Commit b59b153d authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

KVM: x86: allow compiling out the Xen hypercall interface 



The Xen hypercall interface adds to the attack surface of the hypervisor
and will be used quite rarely.  Allow compiling it out.

Suggested-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDavid Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent c462f859

arch/x86/kvm/Kconfig

+9 −0
Original line number Diff line number Diff line
@@ -103,6 +103,15 @@ config KVM_AMD_SEV 
	  Provides support for launching Encrypted VMs (SEV) and Encrypted VMs

	  with Encrypted State (SEV-ES) on AMD processors.



config KVM_XEN

	bool "Support for Xen hypercall interface"

	depends on KVM

	help

	  Provides KVM support for the hosting Xen HVM guests and

	  passing Xen hypercalls to userspace.



	  If in doubt, say "N".



config KVM_MMU_AUDIT

	bool "Audit KVM MMU"

	depends on KVM && TRACEPOINTS

arch/x86/kvm/Makefile

+2 −1
Original line number Diff line number Diff line
@@ -14,11 +14,12 @@ kvm-y += $(KVM)/kvm_main.o $(KVM)/coalesced_mmio.o \ 
				$(KVM)/dirty_ring.o

kvm-$(CONFIG_KVM_ASYNC_PF)	+= $(KVM)/async_pf.o



kvm-y			+= x86.o emulate.o i8259.o irq.o lapic.o xen.o \

kvm-y			+= x86.o emulate.o i8259.o irq.o lapic.o \

			   i8254.o ioapic.o irq_comm.o cpuid.o pmu.o mtrr.o \

			   hyperv.o debugfs.o mmu/mmu.o mmu/page_track.o \

			   mmu/spte.o

kvm-$(CONFIG_X86_64) += mmu/tdp_iter.o mmu/tdp_mmu.o

kvm-$(CONFIG_KVM_XEN)	+= xen.o



kvm-intel-y		+= vmx/vmx.o vmx/vmenter.o vmx/pmu_intel.o vmx/vmcs12.o \

			   vmx/evmcs.o vmx/nested.o vmx/posted_intr.o

arch/x86/kvm/x86.c

+8 −0
Original line number Diff line number Diff line
@@ -3755,11 +3755,13 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) 
	case KVM_CAP_ENFORCE_PV_FEATURE_CPUID:

		r = 1;

		break;

#ifdef CONFIG_KVM_XEN

	case KVM_CAP_XEN_HVM:

		r = KVM_XEN_HVM_CONFIG_HYPERCALL_MSR |

		    KVM_XEN_HVM_CONFIG_INTERCEPT_HCALL |

		    KVM_XEN_HVM_CONFIG_SHARED_INFO;

		break;

#endif

	case KVM_CAP_SYNC_REGS:

		r = KVM_SYNC_X86_VALID_FIELDS;

		break;
@@ -5012,6 +5014,7 @@ long kvm_arch_vcpu_ioctl(struct file *filp, 
	case KVM_GET_SUPPORTED_HV_CPUID:

		r = kvm_ioctl_get_supported_hv_cpuid(vcpu, argp);

		break;

#ifdef CONFIG_KVM_XEN

	case KVM_XEN_VCPU_GET_ATTR: {

		struct kvm_xen_vcpu_attr xva;
@@ -5032,6 +5035,7 @@ long kvm_arch_vcpu_ioctl(struct file *filp, 
		r = kvm_xen_vcpu_set_attr(vcpu, &xva);

		break;

	}

#endif

	default:

		r = -EINVAL;

	}
@@ -5653,6 +5657,7 @@ long kvm_arch_vm_ioctl(struct file *filp, 
			kvm->arch.bsp_vcpu_id = arg;

		mutex_unlock(&kvm->lock);

		break;

#ifdef CONFIG_KVM_XEN

	case KVM_XEN_HVM_CONFIG: {

		struct kvm_xen_hvm_config xhc;

		r = -EFAULT;
@@ -5681,6 +5686,7 @@ long kvm_arch_vm_ioctl(struct file *filp, 
		r = kvm_xen_hvm_set_attr(kvm, &xha);

		break;

	}

#endif

	case KVM_SET_CLOCK: {

		struct kvm_clock_data user_ns;

		u64 now_ns;
@@ -8039,8 +8045,10 @@ void kvm_arch_exit(void) 
	kvm_mmu_module_exit();

	free_percpu(user_return_msrs);

	kmem_cache_destroy(x86_fpu_cache);

#ifdef CONFIG_KVM_XEN

	static_key_deferred_flush(&kvm_xen_enabled);

	WARN_ON(static_branch_unlikely(&kvm_xen_enabled.key));

#endif

}



static int __kvm_vcpu_halt(struct kvm_vcpu *vcpu, int state, int reason)

arch/x86/kvm/xen.h

+23 −1
Original line number Diff line number Diff line
@@ -9,6 +9,7 @@ 
#ifndef __ARCH_X86_KVM_XEN_H__

#define __ARCH_X86_KVM_XEN_H__



#ifdef CONFIG_KVM_XEN

#include <linux/jump_label_ratelimit.h>



extern struct static_key_false_deferred kvm_xen_enabled;
@@ -18,7 +19,6 @@ int kvm_xen_vcpu_set_attr(struct kvm_vcpu *vcpu, struct kvm_xen_vcpu_attr *data) 
int kvm_xen_vcpu_get_attr(struct kvm_vcpu *vcpu, struct kvm_xen_vcpu_attr *data);

int kvm_xen_hvm_set_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data);

int kvm_xen_hvm_get_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data);

int kvm_xen_hypercall(struct kvm_vcpu *vcpu);

int kvm_xen_write_hypercall_page(struct kvm_vcpu *vcpu, u64 data);

int kvm_xen_hvm_config(struct kvm *kvm, struct kvm_xen_hvm_config *xhc);

void kvm_xen_destroy_vm(struct kvm *kvm);
@@ -38,6 +38,28 @@ static inline int kvm_xen_has_interrupt(struct kvm_vcpu *vcpu) 


	return 0;

}

#else

static inline int kvm_xen_write_hypercall_page(struct kvm_vcpu *vcpu, u64 data)

{

	return 1;

}



static inline void kvm_xen_destroy_vm(struct kvm *kvm)

{

}



static inline bool kvm_xen_hypercall_enabled(struct kvm *kvm)

{

	return false;

}



static inline int kvm_xen_has_interrupt(struct kvm_vcpu *vcpu)

{

	return 0;

}

#endif



int kvm_xen_hypercall(struct kvm_vcpu *vcpu);



/* 32-bit compatibility definitions, also used natively in 32-bit build */

#include <asm/pvclock-abi.h>