[Xen-devel] [PATCH v2 16/23] x86: Allow LAPIC-only emulation_flags for HVM guests

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

PVHv2 guests may request LAPIC emulation (and nothing else)

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
v2:
* Note: I kept the code as is (with minor style adjustments). Roger's
  version (with emulation_flags_ok()) has slighly more logic to account
  for dom0. Without that I didn't feel it's worth factoring this code
  into a separate routine.


 xen/arch/x86/domain.c | 26 ++++++++++++++++----------
 1 file changed, 16 insertions(+), 10 deletions(-)

diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index 1133ea2..34a4eb5 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -545,25 +545,31 @@ int arch_domain_create(struct domain *d, unsigned int 
domcr_flags,
     }
     else
     {
-        if ( (config->emulation_flags & ~XEN_X86_EMU_ALL) != 0 )
+        uint32_t emflags;
+
+        if ( is_hardware_domain(d) )
+            config->emulation_flags |= XEN_X86_EMU_PIT;
+
+        emflags = config->emulation_flags;
+        if ( emflags & ~XEN_X86_EMU_ALL )
         {
             printk(XENLOG_G_ERR "d%d: Invalid emulation bitmap: %#x\n",
-                   d->domain_id, config->emulation_flags);
+                   d->domain_id, emflags);
             return -EINVAL;
         }
-        if ( is_hardware_domain(d) )
-            config->emulation_flags |= XEN_X86_EMU_PIT;
-        if ( config->emulation_flags != 0 &&
-             (config->emulation_flags !=
-              (is_hvm_domain(d) ? XEN_X86_EMU_ALL : XEN_X86_EMU_PIT)) )
+
+        /* PVHv2 guests can request emulated APIC. */
+        if ( emflags &&
+            (is_hvm_domain(d) ? ((emflags != XEN_X86_EMU_ALL) &&
+                                 (emflags != XEN_X86_EMU_LAPIC)) :
+                                (emflags != XEN_X86_EMU_PIT)) )
         {
             printk(XENLOG_G_ERR "d%d: Xen does not allow %s domain creation "
                    "with the current selection of emulators: %#x\n",
-                   d->domain_id, is_hvm_domain(d) ? "HVM" : "PV",
-                   config->emulation_flags);
+                   d->domain_id, is_hvm_domain(d) ? "HVM" : "PV", emflags);
             return -EOPNOTSUPP;
         }
-        d->arch.emulation_flags = config->emulation_flags;
+        d->arch.emulation_flags = emflags;
     }
 
     if ( has_hvm_container_domain(d) )
-- 
1.8.3.1


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