[PATCH 5/8] x86/pv: allow reading APIC_BASE MSR

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

Linux PV guests will attempt to read the APIC_BASE MSR, so just report
a default value to make Linux happy.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
 xen/arch/x86/pv/emul-priv-op.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/xen/arch/x86/pv/emul-priv-op.c b/xen/arch/x86/pv/emul-priv-op.c
index ff87c7d769..554a95ae8d 100644
--- a/xen/arch/x86/pv/emul-priv-op.c
+++ b/xen/arch/x86/pv/emul-priv-op.c
@@ -872,6 +872,13 @@ static int read_msr(unsigned int reg, uint64_t *val,
 
     switch ( reg )
     {
+    case MSR_APIC_BASE:
+        /* Linux PV guests will attempt to read APIC_BASE. */
+        *val = APIC_BASE_ENABLE | APIC_DEFAULT_PHYS_BASE;
+        if ( !curr->vcpu_id )
+            *val |= APIC_BASE_BSP;
+        return X86EMUL_OKAY;
+
     case MSR_FS_BASE:
         if ( is_pv_32bit_domain(currd) )
             break;
-- 
2.28.0