[PATCH 05/15] KVM: VMX: Add document to state that write to uret msr should always be intercepted

Lai Jiangshan
2021-11-18T11:10:56Z

And adds a corresponding sanity check code.

Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
---
arch/x86/kvm/vmx/vmx.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index e8a41fdc3c4d..cd081219b668 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -3703,13 +3703,21 @@ void vmx_disable_intercept_for_msr(struct kvm_vcpu *vcpu, u32 msr, int type)
if (!cpu_has_vmx_msr_bitmap())
return;

+ /*
+ * Write to uret msr should always be intercepted due to the mechanism
+ * must know the current value. Santity check to avoid any inadvertent
+ * mistake in coding.
+ */
+ if (WARN_ON_ONCE(vmx_find_uret_msr(vmx, msr) && (type & MSR_TYPE_W)))
+ return;
+
if (static_branch_unlikely(&enable_evmcs))
evmcs_touch_msr_bitmap();

/*
* Mark the desired intercept state in shadow bitmap, this is needed
* for resync when the MSR filters change.
- */
+ */
if (is_valid_passthrough_msr(msr)) {
int idx = possible_passthrough_msr_slot(msr);

--
2.19.1.6.gb485710b