On Tue, Jun 03, 2025, Chao Gao wrote: > On Thu, May 29, 2025 at 04:39:49PM -0700, Sean Christopherson wrote: > >WARN and kill the VM instead of panicking the host if KVM attempts to set > >or query MSR interception for an unsupported MSR. Accessing the MSR > >interception bitmaps only meaningfully affects post-VMRUN behavior, and > >KVM_BUG_ON() is guaranteed to prevent the current vCPU from doing VMRUN, > >i.e. there is no need to panic the entire host. > > > >Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx> > >--- > > arch/x86/kvm/svm/svm.c | 6 ++++-- > > 1 file changed, 4 insertions(+), 2 deletions(-) > > > >diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c > >index 36a99b87a47f..d5d11cb0c987 100644 > >--- a/arch/x86/kvm/svm/svm.c > >+++ b/arch/x86/kvm/svm/svm.c > >@@ -827,7 +827,8 @@ static bool msr_write_intercepted(struct kvm_vcpu *vcpu, u32 msr) > > bit_write = 2 * (msr & 0x0f) + 1; > > tmp = msrpm[offset]; > > not an issue with this patch. but shouldn't the offset be checked against > MSR_INVALID before being used to index msrpm[]? Oof, yes. To some extent, it _is_ a problem with this patch, because using KVM_BUG_ON() makes the OOB access less fatal. Though it's just a load, and code that should be unreachable, but still worth cleaning up. Anyways, I'll place the KVM_BUG_ON()s in the right location as part of this patch. Thanks!
