[PATCH 2/5 v6] nSVM: Check addresses of MSR and IO permission maps

Krish Sadhukhan
2021-04-02T01:33:05Z

According to section "Canonicalization and Consistency Checks" in APM vol 2,
the following guest state is illegal:

"The MSR or IOIO intercept tables extend to a physical address that
is greater than or equal to the maximum supported physical address."

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
---
arch/x86/kvm/svm/nested.c | 23 +++++++++++++++++++----
1 file changed, 19 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index fb204eaa8bb3..b3988b3a3fd5 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -231,7 +231,15 @@ static bool svm_get_nested_state_pages(struct kvm_vcpu *vcpu)
return true;
}

-static bool nested_vmcb_check_controls(struct vmcb_control_area *control)
+static bool nested_svm_check_bitmap_pa(struct kvm_vcpu *vcpu, u64 pa,
+ u32 size)
+{
+ u64 last_pa = PAGE_ALIGN(pa) + size - 1;
+ return (kvm_vcpu_is_legal_gpa(vcpu, last_pa));
+}
+
+static bool nested_vmcb_check_controls(struct kvm_vcpu *vcpu,
+ struct vmcb_control_area *control)
{
if ((vmcb_is_intercept(control, INTERCEPT_VMRUN)) == 0)
return false;
@@ -243,6 +251,13 @@ static bool nested_vmcb_check_controls(struct vmcb_control_area *control)
!npt_enabled)
return false;

+ if (!nested_svm_check_bitmap_pa(vcpu, control->msrpm_base_pa,
+ MSRPM_ALLOC_SIZE))
+ return false;
+ if (!nested_svm_check_bitmap_pa(vcpu, control->iopm_base_pa,
+ IOPM_ALLOC_SIZE - PAGE_SIZE + 1))
+ return false;
+
return true;
}

@@ -275,7 +290,7 @@ static bool nested_vmcb_check_save(struct vcpu_svm *svm, struct vmcb *vmcb12)
kvm_vcpu_is_illegal_gpa(vcpu, vmcb12->save.cr3))
return false;
}
- if (!kvm_is_valid_cr4(&svm->vcpu, vmcb12->save.cr4))
+ if (!kvm_is_valid_cr4(vcpu, vmcb12->save.cr4))
return false;

return true;
@@ -531,7 +546,7 @@ int nested_svm_vmrun(struct vcpu_svm *svm)
load_nested_vmcb_control(svm, &vmcb12->control);

if (!nested_vmcb_check_save(svm, vmcb12) ||
- !nested_vmcb_check_controls(&svm->nested.ctl)) {
+ !nested_vmcb_check_controls(&svm->vcpu, &svm->nested.ctl)) {
vmcb12->control.exit_code = SVM_EXIT_ERR;
vmcb12->control.exit_code_hi = 0;
vmcb12->control.exit_info_1 = 0;
@@ -1207,7 +1222,7 @@ static int svm_set_nested_state(struct kvm_vcpu *vcpu,
goto out_free;

ret = -EINVAL;
- if (!nested_vmcb_check_controls(ctl))
+ if (!nested_vmcb_check_controls(vcpu, ctl))
goto out_free;

/*
--
2.27.0