[4/6] KVM: x86: Introduce KVM_GET_SREGS2 / KVM_SET_SREGS2

Message ID	20210401141814.1029036-5-mlevitsk@redhat.com (mailing list archive)
State	New, archived
Headers	show Return-Path: <kvm-owner@kernel.org> From: Maxim Levitsky <mlevitsk@redhat.com> To: kvm@vger.kernel.org Cc: x86@kernel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)), Jim Mattson <jmattson@google.com>, Vitaly Kuznetsov <vkuznets@redhat.com>, Wanpeng Li <wanpengli@tencent.com>, Sean Christopherson <seanjc@google.com>, Joerg Roedel <joro@8bytes.org>, "H. Peter Anvin" <hpa@zytor.com>, linux-kernel@vger.kernel.org (open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)), Paolo Bonzini <pbonzini@redhat.com>, Thomas Gleixner <tglx@linutronix.de>, Jonathan Corbet <corbet@lwn.net>, Borislav Petkov <bp@alien8.de>, Ingo Molnar <mingo@redhat.com>, linux-doc@vger.kernel.org (open list:DOCUMENTATION), Maxim Levitsky <mlevitsk@redhat.com> Subject: [PATCH 4/6] KVM: x86: Introduce KVM_GET_SREGS2 / KVM_SET_SREGS2 Date: Thu, 1 Apr 2021 17:18:12 +0300 Message-Id: <20210401141814.1029036-5-mlevitsk@redhat.com> In-Reply-To: <20210401141814.1029036-1-mlevitsk@redhat.com> References: <20210401141814.1029036-1-mlevitsk@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk
Series	Introduce KVM_{GET\|SET}_SREGS2 and fix PDPTR migration \| expand [0/6] Introduce KVM_{GET\|SET}_SREGS2 and fix PDPTR migration [1/6] KVM: nVMX: delay loading of PDPTRs to KVM_REQ_GET_NESTED_STATE_PAGES [2/6] KVM: nSVM: call nested_svm_load_cr3 on nested state load [3/6] KVM: x86: introduce kvm_register_clear_available [4/6] KVM: x86: Introduce KVM_GET_SREGS2 / KVM_SET_SREGS2 [5/6] KVM: nSVM: avoid loading PDPTRs after migration when possible [6/6] KVM: nVMX: avoid loading PDPTRs after migration when possible

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index 38e327d4b479..b006d5b5f554 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -4941,6 +4941,49 @@ see KVM_XEN_VCPU_SET_ATTR above. The KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_ADJUST type may not be used with the KVM_XEN_VCPU_GET_ATTR ioctl. + +4.131 KVM_GET_SREGS2 +------------------ + +:Capability: KVM_CAP_SREGS2 +:Architectures: x86 +:Type: vcpu ioctl +:Parameters: struct kvm_sregs2 (out) +:Returns: 0 on success, -1 on error + +Reads special registers from the vcpu. +This ioctl is preferred over KVM_GET_SREGS when available. + +:: + +struct kvm_sregs2 { + /* out (KVM_GET_SREGS2) / in (KVM_SET_SREGS2) */ + struct kvm_segment cs, ds, es, fs, gs, ss; + struct kvm_segment tr, ldt; + struct kvm_dtable gdt, idt; + __u64 cr0, cr2, cr3, cr4, cr8; + __u64 efer; + __u64 apic_base; + __u64 flags; /* must be zero*/ + __u64 pdptrs[4]; + __u64 padding; +}; + + +4.132 KVM_SET_SREGS2 +------------------ + +:Capability: KVM_CAP_SREGS2 +:Architectures: x86 +:Type: vcpu ioctl +:Parameters: struct kvm_sregs2 (in) +:Returns: 0 on success, -1 on error + +Writes special registers into the vcpu. +See KVM_GET_SREGS2 for the data structures. +This ioctl is preferred over the KVM_SET_SREGS when available. + + 5. The kvm_run structure ======================== diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index