Re: [PATCH v6 45/60] i386/tdx: Don't get/put guest state for TDX VMs

Paolo Bonzini
2024-11-05T09:55:07Z

On 11/5/24 07:23, Xiaoyao Li wrote:
> From: Sean Christopherson <sean.j.christopherson@intel.com>
>
> Don't get/put state of TDX VMs since accessing/mutating guest state of
> production TDs is not supported.
>
> Note, it will be allowed for a debug TD. Corresponding support will be
> introduced when debug TD support is implemented in the future.
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
> Acked-by: Gerd Hoffmann <kraxel@redhat.com>

This should be unnecessary now that QEMU has
kvm_mark_guest_state_protected().

Paolo

> ---
> target/i386/kvm/kvm.c | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
> index c39e879a77e9..e47aa32233e6 100644
> --- a/target/i386/kvm/kvm.c
> +++ b/target/i386/kvm/kvm.c
> @@ -5254,6 +5254,11 @@ int kvm_arch_put_registers(CPUState *cpu, int level, Error **errp)
>
> assert(cpu_is_stopped(cpu) || qemu_cpu_is_self(cpu));
>
> + /* TODO: Allow accessing guest state for debug TDs. */
> + if (is_tdx_vm()) {
> + return 0;
> + }
> +
> /*
> * Put MSR_IA32_FEATURE_CONTROL first, this ensures the VM gets out of VMX
> * root operation upon vCPU reset. kvm_put_msr_feature_control() should also
> @@ -5368,6 +5373,12 @@ int kvm_arch_get_registers(CPUState *cs, Error **errp)
> error_setg_errno(errp, -ret, "Failed to get MP state");
> goto out;
> }
> +
> + /* TODO: Allow accessing guest state for debug TDs. */
> + if (is_tdx_vm()) {
> + return 0;
> + }
> +
> ret = kvm_getput_regs(cpu, 0);
> if (ret < 0) {
> error_setg_errno(errp, -ret, "Failed to get general purpose registers");