[v4] TDX QEMU support

[RFC PATCH v4 28/36] i386/tdx: Disable PIC 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 28/36] i386/tdx: Disable PIC for TDX VMs

Posted by Xiaoyao Li 3 years, 9 months ago

Legacy PIC (8259) cannot be supported for TDX VMs since TDX module
doesn't allow directly interrupt injection.  Using posted interrupts
for the PIC is not a viable option as the guest BIOS/kernel will not
do EOI for PIC IRQs, i.e. will leave the vIRR bit set.

Hence disable PIC for TDX VMs and error out if user wants PIC.

Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
---
 target/i386/kvm/tdx.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/target/i386/kvm/tdx.c b/target/i386/kvm/tdx.c
index 7ff4c6a9a7ca..59c7aa8f1818 100644
--- a/target/i386/kvm/tdx.c
+++ b/target/i386/kvm/tdx.c
@@ -333,6 +333,13 @@ int tdx_kvm_init(MachineState *ms, Error **errp)
         return -EINVAL;
     }
 
+    if (x86ms->pic == ON_OFF_AUTO_AUTO) {
+        x86ms->pic = ON_OFF_AUTO_OFF;
+    } else if (x86ms->pic == ON_OFF_AUTO_ON) {
+        error_setg(errp, "TDX VM doesn't support PIC");
+        return -EINVAL;
+    }
+
     if (!tdx_caps) {
         get_tdx_capabilities();
     }
-- 
2.27.0

Re: [RFC PATCH v4 28/36] i386/tdx: Disable PIC for TDX VMs

Posted by Gerd Hoffmann 3 years, 8 months ago

On Thu, May 12, 2022 at 11:17:55AM +0800, Xiaoyao Li wrote:
> Legacy PIC (8259) cannot be supported for TDX VMs since TDX module
> doesn't allow directly interrupt injection.  Using posted interrupts
> for the PIC is not a viable option as the guest BIOS/kernel will not
> do EOI for PIC IRQs, i.e. will leave the vIRR bit set.
> 
> Hence disable PIC for TDX VMs and error out if user wants PIC.

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