Commit 6dba9403 authored by Maxim Levitsky's avatar Maxim Levitsky Committed by Paolo Bonzini
Browse files

KVM: x86: Introduce KVM_GET_SREGS2 / KVM_SET_SREGS2 



This is a new version of KVM_GET_SREGS / KVM_SET_SREGS.

It has the following changes:
   * Has flags for future extensions
   * Has vcpu's PDPTRs, allowing to save/restore them on migration.
   * Lacks obsolete interrupt bitmap (done now via KVM_SET_VCPU_EVENTS)

New capability, KVM_CAP_SREGS2 is added to signal
the userspace of this ioctl.

Signed-off-by: default avatarMaxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210607090203.133058-8-mlevitsk@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 329675dd

Documentation/virt/kvm/api.rst

+48 −0
Original line number Diff line number Diff line
@@ -5034,6 +5034,54 @@ 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 (when supported) replaces the KVM_GET_SREGS.



::



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;

	__u64 pdptrs[4];

};



flags values for ``kvm_sregs2``:



``KVM_SREGS2_FLAGS_PDPTRS_VALID``



  Indicates thats the struct contain valid PDPTR values.





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 (when supported) replaces the KVM_SET_SREGS.





5. The kvm_run structure

========================

arch/x86/include/uapi/asm/kvm.h

+13 −0
Original line number Diff line number Diff line
@@ -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;

	__u64 pdptrs[4];

};

#define KVM_SREGS2_FLAGS_PDPTRS_VALID 1



/* for KVM_GET_FPU and KVM_SET_FPU */

struct kvm_fpu {

	__u8  fpr[8][16];

arch/x86/kvm/kvm_cache_regs.h

+5 −0
Original line number Diff line number Diff line
@@ -125,6 +125,11 @@ 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;

arch/x86/kvm/x86.c

+115 −27
Original line number Diff line number Diff line
@@ -114,6 +114,9 @@ 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);
@@ -817,7 +820,6 @@ int load_pdptrs(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, unsigned long cr3) 


	memcpy(mmu->pdptrs, pdpte, sizeof(mmu->pdptrs));

	kvm_register_mark_dirty(vcpu, VCPU_EXREG_PDPTR);



out:



	return ret;
@@ -3956,6 +3958,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) 
	case KVM_CAP_SGX_ATTRIBUTE:

#endif

	case KVM_CAP_VM_COPY_ENC_CONTEXT_FROM:

	case KVM_CAP_SREGS2:

		r = 1;

		break;

	case KVM_CAP_SET_GUEST_DEBUG2:
@@ -4870,6 +4873,7 @@ 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;
@@ -5242,6 +5246,28 @@ long kvm_arch_vcpu_ioctl(struct file *filp, 
		break;

	}

#endif

	case KVM_GET_SREGS2: {

		u.sregs2 = kzalloc(sizeof(struct kvm_sregs2), GFP_KERNEL);

		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;

	}
@@ -9937,7 +9963,7 @@ 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;
@@ -9970,14 +9996,36 @@ 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);

}



static void __get_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs)

{

	__get_sregs_common(vcpu, sregs);



	memset(sregs->interrupt_bitmap, 0, sizeof(sregs->interrupt_bitmap));

	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 (vcpu->arch.guest_state_protected)

		return;



	if (is_pae_paging(vcpu)) {

		for (i = 0 ; i < 4 ; i++)

			sregs2->pdptrs[i] = kvm_pdptr_read(vcpu, i);

		sregs2->flags |= KVM_SREGS2_FLAGS_PDPTRS_VALID;

	}

}



int kvm_arch_vcpu_ioctl_get_sregs(struct kvm_vcpu *vcpu,

				  struct kvm_sregs *sregs)

{
@@ -10096,24 +10144,23 @@ 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, bool update_pdptrs)

{

	struct msr_data apic_base_msr;

	int mmu_reset_needed = 0;

	int pending_vec, max_bits, idx;

	int idx;

	struct desc_ptr dt;

	int ret = -EINVAL;



	if (!kvm_is_valid_sregs(vcpu, sregs))

		goto out;

		return -EINVAL;



	apic_base_msr.data = sregs->apic_base;

	apic_base_msr.host_initiated = true;

	if (kvm_set_apic_base(vcpu, &apic_base_msr))

		goto out;

		return -EINVAL;



	if (vcpu->arch.guest_state_protected)

		goto skip_protected_regs;

		return 0;



	dt.size = sregs->idt.limit;

	dt.address = sregs->idt.base;
@@ -10123,31 +10170,30 @@ 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);



	if (update_pdptrs) {

		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;

			*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);
@@ -10167,20 +10213,62 @@ static int __set_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs) 
	    !is_protmode(vcpu))

		vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;



skip_protected_regs:

	return 0;

}



static int __set_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs)

{

	int pending_vec, max_bits;

	int mmu_reset_needed = 0;

	int ret = __set_sregs_common(vcpu, sregs, &mmu_reset_needed, true);



	if (ret)

		return ret;



	if (mmu_reset_needed)

		kvm_mmu_reset_context(vcpu);



	max_bits = KVM_NR_INTERRUPTS;

	pending_vec = find_first_bit(

		(const unsigned long *)sregs->interrupt_bitmap, max_bits);



	if (pending_vec < max_bits) {

		kvm_queue_interrupt(vcpu, pending_vec, false);

		pr_debug("Set back pending irq %d\n", pending_vec);

		kvm_make_request(KVM_REQ_EVENT, vcpu);

	}

	return 0;

}



	kvm_make_request(KVM_REQ_EVENT, vcpu);

static int __set_sregs2(struct kvm_vcpu *vcpu, struct kvm_sregs2 *sregs2)

{

	int mmu_reset_needed = 0;

	bool valid_pdptrs = sregs2->flags & KVM_SREGS2_FLAGS_PDPTRS_VALID;

	bool pae = (sregs2->cr0 & X86_CR0_PG) && (sregs2->cr4 & X86_CR4_PAE) &&

		!(sregs2->efer & EFER_LMA);

	int i, ret;



	ret = 0;

out:

	if (sregs2->flags & ~KVM_SREGS2_FLAGS_PDPTRS_VALID)

		return -EINVAL;



	if (valid_pdptrs && (!pae || vcpu->arch.guest_state_protected))

		return -EINVAL;



	ret = __set_sregs_common(vcpu, (struct kvm_sregs *)sregs2,

				 &mmu_reset_needed, !valid_pdptrs);

	if (ret)

		return ret;



	if (valid_pdptrs) {

		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;

	}

	if (mmu_reset_needed)

		kvm_mmu_reset_context(vcpu);

	return 0;

}



int kvm_arch_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu,

include/uapi/linux/kvm.h

+4 −0
Original line number Diff line number Diff line
@@ -1084,6 +1084,7 @@ struct kvm_ppc_resize_hpt { 
#define KVM_CAP_VM_COPY_ENC_CONTEXT_FROM 197

#define KVM_CAP_PTP_KVM 198

#define KVM_CAP_HYPERV_ENFORCE_CPUID 199

#define KVM_CAP_SREGS2 200



#ifdef KVM_CAP_IRQ_ROUTING
@@ -1622,6 +1623,9 @@ 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,  0xcc, struct kvm_sregs2)

#define KVM_SET_SREGS2             _IOW(KVMIO,  0xcd, struct kvm_sregs2)



struct kvm_xen_vcpu_attr {

	__u16 type;

	__u16 pad[3];