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Merge branch 'kvm-fix-svm-races' into HEAD

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This commit is contained in:
Paolo Bonzini
2021-03-31 07:35:52 -04:00
parent 4a98623d5d 3c346c0c60
commit cb9b6a1b19
1 changed files with 20 additions and 12 deletions
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32
arch/x86/kvm/svm/nested.c
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@@ -272,6 +272,13 @@ static bool nested_vmcb_check_cr3_cr4(struct kvm_vcpu *vcpu,
static bool nested_vmcb_valid_sregs(struct kvm_vcpu *vcpu,
struct vmcb_save_area *save)
{
/*
* FIXME: these should be done after copying the fields,
* to avoid TOC/TOU races. For these save area checks
* the possible damage is limited since kvm_set_cr0 and
* kvm_set_cr4 handle failure; EFER_SVME is an exception
* so it is force-set later in nested_prepare_vmcb_save.
*/
if (CC(!(save->efer & EFER_SVME)))
return false;
@@ -291,14 +298,6 @@ static bool nested_vmcb_valid_sregs(struct kvm_vcpu *vcpu,
return true;
}
static bool nested_vmcb_checks(struct kvm_vcpu *vcpu, struct vmcb *vmcb12)
{
if (!nested_vmcb_valid_sregs(vcpu, &vmcb12->save))
return false;
return nested_vmcb_check_controls(&vmcb12->control);
}
static void nested_load_control_from_vmcb12(struct vcpu_svm *svm,
struct vmcb_control_area *control)
{
@@ -449,7 +448,14 @@ static void nested_vmcb02_prepare_save(struct vcpu_svm *svm, struct vmcb *vmcb12
}
kvm_set_rflags(&svm->vcpu, vmcb12->save.rflags | X86_EFLAGS_FIXED);
svm_set_efer(&svm->vcpu, vmcb12->save.efer);
/*
* Force-set EFER_SVME even though it is checked earlier on the
* VMCB12, because the guest can flip the bit between the check
* and now. Clearing EFER_SVME would call svm_free_nested.
*/
svm_set_efer(&svm->vcpu, vmcb12->save.efer | EFER_SVME);
svm_set_cr0(&svm->vcpu, vmcb12->save.cr0);
svm_set_cr4(&svm->vcpu, vmcb12->save.cr4);
@@ -564,7 +570,6 @@ int enter_svm_guest_mode(struct kvm_vcpu *vcpu, u64 vmcb12_gpa,
WARN_ON(svm->vmcb == svm->nested.vmcb02.ptr);
nested_svm_copy_common_state(svm->vmcb01.ptr, svm->nested.vmcb02.ptr);
nested_load_control_from_vmcb12(svm, &vmcb12->control);
svm_switch_vmcb(svm, &svm->nested.vmcb02);
nested_vmcb02_prepare_control(svm);
@@ -614,7 +619,10 @@ int nested_svm_vmrun(struct kvm_vcpu *vcpu)
if (WARN_ON_ONCE(!svm->nested.initialized))
return -EINVAL;
if (!nested_vmcb_checks(vcpu, vmcb12)) {
nested_load_control_from_vmcb12(svm, &vmcb12->control);
if (!nested_vmcb_valid_sregs(vcpu, &vmcb12->save) ||
!nested_vmcb_check_controls(&svm->nested.ctl)) {
vmcb12->control.exit_code = SVM_EXIT_ERR;
vmcb12->control.exit_code_hi = 0;
vmcb12->control.exit_info_1 = 0;
@@ -1251,7 +1259,7 @@ static int svm_set_nested_state(struct kvm_vcpu *vcpu,
/*
* Processor state contains L2 state. Check that it is
* valid for guest mode (see nested_vmcb_checks).
* valid for guest mode (see nested_vmcb_check_save).
*/
cr0 = kvm_read_cr0(vcpu);
if (((cr0 & X86_CR0_CD) == 0) && (cr0 & X86_CR0_NW))