KVM: SVM: Don't save/restore host cr2

The host never reads cr2 in process context, so are free to clobber it.  The
vmx code does this, so we can safely remove the save/restore code.
Signed-off-by: NAvi Kivity <avi@redhat.com>

arch/x86/kvm/svm.c

@@ -81,7 +81,6 @@ struct vcpu_svm {
 
 	u64 host_user_msrs[NR_HOST_SAVE_USER_MSRS];
 	u64 host_gs_base;
-	unsigned long host_cr2;
 
 	u32 *msrpm;
 	struct vmcb *hsave;
@@ -186,19 +185,6 @@ static inline void invlpga(unsigned long addr, u32 asid)
 	asm volatile (__ex(SVM_INVLPGA) :: "a"(addr), "c"(asid));
 }
 
-static inline unsigned long kvm_read_cr2(void)
-{
-	unsigned long cr2;
-
-	asm volatile ("mov %%cr2, %0" : "=r" (cr2));
-	return cr2;
-}
-
-static inline void kvm_write_cr2(unsigned long val)
-{
-	asm volatile ("mov %0, %%cr2" :: "r" (val));
-}
-
 static inline void force_new_asid(struct kvm_vcpu *vcpu)
 {
 	to_svm(vcpu)->asid_generation--;
@@ -2527,7 +2513,6 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 	fs_selector = kvm_read_fs();
 	gs_selector = kvm_read_gs();
 	ldt_selector = kvm_read_ldt();
-	svm->host_cr2 = kvm_read_cr2();
 	if (!is_nested(svm))
 		svm->vmcb->save.cr2 = vcpu->arch.cr2;
 	/* required for live migration with NPT */
@@ -2614,8 +2599,6 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 	vcpu->arch.regs[VCPU_REGS_RSP] = svm->vmcb->save.rsp;
 	vcpu->arch.regs[VCPU_REGS_RIP] = svm->vmcb->save.rip;
 
-	kvm_write_cr2(svm->host_cr2);
-
 	kvm_load_fs(fs_selector);
 	kvm_load_gs(gs_selector);
 	kvm_load_ldt(ldt_selector);