On 10/12/2024 16:47, Sean Christopherson wrote:
> Can you run with the below to see what bits the guest is trying to set (or clear)?
> We could get the same info via tracepoints, but this will likely be faster/easier.
>
> ---
> arch/x86/kvm/svm/svm.c | 12 +++++++++---
> 1 file changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index dd15cc635655..5144d0283c9d 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -3195,11 +3195,14 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
> case MSR_AMD64_DE_CFG: {
> u64 supported_de_cfg;
>
> - if (svm_get_feature_msr(ecx, &supported_de_cfg))
> + if (WARN_ON_ONCE(svm_get_feature_msr(ecx, &supported_de_cfg)))
> return 1;
>
> - if (data & ~supported_de_cfg)
> + if (data & ~supported_de_cfg) {
> + pr_warn("DE_CFG supported = %llx, WRMSR = %llx\n",
> + supported_de_cfg, data);
> return 1;
> + }
>
> /*
> * Don't let the guest change the host-programmed value. The
> @@ -3207,8 +3210,11 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
> * are completely unknown to KVM, and the one bit known to KVM
> * is simply a reflection of hardware capabilities.
> */
> - if (!msr->host_initiated && data != svm->msr_decfg)
> + if (!msr->host_initiated && data != svm->msr_decfg) {
> + pr_warn("DE_CFG current = %llx, WRMSR = %llx\n",
> + svm->msr_decfg, data);
> return 1;
> + }
>
> svm->msr_decfg = data;
> break;
>
> base-commit: fac04efc5c793dccbd07e2d59af9f90b7fc0dca4
Relevant dmesg output with some context below. VM locked up as expected.
[ 85.834971] vfio-pci 0000:0c:00.0: resetting
[ 85.937573] vfio-pci 0000:0c:00.0: reset done
[ 86.494210] vfio-pci 0000:0c:00.0: resetting
[ 86.494264] vfio-pci 0000:0c:00.1: resetting
[ 86.761442] vfio-pci 0000:0c:00.0: reset done
[ 86.761480] vfio-pci 0000:0c:00.1: reset done
[ 86.762392] vfio-pci 0000:0c:00.0: resetting
[ 86.865462] vfio-pci 0000:0c:00.0: reset done
[ 86.977360] virbr0: port 1(vnet1) entered learning state
[ 88.993052] virbr0: port 1(vnet1) entered forwarding state
[ 88.993057] virbr0: topology change detected, propagating
[ 103.459114] kvm_amd: DE_CFG current = 0, WRMSR = 2
[ 161.442032] virbr0: port 1(vnet1) entered disabled state // VM shut down
