lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Message-ID: <CALzav=dZitAYUQhH_-46m-gSB-Q_N_E_GX5K0CaE3-CdafbXxA@mail.gmail.com> Date: Thu, 16 Feb 2017 13:23:38 -0800 From: David Matlack <dmatlack@...gle.com> To: Paolo Bonzini <pbonzini@...hat.com> Cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, kvm list <kvm@...r.kernel.org> Subject: Re: [PATCH] KVM: x86: remove code for lazy FPU handling On Thu, Feb 16, 2017 at 1:33 AM, Paolo Bonzini <pbonzini@...hat.com> wrote: > > The FPU is always active now when running KVM. > > Signed-off-by: Paolo Bonzini <pbonzini@...hat.com> Reviewed-by: David Matlack <dmatlack@...gle.com> Glad to see this cleanup! Thanks for doing it. > --- > arch/x86/include/asm/kvm_host.h | 3 -- > arch/x86/kvm/cpuid.c | 2 - > arch/x86/kvm/svm.c | 43 ++------------- > arch/x86/kvm/vmx.c | 112 ++++++---------------------------------- > arch/x86/kvm/x86.c | 7 +-- > include/linux/kvm_host.h | 1 - > 6 files changed, 19 insertions(+), 149 deletions(-) > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index e4f13e714bcf..74ef58c8ff53 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -55,7 +55,6 @@ > #define KVM_REQ_TRIPLE_FAULT 10 > #define KVM_REQ_MMU_SYNC 11 > #define KVM_REQ_CLOCK_UPDATE 12 > -#define KVM_REQ_DEACTIVATE_FPU 13 > #define KVM_REQ_EVENT 14 > #define KVM_REQ_APF_HALT 15 > #define KVM_REQ_STEAL_UPDATE 16 > @@ -936,8 +935,6 @@ struct kvm_x86_ops { > unsigned long (*get_rflags)(struct kvm_vcpu *vcpu); > void (*set_rflags)(struct kvm_vcpu *vcpu, unsigned long rflags); > u32 (*get_pkru)(struct kvm_vcpu *vcpu); > - void (*fpu_activate)(struct kvm_vcpu *vcpu); > - void (*fpu_deactivate)(struct kvm_vcpu *vcpu); > > void (*tlb_flush)(struct kvm_vcpu *vcpu); > > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c > index c0e2036217ad..1d155cc56629 100644 > --- a/arch/x86/kvm/cpuid.c > +++ b/arch/x86/kvm/cpuid.c > @@ -123,8 +123,6 @@ int kvm_update_cpuid(struct kvm_vcpu *vcpu) > if (best && (best->eax & (F(XSAVES) | F(XSAVEC)))) > best->ebx = xstate_required_size(vcpu->arch.xcr0, true); > > - kvm_x86_ops->fpu_activate(vcpu); > - > /* > * The existing code assumes virtual address is 48-bit in the canonical > * address checks; exit if it is ever changed. > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c > index 4e5905a1ce70..d1efe2c62b3f 100644 > --- a/arch/x86/kvm/svm.c > +++ b/arch/x86/kvm/svm.c > @@ -1157,7 +1157,6 @@ static void init_vmcb(struct vcpu_svm *svm) > struct vmcb_control_area *control = &svm->vmcb->control; > struct vmcb_save_area *save = &svm->vmcb->save; > > - svm->vcpu.fpu_active = 1; > svm->vcpu.arch.hflags = 0; > > set_cr_intercept(svm, INTERCEPT_CR0_READ); > @@ -1899,15 +1898,12 @@ static void update_cr0_intercept(struct vcpu_svm *svm) > ulong gcr0 = svm->vcpu.arch.cr0; > u64 *hcr0 = &svm->vmcb->save.cr0; > > - if (!svm->vcpu.fpu_active) > - *hcr0 |= SVM_CR0_SELECTIVE_MASK; > - else > - *hcr0 = (*hcr0 & ~SVM_CR0_SELECTIVE_MASK) > - | (gcr0 & SVM_CR0_SELECTIVE_MASK); > + *hcr0 = (*hcr0 & ~SVM_CR0_SELECTIVE_MASK) > + | (gcr0 & SVM_CR0_SELECTIVE_MASK); > > mark_dirty(svm->vmcb, VMCB_CR); > > - if (gcr0 == *hcr0 && svm->vcpu.fpu_active) { > + if (gcr0 == *hcr0) { > clr_cr_intercept(svm, INTERCEPT_CR0_READ); > clr_cr_intercept(svm, INTERCEPT_CR0_WRITE); > } else { > @@ -1938,8 +1934,6 @@ static void svm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0) > if (!npt_enabled) > cr0 |= X86_CR0_PG | X86_CR0_WP; > > - if (!vcpu->fpu_active) > - cr0 |= X86_CR0_TS; > /* > * re-enable caching here because the QEMU bios > * does not do it - this results in some delay at > @@ -2158,22 +2152,6 @@ static int ac_interception(struct vcpu_svm *svm) > return 1; > } > > -static void svm_fpu_activate(struct kvm_vcpu *vcpu) > -{ > - struct vcpu_svm *svm = to_svm(vcpu); > - > - clr_exception_intercept(svm, NM_VECTOR); > - > - svm->vcpu.fpu_active = 1; > - update_cr0_intercept(svm); > -} > - > -static int nm_interception(struct vcpu_svm *svm) > -{ > - svm_fpu_activate(&svm->vcpu); > - return 1; > -} > - > static bool is_erratum_383(void) > { > int err, i; > @@ -2571,9 +2549,6 @@ static int nested_svm_exit_special(struct vcpu_svm *svm) > if (!npt_enabled && svm->apf_reason == 0) > return NESTED_EXIT_HOST; > break; > - case SVM_EXIT_EXCP_BASE + NM_VECTOR: > - nm_interception(svm); > - break; > default: > break; > } > @@ -4018,7 +3993,6 @@ static int (*const svm_exit_handlers[])(struct vcpu_svm *svm) = { > [SVM_EXIT_EXCP_BASE + BP_VECTOR] = bp_interception, > [SVM_EXIT_EXCP_BASE + UD_VECTOR] = ud_interception, > [SVM_EXIT_EXCP_BASE + PF_VECTOR] = pf_interception, > - [SVM_EXIT_EXCP_BASE + NM_VECTOR] = nm_interception, > [SVM_EXIT_EXCP_BASE + MC_VECTOR] = mc_interception, > [SVM_EXIT_EXCP_BASE + AC_VECTOR] = ac_interception, > [SVM_EXIT_INTR] = intr_interception, > @@ -5072,14 +5046,6 @@ static bool svm_has_wbinvd_exit(void) > return true; > } > > -static void svm_fpu_deactivate(struct kvm_vcpu *vcpu) > -{ > - struct vcpu_svm *svm = to_svm(vcpu); > - > - set_exception_intercept(svm, NM_VECTOR); > - update_cr0_intercept(svm); > -} > - > #define PRE_EX(exit) { .exit_code = (exit), \ > .stage = X86_ICPT_PRE_EXCEPT, } > #define POST_EX(exit) { .exit_code = (exit), \ > @@ -5340,9 +5306,6 @@ static inline void avic_post_state_restore(struct kvm_vcpu *vcpu) > > .get_pkru = svm_get_pkru, > > - .fpu_activate = svm_fpu_activate, > - .fpu_deactivate = svm_fpu_deactivate, > - > .tlb_flush = svm_flush_tlb, > > .run = svm_vcpu_run, > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index 0e0b5d09597e..9856b73a21ad 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -1856,7 +1856,7 @@ static void update_exception_bitmap(struct kvm_vcpu *vcpu) > u32 eb; > > eb = (1u << PF_VECTOR) | (1u << UD_VECTOR) | (1u << MC_VECTOR) | > - (1u << NM_VECTOR) | (1u << DB_VECTOR) | (1u << AC_VECTOR); > + (1u << DB_VECTOR) | (1u << AC_VECTOR); > if ((vcpu->guest_debug & > (KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP)) == > (KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP)) > @@ -1865,8 +1865,6 @@ static void update_exception_bitmap(struct kvm_vcpu *vcpu) > eb = ~0; > if (enable_ept) > eb &= ~(1u << PF_VECTOR); /* bypass_guest_pf = 0 */ > - if (vcpu->fpu_active) > - eb &= ~(1u << NM_VECTOR); > > /* When we are running a nested L2 guest and L1 specified for it a > * certain exception bitmap, we must trap the same exceptions and pass > @@ -2340,25 +2338,6 @@ static void vmx_vcpu_put(struct kvm_vcpu *vcpu) > } > } > > -static void vmx_fpu_activate(struct kvm_vcpu *vcpu) > -{ > - ulong cr0; > - > - if (vcpu->fpu_active) > - return; > - vcpu->fpu_active = 1; > - cr0 = vmcs_readl(GUEST_CR0); > - cr0 &= ~(X86_CR0_TS | X86_CR0_MP); > - cr0 |= kvm_read_cr0_bits(vcpu, X86_CR0_TS | X86_CR0_MP); > - vmcs_writel(GUEST_CR0, cr0); > - update_exception_bitmap(vcpu); > - vcpu->arch.cr0_guest_owned_bits = X86_CR0_TS; > - if (is_guest_mode(vcpu)) > - vcpu->arch.cr0_guest_owned_bits &= > - ~get_vmcs12(vcpu)->cr0_guest_host_mask; > - vmcs_writel(CR0_GUEST_HOST_MASK, ~vcpu->arch.cr0_guest_owned_bits); > -} > - > static void vmx_decache_cr0_guest_bits(struct kvm_vcpu *vcpu); > > /* > @@ -2377,33 +2356,6 @@ static inline unsigned long nested_read_cr4(struct vmcs12 *fields) > (fields->cr4_read_shadow & fields->cr4_guest_host_mask); > } > > -static void vmx_fpu_deactivate(struct kvm_vcpu *vcpu) > -{ > - /* Note that there is no vcpu->fpu_active = 0 here. The caller must > - * set this *before* calling this function. > - */ > - vmx_decache_cr0_guest_bits(vcpu); > - vmcs_set_bits(GUEST_CR0, X86_CR0_TS | X86_CR0_MP); > - update_exception_bitmap(vcpu); > - vcpu->arch.cr0_guest_owned_bits = 0; > - vmcs_writel(CR0_GUEST_HOST_MASK, ~vcpu->arch.cr0_guest_owned_bits); > - if (is_guest_mode(vcpu)) { > - /* > - * L1's specified read shadow might not contain the TS bit, > - * so now that we turned on shadowing of this bit, we need to > - * set this bit of the shadow. Like in nested_vmx_run we need > - * nested_read_cr0(vmcs12), but vmcs12->guest_cr0 is not yet > - * up-to-date here because we just decached cr0.TS (and we'll > - * only update vmcs12->guest_cr0 on nested exit). > - */ > - struct vmcs12 *vmcs12 = get_vmcs12(vcpu); > - vmcs12->guest_cr0 = (vmcs12->guest_cr0 & ~X86_CR0_TS) | > - (vcpu->arch.cr0 & X86_CR0_TS); > - vmcs_writel(CR0_READ_SHADOW, nested_read_cr0(vmcs12)); > - } else > - vmcs_writel(CR0_READ_SHADOW, vcpu->arch.cr0); > -} > - > static unsigned long vmx_get_rflags(struct kvm_vcpu *vcpu) > { > unsigned long rflags, save_rflags; > @@ -4232,9 +4184,6 @@ static void vmx_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0) > if (enable_ept) > ept_update_paging_mode_cr0(&hw_cr0, cr0, vcpu); > > - if (!vcpu->fpu_active) > - hw_cr0 |= X86_CR0_TS | X86_CR0_MP; > - > vmcs_writel(CR0_READ_SHADOW, cr0); > vmcs_writel(GUEST_CR0, hw_cr0); > vcpu->arch.cr0 = cr0; > @@ -5321,7 +5270,9 @@ static int vmx_vcpu_setup(struct vcpu_vmx *vmx) > /* 22.2.1, 20.8.1 */ > vm_entry_controls_init(vmx, vmcs_config.vmentry_ctrl); > > - vmcs_writel(CR0_GUEST_HOST_MASK, ~0UL); > + vmx->vcpu.arch.cr0_guest_owned_bits = X86_CR0_TS; > + vmcs_writel(CR0_GUEST_HOST_MASK, ~X86_CR0_TS); > + > set_cr4_guest_host_mask(vmx); > > if (vmx_xsaves_supported()) > @@ -5425,7 +5376,7 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) > vmx_set_cr0(vcpu, cr0); /* enter rmode */ > vmx_set_cr4(vcpu, 0); > vmx_set_efer(vcpu, 0); > - vmx_fpu_activate(vcpu); > + > update_exception_bitmap(vcpu); > > vpid_sync_context(vmx->vpid); > @@ -5698,11 +5649,6 @@ static int handle_exception(struct kvm_vcpu *vcpu) > if (is_nmi(intr_info)) > return 1; /* already handled by vmx_vcpu_run() */ > > - if (is_no_device(intr_info)) { > - vmx_fpu_activate(vcpu); > - return 1; > - } > - > if (is_invalid_opcode(intr_info)) { > if (is_guest_mode(vcpu)) { > kvm_queue_exception(vcpu, UD_VECTOR); > @@ -5892,22 +5838,6 @@ static int handle_set_cr4(struct kvm_vcpu *vcpu, unsigned long val) > return kvm_set_cr4(vcpu, val); > } > > -/* called to set cr0 as appropriate for clts instruction exit. */ > -static void handle_clts(struct kvm_vcpu *vcpu) > -{ > - if (is_guest_mode(vcpu)) { > - /* > - * We get here when L2 did CLTS, and L1 didn't shadow CR0.TS > - * but we did (!fpu_active). We need to keep GUEST_CR0.TS on, > - * just pretend it's off (also in arch.cr0 for fpu_activate). > - */ > - vmcs_writel(CR0_READ_SHADOW, > - vmcs_readl(CR0_READ_SHADOW) & ~X86_CR0_TS); > - vcpu->arch.cr0 &= ~X86_CR0_TS; > - } else > - vmx_set_cr0(vcpu, kvm_read_cr0_bits(vcpu, ~X86_CR0_TS)); > -} > - > static int handle_cr(struct kvm_vcpu *vcpu) > { > unsigned long exit_qualification, val; > @@ -5953,9 +5883,9 @@ static int handle_cr(struct kvm_vcpu *vcpu) > } > break; > case 2: /* clts */ > - handle_clts(vcpu); > + WARN_ONCE(1, "Guest should always own CR0.TS"); > + vmx_set_cr0(vcpu, kvm_read_cr0_bits(vcpu, ~X86_CR0_TS)); > trace_kvm_cr_write(0, kvm_read_cr0(vcpu)); > - vmx_fpu_activate(vcpu); > return kvm_skip_emulated_instruction(vcpu); > case 1: /*mov from cr*/ > switch (cr) { > @@ -10349,8 +10279,8 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12, > } > > /* > - * This sets GUEST_CR0 to vmcs12->guest_cr0, with possibly a modified > - * TS bit (for lazy fpu) and bits which we consider mandatory enabled. > + * This sets GUEST_CR0 to vmcs12->guest_cr0, possibly modifying those > + * bits which we consider mandatory enabled. > * The CR0_READ_SHADOW is what L2 should have expected to read given > * the specifications by L1; It's not enough to take > * vmcs12->cr0_read_shadow because