a52f973bdff6..87b680d111f9 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -838,6 +838,13 @@ struct kvm_vcpu_arch { /* Protected Guests */ bool guest_state_protected; + + /* + * Do we need to reload the pdptrs when entering nested state? + * Set after nested migration if userspace didn't use the + * newer KVM_SET_SREGS2 ioctl to load pdptrs from the migration state. + */ + bool reload_pdptrs_on_nested_entry; }; struct kvm_lpage_info { diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h index 5a3022c8af82..201a85884c81 100644 --- a/arch/x86/include/uapi/asm/kvm.h +++ b/arch/x86/include/uapi/asm/kvm.h @@ -159,6 +159,19 @@ struct kvm_sregs { __u64 interrupt_bitmap[(KVM_NR_INTERRUPTS + 63) / 64]; }; +struct kvm_sregs2 { + /* out (KVM_GET_SREGS2) / in (KVM_SET_SREGS2) */ + struct kvm_segment cs, ds, es, fs, gs, ss; + struct kvm_segment tr, ldt; + struct kvm_dtable gdt, idt; + __u64 cr0, cr2, cr3, cr4, cr8; + __u64 efer; + __u64 apic_base; + __u64 flags; /* must be zero*/ + __u64 pdptrs[4]; + __u64 padding; +}; + /* for KVM_GET_FPU and KVM_SET_FPU */ struct kvm_fpu { __u8 fpr[8][16]; diff --git a/arch/x86/kvm/kvm_cache_regs.h b/arch/x86/kvm/kvm_cache_regs.h index 07d607947805..1a6e2de4248a 100644 --- a/arch/x86/kvm/kvm_cache_regs.h +++ b/arch/x86/kvm/kvm_cache_regs.h @@ -120,6 +120,11 @@ static inline u64 kvm_pdptr_read(struct kvm_vcpu *vcpu, int index) return vcpu->arch.walk_mmu->pdptrs[index]; } +static inline void kvm_pdptr_write(struct kvm_vcpu *vcpu, int index, u64 value) +{ + vcpu->arch.walk_mmu->pdptrs[index] = value; +} + static inline ulong kvm_read_cr0_bits(struct kvm_vcpu *vcpu, ulong mask) { ulong tmask = mask & KVM_POSSIBLE_CR0_GUEST_BITS; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index a9d95f90a048..f10a37f88c30 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -112,6 +112,9 @@ static void __kvm_set_rflags(struct kvm_vcpu *vcpu, unsigned long rflags); static void store_regs(struct kvm_vcpu *vcpu); static int sync_regs(struct kvm_vcpu *vcpu); +static int __set_sregs2(struct kvm_vcpu *vcpu, struct kvm_sregs2 *sregs2); +static void __get_sregs2(struct kvm_vcpu *vcpu, struct kvm_sregs2 *sregs2); + struct kvm_x86_ops kvm_x86_ops __read_mostly; EXPORT_SYMBOL_GPL(kvm_x86_ops); @@ -3796,6 +3799,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) case KVM_CAP_X86_USER_SPACE_MSR: case KVM_CAP_X86_MSR_FILTER: case KVM_CAP_ENFORCE_PV_FEATURE_CPUID: + case KVM_CAP_SREGS2: r = 1; break; #ifdef CONFIG_KVM_XEN @@ -4713,6 +4717,7 @@ long kvm_arch_vcpu_ioctl(struct file *filp, void __user *argp = (void __user *)arg; int r; union { + struct kvm_sregs2 *sregs2; struct kvm_lapic_state *lapic; struct kvm_xsave *xsave; struct kvm_xcrs *xcrs; @@ -5085,6 +5090,28 @@ long kvm_arch_vcpu_ioctl(struct file *filp, break; } #endif + case KVM_GET_SREGS2: { + u.sregs2 = kzalloc(sizeof(struct kvm_sregs2), GFP_KERNEL_ACCOUNT); + r = -ENOMEM; + if (!u.sregs2) + goto out; + __get_sregs2(vcpu, u.sregs2); + r = -EFAULT; + if (copy_to_user(argp, u.sregs2, sizeof(struct kvm_sregs2))) + goto out; + r = 0; + break; + } + case KVM_SET_SREGS2: { + u.sregs2 = memdup_user(argp, sizeof(struct kvm_sregs2)); + if (IS_ERR(u.sregs2)) { + r = PTR_ERR(u.sregs2); + u.sregs2 = NULL; + goto out; + } + r = __set_sregs2(vcpu, u.sregs2); + break; + } default: r = -EINVAL; } @@ -9647,7 +9674,7 @@ void kvm_get_cs_db_l_bits(struct kvm_vcpu *vcpu, int *db, int *l) } EXPORT_SYMBOL_GPL(kvm_get_cs_db_l_bits); -static void __get_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs) +static void __get_sregs_common(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs) { struct desc_ptr dt; @@ -9680,14 +9707,30 @@ static void __get_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs) sregs->cr8 = kvm_get_cr8(vcpu); sregs->efer = vcpu->arch.efer; sregs->apic_base = kvm_get_apic_base(vcpu); +} - memset(sregs->interrupt_bitmap, 0, sizeof(sregs->interrupt_bitmap)); +static void __get_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs) +{ + __get_sregs_common(vcpu, sregs); + + if (vcpu->arch.guest_state_protected) + return; if (vcpu->arch.interrupt.injected && !vcpu->arch.interrupt.soft) set_bit(vcpu->arch.interrupt.nr, (unsigned long *)sregs->interrupt_bitmap); } +static void __get_sregs2(struct kvm_vcpu *vcpu, struct kvm_sregs2 *sregs2) +{ + int i; + + __get_sregs_common(vcpu, (struct kvm_sregs *)sregs2); + if (is_pae_paging(vcpu)) + for (i = 0 ; i < 4 ; i++) + sregs2->pdptrs[i] = kvm_pdptr_read(vcpu, i); +} + int kvm_arch_vcpu_ioctl_get_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs) { @@ -9799,11 +9842,9 @@ static bool kvm_is_valid_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs) return kvm_is_valid_cr4(vcpu, sregs->cr4); } -static int __set_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs) +static int __set_sregs_common(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs, int *mmu_reset_needed) { struct msr_data apic_base_msr; - int mmu_reset_needed = 0; - int pending_vec, max_bits, idx; struct desc_ptr dt; int ret = -EINVAL; @@ -9815,8 +9856,9 @@ static int __set_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs) if (kvm_set_apic_base(vcpu, &apic_base_msr)) goto out; + ret = 0; if (vcpu->arch.guest_state_protected) - goto skip_protected_regs; + goto out; dt.size = sregs->idt.limit; dt.address = sregs->idt.base; @@ -9826,32 +9868,22 @@ static int __set_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs) static_call(kvm_x86_set_gdt)(vcpu, &dt); vcpu->arch.cr2 = sregs->cr2; - mmu_reset_needed |= kvm_read_cr3(vcpu) != sregs->cr3; + *mmu_reset_needed |= kvm_read_cr3(vcpu) != sregs->cr3; vcpu->arch.cr3 = sregs->cr3; kvm_register_mark_available(vcpu, VCPU_EXREG_CR3); kvm_set_cr8(vcpu, sregs->cr8); - mmu_reset_needed |= vcpu->arch.efer != sregs->efer; + *mmu_reset_needed |= vcpu->arch.efer != sregs->efer; static_call(kvm_x86_set_efer)(vcpu, sregs->efer); - mmu_reset_needed |= kvm_read_cr0(vcpu) != sregs->cr0; + *mmu_reset_needed |= kvm_read_cr0(vcpu) != sregs->cr0; static_call(kvm_x86_set_cr0)(vcpu, sregs->cr0); vcpu->arch.cr0 = sregs->cr0; - mmu_reset_needed |= kvm_read_cr4(vcpu) != sregs->cr4; + *mmu_reset_needed |= kvm_read_cr4(vcpu) != sregs->cr4; static_call(kvm_x86_set_cr4)(vcpu, sregs->cr4); - idx = srcu_read_lock(&vcpu->kvm->srcu); - if (is_pae_paging(vcpu)) { - load_pdptrs(vcpu, vcpu->arch.walk_mmu, kvm_read_cr3(vcpu)); - mmu_reset_needed = 1; - } - srcu_read_unlock(&vcpu->kvm->srcu, idx); - - if (mmu_reset_needed) - kvm_mmu_reset_context(vcpu); - kvm_set_segment(vcpu, &sregs->cs, VCPU_SREG_CS); kvm_set_segment(vcpu, &sregs->ds, VCPU_SREG_DS); kvm_set_segment(vcpu, &sregs->es, VCPU_SREG_ES); @@ -9869,8 +9901,39 @@ static int __set_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs) sregs->cs.selector == 0xf000 && sregs->cs.base == 0xffff0000 && !is_protmode(vcpu)) vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE; +out: + return ret; +} + +static int __set_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs) +{ + int idx, pending_vec, max_bits; + int mmu_reset_needed = 0; + int ret = __set_sregs_common(vcpu, sregs, &mmu_reset_needed); + + if (ret) + return ret; + + if (vcpu->arch.guest_state_protected) + return 0; + + idx = srcu_read_lock(&vcpu->kvm->srcu); + if (is_pae_paging(vcpu)) { + load_pdptrs(vcpu, vcpu->arch.walk_mmu, kvm_read_cr3(vcpu)); + mmu_reset_needed = 1; + + /* If we are going to enter a nested guest, we had just + * loaded wrong PDPTRs, thus we need to reload them + * on guest mode entry + */ + + vcpu->arch.reload_pdptrs_on_nested_entry = true; + } + srcu_read_unlock(&vcpu->kvm->srcu, idx); + + if (mmu_reset_needed) + kvm_mmu_reset_context(vcpu); -skip_protected_regs: max_bits = KVM_NR_INTERRUPTS; pending_vec = find_first_bit( (const unsigned long *)sregs->interrupt_bitmap, max_bits); @@ -9880,12 +9943,37 @@ static int __set_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs) } kvm_make_request(KVM_REQ_EVENT, vcpu); + return 0; +} - ret = 0; -out: - return ret; +static int __set_sregs2(struct kvm_vcpu *vcpu, struct kvm_sregs2 *sregs2) +{ + int mmu_reset_needed = 0; + int i, ret, idx; + + if (sregs2->flags || sregs2->padding) + return -EINVAL; + + ret = __set_sregs_common(vcpu, (struct kvm_sregs *)sregs2, &mmu_reset_needed); + if (ret || vcpu->arch.guest_state_protected) + return ret; + + idx = srcu_read_lock(&vcpu->kvm->srcu); + if (is_pae_paging(vcpu)) { + for (i = 0 ; i < 4 ; i++) + kvm_pdptr_write(vcpu, i, sregs2->pdptrs[i]); + kvm_register_mark_dirty(vcpu, VCPU_EXREG_PDPTR); + mmu_reset_needed = 1; + } + srcu_read_unlock(&vcpu->kvm->srcu, idx); + + if (mmu_reset_needed) + kvm_mmu_reset_context(vcpu); + + return 0; } + int kvm_arch_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs) { diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index f6afee209620..212a98082c36 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -1078,6 +1078,7 @@ struct kvm_ppc_resize_hpt { #define KVM_CAP_DIRTY_LOG_RING 192 #define KVM_CAP_X86_BUS_LOCK_EXIT 193 #define KVM_CAP_PPC_DAWR1 194 +#define KVM_CAP_SREGS2 196 #ifdef KVM_CAP_IRQ_ROUTING @@ -1616,6 +1617,10 @@ struct kvm_xen_hvm_attr { #define KVM_XEN_VCPU_GET_ATTR _IOWR(KVMIO, 0xca, struct kvm_xen_vcpu_attr) #define KVM_XEN_VCPU_SET_ATTR _IOW(KVMIO, 0xcb, struct kvm_xen_vcpu_attr) + +#define KVM_GET_SREGS2 _IOR(KVMIO, 0xca, struct kvm_sregs2) +#define KVM_SET_SREGS2 _IOW(KVMIO, 0xcb, struct kvm_sregs2) + struct kvm_xen_vcpu_attr { __u16 type; __u16 pad[3];

[4/6] KVM: x86: Introduce KVM_GET_SREGS2 / KVM_SET_SREGS2

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