On 04/12/19 22:40, Jim Mattson wrote:
> According to the SDM, a VMWRITE in VMX non-root operation with an
> invalid VMCS-link pointer results in VMfailInvalid before the validity
> of the VMCS field in the secondary source operand is checked.
>
> Fixes: 6d894f498f5d1 ("KVM: nVMX: vmread/vmwrite: Use shadow vmcs12 if running L2")
> Signed-off-by: Jim Mattson <jmattson@xxxxxxxxxx>
> Cc: Liran Alon <liran.alon@xxxxxxxxxx>
> ---
> arch/x86/kvm/vmx/nested.c | 38 +++++++++++++++++++-------------------
> 1 file changed, 19 insertions(+), 19 deletions(-)
As Vitaly pointed out, the test must be split in two, like this:
---------------- 8< -----------------------
>From 3b9d87060e800ffae2bd19da94ede05018066c87 Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Date: Thu, 5 Dec 2019 12:39:07 +0100
Subject: [PATCH] kvm: nVMX: VMWRITE checks VMCS-link pointer before VMCS field
According to the SDM, a VMWRITE in VMX non-root operation with an
invalid VMCS-link pointer results in VMfailInvalid before the validity
of the VMCS field in the secondary source operand is checked.
While cleaning up handle_vmwrite, make the code of handle_vmread look
the same, too.
Fixes: 6d894f498f5d1 ("KVM: nVMX: vmread/vmwrite: Use shadow vmcs12 if running L2")
Signed-off-by: Jim Mattson <jmattson@xxxxxxxxxx>
Cc: Liran Alon <liran.alon@xxxxxxxxxx>
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 4aea7d304beb..c080a879b95d 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -4767,14 +4767,13 @@ static int handle_vmread(struct kvm_vcpu *vcpu)
if (to_vmx(vcpu)->nested.current_vmptr == -1ull)
return nested_vmx_failInvalid(vcpu);
- if (!is_guest_mode(vcpu))
- vmcs12 = get_vmcs12(vcpu);
- else {
+ vmcs12 = get_vmcs12(vcpu);
+ if (is_guest_mode(vcpu)) {
/*
* When vmcs->vmcs_link_pointer is -1ull, any VMREAD
* to shadowed-field sets the ALU flags for VMfailInvalid.
*/
- if (get_vmcs12(vcpu)->vmcs_link_pointer == -1ull)
+ if (vmcs12->vmcs_link_pointer == -1ull)
return nested_vmx_failInvalid(vcpu);
vmcs12 = get_shadow_vmcs12(vcpu);
}
@@ -4878,8 +4877,19 @@ static int handle_vmwrite(struct kvm_vcpu *vcpu)
}
}
+ vmcs12 = get_vmcs12(vcpu);
+ if (is_guest_mode(vcpu)) {
+ /*
+ * When vmcs->vmcs_link_pointer is -1ull, any VMWRITE
+ * to shadowed-field sets the ALU flags for VMfailInvalid.
+ */
+ if (vmcs12->vmcs_link_pointer == -1ull)
+ return nested_vmx_failInvalid(vcpu);
+ vmcs12 = get_shadow_vmcs12(vcpu);
+ }
field = kvm_register_readl(vcpu, (((vmx_instruction_info) >> 28) & 0xf));
+
/*
* If the vCPU supports "VMWRITE to any supported field in the
* VMCS," then the "read-only" fields are actually read/write.
@@ -4889,24 +4899,12 @@ static int handle_vmwrite(struct kvm_vcpu *vcpu)
return nested_vmx_failValid(vcpu,
VMXERR_VMWRITE_READ_ONLY_VMCS_COMPONENT);
- if (!is_guest_mode(vcpu)) {
- vmcs12 = get_vmcs12(vcpu);
-
- /*
- * Ensure vmcs12 is up-to-date before any VMWRITE that dirties
- * vmcs12, else we may crush a field or consume a stale value.
- */
- if (!is_shadow_field_rw(field))
- copy_vmcs02_to_vmcs12_rare(vcpu, vmcs12);
- } else {
- /*
- * When vmcs->vmcs_link_pointer is -1ull, any VMWRITE
- * to shadowed-field sets the ALU flags for VMfailInvalid.
- */
- if (get_vmcs12(vcpu)->vmcs_link_pointer == -1ull)
- return nested_vmx_failInvalid(vcpu);
- vmcs12 = get_shadow_vmcs12(vcpu);
- }
+ /*
+ * Ensure vmcs12 is up-to-date before any VMWRITE that dirties
+ * vmcs12, else we may crush a field or consume a stale value.
+ */
+ if (!is_guest_mode(vcpu) && !is_shadow_field_rw(field))
+ copy_vmcs02_to_vmcs12_rare(vcpu, vmcs12);
offset = vmcs_field_to_offset(field);
if (offset < 0)
... and also, do you have a matching kvm-unit-tests patch?
Thanks,
Paolo
