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[213.175.37.10]) by smtp.gmail.com with ESMTPSA id b194sm35531293wmg.46.2019.09.30.03.58.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 30 Sep 2019 03:58:54 -0700 (PDT) From: Vitaly Kuznetsov To: Sean Christopherson Cc: Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Reto Buerki , Liran Alon , Paolo Bonzini , Radim =?utf-8?B?S3LEjW3DocWZ?= Subject: Re: [PATCH v2 8/8] KVM: x86: Fold decache_cr3() into cache_reg() In-Reply-To: <20190927214523.3376-9-sean.j.christopherson@intel.com> References: <20190927214523.3376-1-sean.j.christopherson@intel.com> <20190927214523.3376-9-sean.j.christopherson@intel.com> Date: Mon, 30 Sep 2019 12:58:53 +0200 Message-ID: <87a7am3v9u.fsf@vitty.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Sean Christopherson writes: > Handle caching CR3 (from VMX's VMCS) into struct kvm_vcpu via the common > cache_reg() callback and drop the dedicated decache_cr3(). The name > decache_cr3() is somewhat confusing as the caching behavior of CR3 > follows that of GPRs, RFLAGS and PDPTRs, (handled via cache_reg()), and > has nothing in common with the caching behavior of CR0/CR4 (whose > decache_cr{0,4}_guest_bits() likely provided the 'decache' verbiage). > > Note, this effectively adds a BUG() if KVM attempts to cache CR3 on SVM. > Opportunistically add a WARN_ON_ONCE() in VMX to provide an equivalent > check. Just to justify my idea of replacing such occasions with KVM_INTERNAL_ERROR by setting a special 'kill ASAP' bit somewhere: This WARN_ON_ONCE() falls in the same category (IMO). > > Signed-off-by: Sean Christopherson > --- > arch/x86/include/asm/kvm_host.h | 1 - > arch/x86/kvm/kvm_cache_regs.h | 2 +- > arch/x86/kvm/svm.c | 5 ----- > arch/x86/kvm/vmx/vmx.c | 15 ++++++--------- > 4 files changed, 7 insertions(+), 16 deletions(-) > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index a27f7f6b6b7a..0411dc0a27b0 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -1040,7 +1040,6 @@ struct kvm_x86_ops { > struct kvm_segment *var, int seg); > void (*get_cs_db_l_bits)(struct kvm_vcpu *vcpu, int *db, int *l); > void (*decache_cr0_guest_bits)(struct kvm_vcpu *vcpu); > - void (*decache_cr3)(struct kvm_vcpu *vcpu); > void (*decache_cr4_guest_bits)(struct kvm_vcpu *vcpu); > void (*set_cr0)(struct kvm_vcpu *vcpu, unsigned long cr0); > void (*set_cr3)(struct kvm_vcpu *vcpu, unsigned long cr3); > diff --git a/arch/x86/kvm/kvm_cache_regs.h b/arch/x86/kvm/kvm_cache_regs.h > index 9c2bc528800b..f18177cd0030 100644 > --- a/arch/x86/kvm/kvm_cache_regs.h > +++ b/arch/x86/kvm/kvm_cache_regs.h > @@ -145,7 +145,7 @@ static inline ulong kvm_read_cr4_bits(struct kvm_vcpu *vcpu, ulong mask) > static inline ulong kvm_read_cr3(struct kvm_vcpu *vcpu) > { > if (!kvm_register_is_available(vcpu, VCPU_EXREG_CR3)) > - kvm_x86_ops->decache_cr3(vcpu); > + kvm_x86_ops->cache_reg(vcpu, VCPU_EXREG_CR3); > return vcpu->arch.cr3; > } > > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c > index f8ecb6df5106..3102c44c12c6 100644 > --- a/arch/x86/kvm/svm.c > +++ b/arch/x86/kvm/svm.c > @@ -2517,10 +2517,6 @@ static void svm_decache_cr0_guest_bits(struct kvm_vcpu *vcpu) > { > } > > -static void svm_decache_cr3(struct kvm_vcpu *vcpu) > -{ > -} > - > static void svm_decache_cr4_guest_bits(struct kvm_vcpu *vcpu) > { > } > @@ -7208,7 +7204,6 @@ static struct kvm_x86_ops svm_x86_ops __ro_after_init = { > .get_cpl = svm_get_cpl, > .get_cs_db_l_bits = kvm_get_cs_db_l_bits, > .decache_cr0_guest_bits = svm_decache_cr0_guest_bits, > - .decache_cr3 = svm_decache_cr3, > .decache_cr4_guest_bits = svm_decache_cr4_guest_bits, > .set_cr0 = svm_set_cr0, > .set_cr3 = svm_set_cr3, > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c > index ed03d0cd1cc8..c84798026e85 100644 > --- a/arch/x86/kvm/vmx/vmx.c > +++ b/arch/x86/kvm/vmx/vmx.c > @@ -2188,7 +2188,12 @@ static void vmx_cache_reg(struct kvm_vcpu *vcpu, enum kvm_reg reg) > if (enable_ept) > ept_save_pdptrs(vcpu); > break; > + case VCPU_EXREG_CR3: > + if (enable_unrestricted_guest || (enable_ept && is_paging(vcpu))) > + vcpu->arch.cr3 = vmcs_readl(GUEST_CR3); > + break; > default: > + WARN_ON_ONCE(1); > break; > } > } > @@ -2859,13 +2864,6 @@ static void vmx_decache_cr0_guest_bits(struct kvm_vcpu *vcpu) > vcpu->arch.cr0 |= vmcs_readl(GUEST_CR0) & cr0_guest_owned_bits; > } > > -static void vmx_decache_cr3(struct kvm_vcpu *vcpu) > -{ > - if (enable_unrestricted_guest || (enable_ept && is_paging(vcpu))) > - vcpu->arch.cr3 = vmcs_readl(GUEST_CR3); > - kvm_register_mark_available(vcpu, VCPU_EXREG_CR3); > -} > - > static void vmx_decache_cr4_guest_bits(struct kvm_vcpu *vcpu) > { > ulong cr4_guest_owned_bits = vcpu->arch.cr4_guest_owned_bits; > @@ -2910,7 +2908,7 @@ static void ept_update_paging_mode_cr0(unsigned long *hw_cr0, > struct vcpu_vmx *vmx = to_vmx(vcpu); > > if (!kvm_register_is_available(vcpu, VCPU_EXREG_CR3)) > - vmx_decache_cr3(vcpu); > + vmx_cache_reg(vcpu, VCPU_EXREG_CR3); > if (!(cr0 & X86_CR0_PG)) { > /* From paging/starting to nonpaging */ > exec_controls_setbit(vmx, CPU_BASED_CR3_LOAD_EXITING | > @@ -7792,7 +7790,6 @@ static struct kvm_x86_ops vmx_x86_ops __ro_after_init = { > .get_cpl = vmx_get_cpl, > .get_cs_db_l_bits = vmx_get_cs_db_l_bits, > .decache_cr0_guest_bits = vmx_decache_cr0_guest_bits, > - .decache_cr3 = vmx_decache_cr3, > .decache_cr4_guest_bits = vmx_decache_cr4_guest_bits, > .set_cr0 = vmx_set_cr0, > .set_cr3 = vmx_set_cr3, Reviewed (and Tested-On-Amd-By:): Vitaly Kuznetsov -- Vitaly