KVM: nSVM: set fixed bits by hand

mainline inclusion
from mainline-v5.11-rc1
commit 8cce12b3
category: feature
feature: KVM bus lock debug exception
bugzilla: https://gitee.com/openeuler/intel-kernel/issues/I5RHW7
CVE: N/A
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/
commit/?id=8cce12b3

Intel-SIG: commit 8cce12b3 ("KVM: nSVM: set fixed bits by hand")

-------------------------------------

KVM: nSVM: set fixed bits by hand

SVM generally ignores fixed-1 bits.  Set them manually so that we
do not end up by mistake without those bits set in struct kvm_vcpu;
it is part of userspace API that KVM always returns value with the
bits set.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NAichun Shi <aichun.shi@intel.com>

arch/x86/kvm/svm/nested.c

@@ -405,7 +405,7 @@ static void nested_prepare_vmcb_save(struct vcpu_svm *svm, struct vmcb *vmcb12)
 	svm->vmcb->save.ds = vmcb12->save.ds;
 	svm->vmcb->save.gdtr = vmcb12->save.gdtr;
 	svm->vmcb->save.idtr = vmcb12->save.idtr;
-	kvm_set_rflags(&svm->vcpu, vmcb12->save.rflags);
+	kvm_set_rflags(&svm->vcpu, vmcb12->save.rflags | X86_EFLAGS_FIXED);
 
 	/*
 	 * Force-set EFER_SVME even though it is checked earlier on the
@@ -425,8 +425,8 @@ static void nested_prepare_vmcb_save(struct vcpu_svm *svm, struct vmcb *vmcb12)
 	svm->vmcb->save.rax = vmcb12->save.rax;
 	svm->vmcb->save.rsp = vmcb12->save.rsp;
 	svm->vmcb->save.rip = vmcb12->save.rip;
-	svm->vmcb->save.dr7 = vmcb12->save.dr7;
-	svm->vcpu.arch.dr6  = vmcb12->save.dr6;
+	svm->vmcb->save.dr7 = vmcb12->save.dr7 | DR7_FIXED_1;
+	svm->vcpu.arch.dr6  = vmcb12->save.dr6 | DR6_FIXED_1 | DR6_RTM;
 	svm->vmcb->save.cpl = vmcb12->save.cpl;
 }
 
@@ -699,14 +699,14 @@ int nested_svm_vmexit(struct vcpu_svm *svm)
 	svm->vmcb->save.ds = hsave->save.ds;
 	svm->vmcb->save.gdtr = hsave->save.gdtr;
 	svm->vmcb->save.idtr = hsave->save.idtr;
-	kvm_set_rflags(&svm->vcpu, hsave->save.rflags);
+	kvm_set_rflags(&svm->vcpu, hsave->save.rflags | X86_EFLAGS_FIXED);
 	svm_set_efer(&svm->vcpu, hsave->save.efer);
 	svm_set_cr0(&svm->vcpu, hsave->save.cr0 | X86_CR0_PE);
 	svm_set_cr4(&svm->vcpu, hsave->save.cr4);
 	kvm_rax_write(&svm->vcpu, hsave->save.rax);
 	kvm_rsp_write(&svm->vcpu, hsave->save.rsp);
 	kvm_rip_write(&svm->vcpu, hsave->save.rip);
-	svm->vmcb->save.dr7 = 0;
+	svm->vmcb->save.dr7 = DR7_FIXED_1;
 	svm->vmcb->save.cpl = 0;
 	svm->vmcb->control.exit_int_info = 0;