Re: [PATCH] x86: Correctly report max number of hypervisor leaves

["Roger Pau Monné" <roger.pau@citrix.com>]

On 30/05/14 22:11, Boris Ostrovsky wrote:
> Commit def0bbd31 provided support for changing max number of
> hypervisor cpuid leaves (in leaf 0x4000xx00). It also made the
> hypervisor incorrectly report this number for guests that
> use default value (i.e. don't specify leaf 0x4000xx00 in config
> file)
> 
> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> Reported-by: Roger Pau Monne <roger.pau@citrix.com>

Tested-by: Roger Pau Monné <roger.pau@citrix.com>

However I think we should prevent PVH guests from seeing the newly
introduced XEN_HVM_CPUID_APIC_ACCESS_VIRT and
XEN_HVM_CPUID_X2APIC_VIRT flags. I have the following patch, but it
still adds one more is_pvh_vcpu into VMX code. I've tried checking for
vlapic_enabled, but it also returns true for PVH guests.

diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index d45fb7f..ecc010e 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -1660,7 +1660,7 @@ void vmx_hypervisor_cpuid_leaf(uint32_t sub_idx,
                                uint32_t *eax, uint32_t *ebx,
                                uint32_t *ecx, uint32_t *edx)
 {
-    if ( sub_idx != 0 )
+    if ( sub_idx != 0 || is_pvh_vcpu(current) )
         return;
     if ( cpu_has_vmx_apic_reg_virt )
         *eax |= XEN_HVM_CPUID_APIC_ACCESS_VIRT;