[v4] TDX QEMU support

[RFC PATCH v4 27/36] i386/tdx: Disable SMM for TDX VMs

Xiaoyao Li posted 36 patches 3 years, 9 months ago

Diff against v1 v3
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Maintainers: Paolo Bonzini <pbonzini@redhat.com>, Richard Henderson <richard.henderson@linaro.org>, Eduardo Habkost <eduardo@habkost.net>, "Michael S. Tsirkin" <mst@redhat.com>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>, Igor Mammedov <imammedo@redhat.com>, Ani Sinha <ani@anisinha.ca>, Cornelia Huck <cohuck@redhat.com>, "Daniel P. Berrangé" <berrange@redhat.com>, Eric Blake <eblake@redhat.com>, Markus Armbruster <armbru@redhat.com>, Marcelo Tosatti <mtosatti@redhat.com>

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[RFC PATCH v4 27/36] i386/tdx: Disable SMM for TDX VMs

Posted by Xiaoyao Li 3 years, 9 months ago

TDX doesn't support SMM and VMM cannot emulate SMM for TDX VMs because
VMM cannot manipulate TDX VM's memory.

Disable SMM for TDX VMs and error out if user requests to enable SMM.

Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
---
 target/i386/kvm/tdx.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/target/i386/kvm/tdx.c b/target/i386/kvm/tdx.c
index 4a7c149f895c..7ff4c6a9a7ca 100644
--- a/target/i386/kvm/tdx.c
+++ b/target/i386/kvm/tdx.c
@@ -322,9 +322,17 @@ static Notifier tdx_machine_done_notify = {
 
 int tdx_kvm_init(MachineState *ms, Error **errp)
 {
+    X86MachineState *x86ms = X86_MACHINE(ms);
     TdxGuest *tdx = (TdxGuest *)object_dynamic_cast(OBJECT(ms->cgs),
                                                     TYPE_TDX_GUEST);
 
+    if (x86ms->smm == ON_OFF_AUTO_AUTO) {
+        x86ms->smm = ON_OFF_AUTO_OFF;
+    } else if (x86ms->smm == ON_OFF_AUTO_ON) {
+        error_setg(errp, "TDX VM doesn't support SMM");
+        return -EINVAL;
+    }
+
     if (!tdx_caps) {
         get_tdx_capabilities();
     }
-- 
2.27.0

Re: [RFC PATCH v4 27/36] i386/tdx: Disable SMM for TDX VMs

Posted by Gerd Hoffmann 3 years, 8 months ago

On Thu, May 12, 2022 at 11:17:54AM +0800, Xiaoyao Li wrote:
> TDX doesn't support SMM and VMM cannot emulate SMM for TDX VMs because
> VMM cannot manipulate TDX VM's memory.
> 
> Disable SMM for TDX VMs and error out if user requests to enable SMM.

Acked-by: Gerd Hoffmann <kraxel@redhat.com>