on our cr0_guest_host_mask we we > @@ -10963,24 +10893,15 @@ static void load_vmcs12_host_state(struct kvm_vcpu *vcpu, > vmx_set_rflags(vcpu, X86_EFLAGS_FIXED); > /* > * Note that calling vmx_set_cr0 is important, even if cr0 hasn't > - * actually changed, because it depends on the current state of > - * fpu_active (which may have changed). > - * Note that vmx_set_cr0 refers to efer set above. > + * actually changed, because vmx_set_cr0 refers to efer set above. > + * > + * CR0_GUEST_HOST_MASK is already set in the original vmcs01 > + * (KVM doesn't change it); > */ > + vcpu->arch.cr0_guest_owned_bits = X86_CR0_TS; > vmx_set_cr0(vcpu, vmcs12->host_cr0); > - /* > - * If we did fpu_activate()/fpu_deactivate() during L2's run, we need > - * to apply the same changes to L1's vmcs. We just set cr0 correctly, > - * but we also need to update cr0_guest_host_mask and exception_bitmap. > - */ > - update_exception_bitmap(vcpu); > - vcpu->arch.cr0_guest_owned_bits = (vcpu->fpu_active ? X86_CR0_TS : 0); > - vmcs_writel(CR0_GUEST_HOST_MASK, ~vcpu->arch.cr0_guest_owned_bits); > > - /* > - * Note that CR4_GUEST_HOST_MASK is already set in the original vmcs01 > - * (KVM doesn't change it)- no reason to call set_cr4_guest_host_mask(); > - */ > + /* Same as above - no reason to call set_cr4_guest_host_mask(). */ > vcpu->arch.cr4_guest_owned_bits = ~vmcs_readl(CR4_GUEST_HOST_MASK); > kvm_set_cr4(vcpu, vmcs12->host_cr4); > > @@ -11609,9 +11530,6 @@ static void vmx_setup_mce(struct kvm_vcpu *vcpu) > > .get_pkru = vmx_get_pkru, > > - .fpu_activate = vmx_fpu_activate, > - .fpu_deactivate = vmx_fpu_deactivate, > - > .tlb_flush = vmx_flush_tlb, > > .run = vmx_vcpu_run, > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 8d3047c8cce7..c48404017e4f 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -6751,10 +6751,6 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) > r = 0; > goto out; > } > - if (kvm_check_request(KVM_REQ_DEACTIVATE_FPU, vcpu)) { > - vcpu->fpu_active = 0; > - kvm_x86_ops->fpu_deactivate(vcpu); > - } > if (kvm_check_request(KVM_REQ_APF_HALT, vcpu)) { > /* Page is swapped out. Do synthetic halt */ > vcpu->arch.apf.halted = true; > @@ -6856,8 +6852,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) > preempt_disable(); > > kvm_x86_ops->prepare_guest_switch(vcpu); > - if (vcpu->fpu_active) > - kvm_load_guest_fpu(vcpu); > + kvm_load_guest_fpu(vcpu); > > /* > * Disable IRQs before setting IN_GUEST_MODE. Posted interrupt > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > index 2db458ee94b0..8d69d5150748 100644 > --- a/include/linux/kvm_host.h > +++ b/include/linux/kvm_host.h > @@ -221,7 +221,6 @@ struct kvm_vcpu { > struct mutex mutex; > struct kvm_run *run; > > - int fpu_active; > int guest_fpu_loaded, guest_xcr0_loaded; > struct swait_queue_head wq; > struct pid *pid; > -- > 1.8.3.1 >
Powered by blists - more mailing lists