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Mon, 22 Jun 2020 12:21:47 +0000 (UTC) Received: from ovpn-115-200.ams2.redhat.com (ovpn-115-200.ams2.redhat.com [10.36.115.200]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3B38C10013D2; Mon, 22 Jun 2020 12:21:41 +0000 (UTC) Message-ID: Subject: Re: [PATCH v2 01/11] KVM: x86: Add helper functions for illegal GPA checking and page fault injection From: Mohammed Gamal To: Yuan Yao Cc: kvm@vger.kernel.org, pbonzini@redhat.com, linux-kernel@vger.kernel.org, vkuznets@redhat.com, sean.j.christopherson@intel.com, wanpengli@tencent.com, jmattson@google.com, joro@8bytes.org, thomas.lendacky@amd.com, babu.moger@amd.com Date: Mon, 22 Jun 2020 14:21:38 +0200 In-Reply-To: <20200622044453.6t5ssz6hwvnaujwf@yy-desk-7060> References: <20200619153925.79106-1-mgamal@redhat.com> <20200619153925.79106-2-mgamal@redhat.com> <20200622044453.6t5ssz6hwvnaujwf@yy-desk-7060> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.3 (3.36.3-1.fc32) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2020-06-22 at 12:44 +0800, Yuan Yao wrote: > On Fri, Jun 19, 2020 at 05:39:15PM +0200, Mohammed Gamal wrote: > > This patch adds two helper functions that will be used to support > > virtualizing > > MAXPHYADDR in both kvm-intel.ko and kvm.ko. > > > > kvm_fixup_and_inject_pf_error() injects a page fault for a user- > > specified GVA, > > while kvm_mmu_is_illegal_gpa() checks whether a GPA exceeds vCPU > > address limits. > > > > Signed-off-by: Mohammed Gamal > > Signed-off-by: Paolo Bonzini > > --- > > arch/x86/kvm/mmu.h | 6 ++++++ > > arch/x86/kvm/x86.c | 21 +++++++++++++++++++++ > > arch/x86/kvm/x86.h | 1 + > > 3 files changed, 28 insertions(+) > > > > diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h > > index 0ad06bfe2c2c..555237dfb91c 100644 > > --- a/arch/x86/kvm/mmu.h > > +++ b/arch/x86/kvm/mmu.h > > @@ -4,6 +4,7 @@ > > > > #include > > #include "kvm_cache_regs.h" > > +#include "cpuid.h" > > > > #define PT64_PT_BITS 9 > > #define PT64_ENT_PER_PAGE (1 << PT64_PT_BITS) > > @@ -158,6 +159,11 @@ static inline bool is_write_protection(struct > > kvm_vcpu *vcpu) > > return kvm_read_cr0_bits(vcpu, X86_CR0_WP); > > } > > > > +static inline bool kvm_mmu_is_illegal_gpa(struct kvm_vcpu *vcpu, > > gpa_t gpa) > > +{ > > + return (gpa >= BIT_ULL(cpuid_maxphyaddr(vcpu))); > > +} > > + > > /* > > * Check if a given access (described through the I/D, W/R and U/S > > bits of a > > * page fault error code pfec) causes a permission fault with the > > given PTE > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > > index 00c88c2f34e4..ac8642e890b1 100644 > > --- a/arch/x86/kvm/x86.c > > +++ b/arch/x86/kvm/x86.c > > @@ -10693,6 +10693,27 @@ u64 kvm_spec_ctrl_valid_bits(struct > > kvm_vcpu *vcpu) > > } > > EXPORT_SYMBOL_GPL(kvm_spec_ctrl_valid_bits); > > > > +void kvm_fixup_and_inject_pf_error(struct kvm_vcpu *vcpu, gva_t > > gva, u16 error_code) > > +{ > > + struct x86_exception fault; > > + > > + if (!(error_code & PFERR_PRESENT_MASK) || > > + vcpu->arch.walk_mmu->gva_to_gpa(vcpu, gva, error_code, > > &fault) != UNMAPPED_GVA) { > > + /* > > + * If vcpu->arch.walk_mmu->gva_to_gpa succeeded, the > > page > > + * tables probably do not match the TLB. Just proceed > > + * with the error code that the processor gave. > > + */ > > + fault.vector = PF_VECTOR; > > + fault.error_code_valid = true; > > + fault.error_code = error_code; > > + fault.nested_page_fault = false; > > + fault.address = gva; > > + } > > + vcpu->arch.walk_mmu->inject_page_fault(vcpu, &fault); > > Should this "vcpu->arch.walk_mmu->inject_page_fault(vcpu, &fault)" > inside the last brace? > Otherwise an uninitialized fault variable will be passed to the > walk_mmu->inject_page_fault. Good catch. You're right. Will fix it in v3 > > > +} > > +EXPORT_SYMBOL_GPL(kvm_fixup_and_inject_pf_error); > > + > > EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_exit); > > EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_fast_mmio); > > EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_inj_virq); > > diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h > > index 6eb62e97e59f..239ae0f3e40b 100644 > > --- a/arch/x86/kvm/x86.h > > +++ b/arch/x86/kvm/x86.h > > @@ -272,6 +272,7 @@ int kvm_mtrr_get_msr(struct kvm_vcpu *vcpu, u32 > > msr, u64 *pdata); > > bool kvm_mtrr_check_gfn_range_consistency(struct kvm_vcpu *vcpu, > > gfn_t gfn, > > int page_num); > > bool kvm_vector_hashing_enabled(void); > > +void kvm_fixup_and_inject_pf_error(struct kvm_vcpu *vcpu, gva_t > > gva, u16 error_code); > > int x86_emulate_instruction(struct kvm_vcpu *vcpu, gpa_t > > cr2_or_gpa, > > int emulation_type, void *insn, int > > insn_len); > > fastpath_t handle_fastpath_set_msr_irqoff(struct kvm_vcpu *vcpu); > > -- > > 2.26.2 > >