = EMULTYPE_ALLOW_RETRY; > >+ emulation_type |= EMULTYPE_ALLOW_RETRY_PF; > > emulate: > > /* > > * On AMD platforms, under certain conditions insn_len may be zero on #NPF. > >diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > >index fbabb2f06273..92af6c5a69e3 100644 > >--- a/arch/x86/kvm/x86.c > >+++ b/arch/x86/kvm/x86.c > >@@ -6483,10 +6483,11 @@ static bool reexecute_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, > > gpa_t gpa = cr2_or_gpa; > > kvm_pfn_t pfn; > >- if (!(emulation_type & EMULTYPE_ALLOW_RETRY)) > >+ if (!(emulation_type & EMULTYPE_ALLOW_RETRY_PF)) > > return false; > >- if (WARN_ON_ONCE(is_guest_mode(vcpu))) > >+ if (WARN_ON_ONCE(is_guest_mode(vcpu)) || > >+ WARN_ON_ONCE(!(emulation_type & EMULTYPE_PF))) > > return false; > > if (!vcpu->arch.mmu->direct_map) { > >@@ -6574,10 +6575,11 @@ static bool retry_instruction(struct x86_emulate_ctxt *ctxt, > > */ > > vcpu->arch.last_retry_eip = vcpu->arch.last_retry_addr = 0; > >- if (!(emulation_type & EMULTYPE_ALLOW_RETRY)) > >+ if (!(emulation_type & EMULTYPE_ALLOW_RETRY_PF)) > > return false; > >- if (WARN_ON_ONCE(is_guest_mode(vcpu))) > >+ if (WARN_ON_ONCE(is_guest_mode(vcpu)) || > >+ WARN_ON_ONCE(!(emulation_type & EMULTYPE_PF))) > > return false; > > if (x86_page_table_writing_insn(ctxt)) > >@@ -6830,8 +6832,19 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, > > } > > restart: > >- /* Save the faulting GPA (cr2) in the address field */ > >- ctxt->exception.address = cr2_or_gpa; > >+ if (emulation_type & EMULTYPE_PF) { > >+ /* Save the faulting GPA (cr2) in the address field */ > >+ ctxt->exception.address = cr2_or_gpa; > >+ > >+ /* With shadow page tables, cr2 contains a GVA or nGPA. */ > >+ if (vcpu->arch.mmu->direct_map) { > >+ vcpu->arch.gpa_available = true; > >+ vcpu->arch.gpa_val = cr2_or_gpa; > >+ } > >+ } else { > >+ /* Sanitize the address out of an abundance of paranoia. */ > >+ ctxt->exception.address = 0; > >+ } > > r = x86_emulate_insn(ctxt); > > >