igvmbld: Add segment selectors to initial VMSA

The initial VMSA populates the segment registers but does not set values
for the selectors. The current IGVM loader in QEMU requires the
selectors to be set correctly to start the guest. This patch sets the
selectors to the values expected by the SVSM.

Signed-off-by: Roy Hopkins <roy.hopkins@suse.com>

igvmbld/igvmbld.c

@@ -327,14 +327,20 @@ void generate_initial_vmsa(SEV_VMSA *vmsa)
     // Establish CS as a 32-bit code selector.
     vmsa->segments[SevSegment_Cs].attributes = 0xC9B;
     vmsa->segments[SevSegment_Cs].limit = 0xFFFFFFFF;
+    vmsa->segments[SevSegment_Cs].selector = 0x08;
 
     // Establish all data segments as generic data selectors.
     vmsa->segments[SevSegment_Ds].attributes = 0xA93;
     vmsa->segments[SevSegment_Ds].limit = 0xFFFFFFFF;
+    vmsa->segments[SevSegment_Ds].selector = 0x10;
     vmsa->segments[SevSegment_Ss] = vmsa->segments[SevSegment_Ds];
+    vmsa->segments[SevSegment_Ss].selector = 0x10;
     vmsa->segments[SevSegment_Es] = vmsa->segments[SevSegment_Ds];
+    vmsa->segments[SevSegment_Es].selector = 0x10;
     vmsa->segments[SevSegment_Fs] = vmsa->segments[SevSegment_Ds];
+    vmsa->segments[SevSegment_Fs].selector = 0x10;
     vmsa->segments[SevSegment_Gs] = vmsa->segments[SevSegment_Ds];
+    vmsa->segments[SevSegment_Gs].selector = 0x10;
 
     // EFER.SVME.
     vmsa->efer = 0x1000;